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Friday, September 23, 2022

Will DART Save us?

  Closely following this, will be shown live on Monday. Earth will inevitably be hit by a serious space rock again, so its good to be ready now.     Lets learn as much as we can.

NASA’s DART Mission Aims to Save the World. Robotic probe sent to crash into asteroid in test of planetary defense By NED POTTER   in Spectrum IEEE

Armageddon ruined everything. Armageddon—the 1998 movie, not the mythical battlefield—told the story of an asteroid headed straight for Earth, and a bunch of swaggering roughnecks sent in space shuttles to blow it up with a nuclear weapon.

“Armageddon is big and noisy and stupid and shameless, and it's going to be huge at the box office,” wrote Jay Carr of the Boston Globe.

Carr was right—the film was the year’s second biggest hit (after Titanic)—and ever since, scientists have had to explain, patiently, that cluttering space with radioactive debris may not be the best way to protect ourselves. NASA is now trying a slightly less dramatic approach with a robotic mission called DART—short for Double Asteroid Redirection Test. On Monday at 7:14 p.m. EDT, if all goes well, the little spacecraft will crash into an asteroid called Dimorphos, about 11 million kilometers from Earth. Dimorphos is about 160 meters across, and orbits a 780-meter asteroid, 65803 Didymos. NASA TV plans to cover it live.

DART’s end will be violent, but not blockbuster-movie-violent. Music won’t swell and girlfriends back on Earth won’t swoon. Mission managers hope the spacecraft, with a mass of about 600 kg, hitting at 22,000 km per hour, will nudge the asteroid slightly in its orbit, just enough to prove that it’s technologically possible in case a future asteroid has Earth in its crosshairs.

“Maybe once a century or so, there'll be an asteroid sizeable enough that we'd like to certainly know, ahead of time, if it was going to impact,” says Lindley Johnson, who has the title of Planetary Defense Officer at NASA.

“If you just take a hair off the orbital velocity, you’ve changed the orbit of the asteroid so that what would have been impact three or four years down the road is now a complete miss.”

So take that, Hollywood! If DART succeeds, it will show there are better fuels to protect Earth than testosterone.

The risk of a comet or asteroid that wipes out civilization is really very small, but large enough that policymakers take it seriously. NASA, ordered by the U.S. Congress in 2005 to scan the inner solar system for hazards, has found nearly 900 so-called NEOs—Near-Earth Objects—at least a kilometer across, more than 95 percent of all in that size range that probably exist. It has plotted their orbits far into the future, and none of them stand more than a fraction of a percent chance of hitting Earth in this millennium.

An infographic showing the orientation of Didymos,  Dimorphos, DART, and LICIACube.The DART spacecraft should crash into the asteroid Dimorphos and slow it in its orbit around the larger asteroid Didymos. The LICIA Cube cubesat will fly in formation to image the impact.JOHNS HOPKINS APL/NASA

But there are smaller NEOs, perhaps 140 meters or more in diameter, too small to end civilization but large enough to cause mass destruction if they hit a populated area. There may be 25,000 that come within 50 million km of Earth’s orbit, and NASA estimates telescopes have only found about 40 percent of them. That’s why scientists want to expand the search for them and have good ways to deal with them if necessary. DART is the first test.

NASA takes pains to say this is a low-risk mission. Didymos and Dimorphos never cross Earth’s orbit, and computer simulations show that no matter where or how hard DART hits, it cannot possibly divert either one enough to put Earth in danger. Scientists want to see if DART can alter Dimorphos’ speed by perhaps a few centimeters per second. ... '

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