Defense is normally considered what a nation does to prevent an attack from another nation. But as humanity gains a greater understanding of the universe, a new concept, planetary defense, has been coined. It concerns defending the human race from the type of disaster that ended the reign of the dinosaurs.
“The threat of asteroids is real,” NASA scientist Elena Adams said during a panel discussion on international cooperation for planetary defense. Adams is the systems engineer for the first planetary defense mission, known as the Double Asteroid Redirection Test (DART). The DART mission is a collaboration among NASA, the European Space Agency (ESA), and the Italian Space Agency.
According to the journal Interesting Engineering, “Some scientists claim we are overdue for an asteroid impact of the scale that took out the dinosaurs — as these happen approximately once every 50 to 60 million years…In fact, just last year a large asteroid, called ‘2019 OK’, was spotted just a day before flying between the Earth and the Moon. Even scarier than the size and proximity of the asteroid — it was the size of a football field and came within 65,000 km of Earth’s surface — is the fact that it caught researchers off guard…in 1992 a huge asteroid impact did occur and was observed on Jupiter. If the asteroid, called Shoemaker-Levy 9, had hit Earth, it would have created a global atmospheric disaster similar to the one that wiped out the dinosaurs 65 million years ago.”
One recent threat spotted by astronomers involved Bennu, an asteroid about a third of a mile wide. According to a National Geographic report “Nearly all of the riskiest encounters with Bennu will occur in the late 2100s and early 2200s, with the single likeliest impact coming on the afternoon of September 24, 2182.”
Fortunately, early trials of the means to prevent a similar catastrophe have proven successful. After 10 months flying in space, NASA’s Double Asteroid Redirection Test (DART) – the world’s first planetary defense technology demonstration – successfully impacted its asteroid target on Monday, the agency’s first attempt to move an asteroid in space.
“At its core, DART represents an unprecedented success for planetary defense, but it is also a mission of unity with a real benefit for all humanity,” said NASA Administrator Bill Nelson. “As NASA studies the cosmos and our home planet, we’re also working to protect that home, and this international collaboration turned science fiction into science fact, demonstrating one way to protect Earth.”
DART targeted the asteroid moonlet Dimorphos, a small body just 530 feet (160 meters) in diameter. It orbits a larger, 2,560-foot (780-meter) asteroid called Didymos. Neither asteroid poses a threat to Earth.
The mission’s one-way trip confirmed NASA can successfully navigate a spacecraft to intentionally collide with an asteroid to deflect it, a technique known as kinetic impact.
The investigation team will now observe Dimorphos using ground-based telescopes to confirm that DART’s impact altered the asteroid’s orbit around Didymos. Researchers expect the impact to shorten Dimorphos’ orbit by about 1%, or roughly 10 minutes; precisely measuring how much the asteroid was deflected is one of the primary purposes of the full-scale test.
“DART’s success provides a significant addition to the essential toolbox we must have to protect Earth from a devastating impact by an asteroid,” said Lindley Johnson, NASA’s Planetary Defense Officer. “This demonstrates we are no longer powerless to prevent this type of natural disaster. Coupled with enhanced capabilities to accelerate finding the remaining hazardous asteroid population by our next Planetary Defense mission, the Near-Earth Object (NEO) Surveyor, a DART successor could provide what we need to save the day.”
Photo: Asteroid Dimorphos (NASA photo)