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Astronomy Picture of the Day: Asteroids in the distance

Astronomy Picture of the Day: Asteroids

World All-clear after asteroid scare

Press information sheet produced at the Harvard-Smithsonian Center for Astrophysics (CfA), Cambridge, Massachusetts, U.S.A.

Spaceguard UK

March 17, 1998

The Asteroid 1997 XF11 incident demonstrated the British Government's complacency in the face of the impact threat. At no time was there any statement or reassurance from any government department, and it was left to, amongst others, Spaceguard UK and its members to reassure people in the media.

Spaceguard UK will be sending the following letter to John Battle, the minister responsible. If you wish to support us, please reply to the e-mail address below, with your name. If you wish, you could copy the letter below and send it to your local MP. Thanks for your support, and let's hope that this incident can be put to some use!

Jay Tate Director Spaceguard UK

Dear Sir,

The recent public concern, raised by the possibility that asteroid 1997 XF11 might collide with the Earth, has demonstrated the current lack of government interest or policy relating to the threat of cosmic impact. Government departments were noticeably silent during the incident, and no reassurance was given to the public by official bodies. This was because the United Kingdom does not, at present, fund any substantial research into Near Earth Objects, though the country has extensive resources that are eminently suitable.

While the threat from 1997 XF11 seems to have passed, there is no cause for complacency. In fact, XF11 poses little threat, because we know where it is! Our concern lies with the estimated 2000 other Earth crossing asteroids that we have not yet detected, any one of which could pose a substantial threat at any time. Instead of 30 years warning of collision, we are likely to receive no more that 6 seconds should any of these impact.

Spaceguard UK, which counts most of the leading scientists in the field as members has prepared a proposal for British participation in a global surveillance system. This involves the use of the UK Schmidt Telescope in Australia, equipped with a specialist camera, to search for threatening objects. The likely cost of this project would be 2.7 M for capital expenditure and 400k per annum for staff and running costs.

For the United Kingdom, the cost of doing nothing is about 123 million per year; this is what an impact would cost (in lives only - not property), divided by the statistical time period between such events. In this light, the expenditure proposed is almost insignificant, and, as you will agree, constitutes a sensible insurance payment.

Spaceguard UK has challenged Her Majesty's Government to either issue an unequivocal statement that, in the view of the British government (and contrary to the published scientific data), the threat does not exist (thus justifying the lack of action), or to issue an acknowledgement that action is required, the scale of that action (including the source of funding) and upon whom the responsibility for that action will rest. The answer received was uninformed and totally unsatisfactory. We would be grateful for a statement of your views on this subject. Should you require any further information please contact me, or Spaceguard UK (contact details are below), and we will gladly brief you more fully.

Yours sincerely,

Spaceguard UK
35 Pownall Road
Larkhill, Salisbury
Wiltshire SP4 8LX
Tel: 01980 653634
The Spaceguard UK Home Page can be found at:

March 13, 1998

After recalculations NASA scientists say that the asteroid which was feared to be on a collision course with Earth in 2028 will now miss our planet by 600.000 miles (965,600 km). The one-day space scare began when Brian Marsden, director of the Central Bureau for Astronomical Telegrams in Cambridge, Massachusetts, issued an alert.


March 12, 1998


Asteroid 1997 XF11 will pass well beyond the Moon's distance from Earth in October 2028 with a zero probability of impacting the planet, according to astronomers at NASA's Jet Propulsion Laboratory, Pasadena, CA.

The asteroid "is predicted to pass at a rather comforable distance of about 600,000 miles (about 960,000 kilometers) in 2028," reported Dr. Donald K. Yeomans and Dr. Paul W. Chodas, JPL scientists who specialize in computing the predicted orbits of comets, asteroids, planets and other bodies in the solar system.

Data on the asteroid from March 1990 (well before its discovery in December 1997) was integrated into the orbit calculations by Yeomans and Chodas to arrive at the distance the asteroid will pass Earth. The 1990 observations of the object were found today in the Palomar Planet Crossing Asteroid Survey conducted at Caltech's Palomar Observatory, by JPL's Eleanor Helin and Ken Lawrence and by Brian Roman, formerly of JPL.

Even prior to the discovery of the earlier Palomar observations, however, Yeomans and Chodas had determined that the impact probability would be zero. The new calculations further underscore that conclusion, they said.

JPL is a division of the California Institute of Technology.

Archimedes Institute

March 13, 1998


(New York, NY) -- March 13, 1998 -- The announcement by scientists that Asteroid 1997 XF11 will pass close to the Earth in 2028 as well as the upcoming films "Deep Impact" and "Armageddon" have revived interest by the general public and media in the possibility of creating a defense against the possibility of a devastating impact. The Archimedes Institute said today, however, that in addition to the immense technical challenges of protecting the planet against an asteroid or comet, there are a host of thorny legal issues that must be resolved.

"The discovery of Asteroid 1997 XF11 merely serves to illustrate how unprepared the government is to deal with this kind of low-probability, high- consequence risk." said Lawrence Roberts, Director of the Archimedes Institute and a professor at Seton Hall University School of Law. "Our institutions regularly neglect to provide the resources necessary to mitigate the danger from such destructive events."

In the specific case of planetary defense, the policy problems run even deeper. Given the likelihood that nuclear explosions would be necessary to deflect an oncoming asteroid, international agreements designed to reduce tensions during the Cold War present their own obstacles to an effective response. For example, the agreement commonly known as the Outer Space Treaty prohibits the placement of nuclear weapons anywhere in outer space. Just as important to the success of an asteroid defense, the Nuclear Test Ban Treaty of 1963 prevents the testing of any nuclear device in any part of the high frontier.

"Clearly, if it were simply a matter of launching a rocket with a nuclear payload at a wayward asteroid, such legal obstacles would not be a significant consideration. The process of diverting an asteroid, though, is not nearly so simple." Roberts noted. "Any effective response will require years, if not decades, of preparation -- more than long enough for the more 'down to Earth' concerns of nuclear proliferation to intrude. We would be faced with the very real possibility of legal fiddling while the Earth remains in danger of burning."

Despite the danger, these spaceborne hazards are seen as a great opportunity by many in the space advocacy community. Some see the threat as a reason to nudge these small bodies into stable but commercially exploitable orbits, thereby removing the immediate risk to Earth and providing a potentially lucrative mining concern at the same time.

These asteroid mining enterprises, however, pose their own legal problems. "By moving these asteroids from their original orbits, the developers would be risking liability of titanic proportions." says Professor Roberts. "New standards in liability and property rights are needed in order to ensure the protection of all concerned."

The Archimedes Institute is an independent, aerospace law and policy research organization headquartered in New York City. The Institute is working to improve the regulatory climate through the generation and dissemination of reasoned policy analysis, the enhancement of communication between government, academia, the commercial sector and the general public, and the implementation of private policy initiatives.

March 11, 1998


An asteroid will pass close by the Earth in the year 2028 and could conceivably hit us. The asteroid, known as 1997 XF11, would pass as close as 30,000 miles to the Earth. The chance of an actual collision is small, but is not entirely out of the question.

The asteroid was discovered by Jim Scotti in the course of the Spacewatch program at the University of Arizona.

After the discovery observations made by Japanese amateur astronomers during the following two weeks showed that the minimum distance between the orbits of 1997 XF11 and the Earth was very small. Given that the object was perhaps one mile across, it was added to the list of "potentially hazardous objects" (PHAs) that come dangerously close to the earth over the course of the next several centuries. There are currently 108 PHAs.

Calculations show that the asteroid will be closest at 1:30 p.m. Eastern Daylight Time on Thursday, Oct. 26, 2028. The orbit computation indicates a miss distance of only 30 thousand miles from the center of the earth; the earth's radius is about 4 thousand miles. If it really is as close as 30,000 miles it will be quite bright. It will be evening in Europe and the asteroid will be visible there with the naked eye.

There is still some uncertainty to the computation. On the one hand, it is possible that 1997 XF11 will come scarcely closer than the moon. On the other hand, the object could come significantly closer than 30 thousand miles.

It is hoped that continuing observations will be made during the next few months. The object is starting to move into the dusk and to fade week by week. Nevertheless, it should be quite accessible for a while with large telescopes, which in addition to helping establish whether a collision in 2028 is possible, could usefully provide more definite information about the object's size. Further observations of 1997 XF11 should be possible with moderate-sized telescopes equipped with electronic sensors early in the year 2000. A better opportunity will occur in late 2002, when the object should be detectable with quite modest telescopes. On that occasion the closest approach will be on Halloween, but the miss distance will be a safe 6 million miles.

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