View Full Version : reentry
2003-Nov-20, 10:57 PM
Does a space craft have a re enter at a certain speed? I know that it has to enter at the right angle but does have to re enter going 17500 mph or can it go slower? ( i'm aware that in order for a craft to get into space that it must go 17500 mph) but if it could return slower? and if it could why doesn't it ( beside the amount of fuel it would use to slow down) I've ask this question to many of my space friend but all they do is like me scratch their heads LOL
Thank you MBPSR1 :unsure:
2003-Nov-21, 12:54 AM
I would like to just add that this is a very good question. Im really anxious to find out the answer myself. Where's Parker at when you need him lol.......
2003-Nov-21, 01:53 AM
I don't think it does... I think various spacecraft have entered the atmosphere at different speeds over the years, depending on their mass...
For example, the Mercury capsules would be far lighter than the Space Shuttle so I can't see them coming in at that speed....
2003-Nov-28, 03:22 PM
DippyHippy, Thank you or the reply back...
Now I relize that the Mercury capsules would be a lot ligther but it still must maintain a speed of 17,500 mph in order to break the gravitional hold that the Earth has on any object, so it really doesn't matter the size of an object trying to get into space the bottom line is a object that is sent into space must be travaling at at least 17500 so the question that I can't figure out is can a object reenter going less than 17500? or is there a reason that I don't understand why it couldn't reenter at a slower speed ( I relize that the amount of fuel to slow the craft down would be alot) but everybody that I have asked this question to really don't know ( like myself) After the shuttle accident I kept thinking why (beside the anmount of fuel needed to slow the shuttle down) do they reenter going so fast ???
Is there a reason??? If not hey NASA slow down...LOL!
Thank you MBPSR1 / Mark
2003-Nov-28, 08:55 PM
A spacecraft could absolutely return at a slower speed, but the only way that would happen is if if slowed its speed down first before entering the Earth's atmosphere, and that would require lots and lots of fuel.
Spacecraft use the Earth's atmosphere to slow them down, so it doesn't require any fuel.
Keep in mind the size of the shuttle's tank are there to get it up to 17,500 mph in the first place, so it would require an equal amount of fuel to slow it back down again. And then the fuel to lift that fuel, etc, etc.
2003-Nov-29, 08:46 AM
Thank you fraser for you reply as well,
Like I mention before beside the amount of fuel that it would require to slow it down would be so great, but I just wasn't sure if a craft HAD to go that fast (for reasons that I didn't know) so If I understood you correctly a craft in space could re enter Earth's atmosphere at a much slower speed and still land safetly, If a cratf could slow down to say 1000 MPH then would the craft still be engulf in the same amount of heat as one travaling at 17500 or would it be alot cooler and safer?
I know this might sound far fetched but couldn't NASA put a refueling station in the Earth's obit so a craft could refuel in order to have enough fuel to slow down,? ( even if it was able to slow down somewhat)
Please excuse my lack of knowledge on this subject but this has been nagging me ever since the shuttle accident...
Thank you for your time MBPSR1 / Mark
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