Rocket Science 101 for Fun?

Question

All Space Shuttle buffs out there.

In the launch phase for the Space Shuttle I've read that the control surfaces on the rear of the orbiter are used along with the engine gimbles to steer the vehicle into orbit.

1.Do they become useless and lock down at a certain altitude?

2.Why are OHMS engines burns used early in the boost phase on some of the recent launches? Could this be due to weight constraints of the payload?

3.If the shuttle were to carry enough OHMS fuel to be able to abort to the ISS from any orbit in an emergency situation, would that extra weight mean such a difference that it could not carry a substancial payload?

Answer 1

yes it is :)

Answer 2

Hi
1 I am under the definite impression that the control surfaces are locked at launch to protect them from vibration damage.

2 The OMS engine allow for 'fine tuning' the steering done by the main engines.

3Most Definitely Yes- the shuttle can be launched in a wide variety of orbits some of which would require a major burn on the main engines to match with the ISS! Any mass that is used for fuel has to come from somewhere, and like with any plane it comes from payload mass.