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More space news!


tkdguy

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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.

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Re: More space news!

 

 

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.

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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?

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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.

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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.

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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.

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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.)

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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").

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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.

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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.

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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.

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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.

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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.

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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. ;)

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