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KarelXWB
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Nasa Studies Uranus And Neptune Orbiters

Wed Aug 26, 2015 9:23 am

NASA is about to start a study for an orbiter mission to Uranus and Neptune.

Quote:
Led the Jet Propulsion Laboratory, the study will look at ideas for orbiters that could be dispatched Uranus and Neptune in the late 2020s or early 2030s and study the giant planet’s structures, composition and extensive moon systems.

One focus of the study will be designing a common spacecraft platform that could be developed in two copies and launched to Uranus and Neptune for about $2 billion each, according to Jim Green, head of NASA’s planetary science division.

Development could start after the Europa mission in the early 2020s.

Quote:
NASA’s budget for planetary science can only support development of one such costly mission at a time, so only low-level work on a follow-up flagship project is affordable until after the Europa mission departs Earth in 2022.

Source
http://spaceflightnow.com/2015/08/25...as-sights-for-new-robotic-mission/

This would be cool. After Jupiter and Saturn, the final two gas giants in our solar system may get an orbiter mission too.
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Stitch
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RE: Nasa Studies Uranus And Neptune Orbiters

Wed Aug 26, 2015 7:12 pm

That would be totally awesome.

Glad to see NASA is still considering Flagship (big ticket) missions.
 
zanl188
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RE: Nasa Studies Uranus And Neptune Orbiters

Wed Aug 26, 2015 9:28 pm

$2B each is pretty steep. NASA needs to push for international participation on missions like these - everybody benefits.
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RE: Nasa Studies Uranus And Neptune Orbiters

Wed Aug 26, 2015 9:44 pm

NASA undeniably contributes good things to science. I have to say they have a proud history and they still bring it.
 
desertjets
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RE: Nasa Studies Uranus And Neptune Orbiters

Wed Aug 26, 2015 10:13 pm

hehe.... sending a probe to Uranus.

Quoting ZANL188 (Reply 2):
$2B each is pretty steep. NASA needs to push for international participation on missions like these - everybody benefits.

Unfortunately that is the price tag for one mission. To get probes to both it'll be $4billion. Which is roughly the cost of one Zumwalt class DD.
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zanl188
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RE: Nasa Studies Uranus And Neptune Orbiters

Wed Aug 26, 2015 10:39 pm

Quoting desertjets (Reply 4):
Unfortunately that is the price tag for one mission. To get probes to both it'll be $4billion.

For sure... which is why I said $2B each.
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DeltaMD90
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RE: Nasa Studies Uranus And Neptune Orbiters

Thu Aug 27, 2015 1:40 am

Quoting ZANL188 (Reply 2):

$2B each is pretty steep.

It's too bad we pay billions and billions for defense and can't even scrape up enough money for adequate space exploration  
 
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Stitch
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RE: Nasa Studies Uranus And Neptune Orbiters

Thu Aug 27, 2015 2:22 pm

Quoting DeltaMD90 (Reply 6):
It's too bad we pay billions and billions for defense and can't even scrape up enough money for adequate space exploration.   

Harass your Congresscritter.  

When they cancelled New Horizons in favor of the Europa Mission, I bitched to all 435 of them to restore both and I am glad I did (as well as glad so many others did) because of last month.   

With incumbency being what it is, chances are they'll all still be in office in 2020 when it comes time to approve the budget.  
 
zanl188
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RE: Nasa Studies Uranus And Neptune Orbiters

Thu Aug 27, 2015 3:13 pm

Quoting DeltaMD90 (Reply 6):

That's why I'd like to see international involvement. Spread risk, cost, and reward.
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Alfons
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RE: Nasa Studies Uranus And Neptune Orbiters

Thu Aug 27, 2015 4:30 pm

Hello guys,

not really contributing to the main discussion here, but a.net is for sure a good place to find maybe ppl who used to work in that branch and who have some realistic idea.

To my point/question. I know - or I'm well educated by the media - that during the cold war there was some kind of a plan to bankrupt russia by pushing space exploration to extreme levels and military like budgets. At the end of the cold war (1985+) word of mouth started to spread around saying that space exploration is useful for everyday's life, as many researched and newly invented components land one day in the kitchen; most famous example and a million times heard, the ceramic glass in the kitchen. I don't want to discuss the validity of those well marketed statements, the next point interests me.

Even with the biggest debts a country ever had, a democratic president cutting budgets left-and-right for government organizations which are less social welfare- and public-sympathy effective (military, nasa etc.), Nasa still gets to shoot every now and then a bus with sensors into space for each $2B costs, not considering the 24/7 shift operation and all surrounding costs to keep this alive and under control for 10 years until the beauty of desire is reached.

The following point is what I believe, unfounded, as I don't have the tooling and contacts to validate it: also a government handles through business and economic aspects. Every spend needs a "business case", and needs to be analysed if something from that will come back money wise, today or in 5 years. No democratic country will spend (uncorrupted) $1 million for an idealistic procurement, which will never ever bring back this $1 million tomorrow or in 5 years, nevermind by which shape and chemical composition.

So while the cold war and the kitchen glas ceramic sound for me like a valid business case, what about Horizon, Keppler, and those two next sardine boxes which will go to Uranus and Neptun? What did the project manager brought out at the first steering board meeting, to make the financial backers believe that their money will soon come back, and opening their purse?

Anyone has some good ideas?

Thanks.

Alfons
 
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Stitch
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RE: Nasa Studies Uranus And Neptune Orbiters

Thu Aug 27, 2015 5:30 pm

Quoting Alfons (Reply 9):
I know - or I'm well educated by the media - that during the cold war there was some kind of a plan to bankrupt russia by pushing space exploration to extreme levels and military like budgets.

Well that plan didn't work very well since we cancelled Space Station Freedom because it's costs were running into what a major military program required.  

The real plan to bankrupt the Soviet Union was to spend so much on defense that they had to invest most of their GNP and resources into the same to maintain parity with us. And it worked.



Quoting Alfons (Reply 9):
....what about Horizon, Keppler, and those two next sardine boxes which will go to Uranus and Neptun? What did the project manager brought out at the first steering board meeting, to make the financial backers believe that their money will soon come back, and opening their purse?

Well the financial backers of all these programs is the United States Government, so the Return on Investment was not going to be financial rewards, but scientific knowledge and employment for constituents.

[Edited 2015-08-27 10:32:35]
 
TheSonntag
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RE: Nasa Studies Uranus And Neptune Orbiters

Thu Aug 27, 2015 5:59 pm

Obviously Neptune or Uranus would require an SLS class rocket, correct?
 
rwessel
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RE: Nasa Studies Uranus And Neptune Orbiters

Thu Aug 27, 2015 7:53 pm

Quoting TheSonntag (Reply 11):
Obviously Neptune or Uranus would require an SLS class rocket, correct?

Not necessarily. A major constraint on an orbital mission will be the amount of fuel required to decelerate into orbit around the target. A previous discussion here on an orbital variant of New Horizons illustrated that, where I offered some basic number showing the requirements for very large amounts of fuel (on the order of 16,000kg of nitrogen tetroxide/hydrazine for the ~500kg spacecraft) given its flyby velocity. That's obviously absurd.

You can address that in several ways. First, by reducing the speed at which you're approaching the target (the New Horizon's example would reduce the fuel require to some 800kg by reducing the flyby velocity by two-thirds) - this obviously makes for a longer flight to the target, but in particular for Uranus, that may be a pretty easy trade-off. Second both Uranus and Neptune are gas giants and a considerable amount of aerobraking should be possible.
 
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RE: Nasa Studies Uranus And Neptune Orbiters

Fri Aug 28, 2015 1:29 am

I'm a big fan of Uranus and I have long wanted to send a probe there. A probe sent deep up Uranus could reveal many scientific things. I have a tremendous desire to see up close photographs of all the planets and their satellites. This is just the first phase and after that we all know that returning samples etc. will provide incredible insights.

Quoting ZANL188 (Reply 8):
That's why I'd like to see international involvement. Spread risk, cost, and reward.

Agreed, India and China look very interested in space fortunately.

Quoting Alfons (Reply 9):
Anyone has some good ideas?

Spending .001% of your GDP on space exploration should not be very polarizing. Understanding the COSMOS is the key to understanding everything. There are certainly benefits to technology. Voyager 1 and 2 pioneered everything from digital photos, to optics, to programming, to radiation proof electronics, flash memory, long range communications, physics and astronomy. Every first world nation should have a space exploration program within reason but there is no immediate or direct payoff. Space Ex invents technology, builds know how but usually what it does is speed up the rate of technology development. Big plus if you ask me.

Eruope's lack of investment is very disappointing.
 
rwessel
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RE: Nasa Studies Uranus And Neptune Orbiters

Fri Aug 28, 2015 6:56 am

Quoting solarflyer22 (Reply 13):
Spending .001% of your GDP on space exploration should not be very polarizing.

The ~$18.4B NASA budget is about .1% of the ~$18.1T US GDP, not .001%.
 
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KarelXWB
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RE: Nasa Studies Uranus And Neptune Orbiters

Fri Aug 28, 2015 10:13 am

Quoting rwessel (Reply 12):
You can address that in several ways. First, by reducing the speed at which you're approaching the target (the New Horizon's example would reduce the fuel require to some 800kg by reducing the flyby velocity by two-thirds) - this obviously makes for a longer flight to the target, but in particular for Uranus, that may be a pretty easy trade-off. Second both Uranus and Neptune are gas giants and a considerable amount of aerobraking should be possible.

How about slingshots in the opposite direction? Per Wikipedia:

Due to the reversibility of orbits, gravitational slingshots can also be used to reduce the speed of a spacecraft. Both Mariner 10 and Messenger performed this maneuver to reach Mercury.

As an example, the Messenger mission used gravity assist maneuvering to slow the spacecraft on its way to Mercury; however, since Mercury has almost no atmosphere, aerobraking could not be used for insertion into orbit around it.

The MESSENGER mission (launched in August 2004) made extensive use of gravity assists to slow its speed before orbiting Mercury. The MESSENGER mission included one flyby of Earth, two flybys of Venus, and three flybys of Mercury before finally arriving at Mercury in March 2011 with a velocity low enough to permit orbit insertion with available fuel. Although the flybys were primarily orbital maneuvers, each provided an opportunity for significant scientific observations.
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nomadd22
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RE: Nasa Studies Uranus And Neptune Orbiters

Fri Aug 28, 2015 2:54 pm

Quoting KarelXWB (Reply 15):
How about slingshots in the opposite direction? Per Wikipedia:

You can think of Jupiter slingshots in a simple way. If you follow Jupiter in it's orbit while approaching it and go around the leading side to change your trajectory from orbital to more outward, Jupiter's gravity will be pulling you outward for longer than it's pulling you back because you'll be receding from it for a lot less time than you were approaching it.
If your initial trajectory is more straight outbound from the sun and you use Jupiter to change that to a Uranus chasing orbital path by going around the trailing side of the planet, it would cost you speed. But, using Jupiter can also gain you speed if you use your engines to accelerate after you pass it by reducing the time it's pulling you back compared to the time it pulled you in.
Chasing Uranus in it's orbit is slower than a direct approach, but takes a lot less slowing down to get into orbit once you get there.
In other word, there are about a thousand possible ways to get to Uranus orbit, depending on the position of the planets, how much Delta-v you have and how much time you have.
If the Falcon Heavy pans out, it could really change things. $120 million to put a 50 ton payload would be nice. $30 million is reuse works out would change everything. All the need is a good high energy upper stage for interplanetary.
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RE: Nasa Studies Uranus And Neptune Orbiters

Fri Aug 28, 2015 11:59 pm

Quoting rwessel (Reply 14):
The ~$18.4B NASA budget is about .1% of the ~$18.1T US GDP, not .001%.

I meant the EU not the US. I don't think even 1% is that crazy for the USA and it was more than that during Apollo I am pretty sure.
 
rwessel
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RE: Nasa Studies Uranus And Neptune Orbiters

Sat Aug 29, 2015 1:01 am

Quoting KarelXWB (Reply 15):
How about slingshots in the opposite direction? Per Wikipedia:

Slowing down in the vicinity of Uranus is the issue. If you don't mind slowing down at Jupiter, and significantly extending your cruise time... In the case of Messenger, they used a reverse slingshot past Mercury a couple of times (or was it three?) to slow down, but then took another loop around the sun before the next encounter. You certainly *could* do that at Uranus, it would just take about 84 years per loop around the sun (as opposed to a few months at Mercury).

Quoting solarflyer22 (Reply 17):
I meant the EU not the US. I don't think even 1% is that crazy for the USA and it was more than that during Apollo I am pretty sure.

IIRC, the peak NASA/Apollo budget was in 1966, and as a fraction of GDP that was a bit under .75%. It was also about 4.4% of the entire federal budget.

As to "crazy"... I'm a long time critic of the manned space program - it's provided (in relative terms) very modest returns for the vast sums spent. The unmanned program (although repeatedly strangled to fund the manned program), has had a *much* better return on investment.
 
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DeltaMD90
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RE: Nasa Studies Uranus And Neptune Orbiters

Sat Aug 29, 2015 3:38 am

Quoting rwessel (Reply 18):
As to "crazy"... I'm a long time critic of the manned space program - it's provided (in relative terms) very modest returns for the vast sums spent. The unmanned program (although repeatedly strangled to fund the manned program), has had a *much* better return on investment.

Oh boy, this is a heated debate among many smart, smart people. I tend to agree with you. If I had my way we could do it all... science and exploration would thrive. Unfortunately, we have to allocate resources, and as you put it, unmanned programs are much cheaper. Cheaper but just about as enlightening IMO. And cheaper=more room for other projects

That being said, I'm not 100% in either camp, just as I'm sure you're not. We should still set up for a manned exhibition, just don't slash everything else in the meantime to do it
 
solarflyer22
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RE: Nasa Studies Uranus And Neptune Orbiters

Sat Aug 29, 2015 6:59 pm

Quoting rwessel (Reply 18):
in relative terms) very modest returns for the vast sums spent.

There are a number of intangible benefits but until the cost of manned flight comes down or is privatized, you can certainly make a strong argument that it doesn't pass a cost/benefit analysis.

Maybe 1% of Federal Budget is more appropriate. 4.4% is too much.

Quoting rwessel (Reply 18):
It was also about 4.4% of the entire federal budget.

I'm fine using more money for unmanned travel especially if we can return gas or material back home for study. It would be huge tourist draw too.

But again, we blew $1 Trillion in Iraq in 10 years. That would have funded a manned Mars missions and advanced technology and science hugely. So let's avoid the colossal budget disasters first.
 
rwessel
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RE: Nasa Studies Uranus And Neptune Orbiters

Sun Aug 30, 2015 5:36 am

Quoting solarflyer22 (Reply 20):
Maybe 1% of Federal Budget is more appropriate. 4.4% is too much.

It's currently running around .5%.

Quoting solarflyer22 (Reply 20):
But again, we blew $1 Trillion in Iraq in 10 years. That would have funded a manned Mars missions and advanced technology and science hugely. So let's avoid the colossal budget disasters first.

To be sure, a dozen $100B vainglory projects like Apollo or a trip to Mars would be better the $1T Iraq debacle... At those would actually have *some* ROI, and we'd avoid killing a few hundred thousand people in the process...
 
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RE: Nasa Studies Uranus And Neptune Orbiters

Mon Aug 31, 2015 2:31 am

Quoting KarelXWB (Reply 15):
How about slingshots in the opposite direction?

The problem is that there are no other planets out there to provide gravitational slingshot.

It is not like the inner solar system which is so crowded with planets that we can often fly from one planet to another in a year or so.

The last chance of braking for Neptune is Uranus, and it is still a very long way to go from Uranus' orbit to Neptune.

Using Uranus for optimal braking for Neptune orbit insertion means some 10-20 years travel time from Uranus to Neptune.

And it lasts another 50 or 60 years before Uranus and Neptune are in relative positions making such a journey possible.

I am not very optimistic about Uranus and Neptune orbiters in our lifetime, at least not mine. Uranus could be an option, but Neptune is just too far away. With the money available, and today's technology, a trip to Neptune could take 40 or 50 years, and then it is better to wait 30 years for a superior 100 lbs fast spacecraft instead of sending a present day 1000 lbs spacecraft.
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solarflyer22
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RE: Nasa Studies Uranus And Neptune Orbiters

Tue Sep 01, 2015 1:58 am

Quoting rwessel (Reply 12):
Second both Uranus and Neptune are gas giants and a considerable amount of aerobraking should be possible.

I didn't realize how much speed and time is required but the key really is the deep space engine. This is very solvable problem but I don't know where NASA is in the development of a Ion thruster. It is lighter, builds up a higher speed and can slow it down in time.

The key is the engine. NASA launched Deep Space 1 and 2 with the Ion thrusters and both worked. With a limited amount of electricity (a few watts) and a few pounds of metal you get Ions zooming out the back at the speed of light. The notion of heavy lifting chemicals to simply explode into space to build up speed is not going to cut it for deep space travel on a budget.

https://en.wikipedia.org/wiki/Ion_thruster
 
rwessel
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RE: Nasa Studies Uranus And Neptune Orbiters

Tue Sep 01, 2015 5:42 am

Quoting solarflyer22 (Reply 23):
I didn't realize how much speed and time is required but the key really is the deep space engine. This is very solvable problem but I don't know where NASA is in the development of a Ion thruster. It is lighter, builds up a higher speed and can slow it down in time.

The key is the engine. NASA launched Deep Space 1 and 2 with the Ion thrusters and both worked. With a limited amount of electricity (a few watts) and a few pounds of metal you get Ions zooming out the back at the speed of light. The notion of heavy lifting chemicals to simply explode into space to build up speed is not going to cut it for deep space travel on a budget.

https://en.wikipedia.org/wiki/Ion_thruster

The problem with ion thrusters is the power requirement. DS1 was able to devote 2100W to the ion drive, but that was from solar panels, and it stayed fairly close to the sun, where solar power is useful. New Horizons, powered by a GPHS-RTS (solar being useless much beyond the asteroid belt), had about 250W available at launch, and 200W-or-so by the time it got to Pluto. Yes, you can build bigger RTGs, or use several RTGs to boost available power (the RTG on New Horizons was a spare from Cassini, which had three), but Pu-238 availability is a massive problem. Right now the US stockpile plus short term production available to NASA should be enough to build three 125W MMRTGs (smaller than the GPHS-RTGs), like the one on Curiosity, in the next five or six years, and one of those is already allocated to the planned 2020 Mars Rover (and that's literally it). Most of NASA's Pu-238 over the last couple of decades was purchased from Russia, but they're pretty much out too, and no longer selling it either.

Very limited Pu-238 production has been restarted, and over the next few years there is some hope that we can get to the point of producing 1-2 kilograms per year. Note that a (250W) GPHS-RTG needs nearly 10kg of Pu-238, while the smaller MMRTG needs only half that. So if you wanted 1000W for an ion thruster, you'll need the planned/hoped-for production for the next 25-or-so years.

So ion thrusters are great, you just need to figure out how to power them. An actual nuclear reactor (as opposed to an RTG) would be plausible, but is likely impossible from a safety/political standpoint. FWIW, The Soviet Union actually new two types of "real" reactors, the BES-5s (2KW) and the TOPAZ (6KW), although both were intended only for (relatively) short terms (on the order of six months - its unclear how practical a multi-decade lifespan for something on that scale would be). The soviets launched a total of 31 BES-5 and two TOPAZ's, and had a number of accidents with them (not least was Kosmos 954, which scattered radioactive contamination over 50,000 square miles of northern Canada). In the mid-sixties, the US launched a single experimental SNAP-10A reactor, which produced some 600W, before failing after some 43 days (although the failure was not directly related to the reactor). All three of those were fueled with U-235, which at least has the advantage of reasonable availability (FWIW, the BES-5s used about 50kg of U-235 - reactors that small are horribly inefficient users of U-235 - a typical gigawatt-class PWR has about 100t of Uranium total, about 3% of which will be U-235).

Even if you assumed a very small ion thruster, you've still got a very limited power budget to work with - you have to run the rest of the spacecraft as well as the engine. And smaller ion thrusters tend to have lower ISPs, so you're increasing your fuel/mass requirements, which will impact your launch costs and the amount of time you need to slow down.

Again, this is not impossible, it's just very difficult to see how we get there.

Oh, and exhaust velocities are nowhere near the speed of light, typically in the 20-50km/s range.


*The exact amount available for all uses is unclear, but is unlikely to be more than twice the ~12kg (plus a kg or two of new production) available to NASA (note that NASA may also be planning to do a bit of stretching with decayed "old" Pu-238 as well, a limited amount of which is available).

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