Jason Forshaw, Astroscale; Ron Lopez, Astroscale; Akira Okamoto, Astroscale; Chris Blackerby, Astroscale; Nobu Okada, Astroscale
Keywords: End of Life, Debris Removal, ELSA-d, Rendezvous Proximity Operations, RPO, AIT, Launch
Abstract:
The novel End-of-Life Services by Astroscale demonstration mission (ELSA-d) mission promises to be a major step forward in demonstrating rendezvous and proximity operations (RPO) capabilities applicable to future debris removal services. The ELSA-d mission is late in its assembly, integration and test (AIT) stages and due to launch in the early 2020 timeframe. It will demonstrate key technologies and procedures for the rendezvous, capture, and eventual de-orbit of a client satellite.
In this paper, some of the key technologies that will be discussed are rendezvous guidance, navigation, and control (GNC) and a magnetic docking mechanism, where the client satellite will be equipped with a docking plate (DP) which enables it to be captured. While cooperative rendezvous has previously been performed either manually or semi-autonomously, ELSA-d will demonstrate the first semi-autonomous capture of a tumbling client. This will be followed by a search and capture where the client satellite will be intentionally placed outside of the field of view of the relative navigation sensors on the servicer. In the paper, we will describe the use of a walking safety ellipse, a passively safe trajectory, and the combination of sensor scanning and an absolute-to-relative navigation handover that will be necessary to safely track and capture a client that is not in the immediate vicinity of the servicer. Autonomy of the ELSA-d mission is also described: what aspects are performed on-board autonomously and what is performed by an operator, which has implications on the space and ground segment. In the context of the described technologies, the paper will broadly provide an overview of each phase of the concept of operations (CONOPS). As ELSA-d is finalized for its upcoming launch, the paper also provides the latest updates from Astroscale Japans clean room.
With the rise of large satellite constellations in low-Earth orbit (LEO) the number of satellites in key orbits will increase at a much higher rate than today, raising the risk of collision. Systematic spacecraft end-of-life (EOL) management strategies assuring post-mission disposal (PMD) are required to maintain the utility of key LEO assets. The technologies stemming from ELSA-d will lead to safe and effective solutions to maintain accessibility of LEO.
Date of Conference: September 17-20, 2019
Track: Space-Based Assets