Two newly-arrived scientists at NASA's Jet Propulsion Laboratory will play a key role in the search for planets around other stars and the hunt for life beyond Earth. The appointments highlight a new JPL initiative to unite scientists from various disciplines, such as biology and astronomy, to study the evolution of planets and life in the universe.
Dr. Didier Queloz, a Swiss astronomer who co-discovered the first known planet around a star similar to our Sun, is a distinguished visiting scientist at JPL for the next year and a half. Dr. Kenneth Nealson has joined JPL as a senior researcher in astrobiology, a new field whose goal is to understand how planets and life co-evolve.
While at JPL, Queloz will continue his search for planets and help the Lab develop sophisticated search technologies. His work will benefit NASA's Origins Program, a series of planned missions to study the formation of galaxies, stars, planets and life. The program has gained momentum from discoveries by Queloz and, subsequently, other astronomers, of several planets orbiting stars beyond our Sun. Many scientists believe this raises the odds that an Earth-like planet exists with suitable conditions for life.
Queloz, a Swiss citizen, received his degree in physics in 1990 from the University of Geneva and worked on his doctoral thesis at Geneva Observatory with Professor Michel Mayor from 1991 to 1995. Using the French Elodie telescope in Haute Provence, France, they looked for signs of a Doppler shift in nearby stars. As a star moves closer and then farther away from Earth, the star's color shifts from red to blue. By detecting this motion, astronomers can infer that the star is being tugged by gravity from an orbiting planet.
"Back then, these experiments were considered a bit nutty," recalled Queloz. When Queloz and Mayor first detected a Doppler shift from the star 51 Pegasus, Queloz said their first reaction was, "We'd better check our instruments."
Even after they verified the instruments' accuracy, Queloz and Mayor spent several weeks monitoring 51 Pegasus to confirm the discovery. In July of 1995, they were confident enough to buy a large cake and hold a celebration party in the south of France for family and friends. Queloz and Mayor formally announced their discovery, a Jupiter-sized planet orbiting 51 Pegasus, at an October 1995 scientific meeting in Florence, Italy.
Queloz has received several honors, including the Swiss Society for Physics' Balzers Award, the Bioastronomy Medal from the International Astronomical Union, Commission 51, and a Best Thesis in Science honor from a Swiss corporation, Vacheron Constantin.
Queloz is continuing his hunt for new planets with the Elodie telescope and its twin, Coralie, a Swiss telescope in La Silla, Chile. But he and other astronomers face great challenges in finding new and better ways to detect planets more like Earth. Current techniques allow only for the detection of giant, Jupiter-sized planets, which are considered unlikely candidates for life.
While at JPL, Queloz will share his planet-finding experience with engineers who are designing more advanced technologies. Queloz is using a testbed interferometer at Caltech's Palomar Observatory to run tests on stars and prepare for an observing program. This work will help pave the way for other Origins projects, including the W.M. Keck Observatory interferometer in Hawaii, the Space Interferometry Mission, and the Terrestrial Planet Finder, all being planned by NASA.
Interferometry combines and processes light from several telescopes to simulate a much larger telescope, and holds great promise as a tool in the search for Earth-sized planets. "I'd like to play a role in future exploration by helping to define interferometry techniques," Queloz said.
During his stay at JPL, Queloz is living in Pasadena with his wife and their two children.
Until very recently, an astronomer like Queloz would have had little if any interaction with a biological scientist like Dr. Kenneth Nealson. But various disciplines, such as astronomy, geology, biology and chemistry, are joining forces to study the development of life on Earth and the prospects of life elsewhere. Therefore, the work of scientists like Nealson and Queloz is converging to form a broad, interdisciplinary approach.
"After all," said Nealson, "life is not a simple system and no science operates in a vacuum. Younger students are studying several disciplines to gain a more comprehensive view."
Nealson is part of this new wave of scientific training, as a geobiology teacher and faculty associate in Caltech's geology and planetary sciences division. At JPL, a division of Caltech, Nealson has been appointed to head a new astrobiology unit. Nealson said over the next few years, his astrobiology group will develop an understanding of the way life and planets have evolved, and will define the signatures of life.
"Not many foolhardy souls have ventured into this area," Nealson said. "After all, how can you find life if you don't know what you're looking for? This is a very, very important problem to be solved because right now we're not sure how to distinguish life from non-life. Our goal is to develop tools to make that distinction clearly."
In recent years, microbiologists have made startling discoveries about the hardiness of life on Earth, studying living organisms in thermal vents, acid lakes and other unlikely environments. Nealson pointed out, "This has opened the eyes of scientists to the notion that life could exist under seemingly inhospitable conditions on other planets."
Astrobiologists will also study changes in Earth's chemical composition over billions of years. They will then apply this knowledge to other planets to look for "chemical signatures" that might indicate that life has existed or could exist there.
Nealson said astrobiology will be useful for numerous space missions, including the Mars sample return mission, scheduled to bring back Martian rocks in the middle of the next decade. Astrobiology will also benefit the Origins Program's Terrestrial Planet Finder, which will look for Earth-like planets around other stars and hunt for signs of life-sustaining chemicals. Nealson said astrobiological studies may prove valuable in the study of Jupiter's moon, Europa, which may have liquid oceans under its frozen surface. This icy moon is currently being studied by NASA's Galileo Europa Mission, and a new Europa Orbiter has a planned launch in 2003.
Originally from West Liberty, Iowa, Nealson got his bachelor of science degree in biochemistry in 1965 from the University of Chicago. He earned his Ph.D. in microbiology from the University of Chicago and did postdoctoral studies at Harvard University. Nealson taught at Scripps Institution of Oceanography, San Diego, CA, and at the Center for Great Lakes Studies, University of Wisconsin, Milwaukee, WI. His honors include the Guggenheim Fellowship for Sabbatical Leave in 1981, and an appointment as an elected fellow in the American Academy of Microbiology, which he received in November 1993.
Nealson and his wife live in South Pasadena, CA.
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