According to NASA, DART (NASA’s Double Asteroid Redirection Test) Mission Impact Changed Asteroid’s Motion in Space.
Analysis of data collected by NASA's DART research team over the last two weeks reveals that the spacecraft's kinetic impact with its target asteroid, Dimorphos, successfully changed the asteroid's orbit.
Dimorphos used to take 11 hours and 55 minutes to orbit its larger parent asteroid, Didymos, before DART's impact.
Since DART's planned collision with Dimorphos on Sept. 26, astronomers have been using telescopes on Earth to measure how much that time has changed.
Now, the investigative team has confirmed that the spacecraft's impact changed Dimorphos' orbit around Didymos by 32 minutes, that is, reducing the 11-hour and 55-minute orbit to 11 hours and 23 minutes.
However, this measurement has a margin of uncertainty of approximately plus or minus 2 minutes.
NASA had defined a minimum successful orbit period change of Dimorphos of 73 seconds or more, before DART's impact.
But this early data and the results released on Tuesday show DART surpassed this minimum benchmark by more than 25 times.
Before or after DART's controlled collision with Dimorphos, neither Dimorphos nor Didymos pose any threat to Earth.
The team is still collecting data from ground-based observatories around the world, as well as with radar facilities at NASA Jet Propulsion Laboratory’s Goldstone planetary radar in California and the National Science Foundation’s Green Bank Observatory in West Virginia.
They are regularly updating the period measurement to improve its precision with frequent observations.
Now, the focus is shifting toward measuring the efficiency of momentum transfer from DART's roughly 14,000-mile (22,530-kilometer) per-hour impact with its target.
This involves further analysis of the "ejecta" – the many tons of asteroidal rock displaced and launched into space by the collision.
The recoil from this debris blast substantially enhanced DART's push against Dimorphos, similar to how a jet of air streaming out of a balloon sends the balloon in the opposite direction.
More information about the asteroid's physical attributes, such as the characteristics of its surface and how strong or weak it is, is required to correctly grasp the effect of the recoil from the ejecta. These issues are currently being looked into.
NASA Administrator Bill Nelson said,
“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."
He also said, "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.”
Lori Glaze said, “As new data come in each day, astronomers will be able to better assess whether, and how, a mission like DART could be used in the future to help protect Earth from a collision with an asteroid.”
The following telescopic facilities contributed to the observations used by the DART team to determine this result:
Goldstone, Green Bank Observatory, Swope Telescope at the Las Campanas Observatory in Chile, Danish Telescope at the La Silla Observatory in Chile, & Las Cumbres Observatory global telescope network facilities in Chile and in South Africa