How NASA plans to stop killer asteroids

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The impact of a massive asteroid ended the age of dinosaurs, and it’s all but certain that another equally large asteroid or comet will head towards Earth at some point in the future – but unlike the dinos, we can potentially stop a threat from space rocks keep us from shutting down.

The Birth of Planetary Defense

In 1993, scientists determined that Shoemaker-Levy 9 (SL9), a recently discovered comet orbiting Jupiter, would likely collide with the gas giant the following year. This was big news as astronomers have never had the opportunity to witness such an impact event before.

For six days in July 1994, they trained their telescopes on Jupiter and watched as pieces of SL9 slammed into the planet, sending huge clouds of superheated material high into its atmosphere.

“Shoemaker-Levy 9 was kind of a punch in the gut.”

Heidi Hammel

The dark scars SL9 left in Jupiter’s cloud tops dissipated a few months later, but the comet’s impact on the astronomy community lives on in “planet defense” — efforts to discover asteroids, comets, and other near-Earth objects (NEOs) and to pursue. predict potential impacts on Earth and prevent potentially devastating collisions.

“Shoemaker-Levy 9 was kind of a punch in the stomach,” said Heidi Hammel, who led the team that used NASA’s Hubble Space Telescope to observe the SL9 collision, in 2019. “It has our understanding of how.” it is important to monitor, truly empower our local neighborhoods and understand what the potential for future impacts on the Earth is.”

look up

We cannot protect Earth from a menacing asteroid that we do not know exists. That’s why NASA created the Near-Earth Object (NEO) Observation Program in 1998 to fund efforts to identify, track, and categorize NEOs.

In 2005, Congress directed the program to identify at least 90% of the predicted number of NEOs larger than 460 feet across – the size a space rock would need to be to obliterate a city – but only 40% as of June 2021 of which the estimated number of large NEOs has been identified.

This missing data could also have very real consequences. In 2019, an asteroid estimated to be 195 to 425 feet wide flew within 40,000 miles of Earth – about one-fifth the distance to the Moon – and was only spotted on the day of its flyby.

One factor holding the NEO program back is its heavy reliance on ground-based optical telescopes — since these can only be used to hunt for threatening asteroids at night, astronomers cannot see any approaching our planet from the Sun’s direction during the day.

But a wave of new asteroid discoveries could be in sight thanks to the Near-Earth Object Surveyor (NEO Surveyor) space telescope, the world’s first spacecraft specifically designed to search for dangerous NEOs.

“NEO Surveyor operates at thermal infrared wavelengths and is therefore very sensitive to dark objects,” NEO Surveyor principal investigator Amy Mainzer told SpaceNews. “It searches the regions of the sky closest to the Sun, allowing it to find objects with the most Earth-like (and therefore potentially dangerous) orbits.”

NASA has yet to set a launch date for NEO Surveyor — it could launch in 2026, but funding issues could push it back to 2028. In any case, the telescope is expected to start identifying about 66% of the city-threatening NEOs within 5 years and reach the target of 90% within 10 years.

“While a significant impact on Earth is obviously a very rare event, we don’t know when the next one might be, and NEO Surveyor is tasked with finding out,” Lindley Johnson, NASA’s planetary defense officer, told SpaceNews.

“Software can do things today that you wouldn’t even dream of doing 20, 30 years ago, that you wouldn’t even think of doing.”

Zeljko Ivezic

NEO Surveyor isn’t our only hope for discovering more asteroids, either.

In early 2022, the NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS) added two new telescopes, bringing the total to four and making it the first system capable of scanning the entire night sky every 24 hours investigate threatening NEOs.

Researchers from the University of Washington and the Asteroid Institute then introduced THOR in May 2022, a computer algorithm capable of detecting new threatening asteroids in old telescope data – it has already been used to identify more than 100 previously unknown NEOs.

“[S]Often things can now be done that you wouldn’t even dream of doing 20, 30 years ago, you wouldn’t even think of doing,” THOR researcher Zeljko Ivezic told The New York Times.

direct hit

Being able to predict a species-threatening NEO impact is an important part of planetary defense, but it’s not worth much if we actually can’t defend our planet from space rock – we’d be just like the dinosaurs but with the added bonus of knowing that an apocalyptic event is imminent.

After years of focusing on finding NEOs, the “prevention” side of planetary defense recently took a huge leap forward thanks to NASA’s Double Asteroid Redirection Test (DART), the first demonstration of technology that could potentially prevent them could an incoming asteroid hit our planet.

“It’s basically like throwing a tennis ball at a 747.”

Elena Adams

The goal of the DART mission was to ram a refrigerator-sized spacecraft into Dimorphos, a 530-foot asteroid orbiting the much larger asteroid Didymos, in hopes of shifting its orbit.

The asteroids are millions of kilometers from Earth — too far away to pose a collision hazard, but perfectly placed to study the effects of a spacecraft impacting a space rock.

“It’s basically like throwing a tennis ball at a 747,” Elena Adams, systems engineer for DART missions at the Johns Hopkins Applied Physics Laboratory (APL), told CBS News. “If it goes fast enough, you will move it.”

“[DART is] a first test, can we even do that?” She continued.

NASA passed this test on September 26, 2022, when DART successfully reached its target 10 months after launch.

Scientists are now examining observations of the collision collected by space telescopes, DART’s own imaging instrument (before it was destroyed) and a small satellite called LICIACube, developed by the Italian Space Agency, by DART just 15 days before its impact.

This data should help determine if the impact nudged Dimorphos and caused its orbit to shorten around the larger asteroid by about 1%, as NASA had hoped.

While this change may not seem like much, even a slight nudge, if given early enough, could deflect an asteroid off a collision course, meaning DART’s ability to move Dimorphos takes us a big step closer to the ability would bring to protect the earth from a threat NEO.

“NASA works for the good of mankind, so for us, doing something like this is the ultimate accomplishment of our mission — a demonstration of technology that, who knows, could one day save our home,” said NASA Deputy Administrator Pam Melroy.

DART may have been the first demonstration of planetary defense technology, but it likely won’t be the last — China’s national space agency plans to launch its own asteroid deflection test in 2026.

In the more distant future we could see tests of other ways to prevent an impact – planetary defense researchers are studying the viability of systems designed to disassemble NEOs into non-threatening parts and (yes, really) use nukes to destroy them easy to blast high.

The final result

Thanks to these and other planetary defense efforts, we are now better prepared than ever to avert a potentially devastating impact.

That still doesn’t mean we would actually be able to stop a collision – in 2021, NASA’s Planetary Defense Coordination Office failed to prevent an asteroid impact in a simulation exercise.

This hypothetical asteroid was expected to hit Earth just six months after its discovery, and NASA believes it would take 5 to 10 years in advance to effectively deflect a threatening space rock – emphasizing the need for so many dangerous ones Asteroids as possible to discover as fast as possible.

“Our goal is to anticipate potential impacts years to decades in advance so that they can be averted with a technology like DART that is already in place,” Johnson said. “DART, NEO Surveyor and ATLAS are all important parts of NASA’s work to prepare Earth should we ever face the threat of an asteroid impact.”

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