Could a modified space shuttle get to the moon?

[Frozen_Heart]

The shuttle is designed to left cargo and crew up and down from the surface. Its not a deep space vehicle.

If you removed the main engines, filled the cargo bay with fuel, reduced the wing size (both to compensate for the lighter weight and to remove the unnecessarily large cross range capability), and then launched the whole thing on the SLS then maybe it could free return. The heatshield would need to be improved though.

[MockKnizzle]

Why would you waste all the fuel to haul the shuttle and its fat useless-in-space wings all the way to the moon? It's a super-pointless vehicle for that kind of mission, with capabilities that do not match the mission parameters.

Edited September 17, 2014 by MockKnizzle

[Nuke]

this thread isnt about practicality. in my opinion the only place for the ultimate space plane is for surface to leo transport. id rather have a flying fuel tank and nerva that i could dock to a mission package and refuel for each new mission so long as the reactor remains viable. the only role space planes have in that scenario is as fuel tankers.

Technically, you wouldn't. Though it was never done, the shuttle could have taken the external tank with it into orbit. There were ideas to use the tank for stuff like space stations, but nothing ever came of them.

If it were instead refuelled on-orbit and used as a drop tank, with an additional tank in the payload bay, you'd get something like:

Isp = 450 s (SSME)

Orbiter only:

m0 = 69 tonnes

m1 = 94 tonnes

dV = 1300 m/s

External tank:

m0 = 120 tonnes

m1 = 856 tonnes

dV = 8600 m/s

From a pure delta-V perspective, that could make a trip to lunar orbit and back. Indeed it might be possible to use the payload bay for a lander instead of extra fuel.

Of course there are other complications. The SSME's would need modifying to be restartable, and perhaps increased gimballing to propel the shuttle straight. I'm not sure how much of a problem fuel boiloff during the trip would be.

But worst of all, how are you going to get over 700 tonnes of fuel up there to refill the external tank!

i suppose just doing it the old skool way would work. you could use the oms for ullage to get the main engine going again. that still leaves the refueling problem, the way i do that in ksp is to build a massive tanker rocket and dock with it for refueling. the results are worse than apollo.

i was thinking doing that with a nerva main engine upgrade and moar boosters to offset lh2 consumption during launch. these would be repositioned for balance of course. external tank would need to be much larger since it will all be lh2, which takes up more volume. you also need more so you dont use it all on launch. you might also have an air augmentation duct attached to the nerva to provide more thrust from burning the hydrogen exhaust with atmospheric oxygen. this would be ejected when it no longer provides any useful thrust. the nerva needs to have a wide vertical gimbal range to deal with the larger external tank. you could also throw out the oms to save weight. but we have already done a major refit to the shuttle at this point. since you are hacking up the cargo bay anyway you might as well throw in a fuselage extension to make room for more tankage. then do a half length cargo bay for the lander. since you already did all that why not throw out the shuttle and build a new ship using all the knowledge we got operating the shuttle and other vehicles.

Edited September 17, 2014 by Nuke

[NovaSilisko]

I did this in Orbiter once. With the shuttle in orbit, I edited the scenario to re-attach the external tank and fill it up with fuel again, then performed the TLI and LOI maneuvers by hand. I used to have a screenshot from it in lunar orbit but can't find it anymore...

Edit: Found the save

Edited September 18, 2014 by NovaSilisko

[Nibb31]

The only problem is getting the full 1000 ton external tank to orbit...

[cantab]

I did this in Orbiter once. With the shuttle in orbit, I edited the scenario to re-attach the external tank and fill it up with fuel again, then performed the TLI and LOI maneuvers by hand. I used to have a screenshot from it in lunar orbit but can't find it anymore...

Edit: Found the save

http://i.imgur.com/StozHY0.png

http://i.imgur.com/kPKlzR9.png

Nice. So this suggests then that the SSME's are already capable of propelling the shuttle straight with the ET attached. Which kind of makes sense since that's what happens after the SRB's are dropped in a normal launch, though by that point the ET's half-empty.

[KerikBalm]

this thread isnt about practicality. in my opinion the only place for the ultimate space plane is for surface to leo transport. id rather have a flying fuel tank and nerva that i could dock to a mission package and refuel for each new mission so long as the reactor remains viable. the only role space planes have in that scenario is as fuel tankers.

Indeed, and KSP is realistic enough that this is my conclusion in game as well.

I see a lot of SSTO monstrosities meant to get to far off places and back in a single stage: No thanks.

My SSTOs are never for anything beyond LKO, they could go to Mun... but why?

The only SSTO that I ever send beyond LKO, is for Laythe (and it gets refueled before departing LKO).

Otherwise, its SSTOs lifting mission payloads.

[cantab]

A vehicle capable of a trip to (insert destination here) without refuelling is useful both IRL and in KSP. The complexity and duration of the trip are both reduced. Overall cost may also come down if the vehicle can refuel at its destination from fuel produced there, rather than requiring the fuel to be shipped into a depot somewhere.

[Laie]

But worst of all, how are you going to get over 700 tonnes of fuel up there to refill the external tank!

14 shuttle launches?

.

.

.

.

Alright, alright, that would take years. Or they'd need to recycle the shuttles much faster than they ever did. I wonder if the latter scenario would have made the shuttles any more cost-efficient.

[RW-1]

If one did get another full ET in orbit (or refuelled one taken all the way into orbit) and restarted the SSME's, what would the flight time be compared to Apollo? I was thinking in terms of a proposed mission time vs consumables and crew number. The shuttle could go for a week at least, so I believe that could cover it.

[Kryten]

The same. Apollo used a basic Hohmann transfer; there are a few tricks to get there slower with less delta-v, but try to add more and you'll just miss the moon entirely.

[Mr Shifty]

The same. Apollo used a basic Hohmann transfer; there are a few tricks to get there slower with less delta-v, but try to add more and you'll just miss the moon entirely.

I did a quick calculation which could be way off, but a Hohmann transfer to the moon should take about 5 days; the Apollo missions took 3. A free return trajectory is generally more energetic than a Hohmann transfer, I believe.

Calculation:

Transit Time = Period/2

Period = 2*pi*sqrt(a³/GM)

a = (moon's orbital radius + orbital radius of spacecraft in LEO)/2 = (384,000 km + 6,571 km)/2 = 196,000 km

GM = 398,600 km³/s²

EDIT: I'll note, however, that the difference between a Hohmann transfer and the Apollo 11 TLI is only about 100 m/s.

EDIT2: But the Apollo 11 TLI was actually about 100 m/s less than the Hohmann transfer speed. Huh.

Edited September 18, 2014 by Mr Shifty

[Whirligig Girl]

But what if Nuclear Thermal Rockets?

[Nibb31]

A Space Shuttle modified to use NTRs would no longer be space shuttle. If you had NTRs, you would design a ship around them, not the opposite.

[peadar1987]

But what if Nuclear Thermal Rockets?

I had a look at it earlier:

So say we modified the shuttle to use a NERVA, with an Isp of 850s. That's probably the best we'd realistically get with current/very near future technology.

This link here: http://i.imgur.com/SqdzxzF.png says you need about 7.9km/s to get to lunar orbit and back, call it 7, if you allow some bleeding off of speed by aerobraking.

The space shuttle has a dry mass of 78000kg and a payload to LEO of 24000kg (wikipedia)

Plug those numbers into this website, and you get a maximum delta-V of about 2300 m/s, so even if you filled the entire cargo bay with fuel, you couldn't get to the moon.

What you probably could have done was build a modular spacecraft in orbit that could have gotten to the moon and back, but even that would have been difficult, and horrifically expensive.

Even with NTRs, it wasn't ever going to happen.

[Quokka man da best]

Hi, I know I am 7 years late but what about a modified shuttle with a fuel tank instead of a cargo bay? And at the nose a mini shuttle to land and the shuttle is the CSM and the mini shuttle is the LM. Lol

[RCgothic]

As stated earlier in the thread, the orbiter masses 75 tonnes dry and has an OMS ISP of 312s.

With a bare bones Apollo style excursion lander payload weighing 15t (so that the orbiter remains in LLO) it would take about 340t of propellant to get to the moon and back, (assuming multi-pass aerobraking), 430t from LEO total 

That total is about 3.5 times the best mass to LEO STS ever achieved in service. It would need to be refuelled in orbit.

 

The only craft capable of delivering hundreds of tonnes of propellant to LEO is Starship. Starship will be capable of going to the moon by itself *and landing* for a fraction of the cost of an STS launch.

Starship is what Shuttle wishes it could have been.