Swarm is the magnetic field mission of the ESA Earth Observation program composed of three satellites flying in a semi-controlled constellation: Swarm-A and Swarm-C flying in pair and Swarm-B at an higher altitude. Its history in-orbit began in the afternoon of the 22nd of Novem-ber 2013, when the three identical spacecraft separated perfectly from the upper stage of the Rockot launcher at an altitude of about 499 km. Control of the trio was immediately taken over by the ESA’s European Space Operations Centre (ESOC) in Darmstadt, Germany. Following the successful completion of the Launch and Early Orbit Phase (LEOP), commissioning was con-cluded in spring 2014 and precious scientific data have been provided since then.
In order to deliver extremely accurate data to advance our understanding of Earth’s magnetic field and its implications, each Swarm satellite carries a magnetic package, composed by an Absolute Scalar Magnetometer (ASM) and a Vector Field Magnetometer (VFM), an Electrical Field Instrument (EFI) and an Accelerometer (ACC). Unfortunately Swarm-C, due to a failure in LEOP and commissioning, does not carry an ASM.
Two daily ground station contacts per spacecraft are needed to support operations and downlink the scientific data stored in the on-board Mass Memory Unit. Only one ground station pass, however, is supervised by an operator, while in general the missions routine operations are automated, thanks to the Mission Control System used at ESOC and the relevant expertise in mission automation gained from the other Earth Explorers, from GOCE to CryoSat-2.
Many activities and campaigns have been performed through the years to improve instrument anomalies, such as changing the EFI operation’s concept to a limited number of daily science orbits and scrubbing operations to counteract image degradation. In particular, the operations on the EFI, implying a consistent workload for the teams, have been automated with the creation of a new interface with the University of Calgary, in charge of producing a set of files with the required configuration and requests, that are ingested in the FOS Mission Planning System.
Similarly, in the last years the ASM instrument has undertaken more and more sessions in Burst Mode, producing data at 250Hz on request of the Instruments team. Also this activity has been recently integrated in the automated operations concept, to offer flexibility to target this mode based on the space environment’s short-term evolution.
On the platform side, a few anomalies happened and were reacted upon very quickly, e.g. the Swarm-A science data downlink anomaly in 2020, that was solved by routing all science data to the housekeeping storage and re-designing part of the ground segment’s processing to handle this change of concept.
The operations were not affected by the COVID-19 pandemic, in the worst periods of which the teams were mostly working remotely and the operations supervised at ESOC by a reduced team: no outage of science nor change of core operations concept was necessary due to the pandemic.
On the orbits side, a major orbital manoeuvring campaign was undertaken in 2019 to change the relative local time of Swarm-A and Swarm-C, such to meet Swarm-B when the orbital planes were at the closest angular location in Summer to Winter, 2021. This particular scenario called “counter-rotating orbits” implied Swarm-B counter-rotating with respect to the lower pair in a similar orbital plane, a very exciting opportunity for science. In addition to this, the separation along-track of Swarm-A and Swarm-C was tuned down to 4 seconds, then 2 seconds and then kept variable up to 40 seconds to provide different scenarios for science data collection, requiring in total more than 20 orbital manoeuvres.
The presentation will describe the Swarm specific ground segment elements of the Flight Operations Segment (FOS) and explain some of the challenging operations performed so far during this almost-9-years-long journey, from payloads operations to resolution of anomalies and the last orbital dance during the “counter-rotating orbits”. This will offer an interesting overview of the mission’s satellite trio, ready to collect science during the upcoming Solar Cycle… and more.