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article imageRussians looking at stopping Apophis asteroid hit in 2036

By Paul Wallis     Dec 30, 2009 in Science
The asteroid Apophis isn’t considered by NASA to be much of a risk, but Russian scientists aren’t so sure. The Russians are looking at a “space apparatus” to divert Apophis if it gets too sociable.
The asteroid will approach Earth in 2029, inside satellite orbits, the closest approach by any object recorded. It'll be visible from Earth. The concern is that this encounter will alter Apophis' orbit, perhaps setting it up for a hit in 2036.
The idea of a “space apparatus” hasn’t been defined, but obviously looks like an orbiting option. Yahoo has this AFP article, which has been scratched together from Interfax, RIA Novosti and other sources: It quotes the head of Russia’s space agency Anatoly Perminov:
"We will soon hold a closed meeting of our collegium, the science-technical council to look at what can be done" to prevent the asteroid Apophis from slamming into the planet in 2036, Anatoly Perminov told Voice of Russia radio.
Apophis is a pretty large object, 320-350 metres across, which Perminov says could create “a desert the size of France”. According to NASA, there are small possibilities of Apophis hitting in 2029, a 2.8% chance, to be exact.
The trouble with Apophis is some level of real uncertainty about its orbit, and the fact that it seems from charts to contain a bandwidth of proximity to Earth. Matters are not improved by the fact that it’s out of radar range and out of optical observation range until 2011, according to NASA’s 2007 paper. The predicted position contains variables which could indicate a significant change, or “amplification” of its positional changes after encountering Earth in 2029, setting up the uncertainty about what it will do in 2036.
NASA has nevertheless recently updated its figures, and believes that the odds of a hit in 2036 are now “four in a million”.
Russia isn’t looking at a nuclear option. That particular concept was effectively scuttled in the 1990s, when it was discovered that some asteroids aren’t really solid, and even if they were, the effect of a nuclear hit could be to produce asteroid shrapnel, a scattergun effect possibly worse than the problem.
The orbiting apparatus idea is new, and would require some level of maneuverability, range, and the ability to predict deflection. It would also have more flexibility and more options than a "hit or miss" scenario with a missile.
Apophis isn’t in the Deep Impact category, but even a Tunguska-like airburst from a thing that size caused by atmospheric impact would produce massive, nuke-like shockwaves.
Impact estimates, according to Wikipedia, (which seems to have been updated to coincide with the Russian statements) are between 1480 megatons (Russian estimate) and 880 megatons (NASA). Krakatoa was 200 megatons.
The predicted area of hazard is across central Asia central America and northern South America.
(One of the most frustrating things about attempting to get a clear picture of agency responses is the number of sources required. There's plenty of news, but try gluing it into a solid image.From the AFP coverage, you'd think NASA wasn't paying attention, but that's not the case.)
Space.com reports that NASA isn’t being quite as relaxed as it sounds from current press releases about a probe being sent to Apophis:
Concern over asteroid Apophis and the ability to precisely chart its trajectory -- and take steps if needed to deflect the object -- were fervently voiced by the B612 Foundation, chaired by Russell Schweickart, a former Apollo astronaut.
The group requested that NASA carry out an analysis that included the possibility of placing an active radio transponder on the object. Doing so at a fairly early date would yield the requisite orbital accuracy of the asteroid as it sped through space.
The beacon idea is to give an accurate plot, which is what’s missing from the current scenario. The flyby of Apophis in 2029 is expected to alter Apophis’ orbit, and that’s where the problems will be found, if any, with the asteroid’s new course, when it’s modified by the encounter.
NASA gave a qualified “yes” to the idea:
That NASA reply came with an appended detailed analysis by Steven Chesley of NASA'S NEO Program Office at the Jet Propulsion Laboratory (JPL) in Pasadena, California. The study by Chesley dug into Apophis' orbit, under varying conditions, and contained other items pertaining to the space agency's findings about the Apophis matter.
"The key conclusion to be taken from this analysis," Cleave ( Mary Cleave, Associate Administrator for Science Mission Directorate) in the letter, "is that aggressive (i.e., more expensive) action can reasonably be delayed until after the 2013 observing opportunity. For Apophis, the 16 years available after 2013 are sufficient to recognize and respond to any hazard that still exists after that time."
The important science here is that these agencies are developing concepts, rather than exchanging opinions about statistics. Asteroids are a confirmed risk in this neighborhood, with some, like Toutatis, spending time in Earth’s orbit on a regular basis.
A working deflection methodology would represent the first useful ideas for asteroid control. Even relatively minor objects are a real threat, able to do considerable damage. Orbiters are a working proposition in theory, it’ll be interesting to see how they operate in practice.
More about Apophis, Perminov, NASA
 
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