On-Orbit Performance of the BCP-100 Green Propellant Infusion Mission

The Green Propellant Infusion Mission (GPIM) spacecraft was launched in June of 2019 as a secondary payload on the Air Force’s STP-2 Falcon Heavy launch vehicle. GPIM is a BCP-100, a line of ESPA class spacecraft designed by Ball. The BCP-100 was designed around the capability to support multiple payloads on a single platform, and be able to fly in a wide range of orbits without the need to reconfigure the spacecraft in any way. Proving the flexibility and multi-role capability of the BCP-100 design, there are three secondary payloads on GPIM. In addition to the green propellant payload, iMESA, SWATS, and SOS are hosted on the spacecraft. These were provided by the Air Force through their Space Experiments Review Board (SERB) payload list. Finally, an advanced multi-layer insulation (MLI) technology, integrated MLI (IMLI), was employed as insulation for the propulsion subsystem. This technology was developed by Ball and Quest Thermal Group under Small Business Innovative Research (SBIR) funding provided by NASA STMD. GPIM adds to the 15 years of combined flight time for the BCP-100 line. Ball Aerospace built the GPIM spacecraft for NASA’s Space Technology Mission Directorate (STMD) in order to provide a platform to accomplish on-orbit testing and validation of an AF-M315E based green propellant propulsion subsystem. After a very successful spacecraft commissioning phase that was completed in less than 24 hours, check out of the primary green propellant payload commenced. This included testing the primary and redundant catbed heaters, opening the latch valve, and commanding the thrusters in both open loop and closed loop control modes, all of which was accomplished within three and a half days of being on-orbit. The propulsion system employs five protoflight 1 N thrusters, four for attitude control and the fifth for use during delta-v burns to provide higher thrust. Characterization of the green propellant system has been on-going. This characterization includes performing closed loop delta-v burns, 3-axis thruster-based attitude control, and momentum dumping. In addition to these tests, on-orbit measurement of the thruster impulse-bit has been performed over the course of the mission. This measurement involves a complex command sequence in which the spacecraft must execute a delta-v, perform multiple maneuvers, spin down the reaction wheels, and execute a series of 200 msec long open loop thruster pulses. Analysis of the spacecraft motion that results from each thruster pulse provides the amount of force that was applied. This paper provides a brief background of the GPIM program, including objectives of the technology demonstration, and presents on-orbit flight results of propulsion tests performed to date