Institut national de recherche scientifique français Univerité Pierre et Marie Curie Université Paris Diderot - Paris 7

Tribute to Michel Combes (1939-2017)

Monday 13 March 2017

(mise Ă  jour le 17 March 2017)

Michel Combes passed away on March 9, following a week of hospitalization. As a former Director of DESPA and a former President of Paris Observatory, Michel has played a major role in the life of the laboratory, the Observatory, and, beyond, in the development of planetology and of astronomical instrumentation in France.

As a former student of the Institut d’Optique in Paris, Michel joins the Observatory in the early 1960s, in the group of the Electronic Camera chaired by André Lallemand. In 1969, following a sabbatical year of S. I. Rasool, a specialist of planetary space exploration at NASA, in Paris, Michel plays a major role in the establishment of a planetology group at the Observatory, hosted within the Department of Solar Physics.

Mainly interested in optics, Michel is convinced that new projects in astronomy require instrumental innovation. With James Lequeux, he puts forward several suggestions for innovative solutions for the CFH telescope, but these suggestions are probably too innovative to be accepted at the time. In 1973, he leads a campaign in South Africa to observe the occultation of the star Beta Scorpio by Jupiter. This successful experiment makes possible the retrieval of the thermal structure in the stratosphere of Jupiter. In parallel, Michel works on the development of a Fourier Transform spectrometer operating in the thermal infrared, devoted to the spectral analysis of Jupiter. This instrument, ROMEO I, was flown on the Kuiper Airborne Observatory in 1973, and has been mounted on several occasions on the 2,20m telescope of the University of Hawaii and the 3,60m telescope of ESO in La Silla. Another more sophisticated instrument, ROMEO II, will also be operating in La Silla in the early 1980s.

The 1980s are the decade of Comet Halley’s apparition ; Michel wants to take advantage of this unique opportunity. With Tobias Owen in the US and Vassili Moroz in Moscow, Michel thinks of a new instrument for a novel observation, the near infrared emission of comets. To develop this space instrument, Michel manages a successful transfer of the “Groupe Planètes” for inclusion in DESPA, the Space Research Department of Paris Observatory, headed by Jean-Louis Steinberg. With several colleagues from LPSP and CSNSM at Orsay, Michel works on the development of an instrument – IKS - which must be realized in a very short time, and becomes its Principal Investigator. This successful experiment, launched on the Soviet probes Vega 1 and Vega 2, has led to the first measurement of the temperature of a cometary nucleus, and the detection of several parent molecules outgassed from the nucleus.

In the mid-1980s, Michel becomes the Director of DESPA and makes possible its enlargement with the merging of the Groupe Infrarouge Spatial. He drives the laboratory toward the development of one of the two channels of the ISOCAM camera of the Infrared Space Observatory (ISO) of ESA. In parallel, the planetology group gets involved in space projects of planetary infrared sounding. This is the beginning of a series of infrared imaging spectrometers conceived and developed at DESPA, in partnership with IAS in Orsay and several international laboratories. The first ones are devoted to the exploration of Mars, with ISM/PHOBOS and OMEGA/Mars-96 in partnership with Russia, finally installed on ESA/Mars Express after the failure of Mars-96. These instruments inspired the imaging spectrometers of Cassini/Huygens, Rosetta and Venus Express. All instruments and sub-systems built in DESPA will operate successfully, in particular aboard the Mars Express probe still in orbit around Mars.

After Pierre Charvin’s decease in 1990, Michel becomes the Director of Paris Observatory. This duty allows him to express his remarkable human and international relationship qualities, based on his excellent knowledge of men and institutions that he has acquired, in particular, at the National Bureau of the Syndicat National de l’Enseignement Supérieur in the 1960s. As a President, Michel initiates a re-organization of the scientific departments of the Observatory, a delicate task that raises debates and controversies. Michel takes decisions in the respect of all persons and viewpoints. In 1994, the department of millimeter astronomy (DEMIRM) joins the Paris site. In 1996, the computer section of the Bureau des Longitudes joins the Observatory as a new department, IMCCE. n 1998, the Data Processing Center (CAI) joins the Department of Stellar Astronomy (DASGAL). These are the first steps of a global restructuration of the scientific departments, which will be completed later in the early 2000, with Pierre Couturier as the next President.

In spite of his heavy administrative duties, Michel continues to follow the development of infrared space projects at DESPA, in particular the stellar photometry experiment EVRIS, which is part of the payload of the Russian Mars-96 mission with OMEGA. After the failure of the Mars-96 spacecraft just after launch, both EVRIS and OMEGA will be rebuilt in other contexts. Still under the PI-ship of Annie Baglin, EVRIS will become the French mission CoRoT, the first space mission devoted to stellar seismology and to the search for exoplanets. OMEGA is rebuilt as part of the payload of the European mission Mars Express, still under the PI-ship of Jean-Pierre Bibring at IAS. Later, in collaboration with the team led by Angioletta Coradini at INAF-IAPS in Rome, and with other European partners, the VIRTIS-H instrument will be flown on two other European missions, Rosetta and Venus Express.

In 1999, after two mandates, Michel comes back to DESPA to work with LoĂŻc Vapillon on the analysis of images of Titan recorded from the ground with adaptive optics. He is also involved in teaching activities regarding optics. He remains involved in activities dealing with Research and Development, and with the development of instrumental concepts. He also becomes more and more involved in outreach activities within the Service of Communication of the Observatory, as well as within the team working on History of Sciences with his friend Jean Eisenstadt. He will continue these two activities until the end of his life.

Michel will be deeply missed by his friends and colleagues. Thanks to his strong personality, his acute sense of politics, his engagement toward society, his sense of organization and dialog, he has played a major role in the field of planetology but also at the level of the Observatory and beyond. Michel was a leader with a strong sense of responsibility, respectful of his collaborators. He had a very strong capability for bringing teams together – scientists, engineers, technicians, administrative employees – and to make them work together towards a common objective. A close friend of Jean-Louis Steinberg, he has been, like him, a major actor in the development of DESPA – now LESIA. We wish to express our deepest sympathy to Michel’s daughter Isabelle and to his family.

Thérèse Encrenaz, Annie Baglin et James Lequeux

Michel Combes in 1990
Michel Combes in 1990

© Observatoire de Paris/LESIA

Michel Combes during the fiftieth anniversary of LESIA, October 3, (...)
Michel Combes during the fiftieth anniversary of LESIA, October 3, 2013

© Observatoire de Paris/LESIA, photo S. Cnudde

Michel Combes and Roger-Maurice Bonnet, June 3, 2016
Michel Combes and Roger-Maurice Bonnet, June 3, 2016

During the ceremony in tribute to Jean-Louis Steinberg, in the "Salle Cassini" of the Paris Observatory
© Observatoire de Paris/LESIA, photo S. Cnudde