In efforts to develop high-energy rocket fuel during Vietnam, researchers found the fuel they’d developed was a little too powerful, consistently destroying the rockets they powered. After some refinement, the researchers dubbed it Astrolite — the air-scatterable liquid land mine.
Invented by chemist Gerald Hurst while at the Atlas Powder Company, Astrolite technically is a family of binary liquid-state high explosives that are formed when you mix ammonium nitrate and anhydrous hydrazine (the rocket fuel). This produces a clear liquid explosive called Astrolite G — it has a very high 8600m/s detonation velocity — nearly double that of TNT and greater than any other non-nuclear explosive. If you then add aluminium powder to Astrolite G, you get Astrolite A (for aluminium) which has a velocity of detonation of 7800m/s.
Now while they have a very high detonation velocity (it expands very quickly), Astrolite does not have a lot of mass (there’s less explosive to detonate per volume). That means that it’s not suitable for heavy demolition but excellent as an anti-personnel/light armour mine.
As a 1968 issue of Stars And Stripes described it:
Latest development is a “Liquid Land Mine” using Astrolite, the most powerful known explosive…Poured directly onto a dirt road, the stuff soaks into the first few inches of earth, giving tremendous upheaval power. Although the land mine was fired remotely in the test, a pressure-sensitive fuse can be sued that will react to the weight of a passing vehicle…Liquid Land Mine can be simply poured from canteen like containers says its maker, Explosives Corporation of America, or sprayed from trucks or helicopters.
That’s right, you simply just spray it on — as little as 1oz is needed to incapacitate an enemy soldier — and sew in a detonator. It will remain active and detonatable in the soil for four days, unaffected by rain, but will eventually inactivate itself, eliminating the need for de-mining. The most useful feature is the fact that even when active, the Astrolite can’t be detected by normal mine detection equipment.