According to NASA, the collision of their DART mission altered the course of the asteroid it was attempting to deflect (science news).
NASA’s Double Asteroid Redirection Test (DART) analysis of data collected over the previous two weeks confirms that the spacecraft’s kinetic encounter with its target asteroid, Dimorphos, successfully modified the asteroid’s orbit. This is the first large-scale demonstration of asteroid deflection technology and the first time humans have ever altered the path of a celestial object on purpose.
Before the impact of DART, it took Dimorphos 11 hours and 55 minutes to complete one circle around Didymos, its bigger parent asteroid. Astronomers on Earth have been using telescopes to monitor the passage of time since DART’s deliberate collision with Dimorphos on September 26. The collision shortened Dimorphos’ orbit around Didymos from 11 hours and 55 minutes to 11 hours and 23 minutes, as the study team has now established. To the nearest two minutes, this measurement is accurate within.
NASA had established a cutoff of 73 seconds for a successful orbit period adjustment of Dimorphos before the collision. Using these first results, we may conclude that DART is more than 25 times faster than this baseline.
The investigative team is continuing gathering information from ground-based observatories all over the globe, in addition to the radar facilities at NASA’s Goldstone planetary radar in California and the National Science Foundation’s Green Bank Observatory in West Virginia. To increase the accuracy of the period measurement, they are constantly making new observations.
DART collided with its target at a speed of around 14,000 miles (22,530 kilometres) per hour, and attention is now moving to determining how efficiently momentum was transferred during the crash. This involves more study of the “ejecta,” or the massive amount of asteroid rock sent into space after the collision. DART’s push towards Dimorphos was greatly bolstered by the rebound from this burst of debris, which acted like a jet of air shooting out of a balloon, sending it in the other direction.
Ejecta recoil may be better understood with further data about the asteroid’s strength and surface features. Research on these matters is ongoing.
Astronomers will keep studying Dimorphos images taken during DART’s last approach and from the Italian Space Agency’s Light Italian CubeSat for Imaging of Asteroids (LICIACube) to estimate the asteroid’s mass and form. In around four years, the European Space Agency’s Hera project will undertake comprehensive surveys of Dimorphos and Didymos, with an emphasis on the crater produced by the DART crash and a precise assessment of Dimorphos’ mass.
“All of us have a responsibility to protect our home planet. After all, it’s the only one we have,” NASA Administrator Bill Nelson told SFcrowsnest. “This mission shows that NASA is trying to be ready for whatever the universe throws at us. NASA has proven we are serious as a defender of the planet. This is a watershed moment for planetary defense and all of humanity, demonstrating commitment from NASA’s exceptional team and partners from around the world.”
“DART has given us some fascinating data about both asteroid properties and the effectiveness of a kinetic impactor as a planetary defense technology,” added Nancy Chabot, the DART coordination lead from the Johns Hopkins Applied Physics Laboratory in Maryland. “The DART team is continuing to work on this rich dataset to fully understand this first planetary defense test of asteroid deflection.”
