Cancer Posted December 7, 2011 Report Share Posted December 7, 2011 Re: More space news! Following on a post I made in the NGD forum's Voyager thread (here), we are running out of Pu-238, the power source for RTG's used in deep space missions. The US hasn't made any since 1988, and the Russians are playing games with their stocks. (recent popular-media article), (another) The American Astronomical Society spammed its members with an action item (to contact Congress): ACTION ITEM The House and Senate will soon conference to finalize the Energy and Water Development Appropriations bill, perhaps in concert with other appropriations bills. Senator Feinstein and Alexander can include the restart funding during the conference process that was taken out of the Senate appropriations bill and is already included in the House version. Please contact Senator Dianne Feinstein (D-CA), Chair of the Energy & Water Appropriations subcommittee and Senator Lamar Alexander (R-TN), Ranking Member, either by written letter or by phone. When calling the office, ask to speak to the staffer who is responsible for the restart of domestic production of plutonium-238 within the Department of Energy. Senator Dianne Feinstein United States Senate 331 Hart Senate Office Building Washington, D.C. 20510 Phone: (202) 224-3841 Fax: (202) 228-3954 TTY/TDD: (202) 224-2501 Senator Lamar Alexander United States Senate 455 Dirksen Senate Office Building Washington, DC 20510 Phone: (202) 224-4944 Fax: (202) 228-3398 TTY: (202) 224-1546 Sample Communication for either Senator Feinstein or Alexander: Hello, my name is [your name]. I am from [location] and [EITHER a constituent of the Senator] [OR a research scientist interested in the the restart of production of plutionium 238]. I am contacting you to express strong support for funding the $10 million requested for the DOE Office of Nuclear Energy to restart domestic production of plutonium-238 for planetary science missions in the Energy & Water Development appropriations bill during the upcoming conference process and to thank the Senator for their support of this effort by voting to provide NASA $10M for this activity. The Mars Science Laboratory Curiosity Rover, schedule to launch on November 25, is using a large portion of the worlds limited supply of Pu-238. The funding will allow production to begin immediately. Once domestic production is restarted, there will still be at least a five-year delay to have enough Pu-238 for a spacecraft. Full scale Pu-238 production is unlikely until 2018, which is too late to meet all of NASA's needs. The delay will push back the proposed planetary space missions that would require Pu-238. We cannot afford to delay production any longer. The current Visions and Voyages Planetary Science Decadal Survey says that, "the committee is alarmed at the status of plutonium-238 availability for planetary exploration. Without a restart of plutonium-238 production, it will be impossible for the United States, or any other country, to conduct certain important types of planetary missions after this decade." Thank you for your support in maintaining the United States as the world leader in planetary science and expanding human knowledge of the universe. Mailed 6 December 2011 AASMembers mailing list Even if the Pu-238 production restart is funded, there's already going to be about a five-year gap in mission launches. Without the funding, that gap will be ... much longer. Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted December 7, 2011 Report Share Posted December 7, 2011 Re: More space news! I wonder if not funding the making of more Pu-238 is in truth the "back door" way to drive yet another nail into the space exploration coffin. Quote Link to comment Share on other sites More sharing options...
tkdguy Posted December 9, 2011 Author Report Share Posted December 9, 2011 Re: More space news! Private Spacecraft to Fly to ISS in February Lost Moon Rocks Large Asteroids Near Earth Last Lunar Eclipse of 2011 And if you're in the right area, watch out for this phenomenon. Opportunity's 5th Winter on Mars Evidence of Water on Ancient Mars Destination Europa? Quote Link to comment Share on other sites More sharing options...
Old Man Posted December 10, 2011 Report Share Posted December 10, 2011 Re: More space news! And if you're in the right area, watch out for this phenomenon. I'm unlikely to be conscious at 4am, unfortunately. Quote Link to comment Share on other sites More sharing options...
Gnaskar Posted December 14, 2011 Report Share Posted December 14, 2011 Re: More space news! Private Spacecraft to Fly to ISS in February SpaceX finally gets permission to dock with ISS, despite Russian complaints delaying the mission by two months (again). Insistently and in no way related to this, Russia currently has a monopoly on bringing stuff to the ISS for about 6 times the price SpaceX is offering. Meanwhile, Russia also has the world's only know stockpile of Pu-238, a vital component in all deep space power and heating systems. NASA is welcome to it as far as Roscosmos is concerned, for the appropriate price. Remember how international cooperation between the USA and USSR in space was a sneaky plan the bankrupt the Russians? Good luck with that.* * Yes, I know, it worked 20 years ago. That also cost us (humanity) the third most awesome rocket of all time (and the most awesome that was actually launched), but that's a rant for another day. Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted December 15, 2011 Report Share Posted December 15, 2011 Re: More space news! One of the things I find neat is that I was asking about such a possibility just very recently. Quote Link to comment Share on other sites More sharing options...
tkdguy Posted December 16, 2011 Author Report Share Posted December 16, 2011 Re: More space news! Comet's lucky escape Picture gallery of the article Quote Link to comment Share on other sites More sharing options...
tkdguy Posted December 20, 2011 Author Report Share Posted December 20, 2011 Re: More space news! Meteorites Trigger Avalanches on Mars Quote Link to comment Share on other sites More sharing options...
tkdguy Posted December 21, 2011 Author Report Share Posted December 21, 2011 Re: More space news! Earth-sized Planets Found But they're too hot to have liquid water. Quote Link to comment Share on other sites More sharing options...
McCoy Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! They're believed to be too hot to have liquid water. Wasn't that long ago experts were insisting there was no liquid water in the solar system except on Earth. We've pushed the "Goldilocks zone" out to the orbit of Saturn, who's to say it couldn't go closer sunward than we currently believe? Quote Link to comment Share on other sites More sharing options...
Cancer Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! Well, the Habitable Zone is defined by radiative heat input from the star being balanced by radiative losses from the planet. Liquid water in the satellites of the Jovian planets is there because of tidal friction and heating, an entirely different process, and one that depends not at all on stellar energy input. That means, as you're suggesting, that you have to start wondering how relevant stellar radiation is as a requirement for microbial life. If you want an oxygen-rich atmosphere, though, you need to be in the old-fashioned HZ, since it seems that O2 is a product only from photosynthesis. Quote Link to comment Share on other sites More sharing options...
Christopher Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! Liquid water in the satellites of the Jovian planets is there because of tidal friction and heating' date=' an entirely different process, and one that depends not at all on stellar energy input. That means, as you're suggesting, that you have to start wondering how relevant stellar radiation is as a requirement for microbial life.[/quote'] The energy input needs to be relatively stable over long time. Geothermal processes might not do that as reliably as stellar radiation. Quote Link to comment Share on other sites More sharing options...
Cancer Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! Maybe, though that overlooks the wildly variable ultraviolet output that solar-mass stars have for the first billion years or so. That's not too important in terms of their luminosity, but it complicates the early history, and makes you wonder about how biochemistry-friendly the inner part of the star system is going to be. Now, it may be that early planetary atmospheres are more or less guaranteed to be thick enough to block out the UV (it didn't stop life from starting on Earth), but it emphasizes the extreme simplification of the Habitable Zone model. Quote Link to comment Share on other sites More sharing options...
McCoy Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! Well' date=' the Habitable Zone is defined by radiative heat input from the star being balanced by radiative losses from the planet. Liquid water in the satellites of the Jovian planets is there because of tidal friction and heating, an entirely different process, and one that depends not at all on stellar energy input. That means, as you're suggesting, that you have to start wondering how relevant stellar radiation is as a requirement for microbial life. If you want an oxygen-rich atmosphere, though, you need to be in the old-fashioned HZ, since it seems that O2 is a product only from photosynthesis.[/quote'] Only? Isn't there free oxygen on Mars? (Unfortunately mostly as O3 rather than the more user-friendly O2 variety.) Quote Link to comment Share on other sites More sharing options...
Tom Carman Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! Only? Isn't there free oxygen on Mars? (Unfortunately mostly as O3 rather than the more user-friendly O2 variety.) Given that we are utterly dependent on the stuff for survival, I think we tend to overlook how "eager" oxygen is to combine with practically anything at the first opportunity. Without some process to continually generate it, free molecular oxygen doesn't last long (for certain values of "long"). Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! Maybe' date=' though that overlooks the wildly variable ultraviolet output that solar-mass stars have for the first billion years or so. That's not too important in terms of their luminosity, but it complicates the early history, and makes you wonder about how biochemistry-friendly the inner part of the star system is going to be. Now, it may be that early planetary atmospheres are more or less guaranteed to be thick enough to block out the UV (it didn't stop life from starting on Earth), but it emphasizes the extreme simplification of the Habitable Zone model.[/quote'] It was my understanding that life formed in the ocean first, and was restricted to it's protection from UV radiation until enough atmospheric oxygen had built up to allow the UV radiation to create the ozone layer that shields the whole planet, allowing life to expand to the land masses. Afaik, a thick (non-Jovian) atmosphere doesn't really cut it in terms of UV blocking unless it has a good amount of free O2 to be turned into O3. Quote Link to comment Share on other sites More sharing options...
megaplayboy Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! Weird sci-fi question--Assuming the HZ is proportional to luminosity, and that if one were to build a Dyson Sphere/Ringworld or other structure, one would want to conform its dimensions to the HZ of the star it was co-habiting with(orbiting seems like the wrong term here). Wouldn't that mean, for stars of extremely high luminosity(say, 10,000 to 1,000,000+ x Solar luminosity), the HZ distance would be quite large, and consequently any DS around one would be mind-staggeringly ginormous? Just asking because I'm thinking about doing something like that for a campaign. Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! Speaking about extra-solar planets that are earth-sized but not in the HZ, I had a thought. For those planets that are a little too close to their primary (star), I wonder how feasible a "solar filter" would be, essentially a thin, planet-diametered, semi-transparent membrane that reduces the solar radiation, and orbited at the L1 point. Naturally, safeguards against CMEs would need to be developed. Quote Link to comment Share on other sites More sharing options...
dmjalund Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! Temperature at a given distance from a star is proportional to the 4th root (the square root of the square root) of the Luminosity Quote Link to comment Share on other sites More sharing options...
megaplayboy Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! Temperature at a given distance from a star is proportional to the 4th root (the square root of the square root) of the Luminosity So, by that equation, the HZ for a star with a Luminosity of 1,000,000 x our Sun, should be around 32 AUs. That's a big Dyson Sphere. Quote Link to comment Share on other sites More sharing options...
Christopher Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! So' date=' by that equation, the HZ for a star with a Luminosity of 1,000,000 x our Sun, should be around 32 AUs. That's a big Dyson Sphere.[/quote'] I think your asumption about Luminosity = thermal radiation could be very wrong. The sun gives of a lot more Infrared Radiation than Visibile light. Quote Link to comment Share on other sites More sharing options...
megaplayboy Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! I think your asumption about Luminosity = thermal radiation could be very wrong. The sun gives of a lot more Infrared Radiation than Visibile light. ....Isn't most radiation "thermal"? Microwaves, radio waves, uv rays, etc. can all generate quite a bit of heat when concentrated to any extent. Still, I appreciate that input. I'm just trying to get a ballpark figure for the HZ for much brighter stars. At least hypothetically, anyway--it may well be that such stars emit more of the variety of radiation likely to be inimical to life(e.g., gamma rays, uv rays, x-rays, etc.). Just trying to figure out how gigantic one could make a megastructure around such a star. Quote Link to comment Share on other sites More sharing options...
Christopher Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! So' date=' by that equation, the HZ for a star with a Luminosity of 1,000,000 x our Sun, should be around 32 AUs. That's a big Dyson Sphere.[/quote'] Accordign to wikipedia that was right: http://en.wikipedia.org/wiki/Habitable_zone But the distance seems to be calculated differently. It's the Square Root of the Luminosity (realtive to earth sun). So our hypothetical 1,000,000 more Luimnous Star would have a HZ of 1,000 AU. Quote Link to comment Share on other sites More sharing options...
megaplayboy Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! Accordign to wikipedia that was right: http://en.wikipedia.org/wiki/Habitable_zone But the distance seems to be calculated differently. It's the Square Root of the Luminosity (realtive to earth sun). So our hypothetical 1,000,000 more Luimnous Star would have a HZ of 1,000 AU. Wow, that's kinda what I thought initially, since radiation per unit area would vary according to the square of the radius. 1000 AUs, or 3000 AUs for the most luminous star yet discovered--when I have the time tonight, I'm going to work that surface area out, longhand, just to give me a visceral feeling for how enormous that would be. A Dyson Sphere with a surface area 1 million+ times greater than one around our Sun. Finally, a place to hold all my stuff. Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! A place for my MtG collection. Quote Link to comment Share on other sites More sharing options...
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