Asteroid 2008 BT18 passing by Earth today / Why the Arecibo Observatory may save lives

Radar image of asteroid 2008 BT18 from July 7, showing it to be a pair. The smaller asteroid is the dot at the bottom. Credit: NASA/JPL/Arecibo Observatory

Space.com has the news on this asteroid.

Asteroid 2008 BT18 has turned out to be much more interesting than we thought, as it is not just a single asteroid but actually a binary one, with a primary asteroid 600 metres in diameter, with another one 200 metres in diameter orbiting it. The larger one rotates on its axis every 3 hours.

The 2008 in its name means that it was discovered this year, and nothing else was known about it until recently.

One part of the article though I'm not sure I agree with:

It will not strike the planet. But scientists want to learn more about binary asteroids because one day they might find one headed our way. Deflecting a binary off course could be considerably more challenging that altering the path of a single rock.

Really? Imagine we discover an asteroid that we believe to be 1000 metres in diameter heading towards Earth, that turns out to be one some 800 metres in diameter, and another about 250 metres. One of the techniques for moving an asteroid away from the Earth is to go there ahead of time and move the orbit ever so slightly, which over a very long distance would cause it to miss the Earth by a large distance. For techniques involving trying to destroy an asteroid this could prove to be harder, but for those involving simply moving the asteroid I would think that having a moon could prove to be a benefit, since anything that much lighter would be easier to move about, and altering the orbit of one around the other should disrupt its movement enough that it would not cause a problem. Not to mention the possibility of simply plowing the smaller object into the other.

That's just me thinking out loud however, and I could be very wrong.

So what sort of observations are going on of this asteroid? The article says that:

Additional observations from NASA's Goldstone radar in the Mojave Desert in California are expected to reveal more about the density, shapes and orbit of the pair.

All right then. When we spend so much time and effort sending probes up to fly by asteroids, it's nice when an asteroid like this makes its way past us instead. Just as long as we don't get hit.


There is also a thread on the space.com forums about this asteroid. Some posters have made the very good point that it without the Arecibo Observatory we could be under the impression that the asteroid coming towards us is a single asteroid when in reality it is a binary, completely changing the nature of what we need to do to deflect or destroy it. Here's some of what they said:

I agree about the Arecibo comment, it will be a bloody travesty is that closes down due to the lack of a small sum of money. Of course discoveries like this will be far more difficult, if near on impossible without Arecibo.Andrew Brown.
Posted by 3488

and:

Never mind the discoveries, how about protecting our planet? As the article points out, the challenge of deflecting a potential earth impacting asteroid is hard enough (Not that this is the case here, but talking about a so far unknown potential object). Without Arecibo, we might not have found out it was a binary until we got there to attempt to deflect it. What would we do then? Any attempt to deflect the primary could send the "moon" on a direct collision course. If we hadn't considered that possibility in advance, because we didn't know it was a binary until arriving, what would we do then?

Here's the part of the Wikipedia page on the observatory about the funding issues:

A report by the division of Astronomical Sciences of the National Science Foundation, made public on 2006-11-03, recommended substantially decreased astronomy funding for Arecibo Observatory, ramping down from USD 10.5M in 2007 to USD 4M in 2011. If other sources of funding cannot be obtained, this would mean the closure of the observatory. The report also advised that 80% of the observation time be allocated to the surveys already in progress, reducing the time available for other scientific work. NASA gradually eliminated its share of the planetary radar funding at Arecibo from 2001–2006.

Contributions by the government of Puerto Rico may be one way to help fill the funding gap, but are controversial and uncertain. At town hall meetings about the potential closure, Puerto Rico Senate President Kenneth McClintock announced an initial local appropriation of $3 million during fiscal year 2008 to fund a major maintenance project to restore the three pillars from which the antenna platform is suspended to their original condition, pending inclusion in the territorial government's next bond issue. The appropriation would be the first time that the islands' government contributes financially to the operation of a federal installation. However, New Progressive Party president and Arecibo District Sen. Pedro Rosselló announced on September 11, 2007 that he will oppose the bond issue favored by McClintock. The bond authorization, with the $3 million appropriation, was approved by the Senate of Puerto Rico on November 14, 2007, the first day of a special session called by Gov. Acevedo Vilá amd by the Puerto Rico House of Representatives on June 30, 2008. The Governor is expected to sign the measure into law.

Rep. José E. Serrano, a member of the U.S. House of Representatives Appropriations Committee, has asked the National Science Foundation to keep Arecibo in operation in a letter released on September 19, 2007. Language similar to that in the September 19 letter was included in the FY'08 omnibus spending bill.

In October 2007, Puerto Rico's non-voting delegate in Congress, Resident Commissioner Luis Fortuño, along with Rep. Dana Rohrabacher (R-CA), filed legislation to assure the continued operation of the Arecibo facility. A similar bill was filed in the United States Senate in April, 2008 by the junior Senator from New York, Hillary Rodham Clinton.

As the Arecibo facility is owned by the United States, and administered as a national facility by the NAIC, direct donations by private or corporate donors cannot be made. However, as a non-profit, non-government institution,Cornell University will accept contributions on behalf of Arecibo Observatory. It has been suggested by at least one member of the NAIC staff that Google purchase advertising space on the dish as one means of securing additional non-government funds. As of early 2008, no 'anchor' donors (government, non-profit, nor scientific) have publicly stepped forward to provide funding for the observatory nor its radar system.

In September 2007, in an open letter to researchers, the NSF clarified the status of the budget issue for NAIC, stating that the present plan, if implemented, may hit the targeted budgetary revision No mention of private funding was made. However, it need be noted that the NSF is undertaking studies to mothball, or deconstruct the facility and return it to its natural setting in the event that the budget target is not achieved. In November 2007, The Planetary Society urged Congress to prevent the Arecibo Observatory from closing due to insufficient funds, since the radar contributes heavily to the accuracy of asteroid impact prediction, and they believe continued operation will reduce the cost of mitigation (that is, deflection of NEA on collision to Earth), should that be necessary. Note that Arecibo itself cannot deflect an asteroid - however with the potential of Arecibo measuring many NEA orbits more precisely, fewer asteroids will need to be investigated by other, more expensive, means such as spacecraft. (For comparison, Arecibo's total annual budget is currently $12.5M/year, whereas Discovery-class space missions cost in excess of $400M each, albeit commonly spread out over a decade or more).

As recently as July 2008, the UK newspaper, The Daily Telegraph reports that the funding crisis, due to US budget cuts, is still very much alive link title.

SETI@home program is using the telescope as a primary source for the research. Organization is inviting people to send a letter to their political representatives for support in this case.

Here's a view of the receiver array:


Back to the asteroid: there doesn't seem to be a Wikipedia page on Asteroid 2008 BT18 just yet, but I suspect there will be one soon. If not then I'll start it.