[ExI] Planetary exploration by telepresence

[spike]

>... On Behalf Of Giulio Prisco
Subject: Re: [ExI] Planetary exploration by telepresence





>...This is a good paper, but is landing and staying for a while on, say,
Mars, really that more expensive than sending people to Mars orbit to deploy
and operate robots?

Landing and staying for a while on Mars is easier than this scenario if...
the plan is to stay on Mars forever.

You can do the weight calculations a hundred different ways, and always get
the same result: any humans to Mars scenario is a one-way trip.

>...Perhaps yes, if we are obsessed about safety. But I would be happy to
volunteer for a Mars mission even if the probability to die there is 50%...

What if the probability of dying there is 100%?

If you want a pretty good quick estimate of what it takes to soft land on
Mars, the rover Curiosity is a good example.  Curiosity was launched with
one of our heavies, the Atlas V.  It went thru that wicked-cool
aerobraking/retro-rocket/sky-crane maneuver to soft land (and my hat is off
to the controls engineers who worked out all that.)

Curiosity weighs about 900kg (or 2000 lb for Anglophiles.)  So: it costs an
Atlas V per ton soft-landed on Mars.  An Altas V is about 100 Megabucks
under kinda ideal conditions.

When you consider humans to Mars, start with what you hope to land there,
the capsule size, the life support requirements and so forth, then estimate
the mass, then Atlas V per ton, what kind of mission do you end up with?

This I can pretty much assure you: it is most unlikely you will be able to
soft land enough rocket to get you back out of that gravity well.  It's the
same conclusion I reached in 1989 when I first did these calcs, before the
Altas V existed and before we did any of these rovers, and the numbers come
out to about the same now as I had estimated then, for there are no
currently-known shortcuts: it will be a heavy launcher per ton soft-landed
on Mars.

My conclusion: any manned mission to Mars is one way, one very small person,
no going outdoors once you get there, life expectancy after arrival:
Giulio's first comment includes the phrase "staying for a while."  Ja, a
while.  Not all that long really.

That whole notion drew much ridicule at the time, but since then plenty of
others have reached the same conclusion for all the same reasons.

spike