Nuclear powered space probes ...

Are you for or against them?

Why do you formulate your poll choices in order to limit the voters options? I thought limiting the voters options (like the two party system does) was something you were completely against.

Anyway, to answer your question, I'm OK with them as long as there is no risk of a radioactive space probe raining down it's carcinogenic insides onto Earth. Whether it be because of an accident during launch or an Earth fly-by.

I don't agree with any of those options either. My response would be: "I'm for space exploration, by whatever means practical." To me it seems obvious that we have limited resources here, if we don't get creative we'll eventually wither and die here.

Undecided ATM. NASA.. plenty of good ideas. Plenty of failures.

At least the bajillion-year old processors on the shuttles provided stability.. if not speed.

I am definitely for space exploration, and I am also generally for nuclear power, but that is for power plants here on earth. I don't really know enough about the pluses and minuses of nuclear powered space probes to give a completely sure answer.

If I'm not for space exploration, then I must be against:
1. I cannot sympathize with any sort of ambition, goal, hope etc.
2. Leaps for mankind make me itch.
3. Curiosity? Humane virtue, isn't it.
4. I like the idea that this victorious species will be trapped, heaped up on this small planet -who knows where.

Happily following doctor's orders:
"There is no need for you to leave the house. Stay at your table and listen. Don’t even listen, just wait. Don’t even wait, be completely quiet and alone. The world will offer itself to you to be unmasked; it can’t do otherwise; in raptures it will writhe before you."

If NASA uses nuclear power, then they just might use Canadian uranium. Because god knows that that's the only way Canadians will ever make an impact in space.

Plus, if ever there was a mission to Mars, and something went horribly, horribly wrong, and they couldn't come home... Boom!

Nuclear power sources have been used in space probes since before 1961. In fact nearly all long range space probe missions so far including Apollo, Pioneer, Viking, Voyager, Galileo, Ulysses, Cassini and New Horizons as well as many civil and military satellites have used it.

Its a pretty mature technology so I don't see much of a problem with it if it suits the requirements of the mission. With any technology, human error/stupidity can always cause major problems so safety should remain a high priority.

:2 cents:
We should probably be more concerned about more experimental or untested technologies such as the LHC at CERN. Not that the LHC is guaranteed to be dangerous but that the review requirements are not transparent enough or comprehensive enough. The LSAG safety report was late in coming (submitted only 3 months before the go-live date), introduced with very little publicity, and to be officially reviewed by an "independent" group apparently to be selected by CERN. Do companies or organizations regulate themselves very well especially after investing billions?

LHC may indeed be very safe, maybe only a .001% - 5% chance of a global disaster. The fact is nobody knows for sure, as Brian Cox and others readily admit, that's the point of doing experiments after all. But even if the project backers are willing to take a 1% chance with their own lives for huge advances in science, should they be allowed to do so with the lives of everyone else? Allow only 3 months of public scientific review on a topic so complex and with such a wide ranging impact?

(Sorry Prof Voluptuary for the minor hijacking...Just didn't want to leave it with only the first sentence. If Mods feel it is too much of a sidetrack - please edit out.) Thanks.

Weren't they playing around with Ion based propulsion recently? Surely a tad more efficient and safer than jamming the engine block full of microwaves!

I also hear they've made progress with slush hydrogen as a fuel.

stainedblueyes said:

Weren't they playing around with Ion based propulsion recently? Surely a tad more efficient and safer than jamming the engine block full of microwaves!

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You're right, improvements are being made all the time. More than just playing around though, the technology has been around for a while. Some probes http://dawn.jpl.nasa.gov/mission/status.asp have already been sent out using solar generated ion propulsion. The impact of microwaves on the engine in nuclear powered propulsion is not the concern it's the potential release of radioactive fuel during a ground or atmospheric explosion.

Improvements have been made in ion propulsion (and it's always been efficient) but the thrust still isn't sufficient for most of the missions on the horizon such as manned missions and bases on the moon and Mars. The duration would be too long and "slingshot" opportunities missed.

Fundamentally though the issue isn't so much the propulsion system as it is about power generation. Solar panel ion propulsion or enormous solar sails would solve the radiation ground explosion issue but even as deep space probes may in some cases be wanting for thrust as they get farther from the sun or in order to reduce mission duration. For other missions ion propulsion would be just the thing.

I'm not certain which other cost effective methods are available in the near term which allow us to avoid lifting radioactive fuel sources from Earth. Eventually maybe probes launched from the moon powered by Helium-3, a combination of surface based lasers and ion propulsion, or a Bussard ion ramjet scooping fuel from the interstellar medium, who knows.

Eureka!

Preface: I purposely started this thread and then left it for a bit, not posting ... until now.

Ceska said:

Nuclear power sources have been used in space probes since before 1961. In fact nearly all long range space probe missions so far including Apollo, Pioneer, Viking, Voyager, Galileo, Ulysses, Cassini and New Horizons as well as many civil and military satellites have used it.
Its a pretty mature technology so I don't see much of a problem with it if it suits the requirements of the mission. With any technology, human error/stupidity can always cause major problems so safety should remain a high priority.
...
(Sorry Prof Voluptuary for the minor hijacking...Just didn't want to leave it with only the first sentence. If Mods feel it is too much of a sidetrack - please edit out.) Thanks.

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It's really nice to see someone who "gets the perspective" of this.

Especially this part ...

Ceska said:

... Fundamentally though the issue isn't so much the propulsion system as it is about power generation ...

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Ding! Ding! Ding! Ding! Winnah!

Ceska said:

I'm not certain which other cost effective methods are available in the near term which allow us to avoid lifting radioactive fuel sources from Earth.

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I also think people forget that there is far less risk in boosting an encased RTG than there is an Ion Drive, let alone the operational differences.

PlasmaTwa2 said:

If NASA uses nuclear power, then they just might use Canadian uranium. Because god knows that that's the only way Canadians will ever make an impact in space.

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Actually, the Canadians are very active in the Shuttle Transport System (STS). Not only did many of the former Avro Canada engineers come to NASA and other American aerospace firms post CF-105 "brain drain," but Canada is behind the Orbiter's Robotic Arm.

stainedblueyes said:

Weren't they playing around with Ion based propulsion recently? Surely a tad more efficient and safer than jamming the engine block full of microwaves!

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And that would replace the purpose of a RTG how?

stainedblueyes said:

I also hear they've made progress with slush hydrogen as a fuel.

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And that would replace the purpose of a RTG how?

Hint: Referring back to the above "Winnah," the RTG, which people protest against, isn't used for propulsion.

senob44 said:

I am definitely for space exploration, and I am also generally for nuclear power, but that is for power plants here on earth. I don't really know enough about the pluses and minuses of nuclear powered space probes to give a completely sure answer.

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Read up on RTGs and how it's just like any radioactive material in nature, decaying:
http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

Very, very different than the sub-critical reactions of nuclear fission power plants, which purposely excites the materials different than how they exist in nature and decay normally.

BTW, the Wikipedia page has an excellent history on the explosion of RTG in space launches and re-entries. I'll post for your reading.

"There have been six known accidents involving RTG-powered spacecraft. The first one was a launch failure on 21 April 1964 in which the U.S. Transit-5BN-3 navigation satellite failed to achieve orbit and burnt up on re-entry north of Madagascar. Its 17,000 Ci (630 TBq) plutonium metal fuel was injected into the atmosphere over the Southern Hemisphere where it burnt up, and traces of plutonium 238 were detected in the area a few months later. The second was the Nimbus B-1 weather satellite whose launch vehicle was deliberately destroyed shortly after launch on 21 May 1968 because of erratic trajectory. Launched from the Vandenberg Air Force Base, its SNAP-19 RTG containing relatively inert plutonium dioxide was recovered intact from the seabed in the Santa Barbara Channel five months later and no environmental contamination was detected. [10]

Two more were failures of Soviet Cosmos missions containing RTG-powered lunar rovers in 1969, both of which released radioactivity as they burnt up. There were also five failures involving Soviet or Russian spacecraft which were carrying nuclear reactors rather than RTGs between 1973 and 1993.[11]

The failure of the Apollo 13 mission in April 1970 meant that the Lunar Module reentered the atmosphere carrying an RTG and burnt up over Fiji. It carried a SNAP-27 RTG containing 44,500 curies (1,650 TBq) of plutonium dioxide which survived reentry into the Earth's atmosphere intact, as it was designed to do, the trajectory being arranged so that it would plunge into 6-9 kilometers of water in the Tonga trench in the Pacific Ocean. The absence of plutonium 238 contamination in atmospheric and seawater sampling confirmed the assumption that the cask is intact on the seabed. The cask is expected to contain the fuel for at least 10 half-lives (i.e. 870 years).

The US Department of Energy has conducted seawater tests and determined that the graphite casing, which was designed to withstand reentry, is stable and no release of plutonium should occur. Subsequent investigations have found no increase in the natural background radiation in the area. The Apollo 13 accident represents an extreme scenario due to the high re-entry velocities of the craft returning from cislunar space. This accident has served to validate the design of later-generation RTGs as highly safe.

To minimize the risk of the radioactive material being released, the fuel is stored in individual modular units with their own heat shielding. They are surrounded by a layer of iridium metal and encased in high-strength graphite blocks. These two materials are corrosion and heat-resistant. Surrounding the graphite blocks is an aeroshell, designed to protect the entire assembly against the heat of reentering the earth's atmosphere. The plutonium fuel is also stored in a ceramic form that is heat-resistant, minimising the risk of vaporization and aerosolization. The ceramic is also highly insoluble.

The most recent accident involving a spacecraft RTG was the failure of the Russian Mars 96 probe launch on 16 November 1996. The two RTGs onboard carried in total 200 g of plutonium and are assumed to have survived reentry (as they were designed to do). They are thought to now lie somewhere in a northeast-southwest running oval 320 km long by 80 km wide which is centred 32 km east of Iquique, Chile"

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Other than our initial '64 event, which taught us a lot, the US isn't really who you have to worry about today, as usual.
We've destroyed a couple of spacecraft now, retrieved the RTGs, and reused them.

BTW, I'm actually, and pleasantly, surprised to see the votes as they are in general.

Given finding out more about RTG's (thanks Prof) I see no problem with using them to power spacecraft. They seem to be quite safe, posing little threat to us earthlings. I am impressed at the amount that these things seem to have been thought through, especially in recent years. They have addressed any problem I can think of at least.

Re: Eureka!

Prof Voluptuary said:

Actually, the Canadians are very active in the Shuttle Transport System (STS). Not only did many of the former Avro Canada engineers come to NASA and other American aerospace firms post CF-105 "brain drain," but Canada is behind the Orbiter's Robotic Arm.

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Oh yeah, I forgot about the Canadarm... :bowdown: The Professor is a smart guy.

Re: Eureka!

PlasmaTwa2 said:

Oh yeah, I forgot about the Canadarm... :bowdown: The Professor is a smart guy.

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I remember seeing that arm in a shot of the space station. "Canada" emblazoned across it. I was like "Canada has a space program?" Apparently so, at least somewhat!

Re: Eureka!

senob44 said:

I remember seeing that arm in a shot of the space station. "Canada" emblazoned across it. I was like "Canada has a space program?" Apparently so, at least somewhat!

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Hey, we were the third country to launch a sattelite! Granted, we tied it to the end of one of your's using a piece of string, but I haven't seen Mexico getting that far yet! :1orglaugh

All in all nuclear space exploration doesn't seem like all that bad of an idea, although I don't have all the facts about it.

Someone actuall clicked on "Im against space exploration period" whats wrong with you two?

Nuclear power is probably the only way to acheive long space flight, unless they come up with a way of making their own fuel up there.

BlueBalls said:

Someone actuall clicked on "Im against space exploration period" whats wrong with you two?

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Formerly on several debate teams in the past, a key attribute to have is to be able to argue any side of a topic. I found for/against space exploration regularly came up, and it's not hard to skew statistics to favor "against."

BlueBalls said:

Nuclear power is probably the only way to acheive long space flight, unless they come up with a way of making their own fuel up there.

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Actually, the old, legacy concept of a "ramscoop" (for the trace amount of hydrogen in space) and nuclear fusion were common in science circles. Not really sure how viable that is though, especially when it comes to the nuclear fusion aspect.