Simon George, Defence Science and Technology Laboratory; Andrew Ash, Defence Science and Technology Laboratory
Keywords: SSA, Spacecraft Systems, Horizon-Scanning, Astrodynamics
Abstract:
As the space industry transitions into the domain of New Space, market forces are motivating new ways to exploit space driven by much lower entry barrier. As a result, the industry is witnessing a series of rapid changes to the composition and behaviour of operational platforms; enabled by technological improvements to propulsion capabilities, platform/bus designs and onboard autonomy, driven by new mission concepts. From a Space Situational Awareness (SSA) perspective, these developments will provoke more complex spacecraft dynamics that increasingly diverge from assumptions made by existing predictive models which account for perturbations due to natural phenomena but do not model satellite manoeuvres and also assume a simple geometry. Furthermore, such changes could have further implications on our ability to detect and track satellites using current SSA techniques.
In this paper, changing trends in the technologies and hardware operated on future space platforms are analysed and assessed to determine their overall effect on the ability to conduct SSA, including both the resulting satellite dynamics and signatures observed by operational sensors. This work was conducted within the remit of the UKs and EUs research programmes associated with identifying the future challenges for maintaining full SSA in the context of Space 4.0.
The findings are derived from a comprehensive technology-watch activity conducted by the UKs Defence Science and Technology Laboratory (Dstl) to examine trends and developments in current (and future) on-orbit technologies. This focused on:
Technologies facilitating novel, non-traditional orbits including Non-Keplerian Orbits [NKOs]
New Space operations and countermeasures such as Active Debris Removal [ADR], On-Orbit Servicing [OOS] and de-orbit technologies
Subsystem technologies affecting capability for detection and tracking of resident space objects
The paper reports on analysis of these technical and political factors in order to draw conclusions regarding the potential impact that proliferation of these technologies could have on traditional methods of conducting SSA.
In this work, a particular focus was maintained on examining the speculative capabilities of Electric Propulsion (EP) and constant-thrust methods in enabling new, or radical, orbit sets and novel on-orbit dynamics. Future, high-capability EP systems could enable more disruptive (including non-Keplerian) orbit designs and long-duration orbital transfers; these may be poorly modelled by current methods of force modelling and numerical integration techniques for orbit determination and catalogue maintenance. A literature review of EP techniques, along with a speculative assessment of impacts on orbital modelling and dynamics is provided.
The study examined technologies which could facilitate proximity operations and the resulting implications for ground-based detection of closely-spaced objects, e.g. ADR and OOS mission technologies in addition to, satellite swarms and formation-flying/disaggregation concepts. Future Space Tug-type missions could drastically change the operational dynamics and mission profiles witnessed in the operational domain; potentially driving demand for additional services in support of proximity operations, as well as adding additional complexity to the modelling of on-orbit manoeuvre profiles and conjunction modelling. Notional technological solutions to the active removal of large (typical 500+ kg) payloads from LEO are also examined, including: harpoon concepts, direct interface grappling techniques, net-based concepts, electrostatic tractors and ion shepherd devices, adhesive techniques, laser devices and mass driver concepts.
The paper also outlines a qualitative understanding of future spacecraft platform design and composition, including discussion on the implications of increasing spacecraft autonomy, power requirements, subsystem capability, structural composition and platform reconfigurability on the capacity of SSA systems to detect and track future spacecraft. In this respect, some future challenges are associated with proliferation of system modularity, in-orbit construction, standardisation of platforms, and reconfigurable systems which modify their physical configuration during their mission lifetime.
The paper concludes with a supporting summary of the identified top-level impacts of future on-orbit technologies on traditional space surveillance techniques, along with a list of suggested future research topics which should be examined by the SSA community to help mitigate the possible consequences on legacy systems.
Date of Conference: September 17-20, 2019
Track: Space-Based Assets