Comet landing

Certainly my early childhood idea of a comet wouldn't have come up with the idea that we could land on them.

I hope the lander is usable. They haven't said yet.

I have not heard if they have a camera to take shots from the comet's surface. That would be cool.

Quote: rxwine

I hope the lander is usable. They haven't said yet.

There was a glitch with the landing. Apparently the means to anchor the lander to the comet didn't work. The comet's gravity is so weak, the lander may drift off if not anchored.

If that happens, there would remain the rest of the probe in orbit around the comet.

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I have not heard if they have a camera to take shots from the comet's surface. That would be cool.

I should think so. But I stopped taking such things for granted when the part of the Galileo probe that entered Jupiter didn't have one (I know there's little light and Jupiter consists of thick clouds, not to mention the probe lasted only a few hours, but I wonder if we missed on something by not having a camera).

Photos from the comet:

http://www.wired.com/2014/11/rosetta-philae-comet-surface-photos/#x

Quote: Nareed

Photos from the comet:

http://www.wired.com/2014/11/rosetta-philae-comet-surface-photos/#x

Heh, I had to give up on that link, and find them somewhere else. Probably an overload.

Two hour bounce upon landing. That's quite a bounce.

Why don't comets disappear? They shed the particles that make up their tails as they approach the sun, but when do they add them back? Over time, I would think they would eventually be reduced to nothing, but apparently they are as old as the solar system.

Quote: Ayecarumba

Why don't comets disappear? They shed the particles that make up their tails as they approach the sun, but when do they add them back? Over time, I would think they would eventually be reduced to nothing, but apparently they are as old as the solar system.

Comets are mostly loose aggregations of rock, dust and ices. "Ices" means frozen volatiles. "Volatiles" are materials that evaporate easily at high temperatures, such as water, dry ice, ammonia, etc.

When they get close to the Sun, a lot of the latter material evaporates, and none of it goes back in the comet. But there is a lot of such material, it's not evenly distributed, and there are insulating effects by the vaporizing material which keeps the rest from evaporating all at once. The evaporating volatiles, for example, when they take some dust with them, form a cloud around the comet's head which shield the rest, at least partially, from the Sun's rays.

But comets do, eventually, after millions of years, wear out and break up. this has been seen from time to time, in particular with comets which get very close to the Sun.

It takes a long time because a comet spends only a tiny fraction of its lifetime near enough to the Sun to experience any loss of volatiles. the rest of the time it's in cooler regions of the Solar System. Short period comets, like Halley's, wear down more quickly than long period comets. Halley's Comet has a 76-year long orbit, but it evaporates material perhaps for five years or so. A comet with an orbit of 2,000 years, evaporates even less time, as it's speed at perihelion (the closest approach to the Sun) is much faster than a short period comet's.

BTW, the vaporized volatiles are largely invisible. The comet's bright head and tail are made up of loose dust dragged along.

They're reporting its life may be short with just 60hr charge on the battery and not enough sun time. Though they set the drill going, they're afraid the battery may not hold up long enough to send back the analysis.

The harpoon failure was a big factor in where it's ended up I think.

Not sure what city the comet is being compared to.

A boot stepping on an anthill.

Quote: rxwine

Not sure what city the comet is being compared to.

My guess is Los Angeles.