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Planetary News: Space People (2008)Steven J. Ostro, 1946 - 2008By Charlene AndersonDecember 16, 2008
The Planetary Society has just lost a good friend and valued colleague: astronomer Steven J. Ostro died early in the morning of December 15, 2008. The world has lost one of the most skilled scientists tracking and studying the asteroids that pass close by our planet – and might one day threaten the survival of our civilization. Steve was a radar astronomer -- not your garden-variety astronomer who makes passive measurements of reflected sunlight or naturally emitted radiation. Radar astronomy is active -- just like Steve was himself. Radar astronomers send radio transmissions to hit moving targets, then measure the characteristics of the echoes received back on Earth. From those measurements, they can deduce the shape and motions of an asteroid, and whether it is a solid rock or a loosely bound pile of rubble. The Planetary Society got involved with near-Earth asteroids in the early 1980s, beginning with our support for the pioneering discoveries of Gene Shoemaker and Glo Helin at Palomar Observatory. Steve joined JPL in 1984 and headed the asteroid radar group. In 1989, he and his team used the great, 300-meter dish of the Arecibo Observatory to image an asteroid, 4769 Castalia, for the first time. The combination of a superb instrument – the Arecibo antenna – and a passionate scientist – Steve – produced amazing results, amazing results, including the observations that were used to confirm that 99942 Apophis will not collide with Earth when it passes under the orbits of geosynchronous satellites in 2029. And then there was 1999 KW4 -- a bizarre astronomical object by anyone’s appraisal. On its path about the Sun, it crosses the orbits of Mercury and Venus, then approaches Earth’s orbit — with the potential to someday collide with our planet. Fortunately for those of us alive today, Steve’s observations have shown that a collision is unlikely for at least the next thousand years. Even while the Arecibo Observatory was proving its worth in precise tracking of those asteroids that might threaten Earth, budget cuts and internecine government-agency wrangling threatened to shut it down. With his best instrument threatened, Steve turned to The Planetary Society for help and our members responded, bombarding their congressional representatives with demands that Arecibo be kept open and sending their Society representatives to testify to the U.S. Congress in support of the observatory. Arecibo was reprieved – at least temporarily – and to thank The Planetary Society, Steve came to Society headquarters to present us with a model of binary asteroid 1999 KW4, created with painstaking accuracy from his radar measurements. With just a tiny bit of pomp and heartfelt expressions of thanks, he placed it on the table in our conference room. To some of us seeing the model for the first time, the largest or Alpha member of the binary pair looked like a lump of brown clay that someone had tried to form into a ball, but the lump was a little too large for their hands and it bulged unattractively around the middle. The smaller, Beta member resembled nothing so much as a flattened mud ball. But to Steve, asteroid 1999 KW4 was supremely beautiful, a manifestation of the laws of nature whose strange shape he had teased out from columns of numbers recorded by the Arecibo radar. As the model sat on the table, Steve danced around it, his hands skimming its surface, his eyes shining with enthusiasm. It was impossible to resist Steve’s intense passion for his work, and when this morning I learned of his death, I went quietly down to the shelf on which the 1999 KW4 model was displayed and brought it up to my office. It’s sitting on my desk, in all of its mud-ball splendor, as I write this. Remembering Steve, and looking at his asteroid model, I can truly appreciate its beauty. |
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