Selma Zamoum, SpaceAble France; Thomas Husson, SpaceAble France; Fatoumata Kebe, SpaceAble France; Mathieu Barthélémy, IPAG-OSUG/CSUG; Benjamin Gigleux, SpaceAble France; Jacques Sombrin, TéSA Laboratory; Franck Durand-Carrier, TéSA Laboratory and CNES
Keywords: In-Orbit Servicing, Inspection, Space Weather Modeling, Space Data, Rendezvous, Satellite Anomalies, Space Safety
Abstract:
The goal of this paper is to cover the benefits of in-orbit inspection combined with the processing of existing space data for space sustainability.
On the one hand, the number of satellites in orbit continues to increase every year. Todays exponential growth is due to the various recent and future constellation projects. According to the UNOOSA, there are today more than 5400 objects in orbit with a number of deployed satellites that increased with 120% in 2020, compared to 2019.
On the other hand, the space environment is hostile to satellites. Temporary or permanent damage to an equipment or to the whole system may be incurred, which can provoke hazardous events. Consequences can be collisions, explosions, partial loss, or a premature ending of a satellites life before performing an atmospheric reentry (low-altitude satellites) or reaching a graveyard orbit (high-altitude satellites). This, combined with the large number of space objects, highly contributes to the increase of orbital debris and thus takes part in the Kessler syndrome establishment. Hence, monitoring the space weather, detecting anomalies, associating them with causes, and monitoring satellites will sustain the resilience of future generations of satellites in the paradigm of the NewSpace.
Soft and Hard errors affecting the health of spacecrafts are provoked by different space environment factors: spacecraft charging (surface charging and internal charging), Single-Event Effects (SSE), Radiation dose (TID?: Total Ionizing Dose and DDD: Displacement Damage Dose), surface erosion, meteoroids, and orbital debris. In addition, the atmospheric drag affects the spacecrafts orbits. Other causes of anomalies related to non-space environment events can also be found. These concern software and hardware manufacturing design errors, operator errors and technological actions (accidental or malicious). Various anomalies have been reported: device part failures and burnouts, degradation (optical components, electronics, solar cells, thermal properties etc), data corruption, biasing of instrument readings, system shutdown, phantom commands etc.
For all these reasons, satellite monitoring is performed through the analysis of telemetry data both onboard in real time and later on the ground. It is to be noted that thousands of parameter measurements constitute the telemetry data, generally gathered through onboard sensors. On the one hand, some failures are handled by the implementation of FDIR on the onboard software. On the other hand, a finer monitoring is performed on the ground for anomaly detection and prevention. However, due to the limitations of threshold-based anomaly detection methods only certain types of errors can be detected. Moreover, tracing some anomalies back to the source when they are detected appears to be extremely difficult without in-orbit inspection. This is why the attribute Unknown is associated to a vast majority of orbital anomalies or some of them may be erroneously attributed to a meteoroid or orbital debris events. The in-orbit inspection is expected to provide insights from on-orbit encounters that adversely affect satellite operations.
In this paper we provide an analysis of the evolution of catalogued satellite anomalies according to SERADATA database. The goal is to assess and interpret the efficiency of todays means to detect and diagnose anomalies. Furthermore, we present an approach, proposed by SpaceAble, that is based on two complementary systems in order to provide an efficient Space Situational Awareness service for different space actors.
First, a platform that aggregates and processes the complete spectrum of Space Situational Awareness (SSA) data, that is both Space Weather (SWE) and Space Traffic Management (STM) is proposed. Covering both SWE and STM is essential to achieve accurate understanding and models of SWE mechanisms, better understand the rajectography of space objects, and assess their environmental and state conditions in addition to the space weather risks through novel techniques based on artificial intelligence (AI). The goal is to train AI algorithms for SWE nowcasting and forecasting and thus alert operators in case of approaching hazardous events. Moreover, identifying the source of an anomaly after it is detected remains challenging especially when it comes to orbital debris or meteoroid events.
Secondly, in-orbit inspections will narrow the search for the possible mechanisms that have caused a failure whether it is due to natural sources (SWE and debris) or human activity sources (manufacturing design, jamming, orbit insertion). In addition, inspections will validate the models for satellite failures. The issue at stake is to optimize the design of satellites, plan their production and launches to insure the service of constellations with a sustainable Earth orbit. Therefore, a satellite capable of space rendezvous and inspection, also known as the Orbiter, is proposed to complement the data platform through in-orbit diagnosis. The general mission scenario and inspection tasks for possible use cases where the inspection orbiter intervenes are presented in the paper. In addition, a LEO constellation use case is studied in terms of the number of necessary orbiters according to the number of orbital plans, the number of inspections per satellite and the maximum time duration to reach any satellite for an emergency inspection. Finally, a plan to launch cost-effective orbiters, taking into consideration the launch method and the targeted orbit, is proposed.
These two complementary systems are expected to enhance anomaly detection and diagnosis for a longer lifetime of satellites in orbit, mitigate sudden and premature ending of satellites missions, help preparing active debris removal missions, and enhance current SSA capabilities. Such a service highly contributes to the enrichment of available space data for different space insurance actors and launchers.
Date of Conference: September 14-17, 2021
Track: Conjunction/RPO