Mike Lindsay, Astroscale; Toby Harris, Astroscale UK; Sam Cox, Astroscale UK; Matt Duncan, SpaceNav
Keywords: space debris, collision risk, regulation, licensing, modeling, post-mission disposal, sustainability, fragmentation, lethal non-trackables
Abstract:
As more large constellations are deployed, it becomes increasingly important to quantify, understand, and limit the risk of creating a Low Earth Orbit (LEO) region which cannot sustain safe operations for human or robotic missions due to space debris. A significant contributor to this risk comprises debris which is energetic enough to cause catastrophic fragmentation upon collision with other spacecraft, small enough to be difficult to track, and prohibitively expensive to remediate due to quantity and distribution. Currently, the most effective way to reduce the long term risk of such debris is to prevent its creation in the first place, which is why certain administrations require as part of their license application processes compliance with regulations designed to limit the likelihood of events which would generate space debris.
One such regulation used by the United States Federal Communcations Commission (FCC) is the limitation of the probability of collision with large objects. In this instance, a “large object” is any object larger than 10 cm in diameter, and the legacy probabilistic maximum is 0.001 per satellite. To show compliance with this regulation, operators commonly use the Debris Assessment Software (DAS) tool, developed and maintained by NASA. Historically, DAS has provided adequate means for assessing collision risk for single-satellite missions operating in LEO, but given the rapidly changing environment and large numbers of spacecraft that were not envisioned in the drafting of corresponding regulations, let alone DAS itself, it becomes necessary to review the appropriateness using of such an approach for all space missions, and especially large constellations.
This paper will analyze the uncertainties involved with using DAS to show compliance with current regulations and will also analyze the efficacy of the regulations themselves in limiting the risk of catastrosphic fragmentations. In particular, the paper focuses on the impacts of ignoring collision risk stemming from debris objects less than 10 cm in diameter, which may also cause catastrophic fragmentation. These factors likely have significant impacts on how space traffic and debris risk is managed and must be taken into consideration by current regulations as part of ensuring a safe and sustainable space environment for future generations.
Date of Conference: September 14-17, 2021
Track: Conjunction/RPO