By Steve Gorman
– Ten months after launch, NASA’s asteroid-deflecting DART spacecraft came close to an intended impact with its target on Monday in a test of the world’s first planetary defense system, designed to avoid a collision of the day of final judgment with the Earth.
The cube-shaped “impactor” vehicle, about the size of a vending machine with two rectangular solar panels, was going to fly toward the asteroid Dimorphos, about the size of a football stadium, and self-destruct around 7pm EDT (11pm). GMT) about 6.8 million miles (11 million km) from Earth.
The end of the mission will test a spacecraft’s ability to alter the trajectory of an asteroid with sheer kinetic force, penetrating the object at high speed to deflect it enough to keep our planet safe .
It marks the world’s first attempt to change the motion of an asteroid or any celestial body.
DART, launched by a SpaceX rocket in November 2021, has made most of its journey under the guidance of NASA flight directors, with control to be handed over to an autonomous on-board navigation system in the final hours of the journey.
The impact scheduled for Monday evening will be monitored in real time from the mission operations center at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland.
DART’s celestial target is an asteroid “moonlet” about 560 feet (170 meters) in diameter that orbits a parent asteroid five times larger called Didymos as part of a binary pair of the same name, the Greek word for twin.
Neither object poses any real threat to Earth, and NASA scientists said their DART test cannot create a new existential danger by mistake.
Dimorphos and Didymos are small compared to the cataclysmic Chicxulub asteroid that struck Earth about 66 million years ago, wiping out about three-quarters of the world’s plant and animal species, including the dinosaurs.
Smaller asteroids are much more common and pose a greater theoretical concern in the near term, making the Didymos pair suitable test subjects for their size, according to NASA scientists and planetary defense experts.
Additionally, their relative proximity to Earth and double-asteroid configuration make them ideal for DART’s first proof-of-concept mission, short for Double Asteroid Redirection Test.
ROBOTICS SUICIDE MISSION
The mission represents a rare case in which a NASA spacecraft must ultimately crash to succeed.
The plan is for DART to fly directly at Dimorphos at 15,000 miles per hour (24,000 km/h), making it fast enough to bring its orbital path closer to its larger companion asteroid.
Cameras on the impactor and a mini-spacecraft the size of a briefcase launched from DART days in advance are designed to record the collision and send images back to Earth.
DART’s own camera is expected to return images at a rate of one image per second during its final approach, with those images live on NASA TV starting an hour before impact, according to APL.
The DART team said they hope to shorten Dimorphos’ orbital path by 10 minutes, but would consider at least 73 seconds a success, demonstrating that the exercise is a viable technique to divert an asteroid on a collision course with the Earth, if ever discovered. A small hit to an asteroid millions of kilometers away could be enough to deflect it safely away from the planet.
The result of the test will not be known until a new round of ground-based telescope observations of the two asteroids in October. Previous calculations of the initial location and orbital period of Dimorphos were confirmed during a six-day observing period in July.
DART is the latest of several NASA missions in recent years to explore and interact with asteroids, primordial rocky remnants from the formation of the solar system more than 4.5 billion years ago.
Last year, NASA launched a probe on a trip to the Trojan asteroid clusters orbiting near Jupiter, while the OSIRIS-REx spacecraft returns to Earth with a sample collected in October 2020 from asteroid Bennu.
The moon Dimorphos is one of the smallest astronomical objects to receive a permanent name and is one of 27,500 known near-Earth asteroids of all sizes tracked by NASA. Although none are known to pose a foreseeable danger to humanity, NASA estimates that many more asteroids remain undetected in the vicinity of Earth.
NASA has put the total cost of the DART project at $330 million, well below that of many of the space agency’s most ambitious science missions.