Max Q
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Why couldn’t the space shuttle fly to the moon ?

Fri Jul 26, 2019 7:29 am

The space shuttle had an enormous cargo
bay that could carry a large, heavy payload


Enough room for sufficient fuel for a round
trip to the moon and storage space for a lunar lander that could be accessed through an air lock from the flight deck


This lunar lander could be undocked from the cargo bay using the remote manipulator arm, descend to the moons surface, perform the mission then return to the orbiter, once again using the RMA to
dock


Then back to earth


Far fetched ? why not ?
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Armadillo1
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Re: Why couldn’t the space shuttle fly to the moon ?

Fri Jul 26, 2019 7:48 am

Max Q wrote:

Enough room for sufficient fuel for a round

please show us your calculations about how much fuel needed .

Shuttle itself is a 100t dead weight. thats why its a stupid idea from beginning.
 
zanl188
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Re: Why couldn’t the space shuttle fly to the moon ?

Fri Jul 26, 2019 9:34 am

Thermal protection system not designed for lunar return reentries. It would burn up. Fuel required to brake into low earth orbit would be prohibitive from a weight standpoint.
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Max Q
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Re: Why couldn’t the space shuttle fly to the moon ?

Fri Jul 26, 2019 10:25 am

zanl188 wrote:
Thermal protection system not designed for lunar return reentries. It would burn up. Fuel required to brake into low earth orbit would be prohibitive from a weight standpoint.



That makes a lot more sense, re-entry velocity from a moon return would be much higher than earth orbit


Which raises your second point, retrofire braking to slow the orbiter consuming too much fuel

However, if an improved thermal protection
system were developed and installed?
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aumaverick
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Re: Why couldn’t the space shuttle fly to the moon ?

Fri Jul 26, 2019 1:08 pm

Max Q wrote:
zanl188 wrote:
Thermal protection system not designed for lunar return reentries. It would burn up. Fuel required to brake into low earth orbit would be prohibitive from a weight standpoint.



That makes a lot more sense, re-entry velocity from a moon return would be much higher than earth orbit


Which raises your second point, retrofire braking to slow the orbiter consuming too much fuel

However, if an improved thermal protection system were developed and installed?


If the engineers at NASA couldn't develop a better thermal protection system for basic re-entry, I suspect they would have little to no chance of developing a system capable of the increased thermal load for a higher velocity re-entry involved with a moonshot, much less a system robust enough to make it reusable.
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GalaxyFlyer
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Re: Why couldn’t the space shuttle fly to the moon ?

Fri Jul 26, 2019 1:43 pm

It’s about payload—Apollo 15’s Saturn V lifted 312,000 pounds of load into LEO. The heaviest Shuttle load was about 30,000 pounds.

GF
 
mxaxai
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Re: Why couldn’t the space shuttle fly to the moon ?

Fri Jul 26, 2019 4:22 pm

GalaxyFlyer wrote:
The heaviest Shuttle load was about 30,000 pounds.

GF
Actually over 50,000 pounds (Chandra).


Now for some quick maths ...
The ideal rocket equation gives us a straightforward answer how much delta-V we can get by filling the space shuttle's payload bay with fuel. I'm gonna assume here that we'll be mass limited, not volume limited, although the low density of hydrogen means that the latter is most likely to be the case.
With an empty mass of 78 tons, and a maximum payload mass to LEO of 27.5 tons (per wikipedia), the available delta-V in LEO would be 1.34 km/s. In LEO, the space shuttle will orbit at around 7.8 km/s. It needs to reach >10.8 km/s to get into a free-return trajectory around the moon, i. e. the required delta-V is 3.0 km/s. Getting into a low lunar orbit or landing will cost you extra.

In other words, the Shuttle would fall short of the required delta-V by over 50 %. You'd have to significantly beef it up to get it to the moon.

Why couldn’t the space shuttle fly to the moon ?
- It can't carry enough fuel to get there.
 
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Aesma
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Re: Why couldn’t the space shuttle fly to the moon ?

Fri Jul 26, 2019 7:27 pm

You send the bare shuttle in orbit (well not bare, but with everything it needs, and all the fuel possible, and the crew), then you find a way to send an external tank in orbit (strap 4 or 6 boosters to it ?) and assemble the two, and that should do it.

The real question is why ? The Shuttle is a space truck, if you send it to the Moon, you would expect it to bring cargo back. So you'd need even more fuel ! Better to design a spacecraft specifically for that mission.
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flyingturtle
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Re: Why couldn’t the space shuttle fly to the moon ?

Fri Jul 26, 2019 8:35 pm

And the Space Shuttle's SSME engines were built for the ascent to LEO. They're not vacuum-optimized.

It would be more worthwhile to build a ferry that can't withstand atmospherical reentry, and just commutes between earth and moon orbits. Maybe some gentle atmospherical braking, but not more.
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JayinKitsap
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Re: Why couldn’t the space shuttle fly to the moon ?

Fri Jul 26, 2019 10:04 pm

The Saturn V had enough to lift the Apollo capsule, lunar module and the stage to lift the capsule out of the moon orbit. The size of the module or extra fuel to just lift the shuttle out of Lunar orbit would be far bigger. I guess we could use a pair of Saturn V's along with a really large fuel tank to get the shuttle there and back. What is a couple Trillion dollars between friends.
 
Max Q
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Re: Why couldn’t the space shuttle fly to the moon ?

Sat Jul 27, 2019 7:02 am

Excellent answers and interesting perspectives, thanks for that
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opticalilyushin
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Re: Why couldn’t the space shuttle fly to the moon ?

Sat Jul 27, 2019 7:50 am

What a shame the Shuttle-C project was cancelled, it could have provided some heavy muscle into orbit.

Thinking outside the box, perhaps a mini shuttle to get into orbit (the original shuttle should have never been as big and heavy as it was, IMO), dock with the ISS, and connect to a CSM-like reusable manned spacecraft, fly out to the moon, dock up with a reusable single stage lunar module left in orbit by the previous mission, fuelled in orbit from the CSM, undocks, lands, plants the flag, gets some moon cheese samples, launches, then left in orbit while the CSM returns to the ISS in LEO, lunar samples transferred to the mini shuttle, return to earth and break out the ticker tape parade? Good idea or bad? :)
 
GDB
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Re: Why couldn’t the space shuttle fly to the moon ?

Sat Jul 27, 2019 9:13 am

opticalilyushin wrote:
What a shame the Shuttle-C project was cancelled, it could have provided some heavy muscle into orbit.

Thinking outside the box, perhaps a mini shuttle to get into orbit (the original shuttle should have never been as big and heavy as it was, IMO), dock with the ISS, and connect to a CSM-like reusable manned spacecraft, fly out to the moon, dock up with a reusable single stage lunar module left in orbit by the previous mission, fuelled in orbit from the CSM, undocks, lands, plants the flag, gets some moon cheese samples, launches, then left in orbit while the CSM returns to the ISS in LEO, lunar samples transferred to the mini shuttle, return to earth and break out the ticker tape parade? Good idea or bad? :)


You are not kidding, Robert Zubrin has pointed out that in 1988, his team at Martin Marietta started designing a version of STS-C, with what he call a 'decent upper stage, unlike SLS', with the 3 x SSME's and SRB's from STS, with the intention of starting flying in the mid 1990's.
But it goes back way further, I have or had, a Spaceflight Magazine (the official B.I.S. publication), dated March 1975, which included an article by a NASA engineer, which showed an early STS-C concept, 3 or 4 engines clustered on a longer, thinner body where the Shuttle would usually be. With what looked like an Apollo CSM like vehicle on top in one illustrated version, though it was a basic concept drawing.
SLS is essentially a STS-C, though in the hands of contractors who do not have a good record on delivery timescales or cost, though in part lack of a clear mission, until recently, has also been a factor.
 
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Aesma
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Re: Why couldn’t the space shuttle fly to the moon ?

Sat Jul 27, 2019 1:59 pm

The concept of the shuttle is now proven to be a bad idea. SpaceX (and others) provide true reusability of ALL components, and will get people in orbit/to the ISS.
New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
 
zanl188
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Re: Why couldn’t the space shuttle fly to the moon ?

Sat Jul 27, 2019 2:33 pm

Max Q wrote:
zanl188 wrote:
Thermal protection system not designed for lunar return reentries. It would burn up. Fuel required to brake into low earth orbit would be prohibitive from a weight standpoint.



That makes a lot more sense, re-entry velocity from a moon return would be much higher than earth orbit


Which raises your second point, retrofire braking to slow the orbiter consuming too much fuel

However, if an improved thermal protection
system were developed and installed?


Another thought on the reentry equation. Getting to a specific airfield from lunar orbit, without first braking into low earth orbit, would require a very specific trans earth injection burn and lunar orbit parameters. Might limit mission operations.

Apollo, on the other hand, only had to target a specific ocean and had the option to move recovery forces wherever the spacecraft needed to go.
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Max Q
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Re: Why couldn’t the space shuttle fly to the moon ?

Sun Jul 28, 2019 3:03 am

zanl188 wrote:
Max Q wrote:
zanl188 wrote:
Thermal protection system not designed for lunar return reentries. It would burn up. Fuel required to brake into low earth orbit would be prohibitive from a weight standpoint.



That makes a lot more sense, re-entry velocity from a moon return would be much higher than earth orbit


Which raises your second point, retrofire braking to slow the orbiter consuming too much fuel

However, if an improved thermal protection
system were developed and installed?


Another thought on the reentry equation. Getting to a specific airfield from lunar orbit, without first braking into low earth orbit, would require a very specific trans earth injection burn and lunar orbit parameters. Might limit mission operations.

Apollo, on the other hand, only had to target a specific ocean and had the option to move recovery forces wherever the spacecraft needed to go.



Very interesting, thanks for that
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RJMAZ
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Re: Why couldn’t the space shuttle fly to the moon ?

Sun Jul 28, 2019 4:14 am

I believe a modified shuttle could definitely have done a moon landing.

The only problem would have been filling most of the cargo bay with fuel would have more than doubled the shuttles weight. The mounts that hold the shuttle to the boosters would have haf to be made stronger.

The shuttle could easily fit the lander and an 100,000kg of extra fuel in the cargo bay. Bringing the total shuttle takeoff weight to around 250,000kg. Compared to the command and service module the shuttle would weigh more than 10 times the weight. It would require a rocket so much bigger than the Saturn V.
 
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AirlineCritic
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Re: Why couldn’t the space shuttle fly to the moon ?

Sun Jul 28, 2019 10:02 am

RJMAZ wrote:
I believe a modified shuttle could definitely have done a moon landing.


"The shuttle glides onto a smooth landing on the Sea of Tranquility"

(Seems silly to carry those mighty wings to another planetary body. Particularly, as SpaceX has shown, they not particularly necessary on earth side either.)
 
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flyingturtle
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Re: Why couldn’t the space shuttle fly to the moon ?

Sun Jul 28, 2019 10:26 am

...I have a great idea... let's detach these wings, and leave them in earth orbit...
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Max Q
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Re: Why couldn’t the space shuttle fly to the moon ?

Mon Jul 29, 2019 12:51 am

AirlineCritic wrote:
RJMAZ wrote:
I believe a modified shuttle could definitely have done a moon landing.


"The shuttle glides onto a smooth landing on the Sea of Tranquility"

(Seems silly to carry those mighty wings to another planetary body. Particularly, as SpaceX has shown, they not particularly necessary on earth side either.)



Just to be clear, that wasn’t my concept


My thinking was to use the orbiters capacious cargo bay to carry a lunar lander
that could be removed and then re-stowed
using its remote manipulator arm


The Shuttle would be a ‘mother ship’ so to speak


Unfortunately, but accurately, other posters have pointed out the flaws of the overall idea !
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RJMAZ
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Re: Why couldn’t the space shuttle fly to the moon ?

Mon Jul 29, 2019 1:57 am

AirlineCritic wrote:
RJMAZ wrote:
I believe a modified shuttle could definitely have done a moon landing.


"The shuttle glides onto a smooth landing on the Sea of Tranquility"

I thought it was pretty clear that the shuttle itself would not land on the moon.
RJMAZ wrote:
The shuttle could easily fit the lander and an 100,000kg of extra fuel in the cargo bay.

Basically the shuttle allows for the service module, control module and lander parts on the Apollo program to be completely reused. Plus it can land at a runway instead of the ocean with multiple support ships.

The first and second stage booster would have to be so many times larger that this would cancel out the cost savings. Plus the second stage booster will probably burn up.
 
estorilm
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Re: Why couldn’t the space shuttle fly to the moon ?

Mon Jul 29, 2019 1:20 pm

GalaxyFlyer wrote:
It’s about payload—Apollo 15’s Saturn V lifted 312,000 pounds of load into LEO. The heaviest Shuttle load was about 30,000 pounds.

GF

Exactly - and Saturn needed every pound of that to complete the mission, shedding whatever it could at various mission points along the way. Your net capsule at the end of the mission weighs nothing, and was easy / simple / safe for re-entry.

Huge missions like this have zero requirement for reusability, it just makes everything more complicated, expensive, and less safe.

Let's say someone held a gun to your head and made you come up with a solution. You'd literally need to launch a second "auxiliary" shuttle main external tank into LEO, dock with it, and somehow slingshot yourself out of LEO into some type of TLI trajectory to the moon. I have absolutely no clue if the physics of accelerating something with the mass of the shuttle out of LEO into a lunar orbit is even possible.

I will say, life on board the shuttle on the way to the moon would be rather luxurious compared to the Apollo missions!

FWIW, by the time you fire for your return, you'd require at least a few of the RS-25's to fire three times, which has never been done before. From what I gather that wouldn't be a big deal though (and the nice thing in this case is that they gimbal - you probably only need one for TLI and return, so there's plenty of redundancy if you have a failure to fire, etc once in orbit - any of the engines could probably gimbal and put you on a correct path with RCS inputs.)

As others have said though, you'd have to slow the thing down big time.

Maybe physics majors could answer this, but what if you just slowed down the return speed BIG TIME and allowed them two or so weeks on return? Is there any way to re-enter an orbit around the earth?

If you had enough fuel, you could technically turn the shuttle around and fire a few RS-25's (for a fourth time!) to slow the shuttle down almost completely; either for re-entry, or docking with the ISS, re-entering orbit, etc.
 
GDB
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Re: Why couldn’t the space shuttle fly to the moon ?

Mon Jul 29, 2019 3:56 pm

Surely this is where Mr Musk and his very big booster and Starship comes in.
If it works and Space X seem totally serious about this, Saturn V style capability, fully reuseable.
 
opticalilyushin
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Re: Why couldn’t the space shuttle fly to the moon ?

Mon Jul 29, 2019 7:15 pm

It all boils down to whether you think it's better to use 1 almighty ship, with 'all the bells and whistles' that can do everything, or several smaller ships, for example 1 to get into orbit and to return to earth, one to land on the moon, and possibly one to get you there (think an Apollo CSM, but potentially without re-entry capability). Smaller ships are easier to get into space, to keep in space and easier to re-use, provided there is an efficient way to get fuel up there!

The shuttle wasn't ideal, in hindsight it was a super expensive 99 ton glider, which shouldn't have had military intervention to carry 25 ton satellites at the design phase. Unmanned vehicles, whether rockets or shuttles will always be cheaper to run, and lighter in weight than manned ones. I quite like the Sierra Nevada mini shuttle design, I think that's what space agencies should have focused on.
 
WIederling
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Re: Why couldn’t the space shuttle fly to the moon ?

Tue Jul 30, 2019 7:29 am

Max Q wrote:
My thinking was to use the orbiters capacious cargo bay to carry a lunar lander


For Apollo the mission from LEO ( Saturn post second stage staging orbit ) to
Luna Transfer speeds took about 2t of fuel per t of vehicle mass for delivery to Moon orbit.
( handled by the Saturn IV-B third stage.)

there are some nice graphs around that show the various delta_v requirements
for moving around the solar system:
https://external-preview.redd.it/U5iH7h ... _SkLLk.png
Murphy is an optimist
 
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Aesma
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Re: Why couldn’t the space shuttle fly to the moon ?

Tue Jul 30, 2019 9:32 am

This thread wasn't ambitious enough, I propose to use the ISS instead !

I think someone has already worked on the idea to put it in Lunar orbit.
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flyingturtle
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Re: Why couldn’t the space shuttle fly to the moon ?

Tue Jul 30, 2019 11:46 am

WIederling wrote:
there are some nice graphs around that show the various delta_v requirements
for moving around the solar system:
https://external-preview.redd.it/U5iH7h ... _SkLLk.png


Here a link that works:

https://www.explainxkcd.com/wiki/index. ... vity_Wells

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william
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Re: Why couldn’t the space shuttle fly to the moon ?

Thu Aug 01, 2019 4:14 am

opticalilyushin wrote:
It all boils down to whether you think it's better to use 1 almighty ship, with 'all the bells and whistles' that can do everything, or several smaller ships, for example 1 to get into orbit and to return to earth, one to land on the moon, and possibly one to get you there (think an Apollo CSM, but potentially without re-entry capability). Smaller ships are easier to get into space, to keep in space and easier to re-use, provided there is an efficient way to get fuel up there!

The shuttle wasn't ideal, in hindsight it was a super expensive 99 ton glider, which shouldn't have had military intervention to carry 25 ton satellites at the design phase. Unmanned vehicles, whether rockets or shuttles will always be cheaper to run, and lighter in weight than manned ones. I quite like the Sierra Nevada mini shuttle design, I think that's what space agencies should have focused on.


The Sierra Nevada Shuttle is DOA I believe.

Great topic, have wandered this myself. Thank you for the replies. The short answer, the shuttle does not have the rocket power to sling shot to the moon. That slowing down thing coming back is a problem too, though I guess they could fly it backwards and use the aux engines to do it.
 
zanl188
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Re: Why couldn’t the space shuttle fly to the moon ?

Thu Aug 01, 2019 9:57 am

estorilm wrote:

Maybe physics majors could answer this, but what if you just slowed down the return speed BIG TIME and allowed them two or so weeks on return? Is there any way to re-enter an orbit around the earth?



Not enough hydrogen & O2 aboard to keep fuel cells running that long. Some shuttles had the capability to take additional H & O2 tanks along in the payload bay, however that space is already occupied by the lander and fuel/oxidizer tanks. Maybe H & O2 from propulsion system could be used in fuel cells. I believe fuel cells used H & O2 as a gas vs RS-25s which expect liquids.

Speaking of which... Has anyone thought about maintaining H & O2 in liquid form in the payload bay for extended periods?
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estorilm
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Re: Why couldn’t the space shuttle fly to the moon ?

Thu Aug 01, 2019 4:14 pm

zanl188 wrote:
estorilm wrote:

Maybe physics majors could answer this, but what if you just slowed down the return speed BIG TIME and allowed them two or so weeks on return? Is there any way to re-enter an orbit around the earth?



Not enough hydrogen & O2 aboard to keep fuel cells running that long. Some shuttles had the capability to take additional H & O2 tanks along in the payload bay, however that space is already occupied by the lander and fuel/oxidizer tanks. Maybe H & O2 from propulsion system could be used in fuel cells. I believe fuel cells used H & O2 as a gas vs RS-25s which expect liquids.

Speaking of which... Has anyone thought about maintaining H & O2 in liquid form in the payload bay for extended periods?

Yeah I was thinking H/o2 would need to be lifted into LEO separately, but really it shouldn't require too much extra fuel.

Now that you mention it, I don't think you would be able to keep either in liquid state on a long duration mission.

Why don't they just use the OMS rockets on the back? That's what they're designed for, as they're hypergolic.

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