What type of propellant do VASIMR® engines use?
The VASIMR® engines are capable of using almost any gas or substance with a high vapor pressure as a propellant. However, some gases are better suited to forming plasmas than others, and the gas’ mass also plays an important role in rocket performance. For missions near Low Earth Orbit and the moon, argon gas has the highest performance for a 200 kW VASIMR®. However, for missions that are much farther away, e.g. Mars or Jupiter, lighter gases are more desirable and give VASIMR® an optimum performance in these cases.
