* Astronomy

This week the Space Foundation debuted "Asteroid Challenge, Target: Earth," a virtual lab and video science education program featuring the real asteroid Apophis. Third grade students from Manitou Springs Elementary School in Colorado were the first class nationwide to participate in this interactive science program and use scientific methods in a virtual lab to save our planet from destruction by Apophis, now on a path that could bring it dangerously close to colliding with Earth in 2036.

The release of the lab follows the Oct. 3 premiere of NOVA scienceNow on PBS, which also addressed near-Earth asteroids, including Apophis. Dr. Neil deGrasse Tyson is both the host of NOVA scienceNow and featured in "Asteroid Challenge, Target: Earth." Tyson is a Space Foundation board member, astrophysicist, and director of the Hayden Planetarium in the Rose Centre for Earth and Space at the American Museum of Natural History in New York City.

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Tsunamis triggered by asteroid impacts cause a disaster similar to the 2004 Asian tsunami once every 6000 years on average, according to the first detailed analysis of their effects.
Researchers have assumed that tsunamis would make ocean impacts more deadly than those on land. But Steve Chesley at the Jet Propulsion Laboratory in Pasadena, and Steve Ward at the University of California at Santa Cruz, both in the US, are the first to quantify the risks.

The pair first calculated the chance of various size asteroids reaching the Earth's surface, and then modelled the tsunamis that would result for asteroids that hit the oceans.

For example, the model shows that waves radiating from the impact of a 300-metre-wide asteroid would carry 300 times more energy than the 2004 Asian tsunami.

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Got any retirement plans? Sure you do — unfortunately, a 360-yard-wide rock named 99942 Apophis could put a damper on your Centrum Silver years.
That’s because in 2029, the asteroid will zip by Earth at a hair-raising 18,640 miles away — closer than most communications satellites holding orbit above our planet. And, depending on exactly where it passes us, there will be a 1-in-5,500 chance that it will strike the Earth’s surface in 2036.
And, based on the rock’s size, a direct hit would vaporize an area the size of New York City and its surrounding regions.

To see how the odds of getting smacked down by 99942 Apophis stack up against other uncommon occurrences, consider these figures from the National Safety Council: Over your lifetime, the odds of dying while riding a bicycle are 1:4,857. The odds of dying in a car accident are 1:228. The odds of dying by lightning strike are 1:56,439.
Before you freak out and start spending your life savings on Ramen noodles and duct tape, take heed: The illustriously-overpaid minds at NASA have a plan just in case the asteroid decides to go “Armageddon” on us.

Their plan would involve launching a spacecraft to orbit around the rock and using the craft’s gravitational pull to slowly divert the asteroid’s path. Another plan involves a nuclear-powered craft actually landing on the asteroid and using thrusters to gradually change the asteroid’s course.
For now, though, the group of astronauts calling for intervention are pushing for a NASA mission to launch a radio transponder to 99942 Apophis and use it to plot the rock’s course in order to determine more accurately whether or not there is a danger. However, NASA has other ideas. Donald Yeomans, manager of NASA’s near-Earth object program, told CNN that he is confident that radar and telescope observations will ultimately rule out any risk of impact.
A scouting mission to the asteroid would cost NASA a few hundred million dollars out of its massive $14 billion budget.
Does anybody else see a problem here?

Should NASA be content and confident enough to rely merely on telescope and radar readings on which we would bet the future of our planet? A scouting mission to 99942 Apophis would be expensive, sure, but it wouldn’t cost nearly as much as all the missions (successful and failed) to Mars, and would certainly be worth investing in more than the decrepit Space Shuttle program, which the Collegiate Times wrote an editorial about a few months ago.
What NASA needs to do is learn some fiscal management. The world is very lucky that we have over 30 years to decide what to do in case this asteroid becomes a problem, so in that time frame, surely NASA will start caring more about it than it does now and start dropping its money where it needs to go.
Until that time, we’ll just have to be content with the fact that the odds of a direct impact are pretty low. But, weren’t the odds of having a Hurricane Beta this season pretty low, too?

Wake up, NASA. Averting a potential catastrophe is more important than driving around a few toy trucks on Mars.

collegiatetimes.com

Summary of NEO News (08/17/05): Asteroid experts meet at ACM-2005

Clark Chapman reports from the Asteroids/Comets/Meteors 2005 meeting, held last week in the resort town of Buzios, east of Rio de Janeiro, Brazil. This ACM-2005 is the latest of the every-three-year meetings begun in Sweden in the early 1980s. Professional astronomers gathered to discuss, in plenary sessions and poster-talks, advances in the science of small Solar System bodies since the last meeting three years ago in Berlin. Most of the presentations dealt with the fundamental scientific issues concerning these remnants of the primitive "building blocks" that formed the planets 4.5 billion years ago. Recent excitement was generated by Deep Impact's violent examination of Comet Tempel 1, and then by the reported discoveries of three more not-so-small denizens of the far reaches of the solar system, including 2003 QB313, at 97 times the distance of the Earth from the Sun - it is almost certainly significantly larger than Pluto, perhaps deserving the moniker of "tenth planet".

Issues involving the impact hazard were treated by several speakers and even more posters at ACM 2005. Many dealt with the extraordinary circumstances of 2004 MN4, recently given a number (99942) and named Apophis, which once had a 1-in-37 chance of striking the Earth in 2029 and now has a 1-in-8000 chance of striking in 2036 after its spectacular close pass in 2029.

Two months ago, Rusty Schweickart wrote to NASA Administrator Mike Griffin asking for a technical analysis of whether public safety requirements might mandate commitment to a transponder mission to Apophis prior to its next period of visibility in the 2012-2013 timeframe. At ACM, Steve Chesley of JPL's Near Earth Object Program Office presented what may be the technical underpinnings of NASA's forthcoming response. Chesley acknowledged that the usual approaches to error-analysis failed for Apophis, due to unusual circumstances: the projected 10 Earth radii miss-distance (with a conservative uncertainty of 2.5 Earth radii), calculated in late December when the "all-clear" was announced, turned out to be badly skewed when late-January radar data, and subsequent optical observations, yielded a much-closer, and visually spectacular, 5.7 plus-or-minus 1 Earth radius pass on April 13, 2029. (The misestimated uncertainty in December allowed less than 1 chance in a million of this big a change in miss-distance.) Such a large asteroid passing that close to the Earth happens only once every 1,500 years or so, according to Chesley.

Now, the real issue has become whether Apophis will pass by through the "keyhole" in 2029 that would lead to its resonant return, and Earth impact, on April 13, 2036. The 1-in-8000 chance of impact is an unusually high probability for a 300+ meter sized object to strike the Earth in the near future. Thus it ranks at "1" on the Torino Scale, and will likely remain at that level, or even rise to "2" before the next opportunity to observe it happens about 7 years from now. (There is the possibility that radar observations will be successful early next year, but they may serve only to raise the probability of impact by narrowing the uncertainty while still including the 2036 keyhole.)

While much refinement in Apophis' orbit is expected by 2013, there remains an inherent uncertainty due to the unpredictable behaviour of the Yarkovsky Effect - an acceleration of an asteroid due to the asymmetry of solar radiation absorbed from the Sun and re-radiated on the afternoon hemisphere of a rotating body. That uncertainty will eventually be resolved during Apophis' close pass in 2021, but that might be cutting it close (if Apophis is actually on an impact trajectory) to mount a reliable deflection mission. These scenarios, being evaluated by JPL, will presumably be addressed in NASA's response to Schweickart's letter.
But it already seems to Chesley that a transponder mission to Apophis will not be required prior to the expected orbital improvements in 2013. An issue that has come up in the past was the effect of perturbations by other asteroids. While it is clear that such perturbations are important for NEA's that penetrate the main asteroid belt, Chesley now concludes that for Apophis (an Aten class asteroid), this is not much of an issue.

There had been much discussion in January about whether or not it was appropriate to publish the map of possible "ground zeroes" across the Earth for the unlikely cases of impact of Apophis. At ACM, Chesley showed what others had already calculated independently, that the areas that had been at risk - had Apophis turned out to be aimed at Earth in 2029 - certainly would have included parts of Europe and the Middle East, as well as heavily populated parts of India and Bangladesh.
(The error ellipse is exceedingly stretched, so even while it extended beyond the Moon before Christmas, its position was known to within a few hundred kilometres cross-track.)

Illustrating how readily these risk zones can be calculated (or potentially miscalculated, without professional guidance), M. Krolikowska et al. (from Warsaw) presented a poster showing the narrow impact zones across the Earth of several potential impactors. In his ACM talk, G. Sitarski (also of Warsaw) showed a diagram of the zone at risk if Apophis actually does pass through the keyhole and strikes the Earth in 2036.

Although that narrow zone crosses Siberia and Central America, it mainly threatens a tsunami in the Pacific off the west coast of North America.
What will happen if we need to deflect Apophis to keep it from hitting the keyhole that leads back to a collision with the Earth? Chesley concluded his talk by noting that a kinetic energy deflection could be accomplished (Deep Impact style) with a 1000 kg impactor hitting at a few km/sec giving a 25 km deflection after 3 years.
Dan Durda gave a talk discussing the interesting scientific issues presented by Apophis' close pass in 2029. Due to Earth's enormous tidal forces on this body, it is certain to undergo a major change in its spin rate and probable re-arrangement of its internal structure. Durda proposes that the asteroid be outfitted with a seismic net, and that other physical studies be undertaken before, during, and after the 2029 pass, letting "nature do the work" of creating a geophysical rearrangement of the body.

F. Bernardi et al. presented a poster highlighting issues surrounding their unconventional discovery of 2004 MN4 and describing, among other things, the complex - and highly appropriate - reasons for naming the body Apophis. Still other ACM presentations evaluated the progress of the current Spaceguard Survey: it seems unlikely to meet its original target of discovering 90% of NEAs larger than 1 km diameter by early 2008, unless the total number is actually much less than the estimated 1100 (This total number, however, has not been revised based on recent data).

Pan-STARRS, which will begin to come on-line next year in Hawaii, will begin a new era of discovering ever-smaller NEAs. Plans for the later construction of the Discovery Channel Telescope at Lowell Observatory and the LSST were also presented. Still other talks, not specifically oriented towards hazardous NEAs, nonetheless presented information potentially relevant to the logistics of actually deflecting an NEA from Earth impact.
For instance, K. Holsapple argued that small main-belt asteroids (though not necessarily NEAs) are not proven to be rubble-piles simply because of their failure to spin more rapidly than about once every couple of hours. Other speakers, however, argued that an increasing fraction of small bodies may be doubles (or even triples!), and thus more difficult to cope with.

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