Appropriations Bill Threatens Future Space Science Missions
ColdWetDog writes "A brief story in the Atlantic notes that the U.S. Senate's energy appropriations bill has failed to supply funds to continue Plutonium-238 production, needed for radioisotope generators for NASA's interplanetary probe programs. No PU-238 means no more missions like Cassini-Huygens, or ones that go places where solar cells won't produce enough power. The article notes that the only other source of PU-238 is Russia — either through the government or through trolling through Siberia and the Russian coastline looking for old Soviet Era lighthouses and power stations."
NASA is toast. No politician wants to say it out loud, but they've been setting this up for some time now. The space race is over and they've been scrapping various parts of NASA for the last few years now.
SJW: Someone who has run out of real oppression, and has to fake it.
That means no more Explosive Space Modulators for Marvin to use to threaten to blow Earth away!
Why is this a bad thing? Plutonium is one of the most toxic subtances known. If a spacecraft carrying this stuff blew up after lift-off, the resulting radioactive debris field could be massive. That could potentially shower millions of people with radioactive dust. It would be in our clothes, in our eyes and, worst of all, inhaled into our lungs.
Sorry to reply to such an obvious troll, but the point is worth discussing. Pu is a really nasty poison - but then so is hydrazine. Rockets have some nasty stuff. However, a chunk of Pu metal isn't such a hazard - it becomes so toxic when reduced to dust.
Spacecraft carrying RTGs are designed with this hazard in mind (as well as the danger of "roll up") and if the rocket should explode the RTG system is designed to fall from any alitiude and remain a solid lump of Pu.
Socialism: a lie told by totalitarians and believed by fools.
"plutonium trolls you!"
No, no. That was back on Usenet.
What, you've never hears of Ludwig Plutonium and the Plutonium Atom Totality?
Plutonium and Alexander Abian were the net loons supreme on sci.physics for years.
Many short-lived isotopes are in short supply. There's very limited US tritium production, medical radioisotopes production is so limited that there are medical shortages, and there are fewer research reactors operating. Transmutation is almost a dying technology.
Most of the radioisotopes were made in facilities built for bomb programs. Both the US and the USSR now have far too much bomb-grade PU-239, which has a half-life of 24,000 years. The giant nuclear facilities of the Cold War are mostly idle, or are hazardous waste sites.
The smaller nuclear powers are mostly separating uranium isotopes, which today is a centrifuge operation carried out in plants of modest size. The old gaseous diffusion plants were huge - square miles of plant.
Why are the Democrats opposed to Barne&Noble eReaders? They are not really competing in the iPad market,, only against the Kindle and other low cost devices.
Yes, the Russians have been using these mini-reactors on some of their missions.
http://www.space4peace.org/ianus/npsm2.htm#2_2_1
Complexity and weight. A radioisotope thermal generator has exactly zero moving parts. It is almost literally a sphere of nuclear unstable metal, surrounded by some thermocouples. You really can't get much simpler and hardy than that.
What you are missing is how radioactive Pu-238 is compared to U-235 / U-238
Pu-238 half life 87.7 years. U-238 4.5 billion years, U-235 713 million years, so using pure U-235 the material is 8 million times less radioactive. -- So, you need a corresponding bigger lump of U-235. Needless to say, this is quite a different thing.
I know we all love our space projects here and I'm no exception - but the reality is that part of recovering from this unfathomly huge deficit is cutting spending.
If you were looking at your finances and were trying to take care of your debt aggressively you'd cut damned near anything not necessary. I can't really fault the politicians for this per se, but if they're going to make the programs we love suffer they need to continue cutting elsewhere as well (which appears to be happening relatively slowly and painfully). I've heard them mention there'd be sacrifice and thus I'd also like to see them cut their own benefits and salaries; however, I haven't seen such occur yet. (If it has and I've somehow missed it by all means educate me).
My questions to you all:
-If we start slashing budgets in this manner how does this affect jobs? Obviously there will be layoffs but will it be on a scale that's more/less devastating to our economy as a whole?
-Would you approach this specific funding issue differently?
-What else would you cut?
DNS-and-BIND: http://en.wikipedia.org/wiki/Cassini%E2%80%93Huygens#Plutonium_power_source
To quote the article: ASA's complete environmental impact study estimated that, in the worst case (with an acute angle of entry in which Cassini would gradually burn up), a significant fraction of the 32.7 kg[4] of plutonium-238 inside the RTGs would have been dispersed into the Earth's atmosphere so that up to five billion people (i.e. the entire terrestrial population) could have been exposed, causing up to an estimated 5,000 additional cancer deaths[21] (0.0005 per cent, i.e. a fraction 0.000005, of 1 billion cancer deaths expected anyway from other causes; the product is incorrectly calculated elsewhere[22] as 500,000 deaths), but the odds against that happening were more than 1 million to one.
In other words, there was a 1 million to 1 chance that the space craft might have caused an additional 5000 deaths due to radiation. NOT the 10% you came up with. iirc from the news at the time, a malfunction of the space craft in most probable consequences could have resulted in a small population receiving about what you'd get from one X-ray as the PU-238 ball would mostly just fall through the atmosphere.
-=JML=-
What are the millions of children who want to become Astronauts going to dream about at night?
Kids used to dream about being astronauts when they did exciting stuff. Not so much now they just deliver pizza to the space station.
I doubt that many dream of being train drivers anymore either.
OK-dokey, so presume we're trying to put solar panels on Cassini.
Solar flux @ 1 A.U. (Earth's orbit) -- round to 1kW/m^2
Solar flux @ 10 A.U. (Saturn's aphelion) -- 10W/m^2
Power needed: 700W (to be generated by solar panels instead of RTGs)
Space-rated solar panel efficiency: ~10% (conservative figure takes into account degradation due to age and radiation)
Needed area: (700W)/(0.1)/(10W/m^2) = 700m^2
That's a freaking huge panel, almost as big as a pair of U.S. wing arrays on ISS. For a sense of scale, here's how big the darn things are.
Besides, you need extra fuel or energy to keep the damn things oriented towards the sun. This would likely add more weight since Cassini had to, first and foremost, take lots of pictures. Good luck with taking pics *and* pointing the solar panels. Of course you can have batteries like ISS does. All of this hassle adds significant risk to the mission.
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