Hacker News Reader

Comment by CydeWeys | Hacker News Reader

I wish Europe weren't so nuke-averse. The lander should have been powered by a radioisotope thermoelectric generator (RTG), not solar panels. Then it would've had uninterrupted power for years and it could have been returning scientific data continuously since November.

Most of the US's long distance space probes have been powered with RTGs, which don't put nearly the same kinds of limitations on mission profiles. The New Horizons mission to Pluto, for example, is powered with 10.9 kg of plutonium that provides a steady 228 watts and enough heat to prevent the kind of cold-related damage we fear happened on Philae. That mission is so far from the Sun that it wouldn't even be possible with only solar panels.

View on HN

You're blaming this on Europe being nuke averse, but Europe is not a homogenous area. While some European countries may be nuke averse, others have adopted nuclear power to a huge extent.

There are other reasons why an RTG might not have been appropriate for Philae. They're pretty heavy, and the lander is pretty light. Also, it is wasteful to use an RTG that could last many years when the mission is only expected to last several months.

You're right that Europe isn't homogenous, but it's not like every country in Europe has its own independent space agency. They have the ESA, which is nuke-averse. I was using "Europe" as a linguistic short-cut for the European space efforts, which are unified.

Per someone else's comment, RTGs don't have to be heavy. Wikipedia lists one as light as 2.1 kg: https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge... Keep in mind that RTGs replace not just the solar panel and electricity generating systems but also a lot of the heating system as well.

You can see the breakdown on Philae here: https://en.wikipedia.org/wiki/Philae_(spacecraft)#Design It uses about 16 kg total between the power system and thermal control system. You could fit in an RTG with the same or higher power output as the solar panels for the same mass. Philae in total is around 98 kg, which is definitely above the size threshold of craft that could be powered with an RTG.

Not every country has it's own but quite a few do, like Germany for example.

"You could fit in an RTG with the same or higher power output as the solar panels for the same mass."

As an expert you should go work for ESA. I'm sure they need you. Oops, armchair space engineer, I forgot. If you need to look in Wikipedia, you have no clue about the subject matter.

Perhaps you have your causation backward: perhaps the mission was planned to last only months due to power limitations.

Philae is a tiny little 100kg add on … 29 times heavier Rosetta (the orbiter) is the main course, Philae is this tiny little and quite experimental (though admittedly extremely cool – mostly because of exactly its novel mission) little hitchhiker.

RTGs are heavy and consequently have pretty much only been used on much heavier spacecraft and even then mostly only when being solar powered just wasn’t an option. For Philae, besides it being very lightweight, being solar powered was and is an option and the only reason it didn’t work out is because things went wrong during the landing …

How in the hell do you even get the idea that Nasa would have used an RTG in ESA’s place here?! They are not psychic. They couldn’t have predicted things going wrong during the landing … and why then put an RTG on this when that’s something Nasa themselves does only very, very rarely and only for very different missions with much more demanding payloads?!

What is this insanity? Why the need to get onto this political pulpit and spew out some unrelated political propaganda because you feel like what? What’s the point of this deliberate and pointless provocation?! Huh? I’m confused and angry at this abundance of irrationality.

RTGs don't have to be heavy and big. Sure one to power a car sized rover like Curiosity with large motors, science equipment, lasers, etc will be big. But one to power a little probe with 24 watts would be tiny. In the 70s there were actually nuclear powered pace makers implanted inside people, so the technology can definitely scale down: https://www.orau.org/ptp/collection/Miscellaneous/pacemaker....

So why doesn’t Nasa use them all the time?

Two reasons. One, in a lot of situations solar power is essentially guaranteed, and when there's no chance that there won't be sun solar panels are a hell of a lot cheaper. Second, there's a plutonium shortage in the US at the moment [1] making it really hard to secure an RTG.

[1] http://www.wired.com/2013/09/plutonium-238-problem/

I was under the impression that they thought the lander would be blown off the comet when it starts to shed ice and debris in large amounts around perihelion.

The European Space Agency together with the National Nuclear Laboratory are looking for a potential use of americium-241 in developing RTGs. So they aren't completely nuke-averse.

http://www.nnl.co.uk/news-media-centre/news-archive/space-ba... http://www.quora.com/How-does-ESA-plan-to-power-its-future-s...

Also, wasn't NASA's Advanced Stirling Radioisotope Generator canned in 2013 due to budget cuts? And recently there were problems with procuring plutonium-238. RTG isn't a silver bullet.

http://www.economist.com/news/science-and-technology/2164758...

Maybe some country, or company, could start a profitable business of launching RTGs and selling them to the ESA after they are safely in orbit?

I wonder how high insurance costs for "launching radioactive isotopes into orbit" are.

The so-called "green parties" have caused a lot of environmental damage to Europe and the earth. Instead of relatively speaking quite safe nuclear power, in many places we are getting quite dangerous coal power. Pretty much just out of ignorance.

Germany's wind turbines and solar farms disagree. 30% of its energy is renewable.

(This is not technically a reply to you, but just some context in case anyone else is interested.)

For my own benefit, I have attempted to interpret the statistics in this relatively authoritative source: http://www.erneuerbare-energien.de/EE/Navigation/DE/Service/...

As far as I can tell, for the year of 2014, Germany's primary energy consumption breaks down approximately 15/35/20/30 for electricity generation, heating, transportation, and other [p.10]. Approximately 30% of the electricity generation is from renewable sources [p.5], which is split approximately 35/25/20/20 between wind, biofuels, solar, and other (including hydro) [p.6]. Nearly all of the contribution of renewable sources to heating and transportation is from biofuels [p.8--9].

tl;dr: Renewable energy accounts for approximately 30% of electricity generation in Germany. Overall, renewable energy accounts for approximately 11% of primary energy consumption.

In Germany old coal plants that were due to be decommissioned are now still running because nuclear plants are being switched off instead. Are you sure the good done by the greens outweighs the bad?

> In Germany old coal plants that were due to be decommissioned are now still running because nuclear plants are being switched off instead.

As far as I know that was one of the fears stated, but never actually happened. Do you have any sources stating that coal plants meant to be decomissioned now will run longer?

That's a misleading number. Those devices embody a huge amount energy, which China supplied in the form of coal.

It'll be decades before they pay it back, in the meantime they just caused more CO2 in the air.

Nuclear would have been better.

Not that again. No it does not take decades to pay back the energy cost of the production of Wind Turbines or Solar Panels. Win turbines have an average payback time of 2-8 Months. Solar panels are far worse but even there the payback time for the complete System (Panel, Inverter, Installation, Transport) is between 2.5 Years to 1 Year depending on the panel technology [1]. These numbers are from a Frauenhofer Study from 2009 so one can assume that today's payback times are better than that due to slightly increased efficiency.

[1] http://c1cleantechnicacom.wpengine.netdna-cdn.com/files/2013...

100% agree, and all these "pay back" arguments forget the payback time of coal or nuclear systems.

I highly doubt it's that short, that would mean that after 1 year you would make back all your money and everything after is profit?

I've never seen any numbers even close to that, they all give decades to make make back your money, even when selling the electricity at retail, and certainly not when selling at wholesale.

I think nuclear power is safest even in absolute terms not only relatively.

Why? This cursory Google search https://www.google.co.in/search?q=death+per+terawatt seems to say nuclear has less kills per terawatt-hour than coal, though obviously quantifying deaths from all these power sources is hard.

The issue with this is how it calculates deaths per terrawatt.

Nuclear has the whole waste storage (and, in some places, drinking water contamination) issue, while coal has the whole climate change issue.

Both are bad, but just saying that one of them has less short-term, but more long-term deaths isn’t a good argument.

Imho, "the whole climate change issue" is a waste storage issue as well.

Except it doesn't kill people quite as quickly, so we're okay with it just being released into our atmosphere.

Have there been any documented cases of nuclear waste storage causing mortal danger, and if so, how do they compare to coal's waste storage (or, more precisely, the lack thereof)?

I don't know any details on either, but I'd suspect that the latter is a much greater threat than the former, and that the more we transition from coal to nuclear fission (and, alongside that, the more we develop ways to use nuclear waste more productively), the better.

The worst case is rather nasty though: the rendering of a large area uninhabitable and unusable for agriculture. There aren't a lot of sites in Europe where you can site a nuclear reactor far enough away to avoid either evacuating a major city or losing an agricultural region. There is no "away", as people like to say about rubbish.

Compare that large area to that consumed by business-as-usual for the alternatives though. E.g. the area rendered uninhabitable/unusable for hydro power is larger (per kwh). (Of course many people find a reservoir more attractive than a radioactive zone, but both are equally unusable for habitation or agriculture)

area rendered uninhabitable/unusable for hydro power is larger

That can be true of reservoirs (Lake Mead is huge) but isn't necessarily. UK's largest reservoir is https://en.wikipedia.org/wiki/Kielder_Water at a mere 2 miles by <6 miles, supporting a piddly 6MW (yes, megawatts not gigawatts, I had to double check that). But that's subject to planning permission in a way that radioactive exclusion zones aren't. The UK suffered from Chernobyl fallout for years: http://www.telegraph.co.uk/news/uknews/1514492/20-years-on-B...

It's not that nuclear power is bad on average, it's just that the worst case scenarios affect potentially huge areas.

A clarification to the point about Kielder's power generation: Kielder reservoir is primarily for regulating the water supply, rather than power generation. There are many hydro-electric plants in the UK generating much more power.

solar would seem to be safer, presuming you can manufacture the cells without causing environmental degradation.

Nope, at least not according to the figures I've seen (e.g., http://www.forbes.com/sites/jamesconca/2012/06/10/energys-de...). I think the main reason is that installing solar panels isn't perfectly safe. Nuclear comes out a long way ahead of solar -- but both are vastly ahead of coal.

> That mission is so far from the Sun that it wouldn't even be possible with only solar panels.

Maybe there's your answer?

"Europe" isn't nuke-averse; French nuclear plant designs are considered among the world's best, and Germany only backed off nuclear power when Fukushima happened.

In light of Fukushima I wish EVERYONE were more nuke-averse...

In light of Fukushima, everyone should be more aware of what happens when you don't properly maintain, and update your nuclear power plants. In light of global warming, and carcenogens released caused by burning coal, I wish every one were more pro-nuclear.

I would add that I hope we all take flood control recommendations more seriously in light of Fukushima, too. I recall that TEPCO knew that it wouldn't withstand a tsunami of that magnitude, and they proceeded to ignore that risk.

Germany backed off nuclear power in the 90s long before Fukushima. That process was merely slowed down before Fukushima and set back on track afterward.

This has to also be kept in mind when considering nuclear power in Germany. The nuclear plants in Germany are so old that whether you are pro or contra on nuclear power, shutting down the existing plants is more or less a non-issue.

It is probably also a lot easier for the US to launch a space probe with a nuke power source than Europe.

Regulatory requirements are very different and I am sure the US would not be too happy if Europe where to launch something with a nuke onboard without their approval.

Not so much easier.

There were demonstrations in America against the launch of Cassini, which is a nuclear RTG-powered spacecraft in orbit around Saturn.

http://www.cnn.com/TECH/9710/04/cassini/

I remember the demonstrations, but they didn't stop it.

I think putting a nuke on a rocket makes everyone nervous, not just the Americans...

It's not "a nuke", it's a relatively small amount of radioactive material that is sealed inside a very strong capsule designed to survive almost any imaginable catastrophe during launch. The launches are from the coast out over the water. Yes there are still some risks, but in the grand scheme of things, the risks are nothing compared to the importance of exploring the universe.

How about the PR strategy? "The lander wakes up, we get headlines again!"

</sarcasm>

http://www.popsci.com/nasa-can-make-3-more-nuclear-batteries...

http://www.space4peace.org/ianus/npsm2.htm#2_3

Your links are out of date. The US has since resumed Pu 238 production for use in space-borne RTGs: http://www.economist.com/news/science-and-technology/2164758...

Even if we hadn't resumed production, I'd still be arguing that the simple fix is to resume production and continue using the proven technology, not to simply give up on it.

Reply on news.ycombinator.com