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."
Woot! 1/4 of the way to the formation of DNA!
Run Tempel 1, run!
We will bankrupt ourselves in the vain search for absolute security. -- Dwight D. Eisenhower
Cause if it's yellow, then whoever made it didn't use snow...
I'll form my OWN solar system! With blackjack! And hookers!
>the rover/lander will watch on the surface. One important thing to plan: make sure the probe doesn't hit the lander! On the other hand, if it does, you'll get the eternal glory of staging the first extra-terrestrial traffic accident! ;)
Grundes!
12. Profit!
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