David A. Dietzler, 2007
Explosives usually consist of organic chemicals containing hydrogen, carbon and nitrogen. On the Moon these are rare and we made need large masses of explosives for rock blasting. Rather than waste H, C and N that are so valuable for life support systems for making explosives we might be able to use abundant magnesium and oxygen. Wickman determined that magnesium and LOX don't make a good monopropellant because this mixture was shock sensitive and detonated. This might be a blessing in disguise. Magnesium metal tanks might be loaded with a slurry of magnesium and LOX and detonated with an electric spark plug.
Magnesium burns with 10,640 btu per pound. Mixed with the correct amount of oxygen at a ratio by weight of 3:2 we'd get 7090 but per pound of Mg/LOX mix. One pound of TNT releases 2300 btu and one stick of dynamite 2000 btu. So this might be a decent explosive. Flame speed must also be considered. Hydrogen burns with 61,000 btu per pound but only has a flame speed of eight feet per second. Gasoline has 20,500 btu per pound and has a flame speed of 70 to 170 ft/sec. The plastic explosive C4 and RDX, chemically similar to TNT, both have a detonation or flame speed of about 27,000 feet per second. And TNT has about 23,000 feet per second. The actual explosive properties of Mg+LOX must be determined by experimentation.
The volume of one pound of magnesium is about equal to the volume of 9.2 fluid ounces of water and 2/3 pound of LOX would be equal to about 9.4 fluid ounces of water. So a small tank of Mg/LOX with about 7090 btu and roughly the energy of three sticks of dynamite would be a little bigger than a one pint jar. How much explosive power it really has because of its flame speed is something we must research. A valuable discovery may await us.
