Stardust's Hydrazine (N2H4) Fuel: A Potential Contaminant for the Formation of Titanium Nitride (Osbornite)

Abstract

Hundreds of space probes, satellites, and shuttles use ultrapure hydrazine monopropellant for guidance once in orbit. Stardust is the first U.S. mission devoted to exploring a comet and is the first U.S. mission designed to capture samples robotically from a comet and return them to Earth. The spacecraft is equipped with two sets of thrusters that use ultrapure hydrazine as a monopropellant.2,3 One of the biggest scientific surprises of this mission was the detection of tiny (sub-100-nm-size) grains of vanadium-bearing titanium nitride (osbornite).4,5 The use of hydrazine is one of the best significant methods of nitridation, which, precisely, has been used for the specific formation of titanium nitride. Stardust's hydrazine could have acted as a potential contaminant, coreacting with Ti compounds (either from the comet or the spacecraft), for the formation of the titanium nitride (osbornite) particles.