Simon George, Defence Science and Technology Laboratory; Alexander Agathanggelou, Defence Science and Technology Laboratory; Grant Privett, Defence Science and Technology Laboratory; Philippa Halpin, Defence Science and Technology Laboratory; William Feline, Defence Science and Technology Laboratory; Andrew Ash, Defence Science and Technology Laboratory; Paul Chote, University of Warwick; Lauchie Scott, Defence R&D Canada; Jovan Skuljan, Defence Technology Agency; Jason Alvino, Defence Science and Technology Group; James Frith, AFRL/RVSW;
Keywords: SSA/SDA, astrodynamics, experimentation, observation campaign, GEO rendezvous, tracking, electric propulsion, RPO, orbit determination
Abstract:
During February and March 2021, the Mission Extension Vehicle-2 (MEV-2) satellite conducted the second ever commercial, On-Orbit Servicing (OOS) mission in Geostationary Earth Orbit (GEO); rendezvousing and docking with Intelsat 10-02 to begin the provision of augmented manoeuvre capabilities to extend the clients lifetime. Following on from its predecessor, Mission Extension Vehicle-1 (MEV-1), this was the first such mission to undertake this manoeuvre on an operational spacecraft directly on-station in GEO (and in relative proximity of other operational spacecraft), providing a unique opportunity to observe and characterise this type of behaviour taking place within a co-operative servicing mission.
The defence science & technology agencies of the UK, US, Australia, Canada and New Zealand exploited this opportunity to successfully pursue a coordinated SDA experiment, observing the dynamics and behaviours of the two satellite to improve understanding of rendezvous and proximity operations (RPO) in Geostationary Earth Orbit (GEO) through observation and analysis activities. The experiment, known as PHANTOM ECHOES 2, followed-on from an initial campaign undertaken in 2020 on the MEV-1 mission, and which was presented at AMOS 2020. Overall, these form a series of international SDA R&D activities undertaken by Five-Eyes nations on GEO proximity operations, conducted under The Technical Cooperation Program (TTCP) and aligned with the Combined Space Operations Initiative (CSpO).
Within this 6-month experiment, MEV-2 was used as a surrogate target against which to demonstrate how allied R&D sensors and processing tools may be utilised to observe RPO events in GEO and potentially improve space safety for allied spacecraft in GEO. Tracking and observation activities were undertaken by the international team throughout key phases of the MEV-2 mission: during the long-duration, electric-thrust orbit circularisation (August 2020 to January 2021); throughout its approach, rendezvous and docking to its mission client Intelsat 10-02 (February 2021 to April 2021); and once operating as a Combined Vehicle Stack (CVS) with Intelsat 10-02 (April 2021 onwards).
Collection of real-world data on MEV-2s motions offered a unique opportunity to address the SDA challenges of tracking of electric-thrust objects in transit to GEO, and the dynamics and detectability of proximity operations in Geostationary orbit using ground and space-based sensors. In this paper, a report is provided of the Five-Eyes S&T observation activities conducted within PHANTOM ECHOES 2; including how the prototype VerSSA cloud C2 platform (University of Arizona) was utilised to share and automate data processing using SDA software tools contributed by each nation in support of the experiment.
Following MEV-2s launch from Guiana Space Centre (French Guiana) on 15th August 2020, two distinct observation campaigns of two-week duration were conducted using Electro-Optical sensors (both ground- and space-based) from across the FVEYs R&D architecture to investigate the capability to track and maintain custody of vehicles equipped with constant-thrust Electric Propulsion for Geostationary transfer. A federated SSA processing chain was utilised within the VerSSA platform to perform data reduction, astrometric processing, and initial & high-fidelity Orbit Determination [OD] to rapidly process tracking data and provide tracking cues to elsewhere in the sensor network, mitigating latency and precision issues associated with publicly-available tracking data on such objects. Techniques were also trialled for provision of short-term forecasting of future motions and the predicted deviation from Keplerian dynamics, to improve capability to acquire the target using narrow-field sensors. These campaigns were highly successful, demonstrating ability to retain custody of MEV-2 using data and capabilities within the FVEYs S&T network and from commercial data sources a structured discussion of results from this campaign are presented, highlighting experiences of the S&T community in observing and generating orbit solutions on vehicles undergoing finite-duration thrust dynamics in operationally-relevant scenarios.
During January-April 2021, a dedicated data collection campaign was undertaken to observe the approach and rendezvous of MEV-2 with Intelsat 10-02 at longitude of 1°W – Measurement data was collected from a variety of instruments and observers across the UK, Europe and Canada as MEV-2 approached its client and successfully performed a docking operation. A combination of Electro-Optical (metric position data, plus single- and multi-colour photometry) and Radio Frequency capabilities were utilised during a three-month campaign of data collection, including:
Dstl Observatory (Wiltshire, UK)
University of Warwick telescopes (La Palma, Spain)
The UK Space Geodesy Facility (East Sussex, UK)
Safran Data Systems (France)
The Liverpool Telescope (La Palma, Spain)
Sapphire and NEOSSat (Canadian satellites in Low-Earth Orbit)
Goonhilly Earth Station (Cornwall, UK)
Amateur astronomers within the UK [Basingstoke Astronomical Society]
A rich set of observation data was gathered during this campaign, on which a forensic analysis could be conducted in the months following the event: through comparison with known motion and events associated with the mission itself, this enabled analysis of what contextual information could be inferred from ground- and space-based data. In addition, this examined the capability to resolve objects in close proximity at GEO range, as well as capability to resolve and discriminate possible consequences of a proximity event. Exemplar images and analysis are to be presented within the paper, along with a discussion of recommendations for future research areas to support capability to maintain situational awareness around High-Value Assets (HVAs) in GEO. Such insights are poised to help advise development of future operational SSA architectures relevant to the Combined Space Operations (CSpO) initiative and flight safety of assets in GEO.
Date of Conference: September 14-17, 2021
Track: Conjunction/RPO