Mars halo mirror for terraforming?

On 9 Feb, 00:24, Hop David wrote:

If a big object hits Mars with sufficient velocity, much of the
asteroidal material as well as the atmosphere above the tangent plane at
point of impact is sent into space. Loss of most of the asteroidal
material, kinetic energy and a good chunk of Martian atmosphere wouldn't
contribute to terraforming.

That depends on the size and composition. The article referred to
mentioned 100 - 250km diameter objects, and yes, that might well be
counter productive. Zubrin was more modest, proposing 10km diameter
"snow balls", and perhaps using 50 such impacts.

The slower the asteroid impacts, the better. So Jupiter Trojans or
asteroids from the main belt would be better to toss at Mars than KBOs.

Though KBOs have 2 distinct advantages:
1. More ammonia present - and much softer
2. Less delta V needed for impact

All that said, by the time a KBO arrives, the planet should be
settled.

One other possibility is using Phobos. Large chunks could be broken
off, and tethered down to a point where they intercept Mars. However,
Phobos is a very valuable commodity.

On Feb 8, 2:03 pm, "Alex Terrell" wrote:
On 8 Feb, wrote:



On Feb 8, 6:02 am, "Alex Terrell" wrote:

On 8 Feb, wrote:

There is another way to heat up Mars and cause a runaway greenhouse
event, a sufficiently large impact event, engineered by moving
asteroids to impact Mars

http://www.lpi.usra.edu/meetings/six...3/pdf/3247.pdf

This is certainly one way of aiding terraforming. The trouble is, its
not compatible with surface habitation.

Well, since no one is inhabiting the surface right now, and the
surface is more habitable after, then, its not really a problem.

Just a question of appropriate project planning then.

However, to go get a KBO for Mars ramming would take several decades,
making habitation in the mean time temporary.

Yeah, there are plenty of appropriately sized impactors nearby in the
Asteroid belt. Ceres is an interesting possiblity. It would
certainly shake up the place!

Your comment doesn't make any sense though about habitation. No one
has yet set foot on Mars and no one is likely to set foot on Mars
within the next 35 years. Alan Shepherd left the moon over 35 years
ago and no one has returned since. Now 35 years is the period of time
between Lindburgh crossing the Atlantic and Armstrong crossing to the
moon.

Clearly, we have abandoned serious development of space travel in
1972. Otherwise, the visions of 2001 A Space Oddessy, would have been
true in 1990s.

When will we take space development seriously again? I'm an optimist,
so I won't say never. But, if things go badly in our management of
our current system of nation-states, it may be another 100 to 200
years before humanity takes up the notion of interplanetary travel.
Even under the most idealistic of circumstances, it'll be 35 years
before we are at a point we were at in 1972.

So, you idea that habitation will not be possible after an impact
doesn't make sense in the context of the present reality.

It will take decades to carry out the engineering and processes needed
to engineer an impact on Mars. Decades if not centuries more for
things to settle down. But overall, such an event will be easier and
transform mars in a shorter time than building a lot of mirrors.

And these two events need not exclude one another.

Since Mars doesn't seem to have been subject to major collision
events, as the Earth and Venus and Mercury have, there may be
considerable water deep inside the planet. In fact, there may even be
forms of life deep inside Mars. So, this IS a problem if we are
sensitive to the 'rights' of that life - we need to assure ourselves
there is no other life form we would be harming in reprocessing Mars
on a massive scale.

Interesting question: Would such life have more rights than equivalent
life on Earth? i.e about zero.- Hide quoted text -

Well, if they exist, it is their planet? I suppose we'd want the same
regard if a superior life form wanted to reform our world. So, why
shouldn't we establish some sort of precedent now?

As a practical matter we'll have to engineer the impact for it to have
desireable results. this requires getting knowledge from deep inside
Mars. And in the process we'll learn if there is life or not.

As a practical matter many things would make an impact event an
impractical way to teraform mars. So, the presence of life would be
just one in a list of reasons - one that doesn't derive from the
physics of the situation, but the ethics of the situation - which may
be peculiar to us, but if it makes us happy to put it on the list, why
not?