Talk:SNAP-10A

Reactor or RTG?

A recent post claimed the SNAP-10A was not the only nuclear reactor launched into orbit by the United States and cites Cassini as evidence.
The Cassini-Huygens space probe uses a radioisotope thermoelectric generator (RTG) to generate it's electricity. A crude description of an RTG is a large wad of radioactive material undergoing decay which generates enough thermal energy to allow the thermoelectric generation of electricity.
The SNAP-10A was a nuclear reactor, remotely started in earth orbit, which generated heat using nuclear fission. The heat was then converted into electricity using a thermoelectric converter system.
As of this date, the SNAP-10A remains the only nuclear reactor launched into orbit by the United States.
--improperly signed by user:BluegillTriplePrime, 30 August 2009

I question the assertion that it's the only "nuclear reactor" launched by the US. First: who knows everything that's been put into orbit? The wording "only known nuclear reactor" would be more accurate... and cited in some way. Secondly, the assertion needs to be more detailed: what's the distinction between nuclear reactor and RTG? I think it's hair-splitting, but I'd like to see that hair split if the assertion -has- to stay. (I've added a mention of the many RTG's launched into the opening para.) Twang (talk) 22:08, 3 November 2009 (UTC)

nuclear reactors sustain a nuclear chain reaction whilst RTGs just use radioactive decay (rather than induced fission). Rod57 (talk) 04:26, 28 December 2010 (UTC)

It's not hair-splitting. RTGs and reactors are operationally and mechanically quite different, though SNAP-10 is an unusual reactor design that resembles an RTG in some ways (thermocouples). --Robert Keiden (talk) 20:45, 27 August 2012 (UTC)

Robert, Twang, you can't directly compare "RTGs and reactors", as an RTG is a complete electricity generating system while the reactor is just one part of such a system.

In both, SNAP-10 as well as in the more conventional RTG systems, there's a sub-assembly that generates some heat. Rod57 has covered the differences of those very nicely above. Then there's the sub-assembly which turns heat into electricity, and this seems to be very similar, using thermocouples. Now this is in contrast to the US-A setup where the heat from the nuclear reactor is used in a thermionic converter to generate the electricity. (See Kosmos 954.)

--BjKa (talk) 10:36/38, 24 January 2017 (UTC)

Reactor dimensions

<<The reactor measured 22.4 cm wide by 39.62 cm long>> : this seems rather small, plus the third dimension is missing ? --unsigned by user:Herix, 4 September 2010

It's a cylinder, it only needs two dimensions, but good point, that should stated if someone else agrees. --142.25.141.31 (talk) 22:33, 7 October 2010 (UTC)Stargate70

Given that it's a cylinder, it's unambiguous but probably unclear. I'd change "width" to "diameter" unless someone objects. --Robert Keiden (talk) 20:47, 27 August 2012 (UTC)

Naming Confusion: SNAP / SNAPSHOT / SNAP-10A / 10FS-3 / 10FS-4

SNAP and AI Fuel Summary Report. R.E.Lords. Aug 1994 says on p1 (p10 of PDF) "10FS-3 refers to the SNAP 10 Flight System 3 Reactor (a part of the SNAP 10A program which included the SNAPSHOT flight test)." and on p2 "The 10FS-3 reactor was an adaptation of the SNAP-2 reactors for use in meteorological and military reconnaissance satellite applications. Nuclear reactors, particularly those with hydride fuels, were considered promising due to their high power to weight ratio.[9] 10FS-3 set the record for the longest continuous operation of a nuclear reactor system in the free world with its 10,000 uneventful hours of operation.[10] 10FS-3 operated in a simulated space environment on the ground; 10FS-4, another similar reactor, was launched as part of the SNAP 10A program." and references :

• 8. Berg, G.E., "Final SNAPSHOT Performance Report," NAA-SR-11394, August 15, 1966.
• 9. "SNAP 10A Powered Meteorological Satellite Study," NAA-SR-9892, June 15, 1964.
• 10. Hawley, J.P. and Johnson, R.A., "SNAP 10A FS-3 Reactor Performance," NAA-SR-11397, August 15, 1966.
• 11. Staub, D.W., "SNAP 10A Summary Report," NAA-SR-12073, March 25, 1967.
• 22. Golding, T.A., "Post-Operation Evaluation of Fuel Elements from the SNAP 10 Flight System 3 Reactor," NAA-SR-12031, September 15, 1967.

Sounds like article is about 10FS-4, the reactor that was launched into space. Rod57 (talk) 04:47, 28 December 2010 (UTC)

The article said: "The Systems Nuclear Auxiliary Power Program (SNAP) reactor was developed in the 1950s and early 1960s under the SNAPSHOT program overseen by the U.S. Atomic Energy Commission." And cited the Stokely/Stansbury source at that location. This is in clear contradicion to the above, quoted by Rod57, which states that SNAP was the program and SNAPSHOT the actual satellite launch. As I regard the Westinghouse source more authoritative than the "Space Research" source, I corrected that accordingly.
--BjKa (talk) 10:56, 24 January 2017 (UTC)

NaK molten during launch

The SNAPSHOT video says/shows SNAP10A being launched in a thermal cover to keep the NaK liquid until the reactor starts. Rod57 (talk) 06:00, 28 December 2010 (UTC)

1979 anomaly

It would be good to have some more information on this. Is it known why it shed pieces? It says a collision has not been ruled out but is that the most likely possibility or just one among many? Does the debris pose a threat to other things in orbit? Has research subsequent to 1979 helped address the question of whether radioactive material was released? Beorhtwulf (talk) 15:51, 28 February 2011 (UTC)

This is one of the most notable parts of this satellite, and it has a throwaway mention that something happened, backed by two citations to offline sources. I don't have the aerospace connections to find out more and any research I have found is behind paywalls. Anyone with the right university access that can flesh this out would be appreciated. Dmerillat (talk) 18:45, 18 March 2011 (UTC)

Questions

Can someone clarify the purpose of the satellite? Was it reactor research only? Or was there a payload? Was the power output 30kWt and 500W electric (that seems very inefficient)? What did the 500W power? How was the 29.5kW waste heat dissipated? Thanks. --ChrisRuvolo (t) 16:42, 17 January 2012 (UTC)

It appears to have been a technology test (R&D) conducted by the Department of Energy, rather than basic science. Some other nuclear power sources in the SNAP series were used by NASA and the Navy, but those were all RTGs. According to http://etec.energy.gov/Operations/Major_Operations/SNAP_Overview.html thermal to electrical conversion was only 1.83%. Probably due to its size (small reactors waste more) and use of thermocouples instead of mechanical generators. This design will probably never be practical, which is part of why there aren't many SNAP-reactors in space. --Robert Keiden (talk) 22:08, 27 August 2012 (UTC)

Retrograde and polar orbit

I would like to discuss this here a little bit. While I understand that technically a retrograde orbit is defined as one that is greater than 90 degrees, this is definitely close enough to 90 degrees to be considered a polar orbit. It really doesn't make sense to have both of them in the article, as you are either polar, retrograde, or prograde. I think the citation actually helps the point that it is a polar orbit.
What is everyone's thoughts? Kees08 (talk) 04:36, 16 June 2016 (UTC)

How about "a slightly retrograde polar orbit"? It is still retrograde, but it is also definitely polar. I see the terms as overlapping. An orbit is always either retrograde or prograde, as you cannot hit the mathematical number 90° exactly in real life. But then some of these are also called polar, as they do pass over the polar areas. On https://m.reddit.com/r/space/comments/3jhbmm/which_polar_orbit_is_prograde_and_which_is/cup91im someone says that ~70 to ~110 degrees are usually called polar. That's no real source of course, but an indication that there seems to be a rule of thumb out there. --Jhertel (talk) 14:11, 16 June 2016 (UTC)

I am happy with slightly retrograde polar orbit, I think that is more clear and a great compromise. Cheers! Kees08 (talk) 17:17, 16 June 2016 (UTC)

Good to hear that. I changed the article to reflect that. You're very welcome to adjust it if you have a better wording. --Jhertel (talk) 21:35, 16 June 2016 (UTC)

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