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Planetary News: Space People (2008)

Steve Ostro and the fight for Arecibo

By Louis Friedman
December 16, 2008
Arecibo Observatory
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Arecibo Observatory
The 300-meter (1,000-foot) dish of the Arecibo Radio Telescope in Puerto Rico, the largest in the world. Credit: NAIC - Arecibo Observatory, a facility of the NSF

Steve Ostro (1946-2008) was the leader in using radar to track the asteroids that pass dangerously close to Earth in their orbits about the Sun. Radar measurements are much more precise than optical measurements, but they can only be made when the object is very close to the Earth. The largest radar in the world operates from the Arecibo telescope in Puerto Rico. Steve used both Arecibo and NASA’s Deep Space Network radar at Goldstone in California to measure the orbits, shapes and physical characteristics of near-Earth objects.

Late in 2006, Steve called to alert us to the National Science Foundation’s decision to shut down the Arecibo radar.  He was alarmed, not for himself -- his work would have continued at the NASA facility -- but for the world.  Just as we were discovering more asteroids whose orbits were not known well enough to rule out impact danger, the United States was about to close the best facility to collect data about their orbits.  The asteroid Apophis had recently been discovered on an apparent impact orbit and it was only Arecibo measurements that reduced the uncertainty enough that we could be certain that no impact would occur -- at least in 2029, when it makes its next close flyby.

Ostro urged us to help save the Arecibo radar, and we instantly agreed.  Throughout 2007 and into 2008, the Society wrote to all decision makers involved, met with congressional aides and representatives, and testified to Congress on the subject.  Our members swung into action with grass-roots letters to their congressional representatives.  Steve helped by referring us to other scientists who could provide knowledge and expert testimony to Congress.  In all of our interactions, we heard of the immense respect in which Steve was held for his work at the frontier of knowledge.

I had no idea the Arecibo radar would outlive Steve.  It has received a stay of execution for at least two years, and Congress has directed NASA and the National Science Foundation to come up with a plan for continued tracking of near-Earth objects.  Steve will not be part of that work, but I expect that sometime in the next few years, we’ll be remembering Steve and thanking him for a new and important discovery from the Arecibo radar.