Fred L. Whipple
Established the first optical tracking system for satellites, proposed the 'dirty snowball' theory of comet formation.
Fred Lawrence Whipple was born on November 5, 1906, on a farm outside of Red Oak, Iowa. While he was a teenager his father sold the farm and moved the family to Long Beach, California, where Fred worked in the family grocery store. He graduated from Long Beach High School in 1923, and enrolled in Occidental College in Los Angeles, hoping to become a professional tennis player. After transferring to the University of California at Los Angeles (UCLA), he reluctantly abandoned tennis and by his junior year became interested in astronomy. He received a Bachelor's degree in Mathematics from UCLA in 1927, then enrolled at University of California, Berkeley in 1929, teaching astronomy while pursuing a Ph.D. in the subject. After earning his doctorate in 1931, Whipple transferred to the staff of the Harvard College Observatory.
While still a graduate student, Whipple helped map the orbit of Pluto, discovered by Clyde Tombaugh in 1930. Working out of the Harvard Observatory, Whipple discovered or co-discovered five comets and asteroid 1252 Celestia. During World War II, he aided the war effort by inventing a system to counteract German radar by cutting up thousands of fragments of aluminum foil (chaff) to create false radar readings, hiding real targets with radar "static."
Anticipating threats to the spacecraft of the future from space debris, in 1946, Fred Whipple invented the "meteor bumper," now known as the Whipple Shield. A thin outer skin of metal, it protects spacecraft by disintegrating space debris such as small asteroids when they impacted the shield. His invention is still used by NASA to protect spacecraft.
Dr. Fred Whipple may be best known for his "dirty snowball" theory on the substance of comets in 1950. He argued that comets were primarily ice with some rock mixed in, rather than materials such as sand held together by gravity, as was the more accepted belief at the time. Dr. Whipple believed that as a comet approached a star, light from the star vaporized ice in the comet's nucleus. The jets of particles that resulted acted like rocket engines that either slowed or accelerated the comet. He also theorized that the glowing comet tails contained particles that originated from frozen reservoirs in comet nuclei. Whipple was proven correct in 1986, when the European Space Agency's Giotto spacecraft took close-up photographs of Haley's comet.
Fred Whipple was director of the Smithsonian Astrophysical Observatory (SAO) in Cambridge, Massachusetts from 1955 to 1973. Under his leadership, the SAO developed a network of Baker-Nunn cameras that achieved spectacular success in tracking man-made satellites. Anticipating the era of artificial satellites, he had organized the "Moonwatch" group to track them. His was the only organization able to make observations on Sputnik I, man's first satellite, launched by the Soviet Union on October 4, 1957.
During the International Geophysical Year (1957-1958), Dr. Whipple headed a team formed by the National Academy of Sciences and the National Science Foundation, responsible for developing an optical satellite tracking system. His techniques for photographically measuring the speeds and decelerations of meteors, his methods for computing the orbits of comets and asteroids, and his theoretical model for describing the structure of the comets are still scientific standards.
President John F. Kennedy honored Fred Whipple for his tracking project with an Award for Distinguished Public Service in 1963. Whipple also received the Gold Medal of the Royal Astronomical Society in 1983, the Bruce Medal of the Astronomical Society of the Pacific in 1986, and the Henry Norris Russell Lectureship of the American Astronomical Society the next year. In 1968, Dr. Whipple set up the Mount Hopkins Observatory near Amado, Arizona. One of the world's premier observatories, it was renamed in his honor in 1982.
Fred Whipple retired from Harvard in 1977, but continued to conduct astronomical research well into his nineties. Dr. Fred Whipple died in August 30, 2004, in Cambridge, Massachusetts at the age of 97. His legacy includes asteroid 1940 Whipple, the Whipple Observatory, and the "Whipple Shield."