Wikipedia:Reference desk/Archives/Science/2018 December 4

= December 4 =

Fire in zero g
I have read something about a fire on the Mir space station recently which made me curious if there are any videos or the like showing how a fire burning in a zero g environment looks like and how it behaves? I would assume it would look somewhat spherical due to the oxygen being consumed evenly all around it, or am i mistaken there? Were there any controlled experiments conducted involving open flames somewhere, like on the ISS for example? Are there differences in heat, oxygen consumption and so on between a fire on earth and a zero g environment? 37.138.77.85 (talk) 02:50, 4 December 2018 (UTC)


 * From NTRS: Technical Report TR R-246, Flammability in Zero-Gravity Environment (1966).
 * NTRS is probably the best resource to continue searching for more research on this kind of topic.
 * Nimur (talk) 04:09, 4 December 2018 (UTC)


 * They have not conducted open flame tests on ISS, but you may be interested in the Saffire project where they ignited a few fires onboard unmanned cargo ships that had already completed their deliveries. ApLundell (talk) 04:14, 4 December 2018 (UTC)


 * NASA released a video of open flame tests on ISS. [ https://www.youtube.com/watch?v=BxxqCLxxY3M ]. --Guy Macon (talk) 05:26, 4 December 2018 (UTC)


 * They also started fire in water: [ https://www.youtube.com/watch?v=TysrIYJOlpk ] --Guy Macon (talk) 05:33, 4 December 2018 (UTC)
 * Cheers for the links. Looks very interesting and the mention of the 'invisible' heptane fire in the video is also very curious. And it looks rather pretty too (when it actually does burn visibly lol). 85.16.227.219 (talk) 14:06, 4 December 2018 (UTC)

Gravity waves - what turns into energy?
I know when two neutron stars collide, they can lose mass and generate gravity waves. What is happening at the atomic level? What goes away? Tdjewell (talk) 17:49, 4 December 2018 (UTC)
 * We have the article Stellar collision that reports the gravitational wave event GW170817. The neutron star merger event is thought to result in a kilonova, characterized by a short gamma ray burst followed by a longer optical "afterglow" powered by the radioactive decay of heavy r-process nuclei. See also Gravitational wave and Neutron star merger. DroneB (talk) 01:56, 5 December 2018 (UTC)
 * Even without any destruction of matter which occurs there is a lot of gravitational energy which can be released by the merger of two stars. This is the same sort of energy you get by rolling a boulder from the top of a hill to the bottom. There is a gravitational effect a bit like stirring water forms waves so the boulder does not go quite so fast at the bottom of the hill but some of that energy is radiated away instead. Dmcq (talk) 12:57, 5 December 2018 (UTC)