Expert: Jayendra Upadhye - 1/11/2008

Question
hi there.are comets made up of rock ,ice,ground?if yes,they got water to travel farther away from earth.why doesn't nasa travel farther away from earth with spaceships?
thank you
greg

Answer
Hi,
I will rephrase your question and try to answer it.
1 - Comets are made of ice , rock.
2 - If yes, it means water is available in the farthest reaches of the solar system.
3 - Why doesnt Nasa use this fact and send space ships far away?

Well answers are many.
1 - Waste Recycling! It is a stupendous excercise ..recycling limited resources indefinitely, so as to keep a crew "hale and hearty" over long voyages.
  the earth has its oxygen cycle / Co2 cycle / Nitrogen cycle & so on.
  But we cannot implement these large scale processes that are in the end driven by the sun.
  Though chemically waste has been recycled successfully with SOME success.
2 - Food! Humans dont live only on Oxygen and water! Long duration voyages would mean that food would have to be grown / generated out of waste organic material again and again and again! Current technology isnt THAT advanced for that to happen.

3 - Last of all...how to keep the crew occupied meaningfully? How to stave off claustrophobia / boredom / aggression /clashes of personality & so on over long voyages where ISOLATION could trigger -ve aspects of human behaviour? (Hence suspended animation as in "AD 2001 A Space Odessey" & "Aliens")...But we havent done that to our space crew s yet..even for testing!!

That is your answer.
Jayen