# Can thermite burn in a vacuum? **URL:** \ **Category:** Factual Questions\ **Created:** [January 5, 2011, 2:30pm UTC](https://boards.straightdope.com/t/can-thermite-burn-in-a-vacuum/566483 "2011-01-05T14:30:13Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [September 20, 2011, 4:07am UTC](https://boards.straightdope.com/t/can-thermite-burn-in-a-vacuum/566483/21 "2011-09-20T04:07:18Z")
> [@Chronos](#): > > Candles snuff themselves on spacecraft-- It’s been tried. Larger fires can (unfortunately) be self-sustaining, though. > > One possible catch with thermite in vacuum: You need pretty high temperatures to get it started. On Earth, the usual method is a magnesium fuse, but that _does_ require atmospheric oxygen. I’m sure there are other ways to get the required temperature, though. Thermite can ignite below the reaction temperature. The major factor besides heat is the size of the metal particles. Nano-aluminum mixed with water can be ignited with a hot nichrome wire. It’s hard to match the adjoining surface area achieved by using a liquid, but if a solid oxidizer is used, the smaller the particles are, the lower the ignition temperature required. Once the aluminum starts burning it will reach temperatures in excess of 2500c, which will ignite any more aluminum in proximity to oxygen in the area. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 20, 2011, 6:08am UTC](https://boards.straightdope.com/t/can-thermite-burn-in-a-vacuum/566483/22 "2011-09-20T06:08:04Z")
nm ---
**Author:** ![Khristy](https://avatars.discourse-cdn.com/v4/letter/k/57b2e6/32.png) [@Khristy](https://boards.straightdope.com/u/Khristy)\ **Post date:** [September 20, 2011, 6:29am UTC](https://boards.straightdope.com/t/can-thermite-burn-in-a-vacuum/566483/23 "2011-09-20T06:29:55Z")
> [@Chronos](#): > > Candles snuff themselves on spacecraft-- It’s been tried. Larger fires can (unfortunately) be self-sustaining, though. > > One possible catch with thermite in vacuum: You need pretty high temperatures to get it started. On Earth, the usual method is a magnesium fuse, but that _does_ require atmospheric oxygen. I’m sure there are other ways to get the required temperature, though. I believe it can be ignited by a mixture of glycerine and potassium permanganate, with the KMnO4 being a powerfull oxidizer, therefore not requiring any outside O2 source. ---
**Author:** ![drachillix](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@drachillix](https://boards.straightdope.com/u/drachillix)\ **Post date:** [September 20, 2011, 1:54pm UTC](https://boards.straightdope.com/t/can-thermite-burn-in-a-vacuum/566483/24 "2011-09-20T13:54:51Z")
> [@beowulff](#): > > I suspect you could blast it with a fire hose. That would not only cool it, but it would physically separate the powder grains. If it’s a tiny fire yes, any metal fire of any scale tends to use other types of suppression chemicals as even magnesium can be a bitch to put out with water. If you ever see a magnesium wheel catch fire, you will actually see it flare up hitting it with small volumes of water. Aluminum fires are even more tenacious. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [September 20, 2011, 2:47pm UTC](https://boards.straightdope.com/t/can-thermite-burn-in-a-vacuum/566483/25 "2011-09-20T14:47:02Z")
> [@](#): > > Candles snuff themselves on spacecraft-- It’s been tried. Only if you keep the air very still, IIRC If you light a match in zero G and move your hand a bit, you’ve already done enough to move away the CO2. And the Space Station had an air circulating system strong enough to sweep unattached things onto the air filter. That’s why I qualuified with the “theoretically”. ---
**Author:** ![dr.quentin](https://avatars.discourse-cdn.com/v4/letter/d/cc9497/32.png) [@dr.quentin](https://boards.straightdope.com/u/dr.quentin)\ **Post date:** [September 21, 2011, 2:02am UTC](https://boards.straightdope.com/t/can-thermite-burn-in-a-vacuum/566483/26 "2011-09-21T02:02:11Z")
> [@](#): > > Why wouldn’t it? It has everything it needs to burn. The pressure seems immaterial. > Ordinary flames can conceivably have a problem in a zero-G environment, since > zero-G lacks convection to pull away the heated exhaust gases. A zero-G flame can conceivably smother itself. But the thermite doesn’t have that problem, either – it has its own oxygen supply. (I don’t think, in a practical zero-G environment, and ordinary flame would have a problem, either – any existing currents would sweep the CO2 away.) what about particles getting so excited they leave the planet! here’s the math Hrxn=-1.528KJ_2(.15%)2 for simplification sake=-3.056KJmass=Hrxn Hrxn=-3.056KJ_2.4_10^7Kg=-7.33E7 Hrxn=-7.3E7kJ/kg P=F/A Surface area 144,798,500 km2 gravity 3.7m/s/s .0037km/s/s/144798500km2=(5.4x10^5Km^3/S^2)=P P=5.4E5Km3/S2 -3.056/( U + 5.4X10^5_v) mass of reactants … I’ll use mass of constituent parts \* surface area(you do it if you got a better idea for getting the mass of the surface of mars | (180.3gsiO2\*.30 +319.4g\*.10fe2O3+107.9gAl\*.60 )/1000_1.44_10^8 (%comp_surface area )~~2.183_10^7Kg=mass M= 2.183 E7 Kg Q=-7.3 E7 kJ/kg P=5.4E5Km3/S2 D=(5.242 g/cm3\*.2_2.648 g·cm3_.6 )=.00264 kg·cm3~V=8.27 E9 kg·cm3 D=.00264 kg·cm3 M/D=V ;2.183 E7 Kg/.00264 kg·cm3~V=8.27E9 V=8.27 E9 kg·cm3 H-pv=U p=5.4E5 Kpa -7.33E7 kJ/kg(h) - (5.4 E5p \* 8.27 E9 kg·cm3v)=U U=-4.47E15 kj_km3/s2 H= -7.3E7kJ/kg =( -4.47E15 kj_km3/s2U+ 5.4 E5p \*8.27 E9v)u+pv Q=dH=(dU+ PdV+dPv) H=U+PV dH =Hf-Hi 1.2E11KJ/kg-0 R=.008314kj/Kg k T=mv^2/5R _ **3.59 E28 kelvin** _ 35900000000000000000000000000 K\* mars thermite ridiculousness 5,700 K sun temp 33000 k [Zeta Ophiuchi](http://en.wikipedia.org/wiki/Zeta_Ophiuchi) 14500000 k solar class star core its really hot or I did my math wrong **relevant stuff** p=5.4E5 Kpa/5027 m/s kpa =N/m2 n=j/m so j m/ms thus j/s 5.4E8 j/s so 5.4E5 w U=-4.47E15 kj_km3/s2 so 1watt= 1pascal? kN=kg_km/s2 Kw=kg\*km2/s3=KJ/s so kW/U^2 = km/s or Kkpa/U2=m/s \*\*2.70E-26 km/s \*\* 5.027 km/s escape velocity .000000000000000000000027 m/s is SLOW but then it could mean that the planet serface just moved out that much 24.077 km/s is mars’ orbital velocity @686.971 days 3396.2 km radius still only 0.917E-22 KM Coefficient of Thermal Expansion 8.1 E -6 the highest porosity area is only 33.1% for Cobalt as an oxidizer this is of course assuming there is no water on mars’ surface. NO i don’t think mars would not go super nova ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 21, 2011, 5:24pm UTC](https://boards.straightdope.com/t/can-thermite-burn-in-a-vacuum/566483/27 "2011-09-21T17:24:24Z")
Um, what precisely are you calculating there? ---
**Author:** ![dr.quentin](https://avatars.discourse-cdn.com/v4/letter/d/cc9497/32.png) [@dr.quentin](https://boards.straightdope.com/u/dr.quentin)\ **Post date:** [September 21, 2011, 5:37pm UTC](https://boards.straightdope.com/t/can-thermite-burn-in-a-vacuum/566483/28 "2011-09-21T17:37:28Z")
> [@Chronos](#): > > Um, what precisely are you calculating there? I wanted to see if the planet would put its self out by exciting the particles past escape velocity and thus loose any further enthalpy or electrons from the aluminum. ---
**Author:** ![Cheshire\_Human](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@Cheshire\_Human](https://boards.straightdope.com/u/Cheshire_Human)\ **Post date:** [September 22, 2011, 1:09am UTC](https://boards.straightdope.com/t/can-thermite-burn-in-a-vacuum/566483/29 "2011-09-22T01:09:14Z")
The big question here is “can brain cells revivify without available atmospheric oxygen”? Is a n00b virus sufficient to enable them to do so? ---
**Author:** ![Rysdad](https://avatars.discourse-cdn.com/v4/letter/r/7cd45c/32.png) [@Rysdad](https://boards.straightdope.com/u/Rysdad)\ **Post date:** [September 22, 2011, 1:28am UTC](https://boards.straightdope.com/t/can-thermite-burn-in-a-vacuum/566483/30 "2011-09-22T01:28:55Z")
> [@Khristy](#): > > I believe it can be ignited by a mixture of glycerine and potassium permanganate, with the KMnO4 being a powerfull oxidizer, therefore not requiring any outside O2 source. I _know_ it can. [Previous page](https://boards.straightdope.com/t/can-thermite-burn-in-a-vacuum/566483.md?page=1)