Dinosaurs Did Not Have a Planetary Defense Program but NASA Does
By Dr. Matthew Daniels, OSTP Assistant Director for Space Security & Special Projects
NASA’s recent Double Asteroid Redirection Test (DART) mission represented humanity’s first-ever demonstration of an intentional, controlled asteroid deflection.
Consider this: If we ever discover that an asteroid is on a collision course with Earth, the technologies used by DART could serve as humanity’s first line of defense. Many millions of years ago, dinosaurs went extinct because of an asteroid impact. Unlike us, they didn’t have a space program.
The White House Office of Science and Technology (OSTP) led the creation of the first U.S. National Near-Earth Object Preparedness Strategy and Action Plan, which outlines our whole-of-government strategy for planetary defense. The DART mission is a key part of this strategy. New missions and new opportunities for international cooperation will follow in the years ahead.
For the astrophysicists, engineers, and other experts who planned DART, the mission’s grand finale in late September was packed with excitement. For those in the control room observing, there was no shortage of suspense:
The bigger asteroid appeared first. DART’s final countdown had started. Just five minutes from impact.
We could feel the mood tightening and excitement growing in the control room. As DART flew by the larger asteroid, called “Didymos,” it grew steadily on the screen, then suddenly swept by and was out of view.
Only our target remained: the small, never-before-seen moonlet asteroid that orbits around its bigger sibling. The smaller asteroid is “Dimorphos,” and the mission’s objective was to hit it directly while traveling at 14,000 miles-per-hour. This impact would shift Dimorphos slightly, nudging it closer to its bigger sibling-asteroid.
Measurements had previously shown the existence of little Dimorphos, but it was too small to be imaged with ground-based telescopes. So, no one knew what its exact shape would be. As DART approached, there were gasps in the control room as Dimorphos came into view. Imagine a free-floating sphere of rocks and gravel the size of the Statue of Liberty, and you have a pretty good idea of what Dimorphos’s sudden emergence looked like.
One minute to impact.
DART rapidly closed in on the target.
Dimorphos filled screens across the control room. We saw individual rocks. The rocks grew bigger as DART drew closer.
Fifteen seconds to impact.
The last two images showed a rocky surface. A moment of awe: this was one of the million clumps of primordial matter left over from the formation of the solar system. These were among the kinds of rocks that accreted together to form Earth.
Only a small piece of the last image transmitted. The screens went blank and the control room erupted in cheers.
“WE DID IT!”
NASA’s DART spacecraft impacted its target Dimorphos at 7:14 p.m. ET on September 26, 2022.
A worldwide observation campaign rapidly followed, including telescopes on every continent. Last week we received the results, which the DART team then presented at the White House.
Our international partners have also joined the action: a small spacecraft provided by the Italian Space Agency has been beaming back pictures of the impact. In a few years, a new European mission called Hera, the counterpart to NASA’s DART, will go to survey Dimorphos up close.
And right now, in the weeks immediately following the DART mission, observatories around the planet are continuing to work together to study Didymos and Dimorphos, imaging the asteroid pair after the impact and providing NASA with vital information that aids its post-mission measurement efforts.
Preliminary scientific data show that NASA had shifted Dimorphos’ orbital period around its larger sibling by more than 30 minutes, far exceeding NASA’s original definition for mission “success.”
The DART mission was a daring, successful example of Planetary defense, bolstering our nascent efforts to protect Earth from a devastating impact by asteroids. Planetary defense, with missions like DART, gives us a model for other kinds of international cooperation and problem-solving, and spark the imagination of millions.
Around the world, we face a range of large-scale challenges: climate change, health crises, security threats. The DART mission is a reminder that we have the potential to save the world with science and engineering, so long as we prioritize humanity as we develop cutting edge technologies.
What will we do next?