Flight Question Rocket question

[Sandpatch]

Hi,
I have a general question which has been bugging me for a while now.
When a rocket launches a payload there has to be a last stage that pushes the payload into orbit, but what happens then when the payload is released? Does the rocket retrofire to burn up or is it simply staying in orbit too?

regards

 

[MJR]

It all depends. For instance, the SRBs are jettisoned at a low altitude, but the ET is jettisoned at a higher altitude. THe ET's orbit eventually deteriorates while the SRBs just fall down.

 

[Hielor]

Hi,
I have a general question which has been bugging me for a while now.
When a rocket launches a payload there has to be a last stage that pushes the payload into orbit, but what happens then when the payload is released? Does the rocket retrofire to burn up or is it simply staying in orbit too?

regards

In general, when the payload is released, the entire stack is not yet in orbit. After payload release, the payload's own engine (in the case of the Shuttle, the OMS engines at the OMS-2 burn) raise the periapsis above the atmosphere; since the last stage before the payload still has its periapsis below the atmosphere, it will burn up before its next orbit.

I think.

 

[Urwumpe]

In some cases, the rocket has retro rockets, which fire to pull the last stage away from the payload. This is pretty common on old ICBMs, as the warheads had no propulsion at all.

 

[Sandpatch]

But what if the payload didn't have their own engines. Does the last stage of the rocket retroburn so it can burn up in the atmosphere, stay in orbit or do all satellites have their own engines to increase the periapsis?

 

[Zatnikitelman]

For a rocket like the DeltaIV, the second stage on a LEO mission can either stay in the release orbit, or it can vent its remaining volatiles in a retrograde direction increasing the likelihood that atmospheric drag will drag it all the way down into the Atmosphere. Stages that put satellites into a Geostationary Transfer Orbiter probably do something similar, it just takes a bit longer for the atmosphere to grab them and drag them on down. When I fly unmanned rockets in Orbiter, I'll typically use whatever fuel is left in the upperstage to de-orbit it, but then again, I'm not that efficient and frequently have LOTS of fuel leftover!

 

[ex-orbinaut]

Hi,
I have a general question which has been bugging me for a while now.
When a rocket launches a payload there has to be a last stage that pushes the payload into orbit, but what happens then when the payload is released? Does the rocket retrofire to burn up or is it simply staying in orbit too?

regards

Yes, it bugged me, too, for a while. I know that at least some boosters are still up there. If you want to know which ones they are and even try and spot them, try this excellent program....

http://www.softpedia.com/progDownload/Orbitron-Download-71763.html

I do not know if that is ALL of them, however...

 

[Sandpatch]

Thanks a lot everybody, this is my curiosity satisfied

Yes, it bugged me, too, for a while. I know that at least some boosters are still up there. If you want to know which ones they are and even try and spot them, try this excellent program....

http://www.softpedia.com/progDownload/Orbitron-Download-71763.html

I do not know if that is ALL of them, however...

Awesome program, I never though of searching for such programs because I didn't think that somebody would do such a program. :speakcool: This will surely take many hours from me
Thanks

 

[Andy44]

In general, the upper stage of the rocket is in roughly the same orbit as the payload at the time of payload seperation. Unlike the space shuttle, most payloads are satellites which do not have lots of thrust, and whose every drop of propellant is precious for the mission, which will last for years in most cases (as opposed to a few days for a shuttle mission).

The upper stages of most modern rockets can usually restart their engine one or more times, and if there is sufficient propellant, it is fairly common practice to do a de-orbit burn once the stage has separated from the payload a sufficient distance, dropping the stage into the ocean somewhere. For many GTO missions, however, the stage may remain in orbit for a lot longer.

In the old days it was common to leave the rocket up there and forget about it. John Glenn's Atlas booster stayed in orbit long after he returned to earth, for example. Atlas had no restart capability, anyway, and Atlas V still doesn't, but the Centaur upper stage used with Atlas on most missions does. As space junk became a concern the practice of de-orbiting has become more common.