ELSA-d Finalizes De-Orbit Operations
ELSA-d Finalizes De-Orbit Operations
Astroscale Marks Successful Mission Conclusion
ELSA-d, the first commercial mission to prove the core technologies necessary for on-orbit satellite servicing in low Earth orbit (LEO), has completed its mission with the safe and controlled de-orbit operations of the ELSA-d servicer satellite using the remaining operational thrusters. The Astroscale mission, which consisted of two satellites — a servicer designed to safely remove debris from orbit and a client that serves as a piece of replica debris — was launched as a stack from the Baikonur Cosmodrome in Kazakhstan in March 2021.
“Despite the setbacks once in orbit, ELSA-d demonstrated multiple dynamically complex capture capabilities and rendezvous and proximity operations necessary for any future satellite servicing mission.”
Gene Fujii, Astroscale.
While operationally the mission has concluded, the servicer continues to orbit at an altitude of approximately 310 miles and will re-enter and burn-up in approximately 3.5 years — well within the commonly adopted 25-year guidelines. The client satellite, which does not have the ability to maneuver, will naturally de-orbit over the next 10 years.
The mission successfully completed unprecedented demonstrations in orbit, including repeated magnetic capture and rendezvous operations. In the first demonstration, the servicer released the client and manually performed magnetic docking, successfully validating the capture system, on-board sensors and cameras. During the Autonomous Capture demonstration, the servicer released the client and began autonomous relative navigation holding a “home position” for over seven hours. However, anomalous spacecraft conditions were detected and for the safety of the mission, the team decided not to proceed with the capture attempt.
Despite the servicer losing the use of four out of its eight thrusters, the mission went on to complete further controlled close-approach rendezvous operations between its two spacecraft in orbit. The technologies proven in this demonstration included tracking of an object from a great distance, rendezvous with an uncontrolled object, and handover from absolute navigation to relative navigation for a LEO servicing spacecraft. These capabilities are essential for rendezvous and proximity operations and on-orbit servicing, and this demonstration was unprecedented for a commercially funded mission in LEO.
The ELSA-d mission proved other key capabilities required for on-orbit servicing, including:
autonomous guidance, navigation and control algorithms,
closed loop control with on-board navigation sensors,
autonomous thruster rendezvous maneuvering and attitude control,
navigation of a servicer spacecraft from approximately 1,600 km to within 160 m of a client using absolute navigation techniques (GPS and ground-based observations),
transition from absolute navigation to relative navigation using on-board LPR sensor, and
more than two years of servicer and client satellite in-orbit mission operations.
“Despite the setbacks once in orbit, ELSA-d demonstrated multiple dynamically complex capture capabilities and rendezvous and proximity operations necessary for any future satellite servicing mission,” said Gene Fujii, Chief Engineer of Astroscale. “I congratulate the entire Astroscale team, our partners, and supporters for the successful conclusion of this mission. Now we turn our attention to our next launch, where ADRAS-J will showcase our technologies to approach and characterize an existing piece of large debris in orbit.”
Astroscale has harnessed what it learned from ELSA-d and evolved future missions, including the upcoming Active Debris Removal by Astroscale-Japan (ADRAS-J) mission. The mission is the world’s first attempt to safely approach, characterize and survey the state of an existing piece of unprepared large debris through rendezvous and proximity operations. ADRAS-J is designed to rendezvous with an unprepared Japanese H2A upper stage rocket body (approximately 36 feet long, 13 feet in diameter, and weighing approximately 3 tons), demonstrate proximity operations, and gather images to assess the rocket body’s movement and condition of the structure. Unprepared objects in orbit pose an additional challenge as they have not been prepared with any technologies that enable docking or potential servicing or removal. The mission will demonstrate some of the most challenging rendezvous and proximity capabilities necessary for on-orbit services.