10 years into its interplanetary voyage, Rosetta is approaching its target, the Churyumov-Gerasimenko comet. The aim of the probe is to explore the comet’s environment, and to send its Philae lander down to the surface of the comet’s core so that it can collect data. Rosetta is one of the ESA’s (European Space Agency) flagship projects, which should determine whether the models that are currently being developed about the formation process of our solar system and of which comets are the remains, are right or wrong.
On 28 March the mission entered a new phase with the Philae, the 100 kg landing module, which is scheduled to land on the comet in November 2014, being awoken from its hibernation. All its instruments are subjected to a thorough check-up to make sure that they function correctly and today Philae is in a position to transmit the first scientific activity data.
Philippe GAUDON, Rosetta Mission Director at the CNES (National Centre of Space Research) explains: “Rosetta is the first ever probe to be placed in orbit around a comet for a long period of observation and to place a lander on its core. The challenge is a very complex one because Philae has to land on the comet’s core, the composition and behaviour of which are still unknown quantities. This means that the orbits, the manœuvres, and the communication options will only be decided upon at a very late stage even though this information is crucial for preparing the mission plan. The complicated process has been made even more so by the very limited energy and memory that the Lander has for collecting the maximum amount of mission data.”
In the words of Dominique HALLOUARD, Atos, Planning Engineer for Scientific Operations: “During this crucial phase of the Rosetta mission, after the awakening of the Philae or PHC/Post Hibernation Commissioning, we’ll have 3 particularly hectic weeks during which the CNES/Atos mixed teams will be working in 2 ‘shifts’ on: the management of the GO/NOGO for the operations (authorisation or not for carrying out the operations depending on the feedback from the scientists) and the performance monitoring for these operations as well as the management of the equipment and software on board the SONC platform. We’ve got a few stages to get through before landing on the comet but after 7 years of working on this mission we’re getting to the critical part and that’s exciting.”
In order to be able to produce the plans, the Atos team works right at the heart of the Philae mission, the SONC, and uses a very complex restrictive environment planning tool known as MOST, Mission Operations Scheduling Tool. This tool which was specially developed for Philae and has been enhanced by very sophisticated algorithms which were also specially developed for Philae by the LAAS (Laboratory for Analysis and Architecture of Systems, one of the largest research laboratories at the CNRS, the French National Centre for Scientific Research), includes, amongst other things, a very precise data management system and an instantaneous energy management capability so that it is synchronised as closely as possible with the operation of the flight software.
Each of Philae’s 10 instruments has been modelled on its duration, its energy consumption and its data production. The plan had to be put together taking account of several types of constraints: orbital (visibility, cycles day/night…), inter-instrument and instrument/sub-system interferences, scientific needs, as well as the very limited memory and energy available. For the First Science Sequence (FSS), which is the period immediately after Philae lands, the energy available will only be enough for fifty or so hours of operations and each of the 10 instruments must be able to function at least once. All this makes producing the plan very complicated and tricky and all the more so because it must be able to be adapted to any new orbital situation, whilst remaining very precise and under complete control.
As soon as the Philae scientific operations plan has been finalised, it is sent to the Philae control centre (LCC), in Cologne. The LCC includes, by following the schedule supplied by the SONC, the corresponding commands in the overall Philae command plan. This is then sent to the RMOC (Rosetta Mission Operation Center), which is the control centre for the ROSETTA mission at the ESOC, European Space Operations Center, so that it can be incorporated in the overall command plan.
Atos teams have contributed over the past 20 years to the success of more than 50 space programmes and collaborated on numerous projects for the CNES and major industrial players in the aviation sector (European Space Agency, Airbus Defence and Space, Thales Alenia Space). For example: Atos has been selected by the CNES to develop future space mission control centres, a crucial issue in the next 20 years for the French space agency. Atos along with the CNES participates in the NASA Mars Science Laboratory mission.
Atos’ “Space & Aeronautics” Centre of Excellence brings together competences in different topics to meet the challenges of our scientific clients both on IT aspects (complex system architecture, real-time techniques, management of standards in force in the aeronautics and space sectors) and on business aspects (flight dynamics, physics, structural mechanics, digital simulations and probability, orbit determination, satellite navigation, etc.). This team also rely on the Atos group’s numerous skills in embedded, critical and security systems, which have allowed it to be a partner of the French nuclear programme for 30 years and the only large IT services company capable of providing the digital control systems of nuclear power plants.
