Lights OUT for Philae BUT slumbering probot could phone home again as comet nears Sun Philae's final hurrah (for now at least) on Comet 67P/Churyumov-Gerasimenko ended with success, the mission's jubilant boffins confirmed late last night. The fridge-sized, plucky probot, which made the historic landing on the speeding, icy space-rock 300 million miles (or 500 million kilometres) from Earth on Wednesday, was …
Even if we hear nothing more from Philae, we still have Rosetta circling round for who knows how long. Like I've said before, some days you can do without the flying cars and personal jetpacks while we can still achieve shit like this.
That is all, except, a beer to all concerned.
"Am I the only one to realise that was a joke?"
Yes, you were the only one to think it was a joke. And perhaps both of you could gain from a visit to a local mental health professional. I'm sure some of them handle conspiracy theorists.
There has been discussion of designing one in the future for outer solar sysyem probes, and things like a possible boat craft to sail the seas of Titan (as well as work to produce the required nuclear isotopes). For now, there is some R&D to optimise solar array power generation on the surace of Mars, which would also help for future probes similar to Philae.
It's a shame it didn't have a small nuclear battery on board like the Mars rovers.
It's the perennial ignorant refrain whenever a probe like this dies. Philae has already done 80% of everything asked of it: it has to be considered a success. RTGs are are not magical silver bullets but bring their own issues. Do you really think no one on the project even briefly considered one before opting against it? Of course not, it's just they know enough to be able to properly evaluate the pros and cons:
RTGs kick out a lot of heat. Do you really want that heat constantly heating the same area of a body believed to be mostly ice?
RTGs are hugely expensive. If the budget had extended to including one then it would also have extended to including a second unmodified lander. Which would get more science done? If you evaluate the risks and determine that it can probably be powered by solar cells why go to that expense in the first place? The solar power gamble didn't pay off in this instance but that doesn't make it a bad decision.
Only a comparatively small number of isotopes are useful and they are all synthesised and in short supply. No one is making Pu-238, the isotope of choice, anymore and stockpiles of it are rapidly depleting. Even the US lacks all it needs for its Europa mission - they were hoping to source the extra from Russian stockpiles, but that is especially problematic now with the tensions over Ukraine.
Put it another way: which outer solar system mission would you rather was abandoned completely so that this mission might be able to get a small amount of additional science done? If you can't answer that the demand for an RTG is not based in reality.
which outer solar system mission would you rather was abandoned completely so that this mission might be able to get a small amount of additional science done?
Because pols and green freaks can't find their arse with both hands we are left with the choice:
"Do you want to suck a lot or to suck a whole lot?"
(And protest placards will go up in any case while much handwringing will occur in the corridors of power and questions are asked whether that Europa probe might not be better powered with renewable energies)
I know of 2 missions where the agency lost a satellite during eclipse but then recovered it. (the battery ran below the end of discharge threshold, and so everything switched off). When you get power back, you first have to run heaters to defrost some subsystems, including the battery, and then you can start charging it again. As the comet gets nearer the sun, the power available in the solar array will increase substantially (I'm currently doing work for a mission at Jupiter, and there is 1/4 of the power that I'd typically have for the same craft at Earth)
Thanks, that just addressed a question I had that all the official sources or coverage failed to explain - namely why with '1/n' amount of the expected energy incoming the probe can't just simply wake up every 'n' days instead of being on all the time. I guess things just can't be kept appropriately heated in the mean time...
It doesn't orbit in the way you seem to think - the gravity's too weak. It flies a series of dog-legs around the comet, with a powered course change between each one.
Umm, no. It does actually orbit, exactly the way he seems to think (now). It did indeed have a weird path around a comet earlier, but since September it apparently is on a rather classical sort of orbit. See details here...
From the reports, a big problem is that it bounced into a shaded area so limited luck with solar panels.
But...presumably as it gets closer to the sun, there will be more and more outgassing as things heat up, which may well cause the comet to change orientation in random ways, and may cause the shade to go away.
Fingers crossed.
I don't believe a country needs to have nuclear reactors in order to develop a nuclear battery (radioisotopic thermoelectric generator). While it isn't ideal, I believe the Th-228 decay chain could be used for this task. Others have had this idea as well. The presence of a radon species can be good or bad. But, maybe it is possible to take advantage of this, to eject Rn-220 and its daughters from the spacecraft? This would allow one to avoid the monster alpha of Po-212 (almost 9 MeV) and the monster beta of Tl-208. Capturing that alpha wouldn't be much of a problem, but the range of that beta is inconvenient.
...that getting data back from the lander means the mission was a success.
A glance at the mission statement will show you that the idea was to examine a comet as it passed perihelion and started out-gassing, from two positions - orbit and on the surface. Now, because of the bounce into shade, we effectively only have one observation position. Perihelion was when the most interesting science would have been done...
The lander is in a poor photo position. It's also in a poor solar power position, which has resulted in it being closed down fro lack of power. It might come back as the sun gets nearer, though intense cold can damage electronics and batteries. An RTG would have kept it warm, and at least enabled gas sampling experiments to continue up to perihelion in the middle of next year.
ESA are putting a brave face on it, but the mission has been dealt a heavy blow. It's interesting to note that they didn't use an RTG because Pu-238 is pretty rare now that the US stopped making it in the 1980s. ESA are actually commissioning research into making RTGs out of Americium, so that will improve matters.
The big lesson, though, it that it's hard to land on an object with very little gravitational force to help. No doubt that lesson will be applied to later missions...
Sure it's disappointing that Philae landed in a shady area and it's now off-line. There is some hope that'll it wake up later, but it still got 80% of it's mission done. That's a huge accomplishment and a good success for how difficult this mission was to pull off.
ah, hindsight . . . the perfect tool to fix a device built ten years ago and presently 500,000,000km away . . . we'll just run right out there with the pickup and our shop kit and make it all better . . . while we're at it, better remember to bring along a new cold gas valve and actuator, some harpoon grease and a set of jumper cables! . . . the time machine loads up in 15 minutes so don't be late (not that that matters).
as far as i can tell, the mission worked perfectly right up to the point where Philea took its first bounce . . . guess what, we even learned something from that! . . . now some bright young thing will probably spend a year or three obsessing over the size and shape of the crater left by Philea and the changes over time as the comet approaches the sun and come up with a brilliant analysis of the surface conditions right where it hit.
so far i score the mission almost perfect . . . i'm hoping the drill got a sample and it was processed in time for the upload . . . can hardly wait for the analysis of that last(?) data dump.
[to tell you the truth, i'm half expecting one of the flight dynamics boffins to come up with an orbit for Rosetta that does 99% of the desired observations and resonates with the mass distribution of 67P to torque the Philae landing spot into full sunlight . . . only half expecting it though]
The big breakage was the loss of the upper thruster. I've never seen the burst valves fail like that before. If that'd worked, they would have had a better power situation and a lot more latitude in what they could do towards getting the ice screws and harpoons working.
All that said, I've got fingers crossed to hear from it as it nears the Sun.
Go ahead. Build one that does everything... launch it, chase around space for 10 years and lands on a comet. Go ahead.... then tell us how easy it was and that it worked perfectly until the sun ate the comet.
These guys get a very well done and several buckets of respect even if from this moment on everything goes to hell. They built, they launched, they cruised, they orbited and landed, and then did some science. Just being able to find and orbit the darn thing is impressive.
In about 20 years, our descendants will probably be launching a "Potkustart" or whatever Kickstarter will be by then to contact the formerly defunct long dead Philae probe and recharge it using the mothballed RSA orbital laser weather control platforms so it can send back accumulated data about solar flares or something similar.
:-)
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2025
