The Rosetta probe has woken up ...

Albedo = fraction of incoming light that's reflected.

Using the blackbody approximation and Wien's displacement lawWP, the Sun's emission peak is at 0.5 microns, while the Earth's is at 10 microns, and the comet's is not much different.

The amount of energy absorbed = (1 - albedo) * incoming energy
The amount of energy emitted = (1 - albedo) * blackbody or perfect-emitter limit

Received flux = F
Area of emission = A
Stefan-Boltzmann law = F = A*σ*T4giving Tbb = (F/(A*σ))1/4bb = blackbody or perfect emission and absorption

Taking into account absorption and emission albedos, we get T = Tbb * (1 - aabs)1/4 / (1 - aem)1/4a = albedo

If aem > aabs, then one gets a greenhouse effect.
 
Philae should really have been equipped with one of those radioactive thermal generators that some other deep space probes and some of the Mars landers use. For the same weight as the solar panels, it would have provided reliable power for the whole mission, along with some waste heat to keep Philae warm enough to operate. We'd already have months of useful data from it by now.

The reason Philae didn't have such an RTG was that Europe has never developed such technology. NASA wouldn't supply one to the European Space Agency and international agreements and protocols meant that ESA couldn't ask Russia for one of theirs.

It looks to me as though the lander was not equipped as well as it might have been, partly because of the 'anti-nuclear' attitude prevalent in much of Europe.
 
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ceptimus said:
It looks to me as though the lander was not equipped as well as it might have been, partly because of the 'anti-nuclear' attitude prevalent in much of Europe.
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Really? You think this is the prime reason why philae did not have a nuclear reactor as a power source? Would other factors like cost have anything to do with it?
 
CapelDodger said:
While Philae is getting all the coverage, and it is indeed an engagingly plucky little crash-test dummy, you have to hand it to the engineers who built it. Outstanding work to which I am about to drink a toast.
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Hell yes.
Outstanding and I'm proud of their accomplishments.
Huzzah!
 
Rosetta metalhead Matt picks up a rock award

But the mission’s chief scientist Dr Matt Taylor enjoyed a second celebration a day after the news was announced, when he picked up a prize normally reserved for stars involved with a different kind of rock.

Heavily tattooed Matt, who is a huge heavy metal fan himself, picked up the Spirit award at the Metal Hammer Golden Gods event at London’s IndigO2 arena. The award was presented by another rock star famed for his interest in astronomy and space, Dr Brian May of Queen.

Brian told the crowd: I’m here for a very special reason. And that’s to present the Spirit of Hammer award to soemone that you might not expect, and I want to tell you why this guy is, in our opinion, worth of this incredible award. He is truly a god of heavy metal but in a very different way. He is called Dr Matt Taylor and this man has done something extraordinary that has never in the history of Man been done before.

“He and his team hurled a large piece of metal and silicon 300 million miles into space and landed a small pod on a comet. It’s something so incredibly difficult and unusual. Ten years ago they launched this thing…they didn’t even speak to it because it had to rest and then they just hoped that when it switched itself on it would be in the right place. It was in the right place.

“Now you probably think this guy is a very important American; he’s not, he is British, he was born here just a few yards from here in fact. He spent most of his youth in the East End, he went to Liverpool University to get his physics degree, and he went to Imperial College (London) to get his doctorate.
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Continues...
 
Susheel said:
Really? You think this is the prime reason why philae did not have a nuclear reactor as a power source? Would other factors like cost have anything to do with it?
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You can see the question answered by the mission scientist about 50 minutes into the video linked below. He doesn't mention cost - just that RTGs aren't available to Europe, that there are some safety concerns when launching vehicles containing plutonium - and therefore the political decision not to use one on Philae.

The safety concerns are true, of course, but modern RTG design is very unlikely to cause any problems on Earth due to a failed launch. The problem is that the anti-nuclear crowd stir up more public opinion by shouting, 'Warning! Plutonium!' than can be countered by scientists and engineers calmly spelling out the real risks.

https://www.youtube.com/watch?v=7Xm6y0LzlLo

NASA still uses them on deep space probes. There were even radioactive 'heaters' (probably plutonium but I'm not sure) that didn't produce any electric power fitted to the Spirit and Opportunity Mars rovers - although the main power source for those rovers was solar panels. The later Curiosity rover is powered by an RTG.
 
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ceptimus said:
The safety concerns are true, of course, but modern RTG design is very unlikely to cause any problems on Earth due to a failed launch. The problem is that the anti-nuclear crowd stir up more public opinion by shouting, 'Warning! Plutonium!' than can be countered by scientists and engineers calmly spelling out the real risks.
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Yeah, there was a major effort to stop the Earth flyby of Cassini, to send it on its way to Saturn because of the immeasurable risk that the rocket scientists had their calculations wrong and the spacecraft would enter Earth's atmosphere and burn up.
 
Philae now able to work through the night.

"“At present, the lander is operating at a temperature of zero degrees Celsius, which means that the battery is now warm enough to store energy. This means that Philae will also be able to work during the comet’s night, regardless of solar illumination.”

The Guardian
 
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