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The Question
(Submitted April 19, 1998)
Is a manned trip to Mars and back possible very soon?
The Answer
President Bush directed NASA to plan a human landing on Mars by the year
2020. The Space Exploration Initiative that resulted was soon abandoned
though. The current NASA manned space programs (space shuttle, joint
operations with the Russians on Mir, and the new International Space Station)
are not explicitly directed towards putting humans on Mars. There are a
number of very serious challenges that would require solutions to make such
a journey possible, not the least of which is the tremendous cost involved.
Given the current emphasis on cost cutting, putting humans on Mars seems
an unlikely goal for the near future.
Among the problems that would need to be solved before a human trip to
Mars could take place would be:
1/ It's a two year round trip to Mars by a direct minimum energy orbit each
direction, with a few month's wait at Mars as well. The current world record
for the longest duration in space is about half that time and there are
serious medical problems the Russian cosmonauts have encountered when they
return to Earth (American astronauts have only very recently started long
stays in space on the Mir space station and the current record of six months
set by Shannon Lucid last year: see
http://imagine.gsfc.nasa.gov/docs/features/news/28oct96.html).
The medical problems of returning to Earth will require solutions which
research with Mir and the International Space Station might shed light on.
2/ Fuel. To send people to Mars, you'll need to take everything they need to
get there, and live in space, for two years. That's a lot of material!
A direct approach like that used for the Apollo missions to get to the Moon
(take everything you need and throw it away in pieces as it gets used up)
won't work for Mars: the mass required to get to Mars and back is well
beyond the capability of even the most powerful rockets ever made (which
happen to be the Saturn V rockets used for Apollo). So it certainly require
assembly of the parts in space, with multiple launches to get the components
put up there. This kind of assembly in space has been done essentially only
once before with the construction of the Mir Space Station. The new
International Space Station will also be assembled in pieces in low earth
orbit.
3/ Martian environment. What's it going to be like there? Before putting
astronauts on the Moon, NASA needed to explore the Moon in great detail with
probes sent to the Moon to image it, map its gravitational field, study its
surface, etc. NASA and the Russian Space Agency are both sending a number of
probes to Mars in the coming years to explore the planet. Mars Pathfinder
and Mars Global Surveyor are only the first in a fleet of probes heading to
Mars in the next decade. Answers from these missions about Martian weather
and conditions will be necessary to go to Mars.
So although NASA and other space agencies around the world may not be
currently explicitly trying to send people to Mars, many of the current space
activities will be necessary parts of any effort to go to Mars.
Jesse Allen
for "Ask an Astrophysicist"
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