Removing Orbital Debris with Less Risk

Abstract

Deorbit concepts have been proposed for dealing with the growing problems posed by orbital debris. Most devices use large structures that interact with the atmosphere, magnetic field, or solar environment to deorbit large objects more rapidly than natural decay. Some devices may be better than others relative to the likelihood of collisions during their use. Current guidelines attempt to address this risk by applying the metric of area-time product to compare the probability of a large object experiencing a debris-generating impact. However, this approach is valid only for collisions with very small debris objects. The peak in the distribution of the area of orbital debris occurs for objects with a characteristic size close to 2 m. For collisions with such objects, some of which are operating satellites, it is important to incorporate the augmented collision cross-sectional area, which takes into account the size of both colliding objects when computing the area-time product. This new approach leads to a more valid comparison among alternative deorbit approaches, which now indicates that inflatable drag enhancement devices result in the least risk. Finally, one deorbit device, an electromagnetic tether, is shown to have a very large collision cross section for disabling operating satellites.

Optimum sizing of bare-tape tethers for de-orbiting satellites at end of mission

“…The product f/Z, x ¿ represents an ^rea-^'/Mg product characterizing the probability of such accident; for ¿f= 2m and again 63° we find 203, 357, 621 m2year for Ms = 37.5, 375 and 3750 kg respectively, well below values found in the literature (Nock et al, 2013). An obvious result, anyway, would be the tape being cut, aborting the de-orbit operation.…”

Considering the collision probability of Active Debris Removal missions

“…If solar arrays or tethers are struck by debris, they will produce fragments that will have the potential to damage or disable active satellites. Even though such collisions are not likely to cause catastrophic breakups (Nock et al, 2013), they should be avoided because small debris are difficult to track and so the risk they pose to active spacecraft cannot be easily mitigated.…”

“…This would not only negate the benefit of such an initiative but also undermine its support. Comparison of the collision risk associated with different ADR technologies was carried out by Nock et al (2013). Work has also been done on reducing the probability of causing orbital collisions through ADR, e.g.…”

Forecast analysis on satellites that need de-orbit technologies: future scenarios for passive de-orbit devices

“…The study is performed by using the SpaceTrak™ database which provides future launch schedules, and spacecraft information; the de-orbit analysis is carried out by means of simulations with STELA. A case study of a passive strategy is given by the de-orbit mechanism technological demonstrator, which is currently under development at Cranfield University and This paper is based on a presentation at the 5th CEAS Air & Space Conference, Sept. [7][8][9][10][11]2015, Delft, The Netherlands.…”

“…Three different concepts can be identified as drag augmentation devices, Nock describes them in [11] when considering the ATP:…”