CAMBRIDGE, MA – NASA required almost no fuel to reorient the International Space Station (ISS) twice during resupply operations on Aug. 1, using technology developed by Draper Laboratory.
The rotation maneuvers demonstrated the ability to save over 90 percent of the fuel otherwise needed when the Russian Progress resupply cargo spacecraft docked with ISS. This approach, which Draper calls the Optimal Propellant Maneuver (OPM), helps NASA reduce the cost of operating spacecraft like the ISS, and extends their usable life.
The OPM could be applied to many of the maneuvers made by satellites operated by NASA, the Pentagon, and commercial firms, says Nazareth Bedrossian, Draper’s group leader for vehicle dynamics and control systems.
The ISS would have expended over 300 kilograms of fuel during resupply operations, but needed approximately 20 kilograms by using the OPM on Aug. 1.
The OPM also reduced the number of individual thruster firings by more than 70 percent, resulting in lower structural loads and thruster lifetime usage.
Spacecraft typically use thrusters to maneuver in space and to overcome disturbances such as aerodynamic drag and other sources. The OPM takes advantage of disturbances in an approach similar to ships following ocean currents to boost their speed and improve fuel efficiency, Bedrossian said.
The OPM does not require costly changes to a spacecraft’s flight software. Operators on the ground develop commands, and then load them onto the spacecraft’s flight control system for execution.
Draper demonstrated a similar fuel-saving approach with the ISS in 2006 and 2007 using the Zero Propellant Maneuver (ZPM), which enabled the space station to rely entirely on its Control Moment Gyro’s to perform large angle rotations. The OPM extends on ZPM by allowing some fuel usage while reducing the time for maneuvers to improve operational timelines.