A NASA spacecraft being built to protect the Earth from an asteroid strike will crash into the asteroid in September to test the spacecraft’s survival, agency officials announced Tuesday.
The OSIRIS-REx spacecraft will spend a year from July 2019 at the asteroid Bennu. After circling the asteroid for six months and flying by in August of that year, the spacecraft will go into its final orbit around the asteroid.
In September 2021, the spacecraft will use a laser to burn off some of the surface of the asteroid’s rock and dust. At this point, the space agency expects the spacecraft to be flying around the asteroid at about 26,000 mph.
At that time, the spacecraft will embark on its final maneuver, traveling at about 600 mph toward Bennu. The craft will be traveling above the asteroid’s atmosphere, but not impacting the surface. At 3:44 p.m. EDT, engineers will attempt to separate the craft from its thrusters in an atmosphere-accelerating maneuver. That will occur about five seconds after OSIRIS-REx flies within 300 feet of the surface of the asteroid.
The craft will survive to complete its mission.
“We do have a contingency plan if things go wrong, and we’re going to execute that contingency plan,” Dante Lauretta, OSIRIS-REx’s principal investigator from the University of Arizona, said during a news conference.
As is the case when a spacecraft is flying through space, the initial impact on the asteroid is likely to cause it to eject layers of rock and dust in the debris stream that follows. What we don’t know is how the design of the spacecraft, which was tested last year, will fare. But it will pass within a half-mile of the surface of the asteroid.
And, with no substantial shielding of rock or dust, Lauretta expects there could be a small amount of damage. “I don’t expect a lot,” he said. “I think the spacecraft will survive the impact pretty well.”
Some of the special techniques to prevent impacts will be part of a demonstration mission. NASA will drop a capsule containing a parachute into the asteroid to test the technology, as well as test a system that can impact another spacecraft to simulate what could happen to the craft if it hits a celestial body while in orbit around the Earth.
But it could still be another two decades before the technology is useful if a threat is posed to Earth. Scientists say if we do not find and deflect an asteroid or other potential threat before it collides with Earth, the damage could be ruinous.
Such a threat would be the result of a small impact in Earth’s orbit with an asteroid of about 40 meters in diameter, and about 500,000 times smaller than the one that destroyed the dinosaurs. Such a collision, if it were to occur, could be fatal for humans and knock out communications and power.
For many scientists, and for Lauretta, who studies near-Earth asteroids, now is the time to get to the threatened space rock. “Now is the time,” he said. “This is a golden opportunity.”
Unfortunately, the original scheduled launch date for the mission was three years ago. It was pushed back because the spacecraft needed more time to solve some software problems that Lauretta said were not “objectively detectable.”
But the delay, he said, was not the result of any technological difficulties. “The correct launch date will be in 2023,” he said.
Monday’s announcement was the culmination of more than a decade of planning. The $800 million mission was launched in September 2016. OSIRIS-REx was expected to take six years to arrive at Bennu and collect its dust.