NASA is set to start its first effort to save the planet after years of study and debate.
The Russian crisis served as a wake-up call. A meteor the size of a four-story skyscraper roared across the nation on a winter morning in 2013, bursting near Chelyabinsk and wounding over 1,600 people and causing massive property damage.
The 60-foot-wide block of rock and iron served as a harrowing reminder that Earth, which is battered every day with masses of space debris, occasionally collides with enormous planet killers, many of which go unrecorded.
After years of research and debate, NASA is poised to make its first attempt to save Earth from suffering the same fate as the dinosaurs by smashing a space probe into an asteroid to change its speed and path. The DART (Double Asteroid Redirection Test) will launch from California on Nov. 23 local time atop a SpaceX rocket and will travel for ten months to a binary asteroid system.
The concept is that if humans have enough time to react—decades of warning is preferable—enough energy may be put into a hurtling boulder to change its course and cause it to miss Earth, preventing catastrophic events up to and including extinction. (Though a common subject in science fiction, it’s worth noting that Morgan Freeman, Bruce Willis, or nuclear weapons aren’t part of NASA’s current asteroid-nudging toolbox.)
In a November message to members, Casey Dreier, an analyst with The Planetary Society, noted that given the crucial significance of the job, “it’s not a leap to argue that DART may be one of the most impactful missions ever conducted by NASA.”
“This test aims to show that this technology is developed enough that it would be ready if a true asteroid impact danger were discovered,” NASA’s planetary defence chief, Lindley Johnson, stated at a news conference on 4th of November.
The DART ship will target Dimorphos, a tiny, 530-foot rocky body gravitationally connected to the bigger Didymos, which is roughly 2,600 feet wide, in September of next year provided all goes according to plan. The two boulders are roughly a kilometre apart, and Dimorphos circles its larger brother every 11 hours and 55 minutes, “exactly like clockwork,” according to Johnson.
The ship, which weighs 1,344 pounds and measures 59 feet in diameter, will smash head-on with Dimorphos at a speed of nearly 15,000 mph, slowing the rock by a fraction of a second and adjusting its orbital period around the bigger asteroid by several minutes.
“It’s all about calculating momentum transfer: how much momentum do we impart to the asteroid by slamming into it with the spacecraft?” Applied Physics Laboratory at Johns Hopkins University, which constructed and controls the spacecraft, said Andy Cheng, the mission’s chief investigator.
Didymos was found 25 years ago and has undergone extensive research (insofar as asteroids and comets go). Although it isn’t expected to collide with Earth shortly, its proximity provides scientists with an excellent test platform to examine with telescopes from 6.8 million miles away.
DART will pick its hit site automatically using laser targeting and other high-resolution technology. The craft’s camera will relay photographs back to Earth as it approaches the rock. Before impact, a tiny cube satellite launched from the main vehicle will record photographs from a safe distance. One major uncertainty is the surface composition and topography of the smaller body, which are too tiny to be determined from Earth.
NASA has been required by Congress for more than 15 years to classify near-Earth objects (NEOs) larger than 140 metres (460 feet), the size at which an asteroid hit would cause catastrophic damage. According to NASA’s Planetary Defense Coordination Office, “although no known asteroid larger than 140 metres in size has a substantial chance of hitting Earth in the next 100 years,” it’s also estimated that less than half of 25,000 NEOs that are around 140 metres and greater have been perceived too far.
The 2013 Chelyabinsk incident drew the attention of Washington, which increased funding for planetary defence by more than 4,000 percent to $200 million per year over the last decade, with strong backing from both the Obama and Trump administrations, according to Dreier.
The obstacles of detecting these potential planet killers, on the other hand, are formidable. The range of Earth-based telescopes is restricted, objects approaching from the sun can’t be detected, many asteroids reflect practically little light, and they all travel ridiculously fast—on average, 43,000 mph or 12 miles per second.
Furthermore, not all of them are local. Astronomers discovered the first significant visitor from outside the solar system in 2017, Oumuamua, a 400-meter cigar-shaped freak that circled the sun at a sizzling 196,000 mph on its journey back out into interstellar space.
If the mission is successful, NASA hopes to test its trajectory-altering tactics again after it receives data from DART’s destruction at Dimorphos.
Another option under investigation is a “gravity tractor,” which would involve attaching a spaceship to an asteroid to increase its mass and progressively modify its orbit.
Nonetheless, keeping a close eye on things is essential if we want to avoid a recurrence of the dinosaurs’ demise. Last year’s loss of the Arecibo Observatory in Puerto Rico, which played a major role in radar evaluations of near-Earth objects, allowing researchers to establish their size and orbits, has left NASA and other scientists reeling.
“The key to planetary defence is discovering them far before they become an impact threat,” says Johnson, the earth’s defender at NASA.
