By Denise Chow -
NBC News
If an asteroid hurtles towards Earth, can humanity be saved by deflecting it?
NASA is set to find out with a mission, the first of its kind, to deflect an asteroid by intentionally crashing a spacecraft into it.
The mission offers a unique opportunity to test a planetary defense strategy that could protect Earth from a potentially catastrophic collision in the future.
The $ 325 million DART mission, short for Double Asteroid Redirection Test, launched Wednesday at 1:21 am ET from Space Force Base. Vandenberg in California.
The spacecraft entered orbit aboard a SpaceX Falcon 9 rocket.
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The probe will spend nearly a year traveling to an asteroid system located more than 6.5 million miles from Earth.
The mission's target is Dimorphos, a 1.5 meter diameter space rock orbiting a much larger asteroid called Didymos, which is about 1.5 meters in diameter.
Neither Dimorphos nor Didymos pose a threat to the planet, according to NASA, but the system is a "perfect testing ground" for testing whether crashing a spacecraft into an asteroid can change its motion in space.
DART team members conduct a final inspection of one of the spacecraft's two solar panels in August.Ed Whitman / NASA / Johns Hopkins APL
Next fall, NASA will crash the DART spacecraft into Dimorphos at a speed of about 15,000 miles per hour.
Telescopes on Earth have been studying Didymos and its "lunar" Dimorphos for decades, and have observed that the smaller space rock surrounds its larger counterpart once every 11 hours and 55 minutes, according to Nancy Chabot, a planetary scientist at the Physics Laboratory. Johns Hopkins University Apprentice and responsible for mission coordination.
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Chabot and his colleagues want to see if the cosmic collision can alter Dimorphos' orbit, which lasts nearly 12 hours.
NASA estimates that the maneuver will change the speed of the space rock's orbit by just a fraction of a percentage - a difference of only several minutes - but the change should be detectable by ground-based telescopes.
"This is not going to destroy the asteroid, it is just going to give it a little nudge," he explained earlier this month in a briefing.
"It's going to deflect its path around the largest asteroid, so we are demonstrating asteroid deflection in this double asteroid system."
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The DART probe will be destroyed in the test, but a small Italian-made CubeSat nanosatellite that the spacecraft will deploy more than a week before the crash will send photos of the impact and its aftermath.
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A follow-up mission developed by the European Space Agency will conduct a more detailed investigation of the Didymos system and evaluate the result of the drift of the DART probe.
This mission, known as Hera, is scheduled to launch in October 2024.
According to NASA, no asteroid over 450 feet is known to have a significant chance of colliding with the planet in the next 100 years, but the agency said only a fraction of near-Earth objects have been found so far. More smalls.
The agency's Planetary Defense Coordination Office is tasked with searching for near-Earth objects that are potentially dangerous to the planet, including those that venture within 5 million miles (8 million kilometers) of the Earth's orbit. Earth, and objects large enough to cause significant damage if they hit the surface.
If a large space rock is found on a collision course with Earth in the future, tests like the DART mission could help NASA respond to the threat.
"It is very rare for an asteroid to hit Earth," recalled Lindley Johnson, a planetary defense officer at NASA headquarters in Washington DC, "but it is something we want to know well in advance."
