Sea Wasp wrote:
John Schilling wrote:

Your argument might as well be that wintering over at the South Pole is
as easy a trip as a weekend in the local state park, for a Boy Scout
troop. Because, see, only incompetents would make the trip without
adequate training and equipment, therefore the Boy Scouts will have
right training and equipment whether they're going to the state park
or Antarctica, therefore it's just as safe and easy either way.

Not really. It does depend on the assumptions you make, true, but
you exaggerate a number of issues. Mars offers opportunities to support
your marooned astronauts, assuming they brought the right equipment,

Which includes a fully robotic hospital to care for the invalid humans
whilst they re-adjust to Mars gravity after 300 days weightless. Sending
people to Mars with our present technology is pretty futile - humans are
too fragile for interplanetary travel in our crude chemical rockets. All
they will do is contaminate the place and die slowly on the surface (if
they manage to get there alive in the first place).

which the Moon does not. There are reasonable ways for them to make air
and water from what's there, as opposed to the Moon, where you really
CAN'T do that unless you happen to be incredibly lucky about what you
bring and where you land. You can make fuel on Mars a lot more easily
than you can make it on the Moon.

If you assume each one starts with IDENTICAL equipment -- and that
the equipment in both cases is optimized for the Moon -- then hell yeah,
the Mars group is screwed.

The time to reach Mars and mount any kind of rescue is so great that you
are sending them on a one way ticket to their deaths. The transfer
orbits are much slower between planets and the distances immense.

Going to the moon is a picnic by comparison and we haven't done that now
for more than three decades. AT the moment we can't even fly the shuttle

If you assume they each start out with optimal equipment for the
mission in question, they should be roughly equal.

Do you have any idea how much equipment and food that would be for Mars?
(even allowing for subsistence rations and make/find water on planet)

We do not have the lift capacity to send enough gear to Mars to allow
any reasonable chance of success of a manned human mission. It might
make gripping reality TV as they die slowly but that is hardly a good
reason for doing it.

The KEY point about BOTH of them is that it is a nontrivial effort
to mount a rescue mission unless (in both cases) you have such a mission
STANDING BY. To just throw together something that would reach the moon
with sufficient capacity to go down, retrieve your astronauts, and come
back home safely is, likely, somewhat cheaper, and certainly faster,

And faster is pretty important when you are mounting a *rescue* mission.
Not much use turning up so late that they are all dead.

The only *material* difference, as far as I see, is time; if you
assume they have only enough food for, say, a few weeks, yep, Mars is
screwed (fastest reasonable transit, given the right tech and right
orbital parameters, is about 3 months). Mars has water, and if they
brought the appropriate gadgets they can manage to keep up on the
water/air equation, but food isn't something you can make out of raw
materials yet.

Work out the weights of all the food and resources they would need to
subsist for the ~300 daya a Hohmann transfer orbit would take to reach
them. Or are you going to have some hypothetical gofaster rescue ship?

The rescue trip would have to fly with 50% more food resources than the
original mission to cater for the crowded return trip.

Regards,
Martin Brown