-> -> -> 3) If Mars was at one time worth life bearing then why
only Microbes?
-> -> -> What halted further development of life? Is one of the
bigger craters a
-> -> -> kin to the crater that wiped out dinosaurs? If yes then
where is the
-> -> -> evidence for the impact besides the crater?

-> -> What halted further development of life on Mars was it's core cooled,
-> -> magnetic field disappeared and it's atmosphere was literally
-> -> blown away by the solar wind in the absence of that magnetic field.

-> 

-> Decrease in core temperature = loss of magnetic field?

The dynamics are this.
The Earth's core c0onsists of molten circulating metals that generate a
magnetic field same as passing a manet through a loop of wire.

Cool the metals, they solidify, stop circulating and goodby
magnetic radiation shield :-(

Wer'e a long way to go because Earth still has a lot of radioactive
thorium and and uranium decaying in the core.

The Earth's field IS dropping VERY significantly and expected to
reverse north to south soon.
This is recorded in cooling lava rock in the Hawaian Islands where
the magnetic orientation is imprinted in the rock as the rock cools.

This pattern has been checked and the Earth's field seems to reverse
every 120,000 - 370,000 or so years.
A spot in the South Pacific has already reversed field.

Fired ceramic pottery has shown the very recent dramatic drop in
intensity in the last 150 years.                       

If the field hits near zero as expected during reversal scientists
anticipated hundreds of thousands of additional cancer deaths per year
but the process should only last from a thousand years to a few
thousand.

-> Isn't the atmosphere held in place by gravity? And gravity is directly
-> dependent on the mass of a body. So unless Mars lost a lot of mass, why

I believe, but may be mistaken, Mars has .6 Earth gravity.

Solar wind and kinetic energy in gas particles trumphs gravity in the
absence of a magnetic field and goodbye atmosphere.
Likely takes a few hundred thousand years to be blown away if
not a million or more.

-> would it be unable to make the atmosphere stick? I don't see how your
-> suggestion could be true unless the atmosphere was rarified enough to
-> begin with. A low mass atmosphere is more likely to be blown away by
-> solar wind.
                      
See www.pbs.org and click the NOVA link, there's a science show on
precisely what we're discussing.

-> But even if what you say is accurate ... well, it doesn't feel right to
-> me. 
   
Well there IS that damning record in the Hawwian Island lava rock
and Mars has no real detectable magnetic field. 

-> Life begins in a weak atmophere, 
   
Not weak, different.
Methane, ammonia, ect., organic gases like can be found on one of
Jupiter's moons.

-> reaches the microbe level and fails
-> to adapt to an increasingly difficult atmosphere. If it could evolve to
-> the Microbe level in a relative (to Earth) hostile environment, surely
-> it should have evolved further. At least our evolution time scale has
-> been faster than the geological time scale. And Mars is right next to
-> us, not in some remote part of the galaxy. Conditions could not have
-> been SO drastically different.

Venus is close too and far more Earthlike in geology and size.
Runaway greenhouse gas made in hot enough to melt lead and an atmosphere
dense enough it crushed most landers before they touched down.
The soviets got a few to last some hours but they too also soon failed.

Then there's the matter of the carbonated sulfuric acid rain :-(

-> Is there a book on this?

You can the VHS tape from PBS - NOVA.
Lots of books on it but none I've read recently.
I keep current on the internet and educational television
carried by a local university T.V. channel.
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