Philae's Lost Seven Months Were Completely Unnecessary

StartsWithABang writes: This past weekend, the Philae lander reawakened after seven dormant months, the best outcome that mission scientists could've hoped for with the way the mission unfolded. But the first probe to softly land on a comet ever would never have needed to hibernate at all if we had simply built it with the nuclear power capabilities it should've had. The seven months of lost data were completely unnecessary, and resulted solely from the world's nuclear fears.

Comments

Obligatory reading

[rodrigoandrade]

https://en.wikipedia.org/wiki/Nuclear_power_in_space

Re:Obligatory reading

[Anonymous Coward]

Tsunami that's here and gone...

Vs Radiation that could be here for generations...

Gee... I wonder why people are more concerned...

Re:Obligatory reading

[Drethon]

Right, because the number of fatalities due to nuclear power have been horrific! http://www.the9billion.com/201...

HÃ?

[angel'o'sphere]

and resulted solely from the world's nuclear fears.

What bollocks is that? What has an RTG in space to do with a nuclear (fission) reactor on earth?

No one cares how you power your satellites, space probes.

I for my part have no back yard on a comet light minutes away.

Re:HÃ?

[brambus]

What bollocks is that? What has an RTG in space to do with a nuclear (fission) reactor on earth?

Pu238 is produced in reactors here on Earth. Due to all the restrictions and red-tape put up by (supposedly) anti-nuclear activists, it's difficult and very costly to keep producing it, so everybody who had been producing it, simply shut down.
Now to be honest though, this is a poorly constructed argument. Strict regulation of nuclear materials isn't in itself a bad thing and besides, the lack of Pu238 is mainly due to the shutdown of the nuclear weapons industry, not the power industry (which never produced it anyway). Moreover, Philae was a low-value part of the mission to begin with and an RTG wasn't really necessary (needless to say that it can weigh quite a bit, potentially sacrificing other experiments that could be carried in its stead). Regardless, the comet was scheduled to make a close pass by the Sun regardless, so there was always the possibility of getting more power later on in the mission. Where the RTG argument *can* make sense is in missions like Juno. Juno had to go to some pretty serious compromises to be able to explore Jupiter without an RTG, such as having oversized solar panels for its relatively meager scientific payload. Had Juno had an RTG, it would likely have been able to pack a lot more equipment that is also more power-hungry, allowing us to get more out of the mission. Anything beyond the orbit of Jupiter without an RTG is an outright non-starter using solar power, as the scientific return quickly diminishes to zero simply due to the lack of power. Even Mars missions without RTGs were compromised (one of the principal reasons Curiosity got an RTG was so that we could get more power-hungry experiments on it, cause being able to snap pretty pictures only gets you so far).
Overall, it's a soapbox article and sadly, it starts out with the wrong premise.

Re:HÃ?

[sjames]

Actually, the RTG would have survived had the launch vehicle exploded. It also wouldn't be the first RTG to re-enter the atmosphere.

meanwhile, they missed the boat on the launch, so they protested the Earth slingshot maneuver instead.

Re:Not nuclear fear

[hey!]

Still doesn't mean the solar panels aren't cheaper and more effective for the mission, at the cost of some additional risk. That's how engineering works: you don't get unlimited budget to drive risk to zero.

The important thing to realize here is that events have actually validated the engineers' choice to use solar. Had the interesting stuff been happening out at 5+ AU where you'd only be getting only 5% as much solar radiation as Philae is getting now, then failure to orient the lander ideally would have meant mission failure. But that's not the case. The interesting stuff is happening *now* around perihelion, where there's boatloads of solar radiation available even if the solar panels aren't pointed just so. There is not very much if anything substantive lost by the interim inactivity of the lander, other than a few years life expectancy for the program managers.

Given that we now know that the nitrocellulose powering the harpoon system is unreliable after ten years in a vacuum, you wouldn't design the lander the same way today. You might even choose to use an RTG; I don't know. But this result certain bears out the engineers' assessments of the net prior probabilities; in fact the current outcome was no doubt one of the possible scenarios the engineers considered and put in the success column.

Re:Not nuclear fear

[dryeo]

For a space launch, the RTG needs to be protected in case of launch failure and will weigh more then 12 kg. The ones currently used weigh 57 kg compared to Philae's 21 kg.
I also question whether putting a heat source (300+ watts of heat to equal the required 32 watts) on an ice ball would be smart

Re:Not fear but precaution

[kellymcdonald78]

RTGs have a perfect safety record, including cases there the rocket exploded, the RTG fished out of the ocean and used on a subsequent. We're talking about a few kg of PU-239 in an armored casing.

Re:Not fear but precaution

[Rei]

The article's understanding of things is no better.

The reason we don't use Pu238 more as a primary power source isn't NIMBYs - it's because we're almost out of it and it's absurdly expensive. Pu-238 isn't a "waste product" (except as mixed in with other isotopes and costing a fortune to isolate), it's a manufactured product - and with all transmutation, that means "slow" and "taking up neutronicity that could otherwise be going towards generating power". The plutonium to fuel Philae would have not only cost us a lot but also robbed us of the potential of an outer planets mission until our work to increase plutonium production catch up to our consumption.. It's just not worth it.

I agree with the author about heaters - sort of - but that's really a rather minor point compared to the bigger picture. As it stands, no, they should not have powered Philae with an RTG. And be freaking patient, Philae got to observe the surface when it was cold and is now getting to observe it hotter than we ever thought we'd get the chance to observe. And more to the point, you can't shut off an RTG or a radiothermal heater. Meaning if Philae had been nuclear, it'd be overheating today.