An alumnus of the Institut d’Optique, Michel Combes joined the Paris
Observatory in 1960, in the "Electronic Camera" group which was at that
time directed by André Lallemand.
Precursor of space infra-red spectro-imagery
In 1969, following the Paris mission of S. I. Rasool, involved at the NASA in the space exploration of the planetary system, , Michel Combes played a key role in the creation at the Observatory of a new planetology group, the « Groupe Planètes », housed at tht time in the Solar Physics Department, which subsequently became the DASOP, and then the LESIA.
Essentially a specialist in optics, , Michel was convinced that the new projects should be based on instrumental innovation. Together with James Lequeux, he proposed innovative solutions for the Canada-France-Hawaii telescope, which were probably too innovative to be adopted.
In 1973, he organized a campaign in South Africa to observe the jovian ocultation of the star Beta Scorpio par Jupiter. The experiment was a huge success and led to a first ever analysis of the thermal structure of the jovian stratosphere.
At the same time, he was working on the development of a Fourier transfrom spectrometer for the thermal infra-red domain, destined for the spectroscopic analysis of Jupiter. This was the ROMEO I instrument, which was flown on the Kuiper Airborne Observatory in 1973, and which was often used on the l’University of Hawaii 2,20m telescope and on ESO’s 3.6m telescope at La Silla.
This was followed by a more sophisticated instrument, ROMEO II, which was also used at La Silla at the start of the s 1980. These observing campaigns led to the analysis of the chemical composition of the jovian atmosphere, and thence to determine the abundance ratios, thereby imposing constraints on the models for the formation of the planet.
The 1980s decade was marked by Halley’s comet ; Michel Combes hoped to exploit this unique opportunity. Together with Tobias Owen in the USA and Vassili Moroz in the USSR, in Moscow, he submitted a proposal for a new instrument specifically designed for the unprecedented measurement in the infra-red domain of the cometary emission.
To do this space experiment, Michel arranged for the "Planètes" group to return to the DESPA, which as at that time directed by Jean-Louis Steinberg.
Together with many colleagues from the LPSP (precursor to the Institute for Space Astrophysics (Institut d’Astrophysique Spatial)) and from the CSNSM at Orsay, Michel Combes worked on the development of this instrument – the IKS - which had to be finalized very rapidly, and became its scientific PI.
This experiment, launched on the soviet probes Vega 1 et Vega 2, was a huge success, and yielded the first ever measurement of the temperature of the core and the detection of new molecules which emerged from the core.
In the middle of the 1980s, Michel Combes became director of the DESPA and organized its enlargement via the integration of the "Space Infra-red" group. He engaged the laboratory in the creation of one of the channels of the ISOCAM camera for the ESA’s Infrared Space Observatory (ISO) mission.
At the same time, following on the success of the IKS experiment, he involved the planetology group in planetary infra-red sensing missions. Thus emerged a line of infra-red spectro-imagers, designed and built at the DESPA, together with the IAS and various international laboratories.
These instruments were first flown on the martian missions together with the ISM/PHOBOS instruments, and then on OMEGA/Mars-96 with the Russians, redone after the failure of Mars 96 on Mars Express.
These instruments led to the spectro-imagers on Cassini/Huygens, on Rosetta and on Venus Express.
All of these instruments and sub-systems, developed at the DESPA, functioned successfully, and in particular those on the Mars Express mission, still functioning in orbit around Mars.
Two presidential mandates
In January 1990, following the death of Pierre Charvin, Michel succeeded him as President of the Observatory. This post revealed his exceptional human qualities, and his deep understanding of men and institutions, an understanding which he had acquired in particular when he was at the Bureau national du Syndicat National de l’Enseignement Supérieur in the 1960s.
As president of the Observatory, Michel Combes’ main task was to launch the re-organization of the departments, a tricky process involving endless discussions and controversies. Michel arbitrated the conflicts without prejudice to people and points of view.
A new department for millimetre astronomy, the DEMIRM, was created in 1994 ; the computing section of the Bureau des Longitudes rejoined the Observatory (IMCCE) in 1996 ; the Centre d’Analyse d’Images (CAI - Image Analysis Centre) was created and joined the DASGAL in 1998. This was the start of a profound re-organization of all the scientific departments of the Observatory, which was conclude under the directorship of Pierre Couturier during the opening years of the 2000s.
During his two presidential mandates at the Observatory, Michel was also president of the CNAP (Conseil National des Astronomes et Physiciens).
in pIn spite of his heavy administrative load, he continued to follow the development of DESPA’s space projects and the moves to new domains, in particular the EVRIS stellar photometry experiment, flown together with OMEGA on the Russian mission Mars-96.
After the failure to orbit the Mars-96 probe, the EVRIS and OMEGA missions were developed in a new context.
Still under the responsibility of Annie Baglin, EVRIS became the French CoRoT mission, the first ever space mission for stellar seismology and the search for exoplanets ;
OMEGA was reborn in the context of the European Mars Express mission, again under the scientific responsibility of Jean-Pierre Bibring of the AS.
Later still, together with the team of Angioletta Coradini (INAF-IFSA) in Rome and other European partners, the VIRTIS-H experiment was flown on two European missions, Rosetta et Venus Express.
In 1999, after two mandates at the head of the Paris Observatory, he left the presidency and returned to the DESPA (ex-LESIA) to work with Loïc Vapillon on a scientific project which was very dear to him, the analysis of images of Titan obtained with the help of adaptive optics.
He devoted himself to teaching optics. He participated in Research and Technology projects involving the infra-red spectro-imagers, and continued to follow the development of these instruments.
He accompanied to and supported the Direction de la Communication (Communications Directorate) and made significant contributions to the History of Science team together with his friend Jean Eisenstadt, work which he maintained all his life.
His friends and colleagues will deeply regret his death. His strong personality, his clear political vision, his involvement in society, his ability to to organize and to establish a dialogue, enabled himm to play a major role not only in planetology but also at the Observatory and elsewhere.
Dernière modification le 21 décembre 2021