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Old April 7th 08, 02:41 PM posted to sci.space.moderated
Jeff Findley
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Posts: 5,012
Default When is manned spaceflight preferred?

"Herman Rubin" wrote in message
...
Robots cannot even do a good job of surveying Mars.
Robots cannot think, and if one needs a half hour round
time to communicate, it is necessary to be very careful
near the edge of a cliff or a slope. So robots moving
at one mile per day explore little.


The two Mars rovers are often touted as a pair of cheap, unmanned, missions
able to cover more terrain than a lander. While true, they do move very
slowly. Over the years, they have covered distances that are still very
small when compared to what the Apollo astronauts did in the (obviously
manned) lunar rover.

It's also interesting to note that with a man on the spot, equipment like
the lunar rover can be made a lot "dumber" than an unmanned piece of
equipment. The man in the suit can be the control system, communications
system, and even the maintenance system for the equipment. I believe I
recall one of the rovers getting an improvised fender, installed by an
astronaut on the spot. That's more than a bit difficult to do remotely.

Here's a reference (I love Google):

http://www.lpi.usra.edu/lunar/missio...7/surface_opp/

The above shows a nice "traverse map" showing how far the Apollo 17
astronauts were able to travel with the lunar rover as well as a close up
picture showing the "repaired" fender.

The other thing to note about manned missions is that you typically plan on
bringing the astronauts back at the end of the mission, so adding "sample
return" to the mission is far easier than trying to design it into an
unmanned mission. An unmanned sample return mission would be a very good
mission to fly to Mars, but this mission always seems to be just beyond the
limits (technical and cost) of what an unmanned mission can do using today's
launch vehicles.

Jeff
--
A clever person solves a problem.
A wise person avoids it. -- Einstein


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