Pat Flannery writes:

On 1/20/2011 2:58 AM, Jochem Huhmann wrote:

Or to turn that around: Look at a one-way robotic mission that gets the
same mass to Mars as a manned mission needs. Then compare which mission
can do more. You could spray hundreds or thousands of rovers over Mars
for the same mass that a small crew needs just to stumble around in the
dust near their lander for three months and then return.

And the nice thing is, you don't have to worry about getting the rovers
back either; in fact, the longer they stay, the better.

Yes, and this is one reason why robotic missions are so much more
mass-efficient: Instead of carrying lots of fuel, food etc. for the
return leg they can carry actual payload. And of course some bare human
hands and feet are rather useless anyway, so even with a manned mission
you'll need rovers, instruments, labs and other equipment. The crew
and its needs mainly impose a drastic mass penalty.

I think manned missions to Mars have a huge romantic appeal (and I'm all
for them), but if what you're really after is hard scientific data
they're rather pointless. And I also think that as long as most people
propagating manned missions secretly think of the "romantic" part and
just pretend to have "hard" arguments for manned missions nothing ever
will come out of that. Either say "I want manned missions because we CAN
go there and therefore we should" or shut up and go for rovers and
probes...

I always thought we should have built more MER's, considering how well
Spirit and Opportunity did and the low cost of the whole program.

I think one problem is that the landing methods of these things are only
good for a very small part of Mars. You need low elevations with
(somewhat) thicker atmosphere to get them down with parachutes only. And
of course you need enough sun, so that a landing in Valles Marineris
(which would make an interesting target) is probably a bad idea. You
surely get a denser atmosphere in a canyon 7 km deep, but you'll also
get deep shadows all over.

And if you have to redesign the landers and rovers anyway, you can also
go all the way and fix some shortcomings, like the small size and
somewhat tight equipment.


Jochem

--
"A designer knows he has arrived at perfection not when there is no
longer anything to add, but when there is no longer anything to take away."
- Antoine de Saint-Exupery