Spacecraft employing low-thrust propulsion must be able to recover from an event in which the spacecraft stops thrusting due to an unforseen problem. Extra propellant is carried to allow the spacecraft to reach its target in the form of propellant margin. We present an automated method for estimating the propellant margin a spacecraft should carry and apply the method to a transfer to Mars and a solar sail transfer to the NEA 1991 VG. Examining different power levels for the Mars transfer, we show that a 5% margin is sufficient to recover from a 20-day missed thrust for a 10 kW spacecraft, while a 15% margin is required for a 20 kW spacecraft. For the solar sail mission, a spacecraft outage late in the mission may delay arrival by more than 200 days.
展开▼
