Astronomy Picture of the Day 3-15-02

Explanation: Looking for water on Mars, researchers using detectors on board the orbiting Mars Odyssey spacecraft have created this false-color global map of energetic neutrons from the otherwise Red Planet. What do neutrons have to do with water? As cosmic rays from interplanetary space penetrate the thin martian atmosphere and reach the surface they interact with elements in the upper layer of soil, scattering neutrons back into space. But if the martian soil contains hydrogen, it seriously absorbs energetic scattered neutrons. Tracking variations in absorption, neutron detectors can map changes in surface hydrogen content from orbit. Hydrogen content is taken as a surrogate measure of frozen water (H20), the most likely form of hydrogen close to the martian surface. Blue shades in the above map correspond to large concentrations of hydrogen, indicating in particular that the martian south polar region has a high amount of water ice near the surface.

There must have been a large volume of water on the surface of mars at one time, in order for the erosion that is evident to occur. I wonder what happened to it? Is there enough volume of ice in the polar caps to contain this water? And why do they appear to grow and shrink so drastically during the planetary seasons? (I am not suggesting anything tinfoil-hattish, just some things I have wondered about.)

And while I do believe that man will someday make it too the red planet, I don't think that it will be within my lifetime, or even this century. Remember in Apollo 13, when Tom Hanks said to the touring congressmen why space exploration should be justified: "What if Columbus had gone to America, come back and never returned?" That is exactly what we did. Sorry for the rant, but this fact just disappointed me.

I just finished re-re-rereading Apollo 13 today!

Why DID we stop short? I was so disappointed, then and now. The Space Shuttle NEVER had the attraction for me that the Apollo program did. Why is it that we got to the moon repeatedly with 1960s technology -- computers that don't hold a candle to the one I'm using now, for instance -- and now we play parking orbit?

It's like a child who takes that big step, learns to swim in that big ocean, but becomes unsure and self-conscious.
Pretty soon he stays on the beach ("It's safer here.") Sure it is, but it's also giving up the stars for a bucket of sand.

By all rights we should already have bases on the moon, and of course an array of radio and visual telescopes on the far side.

We could - with a moderate effort - have sent a manned mission to Mars before the 20th century ended.

Sure there was once more water on Mars.
In fact, some evidence exists for ambient surface water early on, and catastrophic melting of permafrost later, from meteoric impact, perhaps.

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