Controllers wait on Philae link | Hacker News Reader

Controllers wait on Philae link

bbc.com

30 pointslentil_soup12 comments

> “It’s like flying your car in a snowstorm. You don’t see anything, and that’s quite dangerous,” said Elsa Montagnon [...]

-- from an alternate universe where we got those flying cars.

When asked about her experience of snowstorms, Elsa made a cryptic remark about her sister and then fell silent.

Maybe someone can answer this: the higher resolution images of asteroid surfaces are amazing, but I wonder what video would show in terms of surface dynamics. Is there likely a lot of dust and debris within proximity to the surface or are they just fairly uneventful rocks floating in space? Also, I can look up rotation and other measurements but it's difficult to piece together a whole picture including the relative size of these things.. If I were standing on an asteroid, would I visibly or physically sense rotation?

Its a shame the ESA never invested in RTG technology. Hoping for enough photons to power those solar cells seems crazy, especially for an almost $1.6 billion dollar mission. Sure, pu-238 is in short supply but the ESA consists of the UK and France, both with the nuclear capacities to create some.

Anti-nuclear hysteria is out of control in the EU.

No it's not. An RTG is simply not feasible for the short-lived, low-mass probe in question. Philae is 100kg total and will burn up in a few months when the comet comes near the sun, it would be a giant waste of resources to equip it with an RTG that could yield power for decades.

See http://nucleardiner.com/2014/11/15/wasnt-philae-given-rtg

Its 100kg because its designed without an RTG. Obviously the design would have changed to accommodate it and we wouldn't be sitting here wondering if it has enough juice to work, thus pissing away a significant part of that $1.6b budget.

Note that Philae has already performed most of the experiments that were planned in the first two days it was operational and that all data from those experiments has been received. Philae never was a failure, that it now wakes up again is an additional bonus. Also consider that an additional O(100kg) for an RTG significantly alters your energy requirements to get into orbit (see https://en.wikipedia.org/wiki/Rocket_equation)

TFA:

“The power from the solar arrays is not sufficient, on its own, to drill and analyse cometary samples, for example.”

Its clear that power is an issue and an RTG would have solved it. These don't sound like "bonuses" to me.

Later in the article:

"And eventually, Philae will hopefully get sufficient power in its battery to drill into the comet and analyse its make-up."

Although claiming it was never a failure is pretty laughable.

But if you increase the mass of the probe, you increase the cost of the whole mission. Bear in mind increasing the mass of the power system emans the lander needs more powerful thrusters, more fuel, stronger landing gear, etc. That's the tyranny of the rocket equation.

This could increase the cost of the mission by hundreds of millions of dollars, which means you'd lose the potentially hundreds of million of dollars worth of other science projects that money has been available for.

Whenever somebody suggests a solution to the problem that involved 'just' spending more money that's a red light, right there.

Not false, although if we went back in time and told them it would get stuck in the shade of the one shade tree on the asteroid, they'd probably just have put an arm on it to push against rather than ripping out and redesigning the whole power system. Escape velocity is like 1 MPH so they'd have to move pretty carefully.

I was hoping for an apollo 13 style duct tape solution to move the thing to a better, less shaded spot involving the drilling arm as a pogo stick or something, but that hasn't happened as of yet.

Well, that's just the one failure scenario. An RTG would have solved many more - bad solar cells, cracked solar cells, particulate matter covering cells (ice/snow/dirt), failure to deploy cells, etc.

In fact if an RTG was used on the ESA's Beagle 2, it would also have not failed. The Mars Reconnaissance Orbiter snapped a photo of it recently. Its in one piece, its just its cells didn't deploy correctly due to hitting the ground too hard.

Landers take big chances with solar only power. There are so many things that can, and do, go wrong here. I don't know why taxpayers tolerate such shoddy work.

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