Methane not magic – Merlin mini research satellite under French-German cooperation

Restrictions of Kyoto Protocol are not only referring to carbon dioxide but also to methane. But in case of this gas, cars and industry are not main problem - source of methane are livestock farming and usage of fossil fuels.

One of biggest issues with methane is fact that its effect on global warming is around 25 times stronger than impact of carbon dioxide. For scientists around the world main problem was insufficient method of measuring methane level with instruments installed on Earth. Places important for methane cycle in nature are usually out of range of research centers and are not easily accessible. This important facts about methane, forced intensive development of space methods of measuring level of CH4. First satellite launched with mission to research on methane level on Earth, was GOSAT satellite designed and launched by JAXA on 2009. It was equipped with passive instruments for measuring level of methane based on observing spectra of sunlight backscattered from Earth surface and atmosphere. This method is not very accurate, because of jamming caused by thin aerosol layers and icy clouds. To gather more accurate data, new method was created - basing on active measuring and new instrument called LIDAR. It is basically combination of telescope and laser working like radar, but instead of microwaves laser emitter is used. Rule of operating is quite simple - target is illuminated with laser and next reflected beams are measured and analyzed by computer. LIDAR is able to give high resolution image of atmosphere and methane. Basing on this technology DLR and CNES decided to start developing own remote imaging satellite for French and German scientists researching on methane in Earth atmosphere.

On 8 December 2015 CNES and DLR decided to solemnly reaffirm joint mission for space research on methane levels. General agreement Thierry Mandon, Secretary of State for Higher Education and Research, and Brigitte Zypries, Parliamentary State Secretary at the Federal Ministry for Economic Affairs and Energy and Federal Government Coordinator of German Aerospace and Information Technology Policy confirmed previous statements and general roles for both space agencies in program. It was also announced that date for launching satellite is scheduled for 2020. Both space agencies have different objectives in mission. French side is responsible for developing platform, Germany will develop onboard instruments including main LIDAR. CNES will be also responsible for ground mission control. Satellite will be based on Myriade-Evolution by Astrium (present Airbus Defence and Space) and will be manufactured by Airbus Defence and Space with necessary modifications, under contract with CNES from April 2015. Myriade is reliable bus utilized for mini satellites since 1998. Spacecraft will weigh around 400 kg, will be powered by deployable solar arrays (power generated is at 416 W and scientific payload will consume around 160 W) and will remain on SSO for three years. To meet demands connected with predicted weight of satellite at 400 kg, Airbus modified bus structure, implemented more powerful solar arrays and new AOCS (Attitude and Orbital Control Systems with improved Hydra star tracker and reaction wheels is basing on AS250 AstroSat avionics) was added. Satellite propulsion are four hydrazine fueled thrusters with power at 1N. Dimensions of satellite with folded arrays and without antennas are 57 cm x 98 cm x 102 cm. Gathered data will be stored in 512 Gbit internal memory or, if possible, transmitted on X band frequencies to CNES Earth terminal network stations in Europe, Africa and America. Commands and housekeeping data will be transmitted on S band. After receiving data will be transferred to PLGS (Payload Ground Segment) for further quality control, dissemination and archiving of mission products. In spite of main objective, Merlin mission will deliver various additional data and provide different services like: estimating vegetation vertical structure, detecting cloud boundaries, measuring various layers of aerosol generated by fires, volcanic eruptions and other phenomenon generating different aerosols to atmosphere.