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Richard M. Goldstein, a trailblazer in planetary exploration who used ground-based radars to map planets with techniques that scientists now use to measure geographical changes on Earth, including melting glaciers, died on June 22 at his home in La Ca\u00f1ada Flintridge, Calif. He was 97.<\/p>\n
His daughter, Rabbi Lisa L. Goldstein, confirmed the death.<\/p>\n
In the early 1960s, Dr. Goldstein was a graduate student in electrical engineering at the California Institute of Technology and working part time at NASA\u2019s Jet Propulsion Laboratory when he proposed, as his thesis topic, trying to detect echoes from Venus using the Goldstone Solar System Radar, which had been newly developed by the space agency.<\/p>\n
If successful, scientists would learn the distance from Earth to Venus, essentially laying the foundation to map the entire solar system. His adviser at Caltech was more than skeptical; Venus, in NASA\u2019s description, was a \u201ccloud-swaddled\u201d planet covered by thick gasses, and previous attempts to reach the planet using other radars had produced mixed results.<\/p>\n
\u201cNo echo, no thesis,\u201d Dr. Goldstein\u2019s adviser told him, according to \u201cTo See the Unseen: A History of Planetary Radar Astronomy\u201d (1996) by Andrew J. Butrica, a science historian.<\/p>\n<\/div>\n<\/div>\n
He proceeded anyway. On March 10, 1961, technicians pointed the new radar at Venus. Six and a half minutes later, signals from Venus returned. Dr. Goldstein had proved his adviser wrong. He soon bounced signals off Mercury and Mars, as well as Saturn\u2019s rings.<\/p>\n
The study\u2019s influence on solar system research was immense.<\/p>\n
\u201cThe measurements he did of the distance to Venus made it possible to do accurate navigation within the solar system,\u201d said Charles Werner, a former senior engineer at the Jet Propulsion Laboratory. \u201cIf you know one distance, it\u2019s like a ruler that allows you to calibrate everything else and to be able to navigate spacecraft in the solar system accurately.\u201d<\/p>\n
The radar echoes were the celestial prelude to a long career at the Jet Propulsion Laboratory charting the previously unseen. In the late 1960s and early \u201970s, Dr. Goldstein used radar interferometry \u2014 the splicing together of multiple radar signals over a period of time \u2014 to map the surface of Venus.<\/p>\n
\u201cHigh-resolution radar probes have broken through the thick clouds of Venus and for the first time distinguished features on the planet\u2019s surface, which presents a landscape of huge, shallow craters,\u201d John Noble Wilford, a science reporter, wrote in a front-page article published in The New York Times on Aug. 5, 1973.<\/p>\n<\/div>\n<\/div>\n
\u201cInstead of the blurry shadings of earlier radar maps of the planet,\u201d Mr. Wilford wrote, the images detected by Dr. Goldstein revealed a dozen craters, including one that was 100 miles wide and less than a quarter of a mile deep.<\/p>\n
Dr. Goldstein had used two radar antennas 14 miles apart to produce the images.<\/p>\n
\u201cThis, in effect, gives us stereo reception,\u201d Dr. Goldstein said, \u201cand enabled to pinpoint each area touched on Venus. We were able to see depths better.\u201d<\/p>\n
He later adapted his radar algorithms for use with aircraft and satellites, which have mapped melting glaciers, the movement of tectonic plates and other changes to the Earth\u2019s surface.<\/p>\n
\u201cFrom a civil earth remote-sensing perspective, he was absolutely the pioneer,\u201d said Paul A. Rosen, a project scientist at the Jet Propulsion Laboratory.<\/p>\n<\/div>\n<\/div>\n
Richard Morris Goldstein was born on April 11, 1927, in Indianapolis. His father, Samuel, was an owner of the Goldstein Brothers department store. His mother, Dorothy (Drozdowitz) Goldstein, managed the household.<\/p>\n<\/div>\n<\/div>\n
After graduating from Purdue in 1947 with a degree in electrical engineering, Dr. Goldstein joined the family business and worked in the lamp department.<\/p>\n
\u201cI have a record of selling the most three-way lightbulbs in Indianapolis,\u201d he joked in an oral history interview with the National Radio Astronomy Observatory.<\/p>\n
Eleven years later, Dr. Goldstein moved to California for graduate school and landed a low-level job at the Jet Propulsion Laboratory, where he worked for 43 years, and retired as a senior scientist. (He finished his doctorate at Caltech in 1963.)<\/p>\n
\u201cHe broke every problem down into its fundamentals,\u201d Mr. Rosen said. \u201cHe went about his work quietly. He was not big on telling the world how great he was.\u201d<\/p>\n<\/div>\n<\/div>\n
Dr. Goldstein married Ruth Lowenstam in 1964. She survives him, along with their daughter, Lisa; their sons Samuel and Joshua; three grandchildren; and a great-grandson. His brother, Samuel Goldstein Jr., an astronomer, predeceased him.<\/p>\n
During his time at the Jet Propulsion Laboratory and even after he retired, Dr. Goldstein was an enthusiastic competitor in the organization\u2019s annual invention challenge, in which participants try to solve quirky problems such as creating \u201ca device that can put up to 10 Ping-Pong balls into a Mason jar located five meters away within the one-minute time allotment.\u201d<\/p>\n
\u201cI would say he probably won at least a third of the time,\u201d his daughter said. \u201cHe loved these contests. He was obsessed with figuring out the solution.\u201d<\/p>\n<\/div>\n<\/div>\n