Manned Space Missions

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Discussion

Zaxxon

4,057 posts

161 months

Saturday 6th August 2011
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Why not launch components of a craft that can be assembled and launched from the ISS? It would not need streamlining, could weigh more and could practice manouevers to and from deep space.

Eric Mc

Original Poster:

122,055 posts

266 months

Sunday 7th August 2011
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speedtwelve said:
The lunar Saturn V also weighed 1000 tonnes more than the max take-off weight of the shuttle. Shuttle stack power/weight ratio was a good bit better than the Saturn V. The Shuttle was already doing 100mph by the time it cleared the tower, which I always thought was quite impressive for something so heavy.
For all it's 7.5 million lbs of thrust, the five F1 engines of the Saturn V were burning relatively low energy propellants - liquid oxygen and kerosene. The Shuttle was burning liquid oxygen and liquid hydrogen - plus the solids.

John_S4x4

1,350 posts

258 months

Sunday 7th August 2011
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I always liked the OTRAG project

http://www.astronautix.com/lvs/otrag.htm

Simpo Two

85,543 posts

266 months

Sunday 7th August 2011
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John_S4x4 said:
I always liked the OTRAG project

http://www.astronautix.com/lvs/otrag.htm
Interesting. Makes you wonder how many other good ideas have been killed off by politics. Most if not all I suspect.

Eric Mc

Original Poster:

122,055 posts

266 months

Sunday 7th August 2011
quotequote all
bus pass said:
Eric Mc said:
the shuttle hardly ever exceeded 300 miles
Any idea what the highest the Shuttle ever reached Eric, or high high / far it could have gone?

And why couldn't it have gone further?
A quick Google seems to indicate that the Hubble related missions were the highest. Hubble orbits at 385 miles. I have a dim memory that one mission went to around 500 miles but I canot see any reference to it. Technically the Shuttle could get as high as 600 miles, but with a very limited payload.

The limit was due to weight. The Shuttle needed all that power just to lift itself because, as I said, a lot of the Shuttle's basic structure was totally uneccessary for spaceflight - wings, tailfin, undercarriage, weight for landing systems etc were all "dead" weight as far as geting into space was concerned.


Columbia was so heavy it couldn't actually get to the ISS.

The other limitation on the Shuttle was having orbital inclinations greater than 50 degrees to the equator. To get away from an orbit that is set at Cape Canaverals latitude needs extra power and/or lower payload. The highest ever angle of inclination ever achieved by the Shutle was 62 degrees - and that was on a military mission so we don't even know what the payload was.

It was planned to launch Shuttles into 90 degree polar orbits from Vandenberg Air Force Base in California. To achieve the necessary payload weights, specially lightened Solid Rocket Boosters were designed. After Challenger, the lightweight boosters were abandoned as were any plans for launches from Vandenberg.

Eric Mc

Original Poster:

122,055 posts

266 months

Sunday 7th August 2011
quotequote all
Simpo Two said:
John_S4x4 said:
I always liked the OTRAG project

http://www.astronautix.com/lvs/otrag.htm
Interesting. Makes you wonder how many other good ideas have been killed off by politics. Most if not all I suspect.
OTRAG was a very strange project - set up by oddball Germans and funded by an African dictator - very strange.

funkyrobot

18,789 posts

229 months

Monday 8th August 2011
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Eric Mc said:
There are alternatives and they are being worked on and tested.

For getting off the surface of the earth and into earth orbit, rockets work best and are (fairly) reliable.

Once in space, there are a couple of options. The best alterntive to old fashioned chemical rockets is ion drive. A number of space probes have used this technique already and it works well. Expect to see more ion drive spacecraft over the next few decades.
This Ion spacecraft recently achieved orbit around an asteroid (sorry if this has already been mentioned):

http://dawn.jpl.nasa.gov/mission/spacecraft.asp

It's quite interesting reading about how it got there. The engine never stopped and would increase the acceleration by a tiny amount every day (equal to the force it would take to push a feather). This meant that the spacecraft could be controlled all the way to the asteroid, rather than propelling it and making alterations. It has just sent back some nice pics too. smile

Eric Mc

Original Poster:

122,055 posts

266 months

Monday 8th August 2011
quotequote all
funkyrobot said:
This Ion spacecraft recently achieved orbit around an asteroid (sorry if this has already been mentioned):

http://dawn.jpl.nasa.gov/mission/spacecraft.asp

It's quite interesting reading about how it got there. The engine never stopped and would increase the acceleration by a tiny amount every day (equal to the force it would take to push a feather). This meant that the spacecraft could be controlled all the way to the asteroid, rather than propelling it and making alterations. It has just sent back some nice pics too. smile
Yep - I started a thread just after it got there -


http://www.pistonheads.com/gassing/topic.asp?h=0&a...