[Rockhounds] Terraforming Mars might be impossible? for now

[Axel Emmermann]

In my book there are a few things wrong with Mars ...
1) it doesn't have a strong enough magnetic field to protect the planet from
the solar wind. Any atmosphere that is created by terraforming attempts will
be blown away in a short time period. 
2) it's to small... its gravity would irreparably weaken bones and muscles
of people stat spend more than a few years on its surface. Once beyond a
certain time, "Martians" could no longer return to Earth without grave risk
to their health.
3) It's large enough to have undergone gravitational segregation of the
chemical elements that made up the planet. This means that there is an iron
core. That core would have collected most of the siderophile elements. A
much shorter seismic active history would have separated the lithophile
elements  into a lighter crust and heavier mantle. The mantle is where the
important stuff is, if you want to go mining a planet. The REE are there.
They are also to be found in the planetary crust, provide there is some
seriously evolved volcanism there... Isn't the Red Planet's seismically
active period a bit short for that? 
4) Go a little bit further... just beyond Mars are the asteroids. They are
so small that there has been no gravitational segregation of their elements.
If you want a financial return from space exploration, the asteroids are the
pace to go. No dust storms there too...

Cheers
Axel 


-----Oorspronkelijk bericht-----
Van: Rockhounds <rockhounds-bounces at rockhounds.drizzle.com> Namens Alan
Silverstein
Verzonden: zondag 15 maart 2020 4:44
Aan: rockhounds at rockhounds.drizzle.com
Onderwerp: Re: [Rockhounds] Terraforming Mars might be impossible? for now

> It's OK to dream big, but don't forget that it's just a dream at the 
> moment...

Sure.  I put my notion out there -- explore, evacuate, bombard, return
-- just as a novel out-of-the-box concept to keep in mind.

> I want to hear more about how we harness the sun's energy to 
> accurately move massive bodies 2.7 AU out from the sun's surface...

Not sure if you keep up with various pubs like I do, such as Science News,
Sky & Telescope, and the Planetary Report...  But I see that we've dreamed
up quite a few creative ideas for how to modify asteroid orbits (of course
mainly intended for collision avoidance).  None of them yet proven of
course, but I think one test mission is in the works?  Anyway, just from
memory, here's a summary of possibilities that I can recall:

- Nuclear or other explosions, the brute force approach.

- "Laser bees" or other methods using co-orbiting satellies to direct
  solar energy onto hot-spots that act like low-thrust, long-term rocket
  engines, blasting reaction mass off the object.

- "Gravity tractors" where a sufficiently massive co-orbiting satellite
  propels itself, and tugs on the asteroid.

- Directed YORP effect (however you do it) turning the object into a
  crude solar sail using solar photons.

Of course in all cases, the smaller (less massive) the target, the better.
Hydrating/oxygenating a whole planet, even a small one like Mars, would take
a lot of raw mass, but possibly this can be done using a large number of
smaller objects, each of which is easier to shuffle around.  In each case,
depending on how patient you can be, it doesn't require a lot of oomph to
redirect the orbit.  Yeah there's the angular momentum problem; people don't
realize it can be harder to hit the sun than to escape the solar system; but
you don't need to fully circularize the orbit (more delta-v), just
ellipticize it enough to intersect.
(Beyond that, though, I'm too far removed my undergrad days at Caltech to
actually do the math, sorry.  :-)

What was that sci-fi story years ago where a protagonist worked backwards
from the desired result to play billiards with the Kuiper Belt?  One point
there was that you don't have to massively redirect every single object, if
you can swing it right, you can do some elegant momentum transfers, where
one object, say, hits Mars, while another goes farther out, or escapes
completely.

Cheers,
Alan Silverstein

_______________________________________________
Rockhounds mailing list
Subscription Services:
http://rockhounds.drizzle.com/mailman/listinfo/rockhounds_rockhounds.drizzle
.com
List Usage Policy: http://Tomaszewski.net/Kreigh/Rockhounds/Rockhounds.shtml