RemoveDEBRIS

Mission overview

Rather than engaging in active debris removal of real space debris, the RemoveDEBRIS mission plan was to test the efficacy of several ADR technologies on mock targets in low Earth orbit. The platform carried a net, a harpoon, a laser ranging instrument, a dragsail, and two CubeSats. In the net experiment, one CubeSat (DebrisSat 1) deployed a balloon simulating debris, which the satellite captured in a net and then manoeuvred to fall into Earth's atmosphere. The vision-based navigation experiment involved releasing the other CubeSat (DebrisSat 2) and using lidar and optical cameras to obtain data. A harpoon connected by a tether was fired at a plate on an arm extending from the platform. After other experiments, the dragsail was intended to bring the satellite into the atmosphere but failed to deploy.

Design

The RemoveDEBRIS platform was based on an SSTL X50 bus customised for deployment from the International Space Station. It hosted all experimental payloads and provided power, data, and control, with high autonomy via time-tagged commands. DebrisSat 1 (DS-1, COSPAR 1998-067PM) was a 2U CubeSat (100 × 100 × 227 mm) built by the University of Surrey, containing power, avionics, and an inflatable payload using a Cold Gas Generator to inflate six aluminium booms with small sails. DebrisSat 2 (DS-2, COSPAR 1998-067PR) was also a 2U CubeSat with two deployable solar panels, communications, a GPS receiver, and an inter-satellite link. Its avionics were based on the QB50 stack developed by the Surrey Space Centre and Stellenbosch University's Electronic Systems Laboratory, and it carried a low-cost UART camera.

Timeline

After final testing, RemoveDEBRIS was shipped to Nanoracks in Houston and then to the Kennedy Space Centre in Florida. It was placed in a cargo transfer bag in the pressurised section of the CRS-14 SpaceX Dragon 1, launched 2 April 2018 and arriving at the ISS on 4 April. NASA Astronauts Drew Feustel and Ricky Arnold prepared the satellite and loaded it into the Japanese Experiment Module airlock on 6 June 2018. An airlock cycle was performed on 19 June 2018, and the satellite was moved outside via the airlock slide table, grasped by the Kaber interface on the Mobile Servicing System Special Purpose Dexterous Manipulator, and placed in deployment position.

Deployment from the Kibo module via Canadarm-2 occurred on 20 June 2018; at about 100 kg, it was the largest satellite deployed from the ISS. On 16 September 2018, it demonstrated net capture of a simulated target. On 8 February 2019, the harpoon was fired at 20 metres per second, penetrating a simulated target on a 1.5 m boom. The dragsail deployment targeted for 4 March 2019 failed, likely due to partial or failed inflation of the boom; lessons were applied to two later dragsails on the Spaceflight SSO-A mission.