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Topic: What Is The Deal With The Space Shuttle?
Username: BR715-A1-30
Posted 2008-01-06 21:01:20 and read 7416 times.

After reading so much on it, as well as reading about Challenger, and Columbia, I have determined that to be the biggest hunk of crap I've ever seen in my life.

But the real reason I am making this post is to find out why NASA managers ALWAYS seem to give GO FOR LAUNCH, even when they KNOW something is wrong. In watching the documentary on Challenger, An engineer by the name of Roger Bouijolais (sp?) had warned Morton-Thiokol AND NASA NOT TO LAUNCH due to other mishaps in the SRBs. But they launched anyway.

Does NASA have a BAD case of Go-Fever? Why is it that they don't ever seem to care about anything except launching. Because they were so anxious to launch Challenger, when they were told not to, we lost 7 great Americans.

And then comes the Foam. It had been falling off of several missions for several years, and when they noticed it might have caused damage, they said "to hell with it, we can't fix it, so lets let them come back in, and see what happens." BOOM, 6 more great Americans, and 1 american-israeli GONE.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Pilotboi
Posted 2008-01-06 21:16:36 and read 7373 times.

Lately, they've had a lot more Not-Go-Fever. They've been taking extra special care of every single detail, down to the most tiny thing. Currently, the shuttle is delayed because of some external fuel tank sensors. It was supposed to go up a month ago but at the last minute was cancelled because of these sensors. Then after looking more into it, they decided to bring it back to the building and look more into it.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Mham001
Posted 2008-01-06 21:21:30 and read 7363 times.

If you look at the incessant number of delays throughout its history, I'm not understanding how any reasonable person could come the conclusion of the original poster.

edit: unless you draw those conclusions from an hour of television.

[Edited 2008-01-06 21:22:18]

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Mir
Posted 2008-01-06 21:46:01 and read 7287 times.



Quoting BR715-A1-30 (Thread starter):
But the real reason I am making this post is to find out why NASA managers ALWAYS seem to give GO FOR LAUNCH

They certainly haven't done so of late. The failure of a backup system that probably wouldn't have been needed stopped the launch several times, and delayed it several weeks. I've seen three launches since moving down to Florida last August, and on two of them I had to come back a second day because the first attempt got scrubbed for various reasons. Your statement is not only untrue, but rather unfair to the team of people who are dedicated to keeping the shuttle flying safely. There have been mistakes made, certainly, but to say that NASA has a desire to maintain the schedule at the expense of safety is just wrong - if they did, Atlantis would have already launched, and likely would have been back on Earth already having completed its mission.

-Mir

Topic: RE: What Is The Deal With The Space Shuttle?
Username: SpruceMoose
Posted 2008-01-06 22:44:39 and read 7185 times.

Quoting BR715-A1-30 (Thread starter):
In watching the documentary on Challenger, An engineer by the name of Roger Bouijolais (sp?) had warned Morton-Thiokol AND NASA NOT TO LAUNCH due to other mishaps in the SRBs. But they launched anyway.

Part of the frustration with both the Challenger and Columbia mishaps is that there were clear indications in both cases that something was wrong, but that information was not part of the 'go' decision. The gravity of the threat clearly got lost somewhere in the process.

Edward Tufte has some examples of really poor communication in both cases. Below is a link to an excerpt of an essay he wrote pointing out how the PowerPoint 'pitch' by Boeing led an insufficiently critical management team to the wrong conclusion:

http://www.edwardtufte.com/bboard/q-...fetch-msg?msg_id=0001yB&topic_id=1

(if that doesn't work, go to http://www.edwardtufte.com/tufte/powerpoint and click on the link to the sample from the essay)

As for Challenger -- see Tufte's book "Visual Explanations" (2nd edition) pp 26 and 38-53. On page 26 is the fax from Thiokol recommending launch. On pages 46-48 are Thiokol's awful graphical representations of their blow-by data, and on page 45 is the same data shown in a way that, if available to NASA management at the time, would have made postponing launch a no-brainer. The difference is really stunning. I apologize for not having online links for this, but if you search around Tufte's web site you may find them, or visit your nearest engineering library.

In both of these cases you can go back and find someone somewhere who knew something was amiss. But you can also find lots of evidence to suggest that the people making the final decision thought they were operating within safe margins. The point is, it's a lot more complicated than 'go fever'. I've only scratched the surface in my readings on this and I'm no expert, but the fact that the shuttle flies as much and as safely as it does suggests that the people in the program are smarter and more careful than you're giving them credit for. That fourteen people have lost their lives suggests that even the smart and well intentioned make terrible mistakes, that complacency kills, and that we've always got to scrutinize the evidence to make sure we're not being fooled and that we're not fooling ourselves.

-SpruceMoose

[edited to clean up a little grammar]

[Edited 2008-01-06 22:53:15]

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-07 16:12:18 and read 6961 times.



Quoting BR715-A1-30 (Thread starter):
But the real reason I am making this post is to find out why NASA managers ALWAYS seem to give GO FOR LAUNCH, even when they KNOW something is wrong.

Because nothing is 100% perfect. There is always something wrong... with everything. You have to decide what is an acceptable risk and what isn't, and unfortunately, that decision-making process broke down twice. It is marvelously easy to sit on the sidelines and say "they shouldn't have launched!". It is somewhat harder, of course, to make that decision beforehand.

A ship in port is safe, but that is not what a ship is for.

Quoting BR715-A1-30 (Thread starter):
In watching the documentary on Challenger, An engineer by the name of Roger Bouijolais (sp?) had warned Morton-Thiokol AND NASA NOT TO LAUNCH due to other mishaps in the SRBs. But they launched anyway.

Is there a point to bringing this up 22 years later? There's hardly anyone left in the Shuttle program or its contractors who was around when Challenger was lost. And that might partly be why we lost Columbia 17 years later.

Quoting BR715-A1-30 (Thread starter):
Does NASA have a BAD case of Go-Fever?

No. If they did, Atlantis would have flown last month, the Shuttle wouldn't have stood down after more foam problems on STS-114 in 2005, etc.

Quoting BR715-A1-30 (Thread starter):
And then comes the Foam. It had been falling off of several missions for several years, and when they noticed it might have caused damage, they said "to hell with it, we can't fix it, so lets let them come back in, and see what happens."

Reference? Who said this? It certainly doesn't appear in the Columbia Accident Investigation Board (independent of NASA) report.

The foam debris was a known problem, and had been occuring since STS-1. Fixes were in development after the STS-112 debris event was much worse than had been seen in many years (since STS-30) and had elevated the problem to a higher danger level, but it was still not believed to be a safety issue. The foam liberation and damage was widely believed (by both NASA and contractors) to be a maintenance issue, not a safety of flight issue. Even after Columbia was lost, it took a ground demonstration to show that fall foam really could punch a hole in the wing RCC panel. This was a gigantic shock to most NASA and contractor engineers.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: ZANL188
Posted 2008-01-07 16:35:11 and read 6949 times.



Quoting Thorny (Reply 5):
Even after Columbia was lost, it took a ground demonstration to show that fall foam really could punch a hole in the wing RCC panel. This was a gigantic shock to most NASA and contractor engineers.

The strange thing is that now everyone now accepts that foam fall is a bad thing, launching o-rings at a temperature outside of the experience base is a bad thing, and launching astronauts in capsule containing copious amounts of flammable materials and pressurized 100% O2 atmosphere is a bad thing. All 3 should have been obvious prior to the related accident and yet weren't...

Topic: RE: What Is The Deal With The Space Shuttle?
Username: BR715-A1-30
Posted 2008-01-07 16:40:02 and read 6946 times.

Another question I have is the Challenger launched at 53 degrees (or less). Were the O-Rings not designed for FREEZING temperatures? I mean, 32 degrees Fahrenheit is freezing, so why couldn't they have designed the O-Rings to deal with even sub-zero temperatures?

Slightly off topic, but there have been times when my CO2 tank for my paintball gun cracked and fell off after removing it?

And haven't there been launches where the O-Rings survived even at below 50?

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-07 18:27:15 and read 6921 times.



Quoting BR715-A1-30 (Reply 7):
Another question I have is the Challenger launched at 53 degrees (or less). Were the O-Rings not designed for FREEZING temperatures? I mean, 32 degrees Fahrenheit is freezing, so why couldn't they have designed the O-Rings to deal with even sub-zero temperatures?

No, the o-rings were not designed to work at freezing or below. The ill-fated Challenger launch had to be delayed until air temperature rose above freezing on January 28, 1986. That's why launch was at 11:37am and not 9:30am. They could have been, but with most launches in Florida, low-temperature operation was not a priority for funding.

The problem is that the cold temperature contributed to the o-ring failure, but was not entirely responsible for it. The field joint design was just very deeply flawed and the joints were behaving in unexpected ways at ignition. The joints had been suffering o-ring damage and blow-by even in much warmer conditions. The lower limit of 53 degrees that the engineers were fighting for was based on the previous low temperature for launch... STS-51C a year before the accident. But NASA and Thiokol management saw the paperwork saying that the SRBs were safe down to 36 degrees and demanded the engineers provide data indicating otherwise, something impossible to do in only a few hours.

The design flaw was solved by adding a "capture feature" and a third o-ring to the field joint. O-ring temperature performance was solved by adding heaters to the joints to keep the rings at 80 degrees despite outside temperatures.

Quoting BR715-A1-30 (Reply 7):
And haven't there been launches where the O-Rings survived even at below 50?

No. But there have been test firings in Utah that cold. The joint heaters have solved the temperature problem for the o-rings.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: RedFlyer
Posted 2008-01-09 19:32:08 and read 6695 times.

Quoting Thorny (Reply 5):
Even after Columbia was lost, it took a ground demonstration to show that fall foam really could punch a hole in the wing RCC panel. This was a gigantic shock to most NASA and contractor engineers.

I recall in one of the early press briefings after the loss of Columbia, one of the senior project engineers was asked if the ship may have been lost as a result of the foam shedding (this was after video was made public showing the piece that came off and struck the wing). The engineer (you probably recall who it was) stated pretty emphatically that he didn't think that was a cause of the accident. I remember vividly his comment that a piece of foam the size that was shown in the video had such low mass that it couldn't have done enough damage to doom the ship.

My point is that even the best engineers are sometimes surprised by results. I think it stems from the fact that engineers deal almost exclusively with "knowns" -- hard data. At the time, there just wasn't sufficient data for them to draw the proper conclusions.

[Edited 2008-01-09 19:33:45]

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Blackbird
Posted 2008-01-09 19:53:52 and read 6688 times.

To be honest, I think they should have replaced the space-shuttle with a space-plane back in the eighties.

It would be a hell of a lot easier to operate for one if you didn't have to point the whole thing straight up on that huge vehicle that takes it out to the launch pad (That thing for one is gigantic and probably guzzles fuel to produce the power it does -- oddly nobody ever factored the fuel burn that gigantic machine must burn into the equation.) and instead just start her up on the tarmac and taxi her to a runway and takeoff. It would also be a lot easier to make a powered landing than make a crazy gliding landing on the runway. Additionally, there would be no need for booster rockets, no need for a gigantic fuel-tank that's actually bigger than the spacecraft itself that ends up burnt to a crisp and is not re-used (That tank is the only thing that isn't re-used to my knowledge).


Andrea Kent
Let's hope I don't get a heart-attack, disappear, get some incurable disease, or cancer, die-suspiciously, "commit suicide" etc. Should that happen, you know who to blame...

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Rwessel
Posted 2008-01-09 20:13:22 and read 6675 times.



Quoting Blackbird (Reply 10):
It would be a hell of a lot easier to operate for one if you didn't have to point the whole thing straight up on that huge vehicle that takes it out to the launch pad (That thing for one is gigantic and probably guzzles fuel to produce the power it does -- oddly nobody ever factored the fuel burn that gigantic machine must burn into the equation.) and instead just start her up on the tarmac and taxi her to a runway and takeoff.

The crawler burns about 350 liters/km, and it's only six or seven km from the VAB to the pad (depending on which pad). IOW, the fuel burn for that part of the trip is utterly insignificant.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-09 21:02:17 and read 6666 times.



Quoting Blackbird (Reply 10):
To be honest, I think they should have replaced the space-shuttle with a space-plane back in the eighties.

Space-planes seem to be the worst of both worlds. If you want to go into space, it is best to get out of the drag and heat-inducing atmosphere as quickly as possible (that is what the Shuttle's Solid Rocket Boosters are for... accelleration to orbital velocity is mostly the function of the Main Engines over the succeeding six-and-a-half minutes.)

In any case, a space-plane (X-30) was attempted beginning in 1986, it was cancelled in the early 1990s after billions of dollars spent and lots of "gotchas" and "uh-oh's" thwarted progress. The technology simply was not, and still is not, there. It was suggested then and is now crystal clear, that we should have undertaken a series of much smaller, much less ambitious test vehicles (smaller X-planes) to get the various technologies (and there are many needed) up to what we need for a full scale space-plane. Today, programs like Hyper-X (X-43) and HyShot are finally doing what we should have done 20 years ago.

Quoting Blackbird (Reply 10):
Additionally, there would be no need for booster rockets, no need for a gigantic fuel-tank

Instead of those, you need an engine that can work as both jet and rocket. (That's hard). And you need some way to convert gaseous oxygen from the atmosphere into liquid oxygen for your rocket. And it has to be small enough to fit on a plane. (That's even harder.) And you still need a big tank for the hydrogen, so the plane is still going to be huge.

Worse, since your space-plane has to rely on oxygen from the atmosphere, the plane has to fly in the atmosphere almost all the way to orbital velocity (Mach 25) where we have trouble keeping planes from burning up at Mach 3.

This is just a sample of the problems the space-plane program faced and ended up failing to solve.

Quoting Blackbird (Reply 10):
It would be a hell of a lot easier to operate for one if you didn't have to point the whole thing straight up on that huge vehicle that takes it out to the launch pad (

The Crawler looks like overkill with today's low flight rates (4-6 per year.) But the concept was designed for much higher flight rates (50 per year.) Under those plans, the mobile launcher concept makes much more sense.

Quoting Rwessel (Reply 11):
The crawler burns about 350 liters/km, and it's only six or seven km from the VAB to the pad (depending on which pad). IOW, the fuel burn for that part of the trip is utterly insignificant.

And the cost is indeed factored-in as part of the KSC infrastructure.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: DfwRevolution
Posted 2008-01-09 21:05:35 and read 6669 times.

Quoting Blackbird (Reply 10):
To be honest, I think they should have replaced the space-shuttle with a space-plane back in the eighties.

Reagan instructed NASA to do precisely that. It resulted in an even more complex and more expensive vehicle that never flew: the NASP. What we should have done was realize that we bit-off more than we could chew with the STS program and take a few step backwards.

What we should have done before that was keep the U.S. manned space program flying on the Apollo CSM but with a more economical ELV than Saturn. And while doing that, we should have been testing more ambitions X-planes to test reusable space technologies one at a time, rather than loading them all onto a single project that never gets off the ground or never performs as promised (i.e. X-33 or STS).


Dang, beat to the punch by Thorny.  Wink

[Edited 2008-01-09 21:08:15]

Topic: RE: What Is The Deal With The Space Shuttle?
Username: TheSonntag
Posted 2008-01-10 01:35:21 and read 6627 times.

To me, it does not really matter to ask "what if the shuttle were replaced in the 80s", as the fact is that it wasn't. Instead, I think it is much better to look into the future.

Ares isn't flying yet, but maybe one should start with an outlook beyond the year 2025. What will we see beyond Ares I and V?

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Wvsuperhornet
Posted 2008-01-10 02:19:44 and read 6618 times.

When the first mission of an aircraft is to tae a full day to check to make sure your not going to blow up upon re-entry, then you need to retire it "Period"......

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-10 06:28:21 and read 6598 times.



Quoting TheSonntag (Reply 14):
Ares isn't flying yet, but maybe one should start with an outlook beyond the year 2025. What will we see beyond Ares I and V?

Assuming the Ares project moves forward under the next U.S. President (Obama has already said it won't under him) then 2025 will be when Ares V is just getting into its stride. There will be incremental improvements... probably Ares V-B and Ares V-C eventually. Possibly niche vehicles like Ares III (Ares V with no upper stage, used as a tanker) and Ares IV (Ares V with Ares I Upper Stage).

Quoting Wvsuperhornet (Reply 15):
When the first mission of an aircraft is to tae a full day to check to make sure your not going to blow up upon re-entry, then you need to retire it "Period"......

That's just political CYA.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Checksixx
Posted 2008-01-10 06:38:35 and read 6593 times.

Bottom line is that anytime you strap people into/onto a rocket, there is risk. If anyone thinks there is some miracle system out there that is absolutely safe, they're living in a dream world. I don't mind when they no-go...it means people are doing what they're supposed to be doing. It means hopefully, we won't loose another vehicle or have any post launch aborts like with Challenger.

-Check

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Pope
Posted 2008-01-11 07:24:46 and read 6498 times.

I think the condition of NASA is a national embarrassment.

It took man about 58 years between the first powered flight and the first space flight. It took 8 years between the first flight in space and landing a man on the moon. Now in the absolute best case scenario a manned space mission to Mars will launch in 2020 (don't hold your breath) meaning that at least 51 years will have passed between the time we first stepped foot on the moon and when we explored the next heavenly body.

The space shuttle is a perfect example of how unfocused NASA has become. The STS never achieved its goal of being a dependable reusable LEO launch vehicle. It costs orders of magnitude more in terms of $ and human lives than all the previous US space efforts and has achieved comparably little in return.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-11 13:16:55 and read 6478 times.



Quoting Pope (Reply 18):
I think the condition of NASA is a national embarrassment.

Yet NASA consistently is doing things that no other agency on Earth has ever done, such as successful Mars landers and probes to the outer planets.

Quoting Pope (Reply 18):
Now in the absolute best case scenario a manned space mission to Mars will launch in 2020 (don't hold your breath)

2030 at best. 2020 is return to the Moon.

Quoting Pope (Reply 18):
meaning that at least 51 years will have passed between the time we first stepped foot on the moon and when we explored the next heavenly body.

NASA can only do what it is funded to do. No U.S. administration or Congress has funded a human expedition to Mars. That includes the current one, which is funding only a return to the Moon (and barely funding even that.)

Quoting Pope (Reply 18):
It costs orders of magnitude more in terms of $ and human lives than all the previous US space efforts

No, it hasn't. Order of magnitude = multiply by 10. Apollo killed 3. Shuttle killed 14. Of course, Shuttle carries over twice as many astronauts per flight than did Apollo, and is closing in on an order of magnitude more flights to date. When compared to the number of flights and number of humans aboard those flights, Shuttle is only marginally more dangerous than Soyuz. Apollo's number of flights is so low that no statisically meaningful comparison can be made. (Although Apollo 13 came dangerously close to being fatal, and Apollo 6 would have aborted had a crew been onboard.)

Averaging over the length of the program, Space Shuttle costs about $500 million per launch. Titan IV was about $400 million each. Delta IV is around $250 million. But look at how much more versatile Shuttle is, with a crew of seven included in that cost. Saturn V was around $1 billion in 2004 dollars per launch. (Which is why LBJ and Nixon killed it in favor of something cheaper in the first place.) Shuttle didn't really increase costs over Apollo, but it failed to reduce them in any significant way.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: TheSonntag
Posted 2008-01-11 13:27:13 and read 6474 times.

I would not call Shuttle an embarassment, more a symbol of different times.

Look how many test pilots died in the 1950s and 1960s. This would be completely unacceptable today, as the will to take risks has considerably decreased.

Apollo was extremely risky, nobody today would be willing to take this risk.

Shuttle is a symbol for this, it must be safe, everything must be checked, and thus, the smallest event makes launch impossible.

I think future missions must find a balance between shuttle and Apollo. Spaceflight IS risky. Nevertheless, the hardware must be more reliable than Shuttle. It is unacceptable that almost every Shuttle flight is delayed, while the (less capable, granted) Russians are able to fly on time.

So I think Ares is a good step forward. I hope the US doesn't cancel it. I am not an US taxpayer, but I would love to see the US back on moon with Ares V around 2020.

This is actually the biggest benefit for US foreign relations NASA can offer: Everybody wordwide is impressed and loves the US for their moon landing. NASA is popular. I hope future US governments keep this in mind when thinking about the budget.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-11 18:16:15 and read 6435 times.



Quoting TheSonntag (Reply 20):
Nevertheless, the hardware must be more reliable than Shuttle. It is unacceptable that almost every Shuttle flight is delayed,

Shuttle isn't quite that bad!

31.4% of Shuttle flights were launched on time. Another 24.7% launched late but still on the scheduled day. So about half of all Shuttle flights launched on the scheduled day.

Of the delays, 44.6% were due to weather.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Cloudy
Posted 2008-01-14 11:55:46 and read 6297 times.

If NASA thinks Constellation, even with the whole shebang as originally envisioned, is going to excite people not otherwise excited by space they are under a serious delusion. Spend what we would have spent on constellation on unmanned projects and we could have a lot more exciting stuff. We could have sample returns from all over the inner solar system and perhaps the outer solar system as well. We could take a peak under Europa's ice. Eventually, we could have a telescope capable of not only discovering Earth sized worlds around other stars, but even imaging them. We could more easily try out new tech since in unmanned exploration you can afford a few losses. We wouldn't need the standing army the shuttle needs just to survive. Instead, We would need engineers to design the spacecraft, and more scientists to interpret the data we would be getting. These people would be doing exciting new stuff all the time.

Unmanned probes, rovers, etc. are what can excite people now and do serious science. They do real exploration, going places it takes years to get to and returning images + data about things no one has ever seen before. You can do so many more, different things then manned spacecraft can given equivalent levels of funding. This gap grows with every technological advance since manned space flight has to be conservative to be safe and cheap enough to do. If you want to excite people using something close to NASA's existing budget, unmanned space is the way to do it. Man on the moon 2.0 is not.

A lesson can be learned from the Mars rovers - NASA got more attention for that than they got for the space station - which costs literally a hundred times as much.

Bottom Line - Unless NASA can get a budget many times that necesary for Constellation, there is no use having a real manned space program at all. Better to have a placeholder program, or even nothing, and put the money into what people really want to see. When people unfamiliar with space look at rovers on mars, they think science and progress. When they look at the Space Shuttle and the Space Station, they think of their tax dollars going down the drain. Mostly , they are right.

Quoting Thorny (Reply 21):
Of the delays, 44.6% were due to weather.

I was under the impression, however, that the shuttle suffers more weather related delays then other launch vehicles because of the need to keep open abort options. The shuttle not only needs good launch weather, it needs good landing weather at the launch site and several other possible abort sites.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-14 13:50:48 and read 6255 times.



Quoting Cloudy (Reply 22):
Unmanned probes, rovers, etc. are what can excite people now and do serious science.

Messenger is presently passing a few thousand miles over Mercury, only the second spacecraft (and the fourth flyby) to do so. 50% of Mercury is still unknown to humanity. Yet the popular media has barely even noticed. Compare with Scott "Too Tall" Paracynski's repair of the station's solar wing last year.

Humans in space are an order of magnitude more popular and interesting with the general public.

Robots are excellent precursors, but that is all they are: precursors. They tell us where to look deeper, but we need humans nearby or on the ground to actually do the looking. Exploration of the moon and Mars will both require a consolidated manned/unmanned effort to succeed, even the moon is too far away for telepresence to be realistic in difficult terrain or complex tasks. Robotic technology is always vastly oversold by anti-manned space critics. "Just send probes to do it, it is easier and safer!" That's true, but it is also vastly less productive. One of the Mars Exploration Rover mission scientists pointed out that what Spirit did in a month, a human could have done in a day.

Quoting Cloudy (Reply 22):
I was under the impression, however, that the shuttle suffers more weather related delays then other launch vehicles because of the need to keep open abort options. The shuttle not only needs good launch weather, it needs good landing weather at the launch site and several other possible abort sites.

Correct.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: TheSonntag
Posted 2008-01-14 14:57:03 and read 6239 times.

Also, human spaceflight is more than just science, it is also a highly political issue. This isn't necessarily always a good thing, but certainly, the PR gained from being the first on the moon can hardly be topped again.

The Shuttle and ISS are not as spectacular, as they might seem to only do something Gargarin did in 1961, orbiting the earth. Yet they are a huge step forward for science, and international cooperation in space.

Being the biggest international civil project ever undertaken IS something spectacular. But I really think time has come for the next step. If we can live in orbit half a year, I would love to see a permanent moon station.

Whether we will live to see a manned Mars mission is still debatable. I hope so. And who knows, maybe we will see a manned mission to Jupiters moons in some centuries...

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Wvsuperhornet
Posted 2008-01-15 02:27:00 and read 6181 times.



Quoting Thorny (Reply 16):
That's just political CYA.

Yeah Ok!!!

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Nycbjr
Posted 2008-01-15 13:30:13 and read 6229 times.



Quoting Thorny (Reply 16):
Assuming the Ares project moves forward under the next U.S. President (Obama has already said it won't under him)

and just what is he proposing to replace it with? alllow the shuttle to keep going? or stop man space flight in the US all together.. man is seriously delusional...

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-15 14:15:20 and read 6223 times.



Quoting Nycbjr (Reply 26):
and just what is he proposing to replace it with? alllow the shuttle to keep going? or stop man space flight in the US all together.. man is seriously delusional...

He said he would delay Constellation five years to pay for beefing up Education. There were few other details. A five-year delay would effectively kill Constellation as the Shuttle-heritage workforce and manufacturing that (in the original plan, anyway) made Ares a cheap, straightforward replacement, would vanish and be impossible to reassemble five years later.

Sen. Obama took a little flak for that plan and has backed off on it somewhat, but it is clear where his sentiment lies: don't expect big things in space during his Administration.

I don't have a huge problem with killing Ares. It is a joke of a system (especially Ares I) that bears little resemblance to the "safe, simple, soon" promise on which it was selected. A "Direct" or EELV-based system now seems enormously more sensible. I'd like to see one of the candidates point that out and say "I'm in favor of Constellation, but let's do it the smart way, not this way." The "Direct" approach would cut development time and cost in half. The EELV approach would be a gigantic shot in the arm to the U.S. space launch industry, offering economies of scale that could well make them competitive against Ariane and SeaLaunch. Instead, NASA is building a one-use vehicle of its own that won't even be particularly good at that one use.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: TheSonntag
Posted 2008-01-15 14:30:35 and read 6210 times.

How much is Constellation actually under way? Is ist still possible to cancel it without losing too much money? I mean, sometimes projects have gone so far that it is cheaper to continue them than cancelling them.

And even if it could be cancelled now, this will not be on the agenda before the new president is elected. How far will Constellation be in 2009?

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Curt22
Posted 2008-01-15 16:07:54 and read 6190 times.



Quoting Thorny (Reply 5):
A ship in port is safe, but that is not what a ship is for.

What a fantastic quote!

Much a more economical use of words compared to Teddy Roosevelt's "Man in the Arena" speech, but both the ship and this speech apply well to the subject of NASA critics.

"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs, who comes short again and again, because there is no effort without error and shortcoming; but who does actually strive to do the deeds; who knows great enthusiasms, the great devotions; who spends himself in a worthy cause; who at the best knows in the end the triumph of high achievement, and who at the worst, if he fails, at least fails while daring greatly, so that his place shall never be with those cold and timid souls who neither know victory nor defeat."
Theodore Roosevelt, April 23, 1910

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Cloudy
Posted 2008-01-15 19:14:45 and read 6162 times.



Quoting Thorny (Reply 23):
That's true, but it is also vastly less productive. One of the Mars Exploration Rover mission scientists pointed out that what Spirit did in a month, a human could have done in a day.

I doubt he could do more than the hundreds or even thousands of rovers, etc. that could be sent for the price of getting him there, and all the scientists who would be kept working interpreting the data. There are MANY in the scientific community who think that way, my guess would be the majority. Many have to stay silent for political reasons, and to avoid controversy.

Another reason the manned space program gets less scrutiny than it deserves is that people realize this is not a perfect world. If the Democrats got rid of manned spaceflight, the money saved would go to social programs. If the Republicans got rid of it, they put the the money into the Pentagon. Both would throw bones to their constituents in the form of pork. Not much more would be spent on unmanned spacecraft. As bad as the ISS and Shuttle are, they are more useful then a bridge to nowhere. And any money taken from NASA could not significantly improve the defense department or the myriad of programs we have that claim to help the poor, or the deficit. It would be a drop in the bucket.

Quoting Thorny (Reply 23):
Compare with Scott "Too Tall" Paracynski's repair of the station's solar wing last year.

Humans in space are an order of magnitude more popular and interesting with the general public.

People are not excited by an airless rock such as Mercury, unless some significant discovery is made, and we don't have enough data for that yet. Mars missions get far more attention. So does the new Pluto mission. Messenger was much cheaper than the ISS program, even by some measures cheaper than a single shuttle flight even without payload. I doubt any informed observer would claim that if we spent all the money we spent on ISS and the shuttle on unmanned probes instead, we would have gotten a far greater return in both publicity and science. Apollo may be a different story, since we were doing more new things and a lot of technology we use in probes now was not available then. Even so, wait about 10-20 years and spend about a quarter as much money on sample returns, rovers, etc. and we probably could learn as much as we could have from Apollo. At least that is my Scientific Wild Ass Guess.

Again, no one disputes that manned missions are more effective than unmanned missions. But is it worth the hundred-fold increase in cost? Do you really get THAT much more science and attention out of it, considering just how many more things you can do with robots for far less money?

The march of technology works against manned spaceflight. Robotic spaceflight is getting cheaper and easier at a far faster rate than manned flight is. Every advance in CCD's, long distance transmission, etc. increases the amount of data you can get from unmanned craft. Better yet, unmanned space PROMOTES these advances at a faster rate. Anybody want to guess how much more mature nuclear/solar electric propulsion would be by now if the unmanned program had the same funds as Apollo? Or even the same as ISS?

If you want to see innovation, new technology, good science return for the money, real exploration, etc.
look at the unmanned space program. For pork, politics and political stunts look at manned space flight. If you could get a tenfold increase in NASA's budget, MAYBE it would be more efficient to send people. But it seems to me that for the money people are willing to spend probes are the best bet.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: TheSonntag
Posted 2008-01-16 04:23:40 and read 6125 times.



Quoting Cloudy (Reply 30):
But is it worth the hundred-fold increase in cost? Do you really get THAT much more science and attention out of it, considering just how many more things you can do with robots for far less money?

Maybe the question isn't "Is it really cost effective" at all. I think that the arguments pro human spaceflight are not really of economical nature, and shouldn't be. There is a lot of idealism in it, as well, travelling for the sake of exploration.

And as great a probe mission is (and I really thing it is extremely impressive that Voyager 1 is still able to communicate with earth, although it is so unbelievable far away, or that you can remote control mars rovers from earth, just to name a few achievements so far), this is not the same as having humans living there. "To boldly go where no man has gone before"  Wink

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-16 07:02:30 and read 6105 times.



Quoting Cloudy (Reply 30):
I doubt he could do more than the hundreds or even thousands of rovers, etc. that could be sent for the price of getting him there,

Your costs are a bit messed up here. Spirit and Opportunity, which spend most of their time charging their batteries, cost about $750 million, not including the mission extensions. The plutonium-powered Mars Science Laboratory, scheduled for launch in 2009, is budgeted at $1.7 billion.

Zubrin's Mars proposals in the '90s were in the $30-50 billion range. The quickly abandoned 1989 Space Exploration Initiative was projected at $500 billion, but that included a space depot (independent of Freedom/ISS), lunar exploration and bases, Shuttle II, a new Saturn V, nuclear reactors, a fleet of unmanned rovers, and just about everything else NASA could think of. There is no fundamental reason that human Mars exploration has to cost $500 billion. The spacecraft itself should not cost any more than the hardware that is the International Space Station (and it in fact may well look an awful lot like ISS) which cost around $25 billion. The new Saturn V-class launcher (already in development as Ares V) is budget at around $15-20 billion. The manned Mars Lander will cost perhaps as much as the Space Shuttle Orbiter to develop... around $8-10 billion in today's dollars. We're up to around $55 billion. We'll need things like nuclear reactors for the Mars Base, and improved life support systems. Neither of these will cost $50+ billion. NASA's basic plan is estimated at around $100 billion, and that already allows for a 25% overrrun due to unforeseen problems.

Where the idea of Manned Mars costing hundreds of billions of dollars comes from, I don't know. It is popular among critics, but doesn't seem based in any sort of experience or reality.

And yes, an astronaut (or four) almost certainly could have done more than hundreds of rovers. An astronaut wouldn't have spent a month stuck in a sand pit like Opportunity did. In that 30 days, an astronaut could have gone to 30 different places.

Quoting Cloudy (Reply 30):
Every advance in CCD's, long distance transmission, etc. increases the amount of data you can get from unmanned craft

As well as what you can get from a manned mission. That's the fact that manned space critics always ignore. While technology marches forward to make robots better, the technology for manned space is not standing still, either. The technology, in large part, is the same either way you go (manned or unmanned.)

But until we get "Data" in the 24th Century, a human brain on the scene is always going to be enormously more capable than a robot there. We need robots for places where humans can't go (like Venus or Europa), not for places where we can (the moon or Mars.)

Quoting Cloudy (Reply 30):
Do you really get THAT much more science and attention out of it, considering just how many more things you can do with robots for far less money?

It isn't at all clear you can do many more things with robots. In fact, the opposite is indicated. Opportunity travelled a few miles to Victoria Crater in a few years. That's how far Scott and Irwin travelled in three days on Apollo 15.

My position is not "cancel all the robots and send humans!". It is "send robots to scout the terrain first, then send humans to do the real work."

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Michlis
Posted 2008-01-16 07:19:51 and read 6098 times.



Quoting Thorny (Reply 32):
There is no fundamental reason that human Mars exploration has to cost $500 billion.

Politics is always a fundamental in projects such as this, and my understanding is that the political atmosphere at NASA when the Space Exploration Initiative was drafted was such that everybody's pet idea was included as part of the Initiative and thus the balloned cost. I'm not NASA bashing, but it just seems that nobody took the affirmative step of just saying no to what wasn't needed to get the job done.

As for Zubrin, looks like our favorite Martian is stirring the pot again with a new book on how to get America off oil. You gotta love the guy.

http://www.amazon.com/Energy-Victory...UTF8&s=books&qid=1200496583&sr=8-1

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Prebennorholm
Posted 2008-01-16 16:39:01 and read 6043 times.



Quoting Thorny (Reply 32):
Where the idea of Manned Mars costing hundreds of billions of dollars comes from, I don't know. It is popular among critics, but doesn't seem based in any sort of experience or reality.

 checkmark 

None of us living on planet Earth today will ever witness a manned Mars flight. It is too far away.

After almost 50 years of manned space flight we still get astronauts back in pretty bad shape from six months on the ISS. An multi-year manned mission is fantasy only.

Add to that the fact that landing and take-off from Mars demands a lot more energy than a similar Moon mission like Apollo. And that with life support for a year long journey back home. In the future we will see Mars sample return missions bringing ounces back. We will see live high quality pictures on TV and Internet. But not from a man held camera.

Should manned interplanetary flight one day become practical because of some presently unknown technology breakthrough, then it will most certainly become "prohibited" to land on Mars. The reason is that it would be unavoidable to "pollute" Mars with micro organisms from Earth which could for ever spoil the value of future scientific work on Mars. And Mars is for certain the most valuable planet (next to Earth) in our solar system for exploring planetary developments and especially their climatic, environmental, and biological properties.

For that reason a manned landing on an outer Jupiter moon will come before a manned Mars landing. Even if I cannot see why we should land a man a Jupiter Moon.

For all Mars landings since the very first 33 years ago we have been extremely cautious not to bring micro organisms to Mars in order to maintain Mars as the invaluable scientific treasure it is for investigating planet Earth. We cannot afford to spoil that. That's simply not compatible with a manned landing.

I am also very sceptical about future manned flights to our own Moon. There isn't much more we can learn about the Moon from the surface. That's also the reason why all Moon missions during the last few decades have been Moon orbiters, not landers.

Maybe some future Moon missions will not be for investigating the Moon, but rather to utilize it. One interesting thing could be an astronomical radio telescope on the back side of the Moon. It's the only place in the neighborhood of Earth where we can work on radio astronomy without "pollution" from Earth. It might require manpower to build such a radio telescope on the Moon, but when operational it would certainly be remotely operated via Moon orbiting data relays.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: DfwRevolution
Posted 2008-01-17 14:12:35 and read 5962 times.



Quoting Prebennorholm (Reply 34):
None of us living on planet Earth today will ever witness a manned Mars flight. It is too far away.

I'd take that bet, although I am in my twenties. I'd even wager someone my age could be a member of the crew.

All the fundamental technology needed for a Mars mission exist today. Not all of them are in-service at the moment, but they have all been demonstrated repeatedly. All that holds us back is the cost of integrating and launching the spacecraft to do it. The only incentive for waiting is the hope of better technology that would reduce the total mass we would need to place in orbit. For example:

More reliable systems -> Less redundancy -> Less mass
More effective radiation shielding -> Less shielding -> Less mass
Nuclear upper stages -> Higher ISP -> Less mass

What comes next isn't that surprising. Anytime we need to place less mass in orbit, the program cost goes down. So for a manned Mars mission to take place, we need one of three things:

1. Politicians who just accepts the cost of the Mars Ship at mass X and the expense of launching it at cost Y.
2. Systems technology that lowers the Mars Ship mass to 3. Launch technology that lowers the cost Y to the point where the Mars Ship at mass X is acceptable.

While it won't happen in the next 2-18 years, a U.S. President in 2020-2030 could well have a space agency with the pieces necessary to prepare a Mars mission. We do have the money. In fact, both the Shuttle and ISS were funded by leaders who were not exactly pro-space. Can we discount #1? I don't think so.

At this very moment, there are a number of private space firms seeking to lower the cost of orbital access. If SpaceX is able to reuse their Falcon first stages, it would have a positive effect on launch costs. COTS could prove some important orbital technology, and the combination could (for example) allow NASA to refuel on orbit and reduce the number of heavy-lift Ares V they need for a Mars mission. Can we discount #3? Probably not, either.

The weakest point is #2, but it could certainly play a role in combination with the other two factors.

Ultimately, I understand some of the skepticism because some study always has put Mars "twenty years in the future," as far back as the 80s. But as Thorny points out, we have never said "go" to any of those ideas, so it doesn't follow to say that a Mars mission will always be twenty years out. This is different than say fusion, which always seems 50 years away despite billions specific research in that field.

We can really do it, and in respectable time, if we wanted to.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Connies4ever
Posted 2008-01-17 15:53:17 and read 5941 times.



Quoting Prebennorholm (Reply 34):
None of us living on planet Earth today will ever witness a manned Mars flight. It is too far away.

After almost 50 years of manned space flight we still get astronauts back in pretty bad shape from six months on the ISS. An multi-year manned mission is fantasy only.

1 - Don't be such a pessimist, and
2 - That's EXACTLY why we need nuclear propulsion for long-range missions.

Using NP for a non-Hohmann transfer could mean mission times are vastly reduced, consumable requirements are vastly reduced, and the stress on the human organism is vastly reduced.

Quoting DfwRevolution (Reply 35):
All the fundamental technology needed for a Mars mission exist today.

 checkmark 

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Highlander0
Posted 2008-01-17 16:11:15 and read 5937 times.

If I recall, it is only 62 miles from the surface of the Earth to Space (accoding to the Fédération Aéronautique Internationale). So fuel consumption isn't a major 'biggie'.


I would love to see a shuttle launch, or hell, even a landing at Fairford.
Better get moving if I want to see one though!

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-17 16:23:53 and read 5936 times.



Quoting Prebennorholm (Reply 34):

None of us living on planet Earth today will ever witness a manned Mars flight. It is too far away.

No it isn't. It is much farther away than the moon, but it is not a longer flight than cosmonauts already demonstrated on Mir.

Quoting Prebennorholm (Reply 34):
After almost 50 years of manned space flight we still get astronauts back in pretty bad shape from six months on the ISS.

No, we don't. Readaptation is always a little weird. Witness astronaut Stephanyshyn-Piper who fainted during the press conference last year shortly after landing. She'd only been in space 10 days. Other astronauts have pulled four and six month stints on ISS and walked around the Shuttle after landing. (NASA discourages but does not forbid this, they want to take blood and fluid samples and do other tests as soon after landing as possible before the body readapts to 1g.)

And the bulk of the zero-g issue can be eliminated with artifiical gravity, achieved by spinning the spacecraft on a long tether, probably with the spent booster rocket at the far end.

Quoting Prebennorholm (Reply 34):
Add to that the fact that landing and take-off from Mars demands a lot more energy than a similar Moon mission like Apollo.

That's just bigger fuel tanks. We'll almost certainly manufacture the propellant in-situ so that it doesn't have to be carried from Earth. The same engines used for landing can be used for liftoff. A derivative of the RL-10 burning methane instead of hydrogen seems most promising.

Quoting Prebennorholm (Reply 34):
And that with life support for a year long journey back home.

To be demonstrated on the International Space Station. The first parts of the U.S. closed-loop life support system are already in orbit (it will go fully-online with Node 3 in 2010.)

Quoting Prebennorholm (Reply 34):
Should manned interplanetary flight one day become practical because of some presently unknown technology breakthrough, then it will most certainly become "prohibited" to land on Mars.

No. Only nations which sign such a treaty would be "prohibited". Note that the United States never signed on to the Moon Treaty, either. I will guarantee you that the United States and China, at least, will never agree to that. Japan probably not, too.

Quoting Prebennorholm (Reply 34):
The reason is that it would be unavoidable to "pollute" Mars with micro organisms from Earth which could for ever spoil the value of future scientific work on Mars.

Then the damage is already done. Russia did not decontaminate Mars 2 lander before launch. It landed in 1971 and promptly died. But it did land. Also, there are meteorites from Mars on Earth and almost certainly some from Earth are on Mars. (It's harder to get from Earth to Mars because of Earth's higher gravity, but it is far from impossible.)

Quoting Prebennorholm (Reply 34):
And Mars is for certain the most valuable planet (next to Earth) in our solar system for exploring planetary developments and especially their climatic, environmental, and biological properties

And if the next generation of probes (Mars Science Laboratory, Exomars...) show unequivocably that there is no life today on Mars, as Viking has already strongly suggested...?

Quoting Prebennorholm (Reply 34):
For that reason a manned landing on an outer Jupiter moon will come before a manned Mars landing.

The radiation environment in the Jupiter system is far too dangerous for human exploration. Even the Galileo probe was badly fried by the time it finally ended its mission.

Quoting Prebennorholm (Reply 34):
I am also very sceptical about future manned flights to our own Moon. There isn't much more we can learn about the Moon from the surface. That's also the reason why all Moon missions during the last few decades have been Moon orbiters, not landers.

There is an enormous amount of surface exploration yet to be done. The Apollo flights only visited 16 sites in a narrow swath near the moon's equator and only on the near side. It is now widely regarded that the lunar poles are the most interesting places for research, and it is there that human exploration will re-commence at the end of the next decade.

Until the last few months, there had only been two missions to the moon since the 1970s. Both were orbiters (Clementine and Lunar Prospector) and one of them was a military mission using the moon as a convenient optical target. Japan and China recently launched lunar orbiters as their first lunar missions, so it is not unreasonable that neither mission was a lander. Lunar Prospector did a lunar impact at end of mission, as will LCROSS to be launched this year with NASA's Lunar Reconnaisance Orbiter. So there is in fact significant interest in the lunar surface.

Quoting Prebennorholm (Reply 34):
Maybe some future Moon missions will not be for investigating the Moon, but rather to utilize it. One interesting thing could be an astronomical radio telescope on the back side of the Moon. It's the only place in the neighborhood of Earth where we can work on radio astronomy without "pollution" from Earth. It might require manpower to build such a radio telescope on the Moon, but when operational it would certainly be remotely operated via Moon orbiting data relays.

Agreed, a far-side radio observatory is consistently one of the highest-interest projects for lunar utilization, and it will be man-tended, since people always nearby will contaminate the radio silence. The orbiting relays would contaminate the radio spectrum, so it is possible that a long cable would be strung around to a near-side transmitter, a'la transatlantic cables. The observatory will still have to contend with deep space missions transmitting signals back to Earth.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Rwessel
Posted 2008-01-17 18:43:16 and read 5914 times.



Quoting Thorny (Reply 38):
The Apollo flights only visited 16 sites in a narrow swath near the moon's equator and only on the near side.

Obviously you meant 6, not 16.

Quoting Thorny (Reply 38):
Agreed, a far-side radio observatory is consistently one of the highest-interest projects for lunar utilization, and it will be man-tended, since people always nearby will contaminate the radio silence. The orbiting relays would contaminate the radio spectrum, so it is possible that a long cable would be strung around to a near-side transmitter, a'la transatlantic cables. The observatory will still have to contend with deep space missions transmitting signals back to Earth.

That's not really a big problem. Any relays just need to be designed to operate on astronomically uninteresting frequencies, and in very narrow bands (IOW, very little out-of-band noise). A narrow beam would help too.

Alternatively, you could go the optical route, and use a laser.

A bigger problem would be figuring out where to put the relay satellites, though. Perhaps at L4/5 and a really tall antenna tower.

OTOH, 5500km of optic fiber has a lot to recommend it. Its mass would probably be under 75kg/km, possibly under 50kg/km. And other than needing a (small) repeater station every 40-50km, would need little more than unrolling to put in place.

A series of towers is possible too. At 50m high, you'd need about 200 to go 5500km, but that doesn't look all that attractive compared to just unrolling 26km of cable (approximately the spacing between towers).

And you'd really only need about half that amount of fiber, since you'd put the dish pointing back to earth just far enough inside the near side to not have to worry about the libration. And you might not need to put the observatory in the exact center of the far side either.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Pope
Posted 2008-01-18 13:07:22 and read 5837 times.



Quoting Thorny (Reply 19):
No, it hasn't. Order of magnitude = multiply by 10. Apollo killed 3. Shuttle killed 14. Of course, Shuttle carries over twice as many astronauts per flight than did Apollo, and is closing in on an order of magnitude more flights to date. When compared to the number of flights and number of humans aboard those flights, Shuttle is only marginally more dangerous than Soyuz. Apollo's number of flights is so low that no statisically meaningful comparison can be made. (Although Apollo 13 came dangerously close to being fatal, and Apollo 6 would have aborted had a crew been onboard.)

Averaging over the length of the program, Space Shuttle costs about $500 million per launch. Titan IV was about $400 million each. Delta IV is around $250 million. But look at how much more versatile Shuttle is, with a crew of seven included in that cost. Saturn V was around $1 billion in 2004 dollars per launch. (Which is why LBJ and Nixon killed it in favor of something cheaper in the first place.) Shuttle didn't really increase costs over Apollo, but it failed to reduce them in any significant way.

You make several excellent points. I stand corrected.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-18 13:38:12 and read 5821 times.



Quoting Rwessel (Reply 39):
Obviously you meant 6, not 16.

D'oh! You're right.  embarrassed 

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Prebennorholm
Posted 2008-01-21 13:01:56 and read 5661 times.

I really enjoyed reading those long posts with optimism about manned Mars flights, especially by DfwRevolution and Thorny. I really do hope that you gentlemen one day will experience such a venture. I won't because I'm roughly at twice your average age.

But then I had the advantage to witness - as an (almost) adult man) the fantastic Apollo program from day one, the only extra terrestrial manned space to this very day. I remember hearing JFK on the radio same day as he announced the Apollo program.

I stumbled over a few things:

Quoting DfwRevolution (Reply 35):
I understand some of the skepticism because some study always has put Mars "twenty years in the future," as far back as the 80s.

You can call that "the 60s". If somebody in 1965 had insisted that in 1985 man had still not walked on Mars, then he would have been ignored as an idiot. The optimism and "can do" attitude was enormous in those days. And I believed in most of it.

When around 1970 the Shuttle began to take shape on the drawing board, then it was a 1977 EIS space tug to transport modules for among other things the Mars Ship into space. Six would be built (later reduced to five), and most of the time two shuttles would be working simultaneously in space. NASA talked "turn-around times" as if it was a DC-9 - two weeks, week-ends off duty, and it was ready to go again, year around. The buzzword was "five bucks per pound to space". 15 flights per shuttle per year for 15 years, they wouldn't need replacement until the larger, runway take off 1990 Shuttle successor.

By charging TV companies for launching geostationary satellites the Shuttle would balance at zero on the NASA financial sheet, or even make a profit! That was serious talk in those days.

One more thing: Nuclear power is mentioned as a new means of "really fast" space travel. I won't say it is impossible, but:

Nuclear power is good for producing heat. How do we convert heat into acceleration in space?

There is only one way to accelerate a mass in space. It is to "push" some other mass the other way. Today that other mass is burned rocket fuel, nothing else. The most efficient rocket engines (burning cryogenic, non-long time storable fuel) can reach an exhaust speed of roughly 10,000 feet/sec. That's an impressive number, but still it's only one third or half of low Earth orbit speed. So even if nuclear power could multiply the exhaust power by a factor ten, then still a very significant weight of "fuel" would be needed, well not real fuel, but some mass to push the other way.

If we imagine such an engine to perform a fast track to Mars, brake down to Mars orbit, land, take off, go fast back home, and brake again. We would probably still need 99% of the take-off mass to be exhaustible "fuel". It ain't easy. That's the reason why all long space flights in the solar system go in bent solar orbit and use gravitational pull from Jupiter, Venus and even Earth just to make it within years or sometimes decades.

Quoting Thorny (Reply 38):
Quoting Prebennorholm (Reply 34):
The reason is that it would be unavoidable to "pollute" Mars with micro organisms from Earth which could for ever spoil the value of future scientific work on Mars.

Then the damage is already done. Russia did not decontaminate Mars 2 lander before launch. It landed in 1971 and promptly died. But it did land. Also, there are meteorites from Mars on Earth and almost certainly some from Earth are on Mars. (It's harder to get from Earth to Mars because of Earth's higher gravity, but it is far from impossible.)

That 1971 "landing" was stupid. It was a result of a politically inspired "space race". It won't happen again. Hopefully it didn't do any damage.

The meteorite exchange between Earth and Mars is no problem. They got fried during entry into the atmosphere. We can hope that the Russian Mars 2 suffered the same faith.

But at the end of the day (or earlier) we should all study those fantastic space programs going on right now. It's not as spectacular on TV as Apollo, but going into the details I find it way more interesting than "a man walking on Mars".

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Flighty
Posted 2008-01-21 14:10:18 and read 5640 times.

I think the triumph of NASA is really the Hubble Space Telescope. Nothing else really matches its contribution to science. What a great stroke of luck that was.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-21 14:47:11 and read 5634 times.



Quoting Prebennorholm (Reply 42):
Nuclear power is good for producing heat. How do we convert heat into acceleration in space?

VASIMIR is one interesting concept...

http://spaceflight.nasa.gov/shuttle/...pport/researching/aspl/vasimr.html

Quoting Prebennorholm (Reply 42):
That 1971 "landing" was stupid. It was a result of a politically inspired "space race". It won't happen again. Hopefully it didn't do any damage.

We're not much better these days. Part of what makes the new generation of Mars missions so cheap (relative to Viking) is the shortcuts they've taken, and one of them is total decontamination of the spacecraft. On the budgets they have, it just isn't possible to totally eradicate any germs that might have gotten in. You need computer chips and systems that can survive much higher heat loads if you want to really bake out anything living, but chips that can handle that kind of enrivornment are a lot more expensive. And the higher quality clean rooms to build the spacecraft drive up costs a lot, too. They're taking more care with MSL, at a consequently higher cost.

Quoting Prebennorholm (Reply 42):
The meteorite exchange between Earth and Mars is no problem. They got fried during entry into the atmosphere.

That's far from a scientific concensus. Look up "transpermia".

Topic: RE: What Is The Deal With The Space Shuttle?
Username: TheSonntag
Posted 2008-01-21 15:20:27 and read 5620 times.



Quoting Flighty (Reply 43):
I think the triumph of NASA is really the Hubble Space Telescope. Nothing else really matches its contribution to science. What a great stroke of luck that was.

And it had to be repaired by humans in order to work properly...

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Prebennorholm
Posted 2008-01-21 16:36:10 and read 5602 times.



Quoting Thorny (Reply 44):
VASIMIR is one interesting concept...

Sure! Very interesting. But it does not offer a gigant leap in engine efficiency. Engine efficiency which could change a Mars return flight to a handful of months instead of years.

Also thanks a lot for your roundup about the Mars contamination risks. I read a lot about the Viking landers in the 70'es while they were going on. Somehow I assumed that the same precautions were taken today. We cannot fry modern computer chips, but anyway I would assume that they treat non-fryable modules with various "unhealthy" gasses and pack the landers in bioschields left to burn during entry into the Mars atmosphere.

There is always a risk involved. But that risk is really nothing compared to having sneezing men and women walking around.

Quoting TheSonntag (Reply 45):
And it had to be repaired by humans in order to work properly...

Not only to repair the Hubble, but also to modify and upgrade it with totally new sensors and instruments, and to re-fuel it to serve for decades. Those Hubble service visits are really some of the most spectacular achievements in space ever. That the spin-off from these visits is that we have widened our horizon in the universe in a breathtaking way, that's a fantastic bonus.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Rwessel
Posted 2008-01-21 21:29:32 and read 5557 times.



Quoting Prebennorholm (Reply 46):
Quoting Thorny (Reply 44):
VASIMIR is one interesting concept...

Sure! Very interesting. But it does not offer a gigant leap in engine efficiency. Engine efficiency which could change a Mars return flight to a handful of months instead of years.

Two orders of magnitude increase in ISP isn't a giant leap?! What exactly are you hoping for?

Even using a nuke to run a large-ish collection of ion thrusters would increase ISP by an order of magnitude.

Of course in both cases you have to factor in the quite heavy nuke plant, but that just means you (ballpark) need at least as much reaction mass along as the mass of the reactor to break even. And sure, that implies a fairly large vehicle.

Just for grins, assume a couple of 100,000kg spacecraft. On one add 1,800,000kg of LOX and LH2 and 100,000kg of engines, and on the other add a 500,000kg reactor, 1,200,000kg of reaction mass and 200,000kg of ion engines. A total of 2000t in both cases. Let's ignore the issue of getting the silly things into orbit, and...

The conventional spacecraft will have a total delta-V of about 11.5km/s. The nuke/ion spacecraft will have a total delta-V of about 40km/s.

FWIW, the entire S6G reactor installation on a Los Angeles class attack boat is about 1,500,000kg, and puts out about 150MW. A significant part of that is shielding that you wouldn't need in space, nor would the reactor need to be anywhere near that big. So 500,000kg is very generous. If you halved the mass of the reactor, and added the equivalent amount of reaction mass, your delta-V goes to 64.5km/s.

Nor are the engine mass assumptions favorable to the nuke (they're excessively generous for the conventional vehicle as well, but it makes less difference there).

The reactor based design gives you a fair bit of growth room, whereas the low exhaust velocity of the LOX/LH2 engine will start to get really painful. Consider just adding 2,000,000kg of fuel or reaction mass to each of the proposed vehicles. The conventional spacecraft will have a total delta-V of 14.7km/s, while the nuke gets to 80.5km/s (heavy reactor version) or 99km/s (light reactor).

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Flighty
Posted 2008-01-22 09:26:40 and read 5517 times.

The final Hubble servicing mission (#4) is scheduled for August or September 2008.

6 new guidance gyroscopes, re-boost to higher orbit, new battery, and equipment upgrades. With luck, this will make Hubble last until 2013, at which time it will be retired. According to wikipedia.

Quoting Prebennorholm (Reply 46):
That the spin-off from these visits is that we have widened our horizon in the universe in a breathtaking way, that's a fantastic bonus.

I think in the future there won't be any doubt, the Hubble is probably the most important NASA activity since the moon landings. At least, the most successful. And the difficult repair missions are part of showing how it was truly a spaceflight challenge, not just astronomy alone.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-22 10:56:24 and read 5499 times.



Quoting Flighty (Reply 48):
6 new guidance gyroscopes, re-boost to higher orbit, new battery, and equipment upgrades. With luck, this will make Hubble last until 2013, at which time it will be retired.

They will also attach a docking apparatus so that a future unmanned spacecraft can safely de-orbit Hubble. The apparatus could also be used by a visiting Orion spacecraft, so future repairs are not out of the question.

Quoting Flighty (Reply 48):
I think in the future there won't be any doubt, the Hubble is probably the most important NASA activity since the moon landings. At least, the most successful. And the difficult repair missions are part of showing how it was truly a spaceflight challenge, not just astronomy alone.

Voyager will be a close runner-up.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Prebennorholm
Posted 2008-01-22 11:31:47 and read 5487 times.



Quoting Rwessel (Reply 47):
Two orders of magnitude increase in ISP isn't a giant leap?! What exactly are you hoping for?

Even using a nuke to run a large-ish collection of ion thrusters would increase ISP by an order of magnitude.

Dear Rwessel, we were discussing a fast manned Mars flight, a mission lasting a few months instead of years. That would enable crews "fit for fight" on Mars. That would call for enormous gains in engine efficiency. I was mentioning a factor 10 compared to present day chemical rocket engines, just to say something.

I'm sure you know, but maybe not all readers are fully aware what difference there is between the ordinary way to fly to Mars and a "fast" direct flight. The "ordinary way can be described as "putting the ship into an elliptical sun orbit during a favorable launch window, and shape that ellipse to hit Mars. Then wait on Mars (maybe a year or so) for a similarly favorable launch window for the return flight, also as an elliptical sun orbit which intersects the Earth".

Thanks a lot for your description of future exotic engines. Very interesting! And as you also indicate, it all depends upon at what weight such engines can be produced.

When a reactor is put into a boat, then heat is used to drive a steam turbine. A nuke reaction engine will be an entirely different animal. I'm not sure how it will work. What bothers me most is that 40 years ago our dreams about such exotic engines were very similar to today. Not much has changed, really. It may indicate that the task is simply too big for mankind.

Quoting Rwessel (Reply 47):
...whereas the low exhaust velocity of the LOX/LH2 engine will start to get really painful.

We tend to measure everything else against LOX/LH2 engines, since they are the best we have. But if we need to cope with present day technology, then we can use such engines only for departure from Earth.

That was okay for the Moon landing because of the low gravity on the Moon. To enter Mars orbit, land on Mars, launch into Mars orbit, and finally accelerate to escape velocity on considerably less capable, but long time storeable fuel, that alone will be an enormous challenge, which will make the Moon landings look like a drive to town.

So something new and presently unknown is needed for man to set foot on Mars.

Quoting Flighty (Reply 48):
...the difficult repair missions are part of showing how it was truly a spaceflight challenge, not just astronomy alone.

Exactly!  checkmark 

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-22 12:23:38 and read 5494 times.



Quoting Prebennorholm (Reply 50):
Dear Rwessel, we were discussing a fast manned Mars flight, a mission lasting a few months instead of years. That would enable crews "fit for fight" on Mars.

The other way to do it is to accept the long (9-10 months) flight with ordinary propulsion but use artificial gravity to produce 1/3 g on the trip, so the crew will already be accustomed to Mars gravity upon arrival. The artificial gravity could he accomplished by tethering the spacecraft on a long cable and rotating it around with a counterweight (the spent booster rocket, probably.) The cosmic radiation hazard can be mitigated by building a double-hulled spacecraft and filling the space between the hulls with water. Solar flares could be mitigated by a good warning system (which we'd want for Earth anyway) and having a "storm shelter" on the spacecraft, heavily shielded where the crew can camp out for a day or so until the storm passes.

Quoting Prebennorholm (Reply 50):
To enter Mars orbit, land on Mars, launch into Mars orbit, and finally accelerate to escape velocity on considerably less capable, but long time storeable fuel, that alone will be an enormous challenge, which will make the Moon landings look like a drive to town.

We wouldn't want to use LH2 except on the outbound boost. Storable propellants aren't that big a challenge. Titan II's stood on alert in silos for years with storable propellants. Voyager is still flying with its monopropellant thrusters 31 years later. The ascent from Mars will almost certainly be methane powered, and you can produce methane from the Martian atmosphere. This would be done by a precurssor mission before humans left for Mars, so the return booster will already be fueled and ready upon their arrival. They'll also bring a second return spacecraft, so the next mission's return ship will also already be on station, ready for them when they arrive, or as an emergency backup.

Quoting Prebennorholm (Reply 50):
So something new and presently unknown is needed for man to set foot on Mars.

No. This has all been pretty well thought out. There are no showstoppers with present-day or imminent technology.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: TheSonntag
Posted 2008-01-22 14:05:21 and read 5480 times.

While the thread has drifted from the original topic, I like it very much.

I have a question on the Mars mission. Will the spacecraft on the way back travel as fast as on the way to Mars? How fast would it be (I know in space speed is always relative to something, but if we just simplify, how many kilometers/hour would such a plane travel?) I guess "braking" is the biggest issue.

I am always fascinated that we already are capable of sending probes such long distances and manage to arrive exactly where we want. For a human mission that is vital, of course.

I hope we see these missions in our lifetime, but so far, a manned mission to Moon alone would be great already, as I wasn't born in 1969  Sad.

To bring this slightly back on topic, don't you think that it is a good idea to have a final retirement date for shuttle? I do, as much as its capabilities will be missed. But as long as you had shuttle, your manned mission was limited to Earth orbit, and more ambitious projects simply could not even be seriously considered with the budget Shuttle took.

Now where Shuttle will be retired, there is enough room for thinking beyond. Hopefully Constellation isn't killed by the next administration.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Rwessel
Posted 2008-01-22 15:38:29 and read 5465 times.



Quoting Prebennorholm (Reply 50):
we were discussing a fast manned Mars flight, a mission lasting a few months instead of years. That would enable crews "fit for fight" on Mars. That would call for enormous gains in engine efficiency. I was mentioning a factor 10 compared to present day chemical rocket engines, just to say something.

I'm sure you know, but maybe not all readers are fully aware what difference there is between the ordinary way to fly to Mars and a "fast" direct flight. The "ordinary way can be described as "putting the ship into an elliptical sun orbit during a favorable launch window, and shape that ellipse to hit Mars. Then wait on Mars (maybe a year or so) for a similarly favorable launch window for the return flight, also as an elliptical sun orbit which intersects the Earth".

But the point is that a significant increase in ISP is what will permit a fast path to Mars (or where ever) rather than a boring old minimum energy Hohmann orbit.

There are, at the moment, two basic ways to use a nuclear reactor for (space) propulsion. One is to use the reactor to heat the reaction mass, causing it to expand. That'll about double the currently available ISPs.

Second is to use the reactor as an electric power source, and have it drive something like a VASIMR or an ion engine, which potentially have much higher ISPs yet. I focused on ion engines, since they're probably a bit closer to being practical (in fact a fair number of small models have flown). "Real" reactors (as opposed to the much smaller, less powerful, but more common RTGs) have been flown by both the Soviet and American space programs, although they've all been rather smaller than the one proposed. I mentioned the S6G only for reference, as it's an example of an existing mobile design intended for use in harsh environments, with quite substantial power output, and with fairly well known dimensions.

In any event, I was talking about the transfer vehicle. Launch and landing on both Earth and Mars would likely be separated. If you had 65km/s total delta-V available for your transfer vehicle (total for both directions), you'd knock your flights out and in down to about eight or nine weeks each, with a four or five week stay on Mars.

It's hard to stay too much longer than that since Earth will be moving ahead quite quickly, and you're quickly getting into a very long stern chase situation, with unfavorable orbital geometry to boot.

For comparison, a basic Hohmann transfer will require a total delta-V of about 11.3km/s, and take about nine months each way.

If you want to get to Mars fast you need lots of delta-V. If you want lots of delta-V, you need very high ISPs, or you end up with a transfer vehicle with a ridiculous fuel fraction.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: FXramper
Posted 2008-01-22 17:24:56 and read 5450 times.

I'd recommend checking out at the local library - Space Shuttle: The History of Developing the National Space Transportation System by Dennis Jenkins. Good history of how Rockwell won the bid and then went over budget countless times on the space transportatiom system only to build an inferior machine with countless design flaws.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Prebennorholm
Posted 2008-01-23 13:41:30 and read 5341 times.



Quoting TheSonntag (Reply 52):
Will the spacecraft on the way back travel as fast as on the way to Mars? How fast would it be (I know in space speed is always relative to something, but if we just simplify, how many kilometers/hour would such a plane travel?) I guess "braking" is the biggest issue.

Here we have to go to the basics of space flight. All interplanetary space flight is done as some elliptical orbit around the sun. (Or hyperbolic flight path in case you have reached sun-escape velocity).

We start out with the speed with which the earth rotates around the sun, that is some 30 km/s (108,000 km/h).

Any maneuverable spacecraft has an acceleration potential which can be used for modifying the near circular orbit around the sun until the fuel is spent. That total potential is often called Delta-V. If Delta-V is, say, 20 km/s, then 10 Delta-V (10 km/s or 36,000 km/h) might be used to modify the earth sun orbit to a calculated sun orbit which intersects the goal. The remaining 10 Delta-V might be used to "brake", or rather to modify the sun orbit into a new sun orbit which is identical to the sun orbit of the goal.

If the goal (like Mars) is further away from from the sun, then you would spend the initial Delta-V on increasing the sun orbit speed from the 108,000 km/h, with 10 Delta-V that would be 108,000 + 36,000 = 144,000 km/h. If the goal on the other hand is Venus, then you would spend your Delta-V on reducing the sun orbit speed. That would make you "fall" closer to the sun.

Returning from Mars would be much the same. You would reduce from Mars' speed around the sun (roughly 90,000 km/h and fall inwards closer to the sun. While falling against the sun its gravity will increase your speed and you will arrive back home at a speed not too dissimilar to earth rotation speed around the sun.

Luckily all planets rotate around the sun in almost the same plane and in the same direction. Otherwise interplanetary flights would be a lot more complicated. We just don't know how an energy source which can change some 100,000 km/h to 100,000 km/h in the opposite direction. During some favorable constellation it might be possible to swing by a third planet and let its gravity change flight direction some 180 degrees. We might also just fly very far out in the solar system where the sun gravity is much lower and therefore the rotation speed around the sun is much lower, and make much smaller trajectory corrections out there. But in any case, we are now not talking flights with a duration of months or years, but decades.

But first of all, when leaving a planet you have to reach a relative speed to that planet great enough to bring you out of its gravitational field - out where you are (practically) only influenced by gravity from the sun. That speed depends entirely on the mass of the planet. For earth it is just over 11 km/s or some 40,000 km/h In the same way when landing on a planet or moon without an atmosphere to provide aerodynamic drag for braking, then you will have to land on the engine, meaning that you must "brake" with the same energy as needed to reach escape velocity.

Hope that makes it a little more clear when talking about speeds at interplanetary flights.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: TheSonntag
Posted 2008-01-23 17:12:34 and read 5320 times.



Quoting Prebennorholm (Reply 55):
Hope that makes it a little more clear when talking about speeds at interplanetary flights.

It does, and it reminds me of my physics teacher in Viborg at the year 2001... That has been quite some time ago  Wink

My point simply is, as much as I like all the concepts, travelling half a year through endless void is still extremely long, and shortening this timeframe would be a good thing (while impossible with todays technology)...

If we ever go to Mars (and I hope we will), I am going to have a huge respect for the guys doing that. I can already see the Mars hoax websites getting ready, though  Wink

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Flighty
Posted 2008-01-28 16:23:07 and read 5202 times.



Quoting Thorny (Reply 49):
Voyager will be a close runner-up.

OK definitely. We got pictures of freakin' Neptune in 1987. That was very very impressive. NASA can feel good about that. Still quite amazing that those missions worked at all. Digital imaging was in its infancy too.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Prebennorholm
Posted 2008-01-30 14:04:35 and read 5065 times.



Quoting Flighty (Reply 57):
We got pictures of freakin' Neptune in 1987.

Is my brain fooling me when I say November 1989 ?

Quoting Flighty (Reply 57):
Digital imaging was in its infancy too.

Infancy? Maybe not. But certainly at childhood stage when the Voyagers were launched in 1977.

At that time it had been used for billion dollars spy satellites for quite some time, even if film-return capsules were used way later than that for best quality when urgency was not an issue. But $99.99 digital consumer cameras were definitely not present yet.

Mariner 10 did a fairly good job at Mercury many years before Voyager.

Without doubt NASA had access to imaging technology which had been developed at great cost for military satellites.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-01-30 15:29:32 and read 5050 times.



Quoting Prebennorholm (Reply 58):
Is my brain fooling me when I say November 1989 ?

August, 1989.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Flighty
Posted 2008-01-30 16:49:03 and read 5028 times.



Quoting Prebennorholm (Reply 58):
Mariner 10 did a fairly good job at Mercury many years before Voyager.

To me the Voyager images look dramatically better

Quoting Thorny (Reply 59):

August, 1989.

Yes I was wrong on 1987... Sorry  Smile

Quoting Prebennorholm (Reply 58):
Without doubt NASA had access to imaging technology which had been developed at great cost for military satellites.

Interesting point, very interesting.

Quoting TheSonntag (Reply 52):

I have a question on the Mars mission.

Having been talking about unmanned space vehicles, I feel that we have not exhausted the potential there, yet. Hopefully we can have a new generation of probes to let us all "experience" the solar system using VR type technology. Sending complex robotic ships is so much easier than manned ships... plus, it gives us experience.

Today's cameras and data transfer is so good, we can send enough data for true cinematic experiences of other planets. I think that is what people want, a nice closeup view. We don't need to send humans to get that. In fact I'm not sure I see any point. Humans are not designed to live happily in space.

The whole task of designing a spaceship to house, feed and transport humans is complex to the point of absurdity. Since there is nowhere to visit given present propulsion technology, why not give it a rest until we do.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Nycbjr
Posted 2008-02-01 10:19:45 and read 4928 times.



Quoting FXramper (Reply 54):
I'd recommend checking out at the local library - Space Shuttle: The History of Developing the National Space Transportation System by Dennis Jenkins.

I just received this book from amazon ($15) thanks for the recommendation!

while the shuttle might be a failure in its original mission (of cheap reliable access), it is truly a magnificent machine, I look forward to walking around one when they are retired. (and hope to get to a launch b4 2010)

Topic: RE: What Is The Deal With The Space Shuttle?
Username: DfwRevolution
Posted 2008-02-01 12:34:53 and read 4900 times.



Quoting Flighty (Reply 60):
Humans are not designed to live happily in space.

Nor are we built to fly or travel across oceans, but they are activities integral to our modern society.

Quoting Flighty (Reply 60):
Today's cameras and data transfer is so good, we can send enough data for true cinematic experiences of other planets. I think that is what people want, a nice closeup view.

There are so many obvious examples in life of why this isn't the case.

Quoting Flighty (Reply 60):
The whole task of designing a spaceship to house, feed and transport humans is complex to the point of absurdity.

Absurdity? We've been doing it for more than 40 years now. It's gotten to the point of being so not absurd that people are criticizing NASA for contracting an in-house crew vehicle and launch vehicle rather than buying the service from a commercial supplier like you or I would use FedEx.

Quoting Flighty (Reply 60):
Since there is nowhere to visit given present propulsion technology, why not give it a rest until we do.

High performance LH2/LOX engines (which we have had since the 60s) are entirely capable of accessing the inner planets. You're also incredibly naive to think the innovation necessary to make interplanetary flight easier will come by another means than investing in spaceflight itself. There have been proposals for nuclear this, solar that, ionic-plasmatic such and such for more than a half-century. Chances are, they won't happen until there is a sufficient "market" to move people and payloads in space, and that "market" will never come to fruition if we don't keep pushing exploration with what we do have available today.

We didn't wait for jumbo jets to cross the Atlantic. We don't need to wait for the VASIMR or Orion or Starship Enterprise to send Mars sortie missions.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Chksix
Posted 2008-02-02 02:21:33 and read 4826 times.

I'm all for human exploration but it's not something that must happen asap since rushed programmes without a true goal won't lead anywhere.

The Apollo programme was cut short due to this. A Mars mission in the same vein will be a huge money sink and we will have almost nothing to show for it afterwards.

We need a system that can stage from the moon and bring one or two teams of maybe 10 people to set up a base there on Mars. The mission will be exploration and sampling for future development until it's time for launch back to earth several months later.

The problem is that this goal will be cut short in a bad way. 3 people or maybe even just two will be sent off, they try to manage in a little capsule (Orion style) then land and plant a flag. They lift off 3 days later since the launch window can be held open that long (guessing here). The return trip in the little capsule is not funnier than the outbound trip.

I just hope my grandchildren will see the first option!

Topic: RE: What Is The Deal With The Space Shuttle?
Username: DfwRevolution
Posted 2008-02-02 08:27:40 and read 4801 times.



Quoting Chksix (Reply 63):
We need a system that can stage from the moon and bring one or two teams of maybe 10 people to set up a base there on Mars.

The Moon is a poor staging ground for anything other than doing stuff on the Moon. While the Moon has low gravity, the fact that it has gravity at all requires an extra propulsive maneuver to set-out for Mars.

The most plausable Mars missions will stage from LEO, HEO, EML1, or EML2.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-02-02 09:19:53 and read 4787 times.



Quoting Chksix (Reply 63):
The problem is that this goal will be cut short in a bad way. 3 people or maybe even just two will be sent off, they try to manage in a little capsule (Orion style) then land and plant a flag. They lift off 3 days later since the launch window can be held open that long (guessing here). The return trip in the little capsule is not funnier than the outbound trip.

Baseline is a crew of six in most proposals. This allows three eight-hour shifts a day with two people working each shift (probably outside or remotely operating rovers and blimps.)

The Orion spacecraft will only be used to go to and from the Mars Transit spacecraft assembled/fueled in Earth orbit. It may also serve as a "storm shelter" during solar flares.

The Mars Transit ship, including Orion ferry and Mars Lander, and fuel, is estimated to weigh about 1 million pounds. (Requiring about five launches of an Ares V, or a fuel depot in orbit supported by many flights of cheaper tanker rockets.)

The Mars Transit spacecraft will likely be built out of Space Station-like modules, that is, larger than Mir where a cosmonaut has already done a 16 month stay (much longer than a Mars transit.)

An inflatable habitat is the most likely housing once on Mars.

Mars stay-time is likely to be either 30 days (short stay) or 20 months (wait for next Earth/Mars alignment.) Total mission time on the long-stay approach would be about three years, or about the same as Magellan's circumnavigation of the Earth.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Chksix
Posted 2008-02-02 09:58:15 and read 4781 times.

Thorny, that's what I'm dreaming of happening in the future.
It's just that the inevitable budget cuts will transform it into an "option 2" mission in my opinion.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Nycbjr
Posted 2008-02-04 07:31:49 and read 4678 times.

So I've been reading the book.. and so far I'm impressed this guy did a great job.. covers allot. The thing that facinates me at the moment is that during phase A and B the manufacturers had airlines as there partner for the "maintainence" of the shuttle! I don't have the book in front of me but I think that McDonald Douglas had PanAm and Boeing had Eastern.. very interesting stuff!

cheers

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Prebennorholm
Posted 2008-02-04 13:13:25 and read 4624 times.



Quoting DfwRevolution (Reply 62):
High performance LH2/LOX engines (which we have had since the 60s) are entirely capable of accessing the inner planets.

One obstacle is that LH2/LOX is not a store-able fuel. It can be used for getting on the way to Mars.

For breaking to Mars orbit, landing on Mars, take-off from Mars and for the return trip a store-able fuel is needed.

That's how the Moon landing were done. The big difference is the much greater gravity on Mars, and the much heavier supply needed for a 15 - 18 months long flight.

The consequence is that a manned Mars flight based on present or presently imaginable technology is way beyond the willingness of any earthbound taxpayer.

Another major obstacle is that after almost half a century of manned space flight we are still unable to guarantee that the crew after such a long flight can arrive on Mars in reasonably good physical shape. And we are almost sure that they will return in really bad shape.

Sorry fellas, not in our lifetime...

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-02-04 14:01:14 and read 4614 times.



Quoting Prebennorholm (Reply 68):
For breaking to Mars orbit, landing on Mars, take-off from Mars and for the return trip a store-able fuel is needed.

Not a problem. Storable propellant is less energetic, so you need more of it versus LOX/LH2, but it is also denser, so it can use smaller, lighter tanks than LOX/LH2. The result is not that serious a penalty. You just need more propellant at launch, but propellant and tankage is cheap (compared to engines and spacecraft.) The US and Russia both had storable propellant ICBMs standing on alert for decades. This is 50-year-old technology. And if to absolutely must use LH2/LOX, it isn't impossible, you just need active cooling instead of passive insulation. Heavier, but perhaps worth the weight.

Quoting Prebennorholm (Reply 68):
The big difference is the much greater gravity on Mars, and the much heavier supply needed for a 15 - 18 months long flight.

Yes, it will be a much larger spacecraft, probably similar in size to the pressurized volume of the International Space Station. No one (except Chksix!) denies that. Two or three supply modules (based on ISS logistics modules, probably) will suffice. They can jettison the modules as the supplies are used up and they're filled with trash. Supplies can (probably will) be prepositioned on Mars by the precursor flight (which will also have a navigation beacon to guide the crew in.)

Quoting Prebennorholm (Reply 68):
The consequence is that a manned Mars flight based on present or presently imaginable technology is way beyond the willingness of any earthbound taxpayer.

Don't lose perspective. The best estimates today, assuming NASA business as usual and allowing for the inevitable cost over-runs, is that it will cost $105 billion for the lunar program. That's about 25% more than what the U.S. alone spent on the International Space Station from 1984 through expected termination in 2015. That's less than half what the U.S. plans to spend on the Joint Strike Fighter (F-35) program over the next 20 years. The Mars program will almost certainly use much of the hardware already designed for the lunar program, specifically the Ares launch vehicles, launch facilities, closed-loop life support systems, and Orion crew ferry. It can also use many hardware designs already in service on the Space Station (pressurized modules, common berthing mechanism, solar arrays, etc.) Additional spending to go from moon to Mars could be as little as $20 billion, mostly for the Mars Lander and Ascent Vehicle.

President Bush just sent to Congress a $3.1 Trillion budget for FY09.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: DfwRevolution
Posted 2008-02-04 17:15:25 and read 4585 times.



Quoting Prebennorholm (Reply 68):
One obstacle is that LH2/LOX is not a store-able fuel. It can be used for getting on the way to Mars. For breaking to Mars orbit, landing on Mars, take-off from Mars and for the return trip a store-able fuel is needed.



Quoting Thorny (Reply 69):
Storable propellant is less energetic, so you need more of it versus LOX/LH2, but it is also denser, so it can use smaller, lighter tanks than LOX/LH2. The result is not that serious a penalty. You just need more propellant at launch, but propellant and tankage is cheap (compared to engines and spacecraft.)

Or you account for the predictable boil-off losses when designing the mission. Zubrin accounted for LH2 boil-off in his Mars Direct architecture and it was determined to be a minor issue.

Mars Direct (and I believe the later NASA DRM) preposition a large quantity of LH2 on Mars' surface before the crew launches, and converts the hydrogen into liquid methane using the CO2 in the atmosphere. Methane is easier to store, but still highly energetic and capable of lofting the crew back to their transfer vehicle.

Quoting Prebennorholm (Reply 68):
Sorry fellas, not in our lifetime...

As has been pointed out before, that is relative to the lifetime you have remaining.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Chksix
Posted 2008-02-05 08:03:38 and read 4518 times.

I don't deny or wish for a small vehicle  Smile I'm just a bit pessimistic about congress and the international partner's willingness to go all the way and do a serious flight with big hardware.

The supplies for the stay could be sent to the surface with unmanned cargo ships well ahead of the arrival or even launch of the crew.
When I was younger and had more time I had the idea of building a transfer space station that would stay in orbit between the Earth and Mars where transit crews would dock and on their way outbound and homeward. The orbit of that space hotel would come close to both planet's orbits to allow ease of transfer and docking.

I'm no orbital mechanic so I'm not sure that idea would help or increase the available flight "slots" to/from Mars...

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Thorny
Posted 2008-02-05 08:29:35 and read 4517 times.



Quoting Chksix (Reply 71):
The supplies for the stay could be sent to the surface with unmanned cargo ships well ahead of the arrival or even launch of the crew.

That's close to the "Cycler Ship" concept advanced by Buzz Aldrin in the late '80s, early '90s. Not a Space Station in solar orbit, but a mothership which continually makes the transit between Earth and Mars. I'm not sure how the orbital mechanics worked on that, either.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: Cloudy
Posted 2008-02-05 08:33:05 and read 4517 times.



Quoting Thorny (Reply 69):
Additional spending to go from moon to Mars could be as little as $20 billion, mostly for the Mars Lander and Ascent Vehicle.

President Bush just sent to Congress a $3.1 Trillion budget for FY09.

Most of the federal budget goes to entitlements(Medicare, Medicaid, etc.) and defense. The share of the budget taken by everything else (usually called "domestic discretionary spending") has been going down with time, mostly because entitlement costs have ballooned. Nearly everyone compares the cost of their favorite program to the entire federal budget or to some specific military program. A more true picture to compare it to domestic discretionary spending, because other domestic programs is what NASA competes against. Congress does not choose to fund either a new warplane or Constellation. It decides whether to fund Constellation or use the money for other domestic discretionary programs. Defense spending is allocated separately. In short, NASA and other science programs still amount to a drop in the bucket, but the bucket is a bit smaller then it first appears.

Also, one must keep in mind Everett Dirksen's saying - "A billion here, a billion there, and sooner or later it adds up to real money." For each of us that loves space, there is another that loves farm subsidies. Or infrastructure projects. Or clean energy - etc., etc. etc. We are all more willing to lobby for MORE spending in the programs we like then we are to lobby for LESS spending in what we don't like. Its pretty safe to say that the vast majority of people lobbying congress regarding NASA's budget would like to see it increased, or for a greater share of it to go to their pet project.
The trouble is, the same is true of nearly every federal program. Each has its advocates and all claim (most truthfully) that what they want amounts to a drop in the bucket. But if you put enough drops in a bucket, it will overflow. Especially when everyone wants to put a drop in and no one wants to take a drop out.

If I were a house committee chair I would require everyone who testifies in front of my committee in favor of more spending to specify what he would cut to get the money for it, and then testify AGAINST that program. If the program's advocates couldn't agree on what to cut, I would lean strongly against giving them the money. Nowadays, the vast majority of people who give information to congress have as their main goal more spending of one sort or another. They don't care where Congress gets the money as long as they get it. There are people who argue for fiscal conservatism, but they rarely have time to lobby against specific programs since there are so many of them. They only have time to argue the general case for less spending - and are generally not effective in doing so. This is mainly because little is heard against specific programs - except in the most egregious cases.

Topic: RE: What Is The Deal With The Space Shuttle?
Username: TheSonntag
Posted 2008-02-05 08:41:58 and read 4515 times.



Quoting Cloudy (Reply 73):

A very good analysis, which describes how the system works in every country. This is one of the reason why NASA needs ambitious programmes, which have lots of symbolic importance to the general public. With other words, a spectacluar return to moon or colonize Mars mission can help NASA to get funds for "yet another deep space probe"...

I think Nasa is very professional when it goes about PR. I could not imagine a German federal agency to lobby so much for their interests.

As much as the internationality of the ISS programme made it expensive, it also saved it from being axed, because sometimes it is more economically/politically viable to continue a programme than axing it, and both the Russians, Europeans and NASA could not have stopped it without pissing off their partners, damaging future relations. Future space programmes must take this approach, as well. They need to survive until they are so important that they have reached a point of no return. This does not necessarily mean they have to be international. Just spread the production facilities to so many states that they have a majority in Senate  Wink


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