Does the space shuttle have any on board fuel tanks?

Question

Hi. I don't think that the shuttle orbiter is capable of firing its main engines after it ditches it's external tank but my science teacher thinks otherwise. Shes' wrong, aint' she?

Answer 1

The shuttle has 3 main engine systems. The Solid Rocket Boosters (SRBs), which are the most powerful single rocket engines ever built, are used to get the orbiter started in it's ascent to orbit. They use Ammonium Perchlorate Composite Propellant (APCP), which is a solid (hence the name) as a fuel. Once ignited, they cannot be shutdown. They last for about 2 minutes after which they are jettisoned and recovered.

On the shuttle itself are the SSMEs or Space Shuttle Main Engines. These are the three large engine bells you are familiar with. They burn a mixture of liquid hydrogen and liquid oxygen, which is all stored in the orange external tank. They fire for the full 8+ minute duration of the ascent to orbit. After being shut down, they cannot again be re-ignited, and the external tank is jettisoned, and any remaining fuel in the system is purged. These engines will not (and cannot) be used again for the duration of the mission.

The third engine system is the OMS, or Orbiter Maneuvering System. These are the two smaller engine bells you see on the rear of the shuttle. These use the hypergolic propellant combination of Monomethyl Hydrazine and Nitrogen Tetroxide. When these two materials come into contact with each other, they ignite, requiring no external ignition source. They are stored in seperate tanks on board the orbiter itself. Hydrazine is very toxic however, and this is why there is a lot of saftey precautions taken when safing the vehicle after landing.

The OMS engines are used for on-orbit maneuvers (along with the smaller RCS engines). Sometimes they are used during part of the ascent (called an OMS-assist). They are used to perform final orbit insertion and also to adjust orbits for interception of other orbiters like the space station or another satellite. They are also used for de-orbit. Unlike what a previous answerer said, the shuttle does indeed turn around to a retrograde direction (facing away from the direction of orbit) to fire the OMS engines for around a minute or so to perform the de-orbit maneuver that will send the shuttle into the atmosphere about 30 minutes later. After this burn is performed, it will return to a prograde direction and prepare to assume the re-entry profie.

So you are right, the main engines are not used after the ascent is completed. The shuttle does not keep the fuel required for those engines on board (it's contained entirely in the external tanks), and it has no way to ignite those engines in orbit anyway.

Answer 2

Well the Space shuttle main engines stop once the ditch the tank. To get the rest of the way into space and to slow themselves down for re-entry the shuttle uses it's OMS Engines pods, they are the two little engines sitting on either side of the top most main engine and they have a separate fuel tank from the main engines. Other then that they use RCS thrusters to maneuver the the craft in orbit.

~D

Answer 3

Your teacher and the first poster is wrong.

The three big SSMEs (Space Shuttle Main Engines) cannot fire after the big rust-colored external tank is jettisoned.

What the shuttle uses to maneuver in space are the low-power OMS (Orbital Maneuvering System) thrusters, and they are a completely separate system. The OMS consists of the two smaller nozzles above the three SSME thrusters on the back, plus thrust ports on the sides of the OMS nacelles, and sides and top of the nose.

The shuttle DOES NOT flip over backwards to fire the rear engines for re-entry. The retro-rockets used for re-entry is also on the nose below the cockpit windscreens. That way, the shuttle can enter the atmosphere with its heatshield pointed in the right direction.

The OMS carries its own fuel supply yes, but the amount used by the OMS is tiny compared to what the SSMEs burn to get the shuttle into space.

Hope this helps.

Answer 4

Yes, she's wrong. The shuttle does, however, have onboard fuel tanks, which fuel the orbital maneuvering system, the two smaller rocket nozzles above and outboard of the main engines. Other tanks fuel the attitude control rockets, which orient the ship in the direction it must face for various on-orbit tasks, such as deploying satellites, docking with ISS, and so forth. Sounds like you're not getting a very good education in science. What a pity. You'll just have to educate yourself, but it appears you're already doing so. BTW, AZ imagined is completely wrong- you win.

Answer 5

The big red tank is the fuel tank which after separation falls away and is burnt up by atmospheric friction. The solid fuelled rockets are the only things that are reused after falling back into the ocean.

Answer 6

I'm certain that it has fuel tanks for every one of its retro rockets and minor adjustment rockets; the big ones, I'm not sure. I do know that there is a medium engine on the stern next to the huge engines.
Actually, I'm certain that the orbiter fires its rear rockets when it is entering the atmosphere backwards and upside down; they are necessary for slowing it down from orbital velocity so that, once entering the atmosphere, friction heat is minimal.

Answer 7

How then does the Shuttle propel itself to final approach with a glide speed of ~165 KTS without engines. Watch this video. https://www.youtube.com/watch?v=sjNLcVbTXjk

Answer 8

Your teacher is correct...you lose.

In fact, the shuttle fires its main engines in order to come back to Earth.