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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 crushed ice industry will surely be intrigued by such results. I wonder how long it will be before probes are mining ice to be returned to earth.
It's space-debris, but not as we thought we knew it.
There's a comet in the skies these days, which will be closest in a couple months. Unfortunately, I seem to have grabbed the wrong printout before leaving home. :-(
A feeling of having made the same mistake before: Deja Foobar
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!
I the commet's water didn't contain life in the first place, mayby we just contaminated it with whatever cleaver microbes hitched a ride on the impactor. That'd be sweet.
We'll melt the ice, bottle it and make millons$$$$$$
Alert President Morgan Freeman!
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Maybe it's just me but the term "water ice" makes me cringe.
I understand they need to differentiate between other materials that could be termed "ice".
Why not just say "frozen water"?
Could that be interpreted as something other than H2O as a solid?
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.
Of course, the Heaven's Gate members already knew all of this...
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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
It's nice to know that one of those questions just got answered (so it's time to update the wikipedia article :)
Actually we know the answer to the third question as well: No! Duh...we just rammed a probe into it!
Note to self: Stop putting jokes in my insightful comments so I can get something other than +1 Funny!
Yep, I am thinking road pothole leavings -- a conglomerate of silicates, hydrocarbons, with a little bit of ice mixed in. Arthur C Clark has a plot point in one of his 2001 spinoffs that a spaceship could land on Halley's Comet, load up on slush, and use this for thrusting mass for some kind of fusion-thermal rocket drive, only the carbon in the slush would make for a spectacular incandescent rocket exhaust. My view is that the comet surface may be kind of crumbly, but it won't more very well and likely clog up some valves if used as rocket fuel.
Let me try to solve your mental anguish j/k :)
:)
:)
Heard about the Stardust mission right? They collected particle samples in aerofoam and then slammed it into earth on the return without disturbing/destroying said particles.
So make your slug of metal hollow, insulate the rover with as much aerogel and shockabsorbing devices as possible (like airbags with timed deflation). Make the slug in such a way that it will crack open in a controlled manner when hitting the comet (most bullets do this). Launch. Hit. Drive rover out of destroyed open slug.
Might not be the most practical or cheapest way to go about it but it has a certain elegance imo
Btw the timing of everything could be controlled/timed by an impact fuse & physics in just the same way ordinary armorpiecing rockets work, although not to the same effect of course... I'm sure this would make for a fun lunchbreak napkin sketch & diagram for some NASA wizard
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Oh, wow!
Interesting idea, but unfortunately, you don't quite seem to have grasped the relative velocities involved, and what they mean in terms of impact energy. The (brilliantly successful) Mars rovers used robust construction and airbags to survive an impact at 12 miles per hour (i.e. the equivalent of a low-speed car collision) (see here for more)
Deep Impact hit a comet at 10.2km/s (or about, what, 6 miles per second?) releasing energy equivalent to 4.8tons of TNT - somehow, I don't there there's much you can do to protect a lander from the equivalent of being loaded into the middle of a truck-load of detonating explosives...
A slow delta-V rendezvous is what you need, and that's gonna be awfully hard to achieve, given the high (10km/s+) speeds of average comets.
As for the dirt being souffle-like -- what do you expect? There's barely enough gravity to keep the comet together, and almost nothing to force the residual dust to compact. When it's warm, the sublimation of the ice underneath is going to push the dirt out. When it's cold, any residual vapor is going to freeze and cement the dirt in place.
Over the aeons, you're going to be left with a layer of dust that's incredibly lightly packed over a core of ice.
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Ice may be a more minor constituant of these things -- a lot of the water may be more in the form of hydrated minerals than just plain water. SiO2 may be more abundant out there than H2O. If someone were making book on this kind of thing, I am wagering at long odds that when the first spacecraft brings back a chunk of comet, it will be more like the piece of road spalled off a pothole than the dirty, sandy ice filling that pothole.