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Deep Impact Mission Reveals Comet Ice
Ant writes "New Scientist reports water ice is present on the surface of Comet Tempel 1." From the article: "The finding was made via observations from NASA's Deep Impact mission. This is the first direct detection of exposed water ice on a comet. The mission's science team says the water ice is present in surprisingly small amounts, covering less than 1% of Comet Tempel 1's surface. The finding suggests the comet's surrounding cloud of gas and dust may largely be fed by underlying ices, rather than by gas streaming off its surface."
The team also found the comet was much weaker structurally than previously believed; the soufflé-like comet is more empty space than rock and ice.
From the wikipedia article on Deep Impact:
The Deep Impact mission will help answer fundamental questions about comets, such as:
Is the nucleus layered?
Are cometary nuclei highly cohesive and tightly-packed, or porous conglomerates? (Checked!)
Do any parts of a cometary nucleus contain pristine material that have been untouched since the creation of the comet during the Solar System's early history?
It's nice to know that one of those questions just got answered (so it's time to update the wikipedia article :)
Congratulation to all the staff behind the Deep Impact project.
1. Get a pile of anything that consists mostly of C,H,O&N. ...
2. Let ultraviolet or similar things affect it.
3. Watch it spawn amino acids and the rest of important chemicals.
4. Proceed for a looooong time, while combinations of simple proteins form and get broken down.
5. After enough time, watch a protein complex have the ability to copy itself.
6. Have it die, then spawn elsewhere every a million years or so.
7. Watch one of such complexes survive long enough to have one of its many copies hit by ultraviolet (mutate) to form something more complex.
8. Have the pre-life grow a cellular wall, turning sparse pools of dirty water turn into small, concentrated tiny blobs of life. Organisms.
9. With actual cells, everything goes downhill.
10. Watch someone invent (create) the underpants gnomes.
11.
Once a structure gets the ability to multiply, it can form new structures. Another example: since creationism and most religions include an urge to preach to non-believers, it _does_ survive. And, it does mutate and evolve into forms such as ID which have a better chance of survival in the hostile environment.
The creatures outside looked from Alt-Right to Antifa; but already it was impossible to say which was which.
The finding suggests the comet's surrounding cloud of gas and dust may largely be fed by underlying ices, rather than by gas streaming off its surface.
This is hardly surprising. Out in my backyard, there's the remains of a snowman my daughter made a couple of weeks ago. It's black.
Oh, it was white -- and much bigger -- when she made it, but in rolling up the snow (only a couple inches deep) to make it, the snow picked up a fair bit of sand and dirt. Now, after the outer few inches has melted, the dirt that was in those few inches has settled back to the new surface while the water has melted/evaporated away. The result -- a fairly solid dirt surface.
Any city dweller in the northeast sees this every spring in the dirty snowbanks beside plowed roads.
It's hard for gas to stream off a surface that's a thick layer of dust and grit. More likely for it to come from the ices underneath. What would be interesting -- and would require a soft landing on a comet -- is to measure the thickness of the outer dirt "crust" and look at the volume of dirt per unit volume of ice underneath that. That'd let you calculate the approximate thickness of the ice already evaporated from the comet.
-- Alastair