Sounding like a science fiction plot, NASA‘s next mission from Vandenberg Space Force Base will aim to nudge — at 15,000 mph — an asteroid off its flight path in a test of a technology to defend planet Earth.
A Space Exploration Technologies Falcon rocket will carry the NASA spacecraft into orbit after a liftoff from Space Launch Complex-4 on the South Base at 10:21 p.m. Tuesday. The mission has an instaneous window or just one chance a day to get off the ground for its proper placement in space.
That spacecraft, the Double Asteroid Redirection Test, or DART, will explore whether intentionally crashing a spacecraft into an asteroid can change its course in a $330 million mission.
DART’s target is an asteroid moonlet called Dimorphos — Greek for “two forms.” Dimorphos orbits a larger asteroid named Didymos, or twin.
Scientists say the Didymos system is the ideal candidate for DART because it poses no threat to Earth. They also can measure any change in Dimorphos’ orbit around Didymos with ground-based telescopes.
“It’s very rare for an asteroid to impact the Earth, but it’s something we want to know about well ahead of time,” said Lindley Johnson, planetary defense officer for NASA’s Planetary Defense Coordination Office at NASA headquarters.
“We’re out there searching the skies, developing the catalog of all of asteroids and comets that can come near Earth,” he said.
In addition to identifying the objects, the Planetary Defense staff determines the sizes and threat they create and responses to mitigate the danger.
“Hopefully, we are able to do that well out into space before the asteroid is in any imminent danger of impacting the Earth,” Johnson said. “That’s what DART is all about — test of a capability to deflect an asteroid.”
Scientists chose DART’s target for many reasons, including the fact they aren’t a danger to Earth.
“What really makes these asteroids ideal for this first test is because it’s a double asteroid system,” said Nancy Chabot, DART coordination lead at the John Hopkins University Applied Physics Laboratory.
The larger asteroid, Didymos, is estimated at 2,559 feet in diameter while its smaller moon, Dimorphos, is 525 feet in diameter, with both observed for decades via telescopes.
Because of those telescopes on Earth, scientists know that the smaller asteroid orbits the larger once every 11 hours, 55 minutes — “just like clockwork,” Chabot said.
“What DART is going to do is it’s going to come speeding in really fast, 15,000 miles per hour, and it’s going to target onto Dimorphos, the smaller of those two asteroids,” Chabot said.
DART also carries a smaller briefcase-size satellite from the Italian space agency, set to be kicked off 10 days in advance to fly by after DART crashes into Didymos to snap images of the aftermath. Telescopes on Earth will help scientists determine how much the impact with DART deflected the asteroid’s path around the larger asteroid.
The DART spacecraft is about 100 times smaller than its target Dimorphos.
“You can see this isn’t going to destroy the asteroid. It’s just going to give it a small nudge,” Chabot said, adding that the change will be 1% in the orbital period.
The mission aims to change the orbit by at least 73 seconds.
“All the models show that it will be much more than that,” she said.
If an asteroid threatens Earth, this technique could be done years or decades in advance “such that you would give this asteroid a small nudge, which would add up to a big change in its future position, and then the asteroid and the Earth wouldn’t be on a collision course.
“Using this double asteroid system to develop this capability, take this first step to being able to deflect asteroids in the future, is really a smart and a safe way to do this test,” Chabot said.
The road to launch for DART began about five years ago, according to Elena Adams, DART mission systems engineer at the Johns Hopkins Applied Physics Laboratory.
To reach the asteroid, DART must launch between late November and Feb. 15.
The team will need a bit more patience since the rendezvous won’t occur for 10 months, cruising toward Dimorphos and arriving when the asteroid is closest to Earth and its telescope, Adams said.
In connection with DART, a website, available here, lets people become “planetary defenders.”
On Friday, SpaceX announced completion of a static fire test in preparation for liftoff. However, Vandenberg firefighters battled a spot fire sparked by the test, which involved igniting the first-stage but the rocket not lifting off.
Depending on the weather, the Falcon rocket launch can be seen from several off-base locations around the Lompoc Valley, including western Ocean Avenue and in Vandenberg Village.
— Noozhawk North County editor Janene Scully can be reached at jscully@noozhawk.com. Follow Noozhawk on Twitter: @noozhawk, @NoozhawkNews and @NoozhawkBiz. Connect with Noozhawk on Facebook.
