Author Topic: Wired article on Pu-238 production for space missions  (Read 29574 times)

Offline Steven Pietrobon

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Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #21 on: 03/22/2014 03:54 AM »
Here's an article in Space News about there being only enough Pu238 for Curiosity 2.

http://bt.e-ditionsbyfry.com/publication/?i=201481&utm_source=WhatCountsEmail&utm_medium=Digital%20Issue%200317_14&utm_campaign=Weekly%20Digital%20Issue%20v6_TextOnly&_wcsid=3F1D8990C5FCAF89B15F03172AEE39DAC523C6857676BDD52E6AE64CBF1B101C

That's not really what it says. It's not available for the next Discovery call, but that's a temporary production issue. The stockpile is significant. They have enough for Mars 2020 plus Europa. I thought I posted the inventory information here a week or two ago.
« Last Edit: 03/22/2014 03:56 AM by Blackstar »

Offline Steven Pietrobon

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Re: Wired article on Pu-238 production for space missions
« Reply #22 on: 03/22/2014 05:26 AM »
Thanks for the clarification Blackstar. I came to that conclusion after reading this paragraph.

"With Stirling out of the picture, NASA says there will not be enough plutonium-238 ready at the end of the decade to fuel comparatively inefficient Multi-Mission Radioisotope Generators for both the Mars 2020 Rover and the Discovery 13 mission."
« Last Edit: 03/22/2014 05:30 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #23 on: 03/22/2014 12:39 PM »
Thanks for the clarification Blackstar. I came to that conclusion after reading this paragraph.

"With Stirling out of the picture, NASA says there will not be enough plutonium-238 ready at the end of the decade to fuel comparatively inefficient Multi-Mission Radioisotope Generators for both the Mars 2020 Rover and the Discovery 13 mission."

I have the slides somewhere. I thought I posted them here. I think it works out that by 2020 they will have enough for Mars 2020, Europa, and 2 Discovery/New Frontiers missions. I forget how many MMRTGs that means for the latter. They have a chart that shows all this (it's called something like an offramp chart or something, and it's like a river, showing how much Pu-238 is in the pipeline and then how much gets subtracted for each mission and how much is added when production ramps up, etc.).

One of the questions is when production will get full going. They've found that some of the infrastructure has to be replaced and that will take time. Another issue is the particular power levels required/available for each mission. This stuff ls like a stew, with each mix being a different combination of Pu-238, some old, some slightly old, some less old (but all old), and so they have to do a lot of different balancing.

Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #24 on: 03/22/2014 05:16 PM »
Somebody sent it to me and saved me the effort of looking for it. Here it is.

Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #25 on: 03/22/2014 10:11 PM »
Okay, to interpret that chart for you a bit--the green stuff is NASA's existing Pu-238. It's green because that means it is essentially hot enough to fuel current MMRTGs and provide enough power. Figure that most of that was manufactured in the late 1980s.

The yellow stuff is the Pu-238 that was made newly available to NASA starting last year. That is older stuff, dating probably from the 1970s into the early 1980s. There's a lot of it, but its energy density is lower, meaning it is cooler. You have to mix that stuff in with newer material (which is hotter) to get the energy density up. (A good question is why the DoE was keeping that material in reserve. What was it for? My suspicion is that it had a nuclear weapons use--not directly, because bomb grade material is Pu-239--but as some kind of add-in material.)

The hot stuff (red) is the newly manufactured stuff.

There is a version of this chart (I have it somewhere) that takes away both the red and the yellow. You can see the effects pretty easily--enough material for Mars 2020 and maybe 4 MMRTGs. Considering that a Europa mission requires (I think) at least 3, you can see that without the newly acquired material, and the newly manufactured material, NASA could do Europa and Mars 2020 and maybe have 1 MMRTG left over. Or NASA could do Mars 2020 and a couple of Discovery or New Frontiers missions.

(Caveat: this is all variable. Even though you have a big slice there that is colored green, it is not all equal in power. Some is newer and higher energy density, and some is older and lower energy density. It all depends upon how it gets mixed together, like a stew. Simply put, although we can talk broadly about X number of MMRTGs being available, the reality is that the number is squishy, and you could get one more or one less.)
« Last Edit: 03/23/2014 02:31 PM by Blackstar »

Online Hog

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Re: Wired article on Pu-238 production for space missions
« Reply #26 on: 03/23/2014 08:11 PM »
Okay, to interpret that chart for you a bit--the green stuff is NASA's existing Pu-238. It's green because that means it is essentially hot enough to fuel current MMRTGs and provide enough power. Figure that most of that was manufactured in the late 1980s.

The yellow stuff is the Pu-238 that was made newly available to NASA starting last year. That is older stuff, dating probably from the 1970s into the early 1980s. There's a lot of it, but its energy density is lower, meaning it is cooler. You have to mix that stuff in with newer material (which is hotter) to get the energy density up. (A good question is why the DoE was keeping that material in reserve.
What was it for? My suspicion is that it had a nuclear weapons use--not directly, because bomb grade material is Pu-239--but as some kind of add-in material.)

Nuclear PAL (Permissive Action Links) that disallow unauthorized detonation of many nuclear weapons use Pu-238 RTG's.  They are small and wouldnt need to be very hot.
« Last Edit: 03/23/2014 08:12 PM by Hog »
Paul

Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #27 on: 03/23/2014 10:08 PM »

Nuclear PAL (Permissive Action Links) that disallow unauthorized detonation of many nuclear weapons use Pu-238 RTG's.  They are small and wouldnt need to be very hot.

I don't think that's it. That is a publicly acknowledged use. I think the stockpile came from reserves for some other use.

Offline Steven Pietrobon

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Re: Wired article on Pu-238 production for space missions
« Reply #28 on: 03/24/2014 01:53 AM »
Someone sent me the link for where the above slide came from

http://www.lpi.usra.edu/opag/jan2014/presentations/6_Green.pdf

I've attached the document as well. We see two MMRTGs being produced in 2018 and four MMRTGs produced in 2024. Are these all for NASA missions?

Also attached is a Europa Clipper presentation. That currently has five MMRTGs, but they are looking at reducing that to four.

http://www.lpi.usra.edu/opag/jan2014/presentations/9_Clipper.pdf
« Last Edit: 03/24/2014 02:04 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #29 on: 03/24/2014 03:17 AM »
Someone sent me the link for where the above slide came from

http://www.lpi.usra.edu/opag/jan2014/presentations/6_Green.pdf

I've attached the document as well. We see two MMRTGs being produced in 2018 and four MMRTGs produced in 2024. Are these all for NASA missions?

Also attached is a Europa Clipper presentation. That currently has five MMRTGs, but they are looking at reducing that to four.

http://www.lpi.usra.edu/opag/jan2014/presentations/9_Clipper.pdf

They are actually producing one per year. Just finished the one for Mars 2020. What you're seeing is the ones used for missions, but they should have more sitting around, unfueled. NASA is producing them at the rate of one per year to maintain the skillset. (I suspect that the actual production rate is a bit below one per year, but that's what I was told.)

I have a few other related presentations that I'll post when I get to the office. They cover similar things. I've also got a flyer on the eMMRTG (for "enhanced") but I haven't looked at what that is or how much it increases the power level.


Online Hog

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Re: Wired article on Pu-238 production for space missions
« Reply #30 on: 03/24/2014 01:04 PM »

Nuclear PAL (Permissive Action Links) that disallow unauthorized detonation of many nuclear weapons use Pu-238 RTG's.  They are small and wouldnt need to be very hot.

I don't think that's it. That is a publicly acknowledged use. I think the stockpile came from reserves for some other use.
Who knows, I no longer have my security clearance. Do you have any guesses? If its from a non publically acknowledged use, that's all we have are guesses, though educated guesses are exciting fodder for discussion.

BTW Thanks for that illustration, it is a neat package of info.  There might be some future "donations" of fuel, but again, who knows?
Paul

Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #31 on: 03/24/2014 03:58 PM »
Who knows, I no longer have my security clearance. Do you have any guesses?

No. I have not designed nuclear weapons since grade school.


Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #32 on: 03/24/2014 03:59 PM »
These two presentations have a lot of information on this subject.

Offline arachnitect

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Re: Wired article on Pu-238 production for space missions
« Reply #33 on: 03/24/2014 05:53 PM »

Nuclear PAL (Permissive Action Links) that disallow unauthorized detonation of many nuclear weapons use Pu-238 RTG's.  They are small and wouldnt need to be very hot.

I don't think that's it. That is a publicly acknowledged use. I think the stockpile came from reserves for some other use.
Who knows, I no longer have my security clearance. Do you have any guesses? If its from a non publically acknowledged use, that's all we have are guesses, though educated guesses are exciting fodder for discussion.

BTW Thanks for that illustration, it is a neat package of info.  There might be some future "donations" of fuel, but again, who knows?

US supposedly ran a pretty involved undersea surveillance program at one point (Operation Ivy Bells) that would have used RTGs on eavesdropping equipment. Perhaps that mission has become obsolete from new communications technology (and other countries figuring it out), and therefore DOE no longer needs to stockpile material for it.

That said, Ivy Bells was compromised 30 years ago, so I don't know why DOE didn't hand over the Pu before now.

Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #34 on: 03/24/2014 09:07 PM »
US supposedly ran a pretty involved undersea surveillance program at one point (Operation Ivy Bells) that would have used RTGs on eavesdropping equipment. Perhaps that mission has become obsolete from new communications technology (and other countries figuring it out), and therefore DOE no longer needs to stockpile material for it.

That said, Ivy Bells was compromised 30 years ago, so I don't know why DOE didn't hand over the Pu before now.

My point is that I have a strong suspicion that this newly acquired (but older) material was from a use that has not been publicly revealed before. I don't know what that is, but I suspect it's weapons-related.

I suspect that if something like the Ivy Bells mission is still underway they have a better way of powering them, such as long-lived underwater batteries. There are many good reasons to not leave Pu-238 in places where somebody might recover it, even by accidentally picking it up in a fishing net.

Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #35 on: 03/25/2014 02:06 AM »

Offline Steven Pietrobon

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Re: Wired article on Pu-238 production for space missions
« Reply #36 on: 03/25/2014 06:15 AM »
Thanks Blackstar. We can deduce from page 24 of the APL presentation that 11 RTG's have been used for 9 non-NASA missions.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Blackstar

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Re: Wired article on Pu-238 production for space missions
« Reply #37 on: 03/25/2014 01:22 PM »
Thanks Blackstar. We can deduce from page 24 of the APL presentation that 11 RTG's have been used for 9 non-NASA missions.

That would include the LES satellites for DoD. Also Transit.
« Last Edit: 03/25/2014 01:22 PM by Blackstar »

Offline Steven Pietrobon

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Re: Wired article on Pu-238 production for space missions
« Reply #38 on: 03/26/2014 05:57 AM »
Thanks Blackstar. OK, here is my table of the missions and RTG's but they don't match up with the APL presentation. The only number that matches is the total number of missions of 27. These numbers do not seem to include any classified missions. Can anyone see any errors?

Non-NASA Missions
-----------------
 1) Transit 4A    SNAP-3B     (1)
 2) Transit 4B    SNAP-3B     (1)
 3) Transit 5BN-1 SNAP-9A     (1)
 4) Transit 5BN-2 SNAP-9A     (1)
*5) Transit 5BN-3 SNAP-9A     (1)
 6) Triad-01-1X   Transit-RTG (1)
 7) LES 8         MHW-RTG     (2)
 8) LES 9         MHW-RTG     (2)

Total Non-NASA Missions:  8 (APL  9)
Number of Non-NASA RTGs: 10 (APL 11)

NASA Missions
-------------
*1) Nimbus B      SNAP-19B    (1)
 2) Nimbus III    SNAP-19B    (1)
 3) Apollo 12     SNAP-27     (1)
 4) Apollo 13     SNAP-27     (1)
 5) Apollo 14     SNAP-27     (1)
 6) Apollo 15     SNAP-27     (1)
 7) Apollo 16     SNAP-27     (1)
 8) Apollo 17     SNAP-27     (1)
 9) Pioneer 10    SNAP-19     (4)
10) Pioneer 11    SNAP-19     (4)
11) Viking 1      SNAP-19     (2)
12) Viking 2      SNAP-19     (2)
13) Voyager 1     MHW RTG     (3)
14) Voyager 2     MHW RTG     (3)
15) Galileo       GPHS RTG    (2)
16) Ulysses       GPHS RTG    (1)
17) Cassini       GPHS RTG    (3)
18) New Horizons  GPHS RTG    (1)
19) Curiosity     MMRTG       (1)

Total NASA Missions: 19 (APL 18)
Number of NASA RTGs: 34 (APL 35)

Total Missions: 27 (APL 27)
Number of RTGs: 44 (APL 46)

* Launch failure
« Last Edit: 03/26/2014 06:05 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline cartman

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Re: Wired article on Pu-238 production for space missions
« Reply #39 on: 03/26/2014 10:42 AM »
Maybe you are missing this one http://en.wikipedia.org/wiki/SNAP-10A ?

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