NASA has successfully crashed a spacecraft into an asteroid 7 million miles from Earth.
The final image from the “vending machine-sized” collider shows the surface of the asteroid Dimorphos seconds before impact.
The Double Asteroid Redirection Test (DART) is the first test of a “planetary defense system”.
If the orbits of asteroids could be altered by objects sent into space, humans might have a chance to protect themselves from the kind of catastrophe that the dinosaurs suffered.
NASA and the international team of astronomers they work with carefully selected their targets. To prove successful, they needed an asteroid that could be carefully monitored after a collision. They also need to make sure that any impact doesn’t send a previously harmless rock swirling toward Earth.
They picked a pair of asteroids: Didymos, which is 780 meters wide, and its 160-meter-wide moon Dimorphos — about the size of the Great Pyramid.
DART Approaches Dimorphos
Because Dimorphos was already safely orbiting its larger companion, they could study how its behavior changed after a collision.
Dimorphos is also a fairly common asteroid. While much smaller than the one-kilometer-wide Planet Killer, it’s big enough to destroy a city.
“Dart went there to prove that we do have a dynamic deflection system that pushes them away and pushes them away,” said Betsy Congdon, a mechanical systems engineer at DART at Johns Hopkins University in Maryland.
If you’ve watched the Hollywood disaster films Deep Impact, Armageddon, or the recent Don’t Look Up, prepare for a slight disappointment.
Despite smashing the half-ton spacecraft into Dimorphos at nearly 15,000 miles per hour, the impact on the asteroid is expected to be minimal – checking its speed at just 0.4 millimeters per second.
But over time, this should have a measurable impact on its orbit. A series of terrestrial and space telescopes, including NASA and ESA’s new James Webb Space Telescope, will study the asteroid to measure the test results.
Schematic illustration of NASA’s DART spacecraft colliding with the asteroid Dimorphos. Image: NASA/Johns Hopkins APL
While this is a modest goal, the engineering involved is a major undertaking. Didymos is too small and too far for DART to be guided into it from Earth. The probe had to use an autonomous guidance system to target the asteroid, which was so small it was only visible in DART’s cameras about 50 minutes before impact. But the sat nav seems to be working fine.
The hope is that if the impact is far enough away, a tiny nudge might be enough to deflect a future asteroid off-target for a collision with Earth.
Astronomers estimate that they have tracked the orbits of 95 percent of asteroids large enough to destroy life on Earth, none of which is currently in the process of a collision. But there are many smaller ones. According to NASA, no known asteroid larger than 140m in diameter could hit Earth in the next 100 years. But they think they have only found 40% of them.
NASA team celebrates DART hitting Dimorphos
About 66 million years ago, a 10-kilometer-wide asteroid struck what is now Mexico’s Yucatan Peninsula. It left a crater 110 miles wide and 12 miles deep. The resulting changes in Earth’s climate are thought to be responsible for the Cretaceous-Paleogene extinction event. The impact wiped out 75 percent of the planet’s plant and animal species and ended the reign of flightless dinosaurs.
But even tiny space rocks can cause a bad day on Earth. In 2013, a 20m-wide asteroid exploded in the form of a meteorite over the city of Chelyabinsk in Russia’s Urals region. The explosion was equivalent to 500 tons of TNT, about one-third the power of the Hiroshima atomic bomb. While no deaths were reported, there were more than 1,400 casualties, some seriously.
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“Asteroid strikes are the kind of natural disaster we’re likely to see decades from now,” said DART team member Professor Colin Snodgrass from the University of Edinburgh.
He helped build a telescope in Kenya to monitor impacts from Earth. “If a [the size of Dimorphos] It has been discovered that it can do something when it comes to earth, which seems to be a very sensible technology. “