FAST: A New Mars Express Operations Concept, Quickly

Lakey, Daniel T.; Schulster, Jonathan; Reboud, Olivier; Ormston, Thomas; Pols, Kees Van Der; Denis, Michel; Godfrey, James

doi:10.2514/5.9781624102080.0431.0454

Cited by 3 publications

(2 citation statements)

References 8 publications

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“…HE recovery of nominal operations of Mars Express, ESA's Mars orbiter in Martian orbit since late 2003, was achieved in a large part by switching from a command-stream based operations concept, to a file-based operations concept 1 . A series of anomalies in the Solid State Mass Memory (SSMM) resulted in a switch from an SSMM-based to a much smaller in-memory Mission Time-Line (MTL), using Delayed-execution Telecommand Files (DTCFs) to "top up" the memory on a just-in-time basis, with a roll-back mechanism in case the execution of the file was incomplete.…”

Section: Introductionmentioning

confidence: 99%

Truly File-Based Operations at Mars: Lessons Learned and Ideas for Future Missions

Lakey¹,

Blake²,

Sousa³

et al. 2014

SpaceOps 2014 Conference

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Since 2011 Mars Express has been flying a truly "file-based" concept for commanding the spacecraft and science operations, after a hardware anomaly forced a change from the previous "on-board schedule of commands" approach. As a consequence of the anomaly, new concepts had to be developed and applied to not just the technologies of file transfer and file management, which have received much attention over the years, but also to answer the questions: What are file-based operations? What goes in the files? How are they practically used both on ground and on board? ESA's first generation of deep space missions implement a packet-based large file transfer protocol to enable "files" to be transmitted from ground and guarantee the completeness on-board. However this is a transport-layer protocol and does not address the usage of the files operationally. Similar proposed standards (such as CCSDS File Delivery Protocol) also do not address the functionality of the files, and so by themselves do not necessarily lead to file-based operations. The Mars Express approach relies on seeing spacecraft operations not as a stream of commands, relayed from a mission planning system to the spacecraft via files, but as a collection of discrete activities, with one commanding file per activity. The contents of the file is the responsibility of the science planners, combining elementary sequences as per the rules defined by the spacecraft/payload operations engineers to construct self-contained, fail-safe sets of commands. For example, one science observation activity includes power, thermal, data link and instrument configuration changes that can be combined into one file (of telecommands, as an On-board Control Procedure, or a combination). Rather than individually scheduling the low-level commands, the activity file is simply executed at the correct time. If the observation needs to be modified or cancelled, the file is replaced or deleted. Spacecraft operations can conveniently be abstracted to the simpler paradigm: "which file to execute and when?" -the low-level constraints and resources checking having already been performed at mission planning level when that activity was planned. The ratio of commands-in-files to scheduled "execute" commands (the amount by which operations have been "compressed" by considering the higher-level "activity" file rather than low-level commands) is about 30:1 but is limited by available memory resources. Future missions with larger memories should achieve better than this, with fewer files containing more complex operations, resulting in even more abstracted operations overall. Mars Express has demonstrated a use case and implementation of file-based operations with regards to spacecraft commanding, but this is only half of the picture. The return of science data and housekeeping telemetry remains based on "packet stores". Packet stores are akin to looped SpaceOps Conferences magnetic tapes, in that the data is stored in the order in which it was written. For Mars Express this is not usually a pro...

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Section: Introductionmentioning

confidence: 99%

Truly File-Based Operations at Mars: Lessons Learned and Ideas for Future Missions

Lakey¹,

Blake²,

Sousa³

et al. 2014

SpaceOps 2014 Conference

Self Cite

View full text Add to dashboard Cite

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“…The Mars Express solution had the following aims [2] ; 1) To shift the execution of the MTL from the mass memory to a smaller (117 commands) RAM based 'safe mode' MTL. This ensured that a failure of the mass memory would never directly fail the MTL execution.…”

Section: Future Developmentmentioning

confidence: 99%

Mission Planning on ESA’s Billion Star Surveyor Gaia Mission

Milligan¹

2016

SpaceOps 2016 Conference

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This paper details the bespoke aspects and enhancements to mission planning on ESA's Gaia mission. Tasked with mapping 1 billion stars to unprecedented precision (to the microarc-second level, comparable to the width of a coin on the Moon as viewed from Earth). ESA's Science cornerstone mission is expected to also discover and chart 100,000's of new objects including near Earth Asteroids, exoplanets, brown dwarfs and Quasars. After a flawless launch 19 Dec 2013, Gaia was brought the circa 1.5 million kms into L2 via a sequence of technically demanding orbit transfer manoeuvres using onboard thrusters in thrust vectoring mode. Starting in parallel to this, and lasting 6 months, the full spacecraft was commissioned and brought gradually up to the highest operational mode. The commissioning phase involved detailed checks also of the relatively high number of bespoke units, including the 106 CCD focal plane assembly, telescope in the loop AOCS control, micro-propulsion, atomic clock and electromagnetically steerable phased array antenna for downlink. Gaia needs to downlink large amounts of science data to ground, used by the science segment. For this reason, Gaia is the largest user of the ESTRACK 35m ground stations. The ground station time required for the downlink of this data has been heavily optimized through long-term mission planning, involving modeling of the onboard data acquisition rates (via stellar density and telescope pointing) and link budget. Although originally conceived of as a very low commanding volume mission, commanding volume has significantly increased in flight (which has allowed increased science return from the mission). Innovative enhancements in the planning have allowed an increase of effective commanding volume whilst simultaneously allowing command uplink far into the future, taking advantage of the onboard atomic clock and the TC file functionality.

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Staring At The Sun: Implementing the Remote Sensing Window Concept for Solar Orbiter

Lakey¹,

Pantaleoni

Watson³

et al. 2014

SpaceOps 2014 Conference

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ESA's Solar Orbiter mission, scheduled for launch in 2017, will enter into an elliptical orbit around the sun with a perihelion of 0.3 AU and an increasing inclination of up to 35°. Three ten-day "remote sensing windows" will be centred on the closest, most northern and most southern points of each 160-day orbit. During this remote sensing window, remote sensing instruments will peer through slots in the spacecraft's heat shield to observe the evolution of solar features and will only see a small fraction of the solar disk. However, due to the difficulty of modelling the movement of these features, they can migrate out of the instrument's field-of-view within about 3 days. It is therefore mandatory for Solar Orbiter to implement ground-based feature tracking as part of the science planning process. With ground-and Earth-orbit based observatories not always able to observe the same part of the sun as Solar Orbiter, the instruments themselves will need to provide data which can be used by the science planning team to select and track the path of the features across the solar surface. A subset of "quick look" data will need to be defined which is sufficiently detailed to enable the analysis of the movement but also small enough to be downlinked completely in one ground station pass. The rapid processing by the science ground segment located at ESAC in Spain will be critical to turn this "quick look" data into data sets that can be analysed and form the basis of spacecraft pointing requests. Flight Dynamics will be required to check and convert these pointing requests into spacecraft commands forming a complete chain of attitude segments, one for each day of the science window, such that a complete and coherent guidance profile is always available to the spacecraft. Finally, the uplink to the spacecraft must be performed on a daily basis, in such a way as to minimise disruption to on-going science observations. Furthermore, there's the question of how this can actually be achieved operationally in a safe manner. What if a ground-station pass is lost? How do we prioritise the downlink of the quick look data? How do we uplink the new guidance profile safely? How do we transition from one guidance profile segment to the other in a smooth manner, that doesn't interrupt on-going observations? The remote sensing

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FAST: A New Mars Express Operations Concept, Quickly

Cited by 3 publications

References 8 publications

Truly File-Based Operations at Mars: Lessons Learned and Ideas for Future Missions

Truly File-Based Operations at Mars: Lessons Learned and Ideas for Future Missions

Mission Planning on ESA’s Billion Star Surveyor Gaia Mission

Staring At The Sun: Implementing the Remote Sensing Window Concept for Solar Orbiter

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