A NASA probe hit an asteroid during a planetary defense test


Seven million miles from Earth, a NASA spacecraft slammed head-on into a small asteroid at 14,000 mph on Monday, the first real-world test of humanity’s ability to deflect a threatening body off course before it could hit Earth.

The asteroid in question, a 525-foot-wide body known as Dimorphos, is actually a moon orbiting a 2,500-foot-wide asteroid called Didymos. Neither poses any threat to Earth, either before or after the 1,260-pound Double Asteroid Redirect Test (DART), NASA’s spacecraft.

But the twin asteroid system offered an ideal target for the $330 million DART mission because the effects of the probe’s impact can be measured from Earth by precisely timing how the moon’s orbital period around Didymos changes as a result of the impact.

The DART probe sent back images of Dimorphos once a second, giving scientists an exciting look on board as the spacecraft locked and sped toward its quarry, first seeing it about an hour before impact when the target was still 15,000 miles away. .

Images from DART’s camera as it approached the double asteroid Didymos and its small moon Dimorphos.


Covering the last 1,000 miles in about four minutes, DART’s camera showed the target growing larger and larger, from a faint point of light until it filled its entire field of vision seconds before impact, while traveling seven times faster than an assault rifle bullet.

“For God’s sake, look at that!” someone shouted in the control room seconds before impact as rocks and boulders appeared on the surface of the Dimorph.

“This is amazing, guys! Oh my god, look at this! Unbelievable!” said Elena Adams, a DART mission systems engineer at Johns Hopkins University’s Applied Physics Laboratory who helped oversee the spacecraft’s final moments.

The broadcast stopped at the moment of impact when the spacecraft collided with Dimorphos, disintegrating on impact and blasting a fresh crater on the rocky surface. Since the collision occurred 7 million miles from Earth, the last few images needed about 45 seconds to cross the gulf and reach NASA’s computers and live feed.

Images from DART’s camera as it approached the double asteroid Didymos and its small moon Dimorphos.


And at that moment, after years of planning and a 10-month voyage from Earth to the Didymos-Dimorphos system, the flight controllers at APL, where the DART spacecraft was being controlled, erupted in cheers and applause.

“Congratulations! Boy, Team DART, you really nailed this,” said NASA Administrator Bill Nelson. “I believe it will teach us how to one day protect our own planet from an incoming asteroid. So thank you to this international team. We are showing that planetary defense is a global effort and it is very possible to save our planet.” “

Lori Glaze, director of planetary science at NASA, agreed, saying the DART mission shows that “we’re entering a new era for humanity, an era where we potentially have the ability to protect ourselves from something like a dangerous asteroid impact.”

Images from DART’s camera as it approached the double asteroid Didymos and its small moon Dimorphos.


“What a wonderful thing!” she said. “We’ve never had this ability before.

A small Italian tracking craft known as LICIACube, released from DART earlier this month, attempted to photograph the collision and the debris blasted back into space, but those images were stored on board and will later be beamed back to Earth.

The Virtual Telescope Project, which offers robotic telescope time to both professional and amateur astronomers, has released a report views of the double asteroid during impact which showed dramatic brightening from supposed clouds of rock and dust blown into space around Dimorphos.

“Planetary defense is a globally unifying effort that affects everyone on Earth,” NASA Chief Science Officer Thomas Zurbuchen said in a statement. “We now know that we can target a spacecraft with the precision needed to impact even a small body in space. Just a small change in its speed is all we need to significantly change the path the asteroid travels.”

The Didymos-Dimorphos twin asteroid system offered an ideal test bed for planetary defenses, as the Moon’s orbit carries it directly in front of and then behind Didymos as seen from Earth, allowing scientists on Earth to precisely measure minute changes in the combined reflected light from both asteroids. .

The white trace shows the current 11 hour 55 minute orbit of the target asteroid Dimorphos, while the blue line shows how the orbit might be altered by the impact force of the DART spacecraft at 14,000 mph. Scientists say the collision could shorten the orbital period by about 10 minutes.


By timing the light’s dimming and brightening, the researchers calculated how long it takes Dimorphos to complete one orbit — 11 hours and 55 minutes — and post-impact observations will allow them to determine what effect DART may have had.

Researchers expect the crash to shorten the asteroid’s orbital period by about 10 minutes, but telescopes around the world and in space, including the Hubble and James Webb space observatories, will take days to weeks to make the necessary measurements. write down the number.

“The Double Asteroid Redirection Test is a test,” said Tom Statler, DART program scientist. “We do this test when we don’t need it, on an asteroid that doesn’t pose a threat, just in case we ever need it and we discover an asteroid that does.”

He said the DART mission has two primary goals, the first being a test of “our ability to build an autonomously piloted spacecraft that actually achieves a kinetic impact on an asteroid.”

Dimorphos and Didymos scaled with known landmarks on Earth.


“The second is a test of how a real asteroid reacts to a kinetic impact,” he said. “Because at the end of the day, the real question is how efficiently did we move the asteroid, and can this kinetic impact technique be used in the future if we ever needed to?”

Unlike Hollywood thrillers like “Armageddon” and “Deep Impact,” which envisioned manned flights carrying nuclear bombs to deflect or destroy their targets, DART’s target is much simpler and much less destructive.

While nuclear devices may be a last resort in some future Armageddon-class scenario, the goal would still be diversion, not destruction.

“You just don’t want to blow it up because it doesn’t change the direction of all the material,” Lindley Johnson, NASA’s “planetary defense” officer, told CBS News before DART’s launch last November. “It’s still flying at you, it’s just buckshot instead of a rifle ball.

“You just want to change the speed at which it’s all moving just a little bit. Over time, that will change the position of the asteroid and its orbit.”



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