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The Planetary Society Blog
By Emily Lakdawalla
Arecibo eliminates one threat, but faces another
Nov. 17, 2006 | 17:34 PST | Nov. 18 01:34 UTC
There's a new news story on the site on how a near-Earth asteroid named (66391) 1999 KW4 is no longer considered to be a threat to Earth, at least for the next thousand years. It's based on an article released online at Science Magazine, by Steve Ostro and a pile of coauthors: "Radar Imaging of Binary Near-Earth Asteroid (66391) 1999 KW4." The full paper is available for free from Ostro's asteroid radar research website.
In a nutshell, in 2001, Ostro et al used the giant Arecibo observatory in Puerto Rico and the Goldstone antenna in California to image KW4 and find it to be a binary. The radar data also allowed them to pin down KW4's path more accurately, which has shown that it won't hit Earth for 1000 years at least. It does get pretty close though; you can check out a table of KW4's close approaches to Earth here. You can also see the shape of its orbit at JPL's Near Earth Object program website. It's quite an elliptical orbit, with apoapsis near Earth's orbit.
The timing of this publication was ironic, because the National Science Foundation has just issued a 92-page report on the future plans for the astronomical facilities that it maintains, and apparently those plans do not include continued funding for radar research on asteroids -- or indeed any other research -- at Arecibo. The Division of Planetary Sciences of the American Astronomical Society has issued a statement that politely but sharply criticizes the National Science Foundation's decision: Dear Dr. Van Citters,
It is with great interest that I have read the report of the National Science Foundation senior review committee, From the Ground Up: Balancing the NSF Astronomy Program. Recommending the eventual decommissioning of a telescope or system is never a pleasant task, and I respect the honesty with which this commission approached these hard choices.
However, given the complexity of the issues it is inevitable that some aspects can get overlooked. In this regard, noting that the senior review committee did not have representation from the planetary sciences community, I must point out that the discussion of scaling back and possibly decommissioning the Arecibo telescope appears to have overlooked an aspect of its work that is in fact of major importance to the planetary community: its unique abilities as a tool in studying solar system bodies, especially near Earth asteroids, by radar.
There is in fact only one reference to radar in the entire 78 page document, and no mention at all of asteroids. But the Arecibo radar results are key to understanding near earth object sizes, shapes, and dynamics. Besides having a central scientific importance, both of themselves and as samples derived from the main asteroid belt, near earth asteroids may represent a significant hazard to Earth and also a potential source of future resources. To decommission one of our primary tools for studying them would deal a serious blow to both our science and our safety.
I note, finally, that the recommendation in this report to limit future NSF funding of Arecibo is based on the eventual run-out of current ongoing radio astronomy survey work. As noted before, the report says virtually nothing about radar, much less recommending its elimination. Thus we feel especially disconcerted that, although the Arecibo administration has indicated that it will make every effort to seek other sources of support, the NSF funding cut to $8M/yr allows operation of the S-band planetary radar system only until 30 September 2007. Ending the operation of the S-band radar, the basis of a vibrant program as indicated by its 40% share of recent Arecibo abstracts and so important especially for asteroid studies, does not follow either the spirit or the letter of the recommendations in the NSF report. Speaking for the planetary sciences community and the AAS Division for Planetary Sciences, I strongly urge that this proposal be reconsidered.
Sincerely yours,
Guy Consolmagno SJ,
Chair, Division for Planetary Sciences of the American Astronomical Society
Vatican Observatory; Loyola Chair 2006-2007, Fordham University (Yes, the DPS chair is a staff member of the Vatican Observatory. Catholicism and astronomy are NOT mutually exclusive.)
I don't know enough about what other facilities are available for asteroid research to have an independent opinion on the potential decommissioning of Arecibo. I do have to say that the idea of decommissioning it seems tragic to me -- as a site for radio astronomy, with its enormous, 300-meter dish occupying the bowl of a crater in the middle of a jungle, the Arecibo Observatory is unique. I hope very much that I get to visit it someday.Arecibo ObservatoryThe 300-meter (1,000-foot) dish of the Arecibo Radio Telescope in Arecibo, Puerto Rico, the largest in the world. Credit: NAIC - Arecibo Observatory, a facility of the NSF |
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