Hydrazine (N2H4)
H H
\ /
N - N
/ \
H H
Primarily used as a
fuel, especially in satellites for
station-keeping.
Hydrazine itself is
toxic,
flammable,
caustic, and has strong
reducing properties and smells vaguely of
ammonia. It is
soluble in
water and most
alcohols. Fuel grade Hydrazine has a
density of 1.01g/cc, freezes at 2.00 C and boils at 113.00 C.
The creation of hydrazine is done through the Raschig process. This
involves the oxidation of ammonia to chloramine. Chloramine is then
reacted with ammonia again. In 1959, the cost of anhydrous hydrazine
in industrial quantities was $7.00/kg. It was projected that the
price per unit would drop to $1.00/kg from large scale commercial
production, however due to environmental regulations, NASA was paying
$17.00/kg.
NASA Lewis Research Center and Primex Aerospace Company have developed
an environmentally friendly monopropellant that is intended to replace
the use of hydrazine thrusters on most spacecraft. This compound is
hydroxylammonium nitrate (HAN). Tests on these new thrusters show
that it has a specific impulse of 195 sec
and a density-specific impulse of 275 g-sec/cm3.
This is about 25% greater than current state of the art hydrazine thrusters.