초록 ▼

A spacecraft uses monopropellant arcjets for velocity change such as for north-south stationkeeping. It has been discovered that, while an arcjet cannot be modulated by pulsing the fuel supply, the amount of thrust can be varied by modulating the power applied to the arc, without extinguishing the a

A spacecraft uses monopropellant arcjets for velocity change such as for north-south stationkeeping. It has been discovered that, while an arcjet cannot be modulated by pulsing the fuel supply, the amount of thrust can be varied by modulating the power applied to the arc, without extinguishing the arc. While the specific impulse (ISP) of the arcjet is thereby reduced from the maximum ISP of which the arcjet is capable, the resulting ISP may still be larger than the combined ISP of an unmodulated arcjet in conjunction with a modulated chemical thruster in a typical scenario. According to the invention, attitude control is provided in conjunction with north-south stationkeeping or other velocity change by, in response to an error signal generated by an attitude control system, modulating the arc power(s) of an arcjet thruster(s), which provides the velocity change. The arc is not extinguished during the stationkeeping maneuver, but is varied in magnitude. In addition to improving the overall ISP, an arrangement according to the invention allows dispensing with the chemical thrusters on the north face, thereby reducing spacecraft weight and complexity. Reliability is not seriously affected, because failure of arc allows an arcjet to continue to be used as a chemical thruster.

대표청구항 ▼

A spacecraft, said spacecraft comprising: a body defining a side when in orbit; a supply of propellant; a chemical thruster connected to said supply of propellant and to said side of said body, for expelling propellant mass for generating thrust, whereby the attitude of said spacecraft may deviate f

A spacecraft, said spacecraft comprising: a body defining a side when in orbit; a supply of propellant; a chemical thruster connected to said supply of propellant and to said side of said body, for expelling propellant mass for generating thrust, whereby the attitude of said spacecraft may deviate from a desired attitude during said thrust; electrical arc generating means coupled to said thruster for increasing the enthalpy of said propellant mass; and attitude sensing means coupled to said body and to said electrical arc generating means for, without extinguishing said arc, modulating the magnitude of said arc in response to said deviations from said desired attitude for tending to reduce said deviations.