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Armand H. Delsemme (1918–2017)

Published onDec 01, 2018
Armand H. Delsemme (1918–2017)

Armand H. Delsemme, Professor Emeritus of Physics and Astronomy at the University of Toledo, passed away on Saturday. July 22, 2017. He was 99 years old. Armand Delsemme was born in Verviers, Belgium, on February 1, 1918. He was interested in science, and especially astronomy, from a young age. Physics, chemistry, and astronomy were never far from the various twists and turns of his life. Armand started his formal scientific education at the University of Liège, Belgium, from 1936 to 1940, where he studied molecular spectroscopy, with the goal of becoming an astronomer. While still a student at the University, he founded the Astronomical Society of Liège (SAL), which still exists today with nearly 600 members. His Master's thesis on the FeO spectrum was submitted, despite delays and uncertainty resulting from the invasion of Belgium in the early part of World War II.

During the war he was a member of the Belgian resistance movement, collecting information about the locations and wavelength of the first German radar stations in Belgium, which was radioed back to London in coded messages. Because of his efforts, he was eventually sought by the Gestapo and escaped through France and into Spain, where he was captured and spent a year in the Miranda de Ebro Concentration Camp. He was subsequently released in an Allied trade of Belgian prisoners for Canadian grain. The released prisoners traveled through Portugal and eventually to England. After convincing the British that he was not a spy and that he actually worked for the Belgian resistance, he was recruited to work with the British Secret Service, MI6, learned to parachute, and was parachuted back into France for a mission. During his time in England he met Gladys Arrowsmith. They married, moved back to Belgium after the war, and had three children. Tragically, Gladys passed away when the children were still quite young. In 1956 he married Delphine Jehoulet, an astronomer in her own right in Liège, who had completed research for her Ph.D. after working for a year in the US at several observatories, but sadly never completed her thesis.

After the war Armand returned to Belgium to work full time as a researcher for l'Azote and pursued a Ph.D. in molecular spectroscopy at the University of Liège. It was at this time that Professor Pol Swings (well known for the "Swings Effect" among many other discoveries) had shown him one of the then recent and now famous papers by Fred Whipple on the nature of comets. This was the time (1949-1952) of the great revolution in our understanding comets. In addition to Whipple's papers there was the paper of Jan Oort on the origin of cometary orbits and the paper by Ludwig Biermann suggesting a high-speed solar wind was responsible for cometary ion tails. After reading Whipple's paper, Armand realized that the activity of comets could not be explained by the sublimation of the kinds of ices like methane, hydrogen cyanide, and ammonia discussed by Whipple because the sublimation temperatures were far too low. He had some experience with clathrate hydrates and realized that it was possible to trap a substantial fraction of supervolatiles in a water ice matrix that would behave thermodynamically essentially like water. As a result he then published his seminal paper, Delsemme and Swings (1952), which showed that comet activity was dominated by a large fraction of water ice.

After his Ph.D. he remained working as a researcher in Belgium until 1956. From 1956-1958 he directed the building of the Institute for Scientific Research in Central Africa (IRSAC) optical telescope in the Congo, Africa. While in Africa he was asked to participate in a geological expedition to the Nyiragongo volcano for which he constructed a field spectrometer to record the first spectra of volcanic gas flames emanating from a vent within the volcano crater. He returned to Europe and then worked in science administration in Paris, France, from 1960-1966 as the head of Basic Scientific Research at the Organization for Economic Cooperation and Development (OECD), working on international cooperation. In 1965 he began to return again to comet research. In 1966 he accepted a professorship at the University of Toledo, where he was the first astronomer in what had been a Physics department. One of his first duties was to direct the completion of a new observatory on campus that consisted of a 40-inch Cassegrain telescope, which has been used for stellar and cometary spectroscopy since then.

During his scientific career at the University of Toledo, he made early important contributions to virtually every sub-discipline of cometary research, including nucleus activity, cometary orbital origin studies, laboratory studies of ices, the dynamics and appearance of gas and dust in the coma, and comet compositional chemistry and its connections to interstellar matter, the origin of the solar system and the volatile content of the Earth and life. Professionally he served as President and Vice-President of Commission 15, Physical Study of Comets and Minor Planets of the International Astronomical Society. He organized and edited the book following the first Comets-Asteroid-Meteorites conference in Uppsala, Sweden, which led to the ongoing Asteroids, Comets and Meteors Conference series. Armand was selected to serve as an Interdisciplinary Scientist for NASA's Comet Rendezvous Asteroid Flyby (CRAF) mission in 1986 that was unfortunately cancelled just after its official new start in 1992.

For his lifetime contributions to cometary and planetary science Armand was awarded the Gerard P. Kuiper Prize in 1998 by the Division for Planetary Sciences of the American Astronomical Society. He was also awarded the Jules Janssen Prize of the Astronomical Society of France (SAF). Asteroids Delsemme (2954) and Delphine (3218) were named after Armand and his wife Delphine. In 1994 he published his book, "Our Cosmic Origins" in French, that was later published in English in 1998. Armand Delsemme continued working and writing well into his 80s. He is survived by 3 children, 2 in the US and 1 in Belgium, 4 grandchildren and 3 great-grandchildren.

Personal note from the author: Armand Delsemme was my Ph.D. thesis advisor at the University of Toledo in the 1970s. His unbridled enthusiasm in everything he did combined with his research at the time on many of the fundamental issues of cometary science attracted me as a young graduate student. Every year or two, he and his wife, Delphine, would host a reception at their house for the department faculty, staff, and grad students. A few times he would show his impressive home movie of his expedition to the volcano Nyiragongo. After climbing down 180 meters from the volcano rim, he was lowered by cable in a parachute-like harness to the inner terrace 180 meters below that and just above the lava lake, where he made his spectroscopic measurements. As the film showed him being lowered by crane inside the volcano, he was seen smiling and waving at the camera. He would narrate the movie with "You see I am smiling, but I was not very happy!" At such gatherings he would also tell us about his exploits in the Belgian resistance and his year in the Spanish prison camp, where the prisoners were able to barter goods with the guards like chocolate that they were given by the International Red Cross. He was able to construct a makeshift camera and bartered with the guards for a roll of film. Once he was released he was able to get the film developed and amazingly had pictures of himself while a prisoner in the camp. One of my favorite anecdotes of those times was when he described how his release came from a trade of prisoners for Allied grain, and his wife, Delphine, would tease him, telling him all he was worth was a sack of flour. Clearly the value of his amazing adventure-filled life and his fundamental scientific accomplishments must not be underestimated.

Accoring to the author, Michael Combi, the photo is cropped from a picture taken in 1957 of Armand Delsemme on top of the dome of the Gentili Telescope at Pic du Midi.

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