The planetary defense mission’s spacecraft spent the next 10 months traveling toward its target in what officials called both a technology demonstration as well as a science experiment with impact occurring at 4:15 p.m. Sept. 26.
The asteroid that the refrigerator-sized DART hit while traveling 14,000 mph actually is a moonlet Dimorphos orbiting a larger asteroid called Didymos.
Neither the moonlet nor the larger asteroid threatened Earth.
On Tuesday, NASA officials provided an analysis of the mission, saying knocking the moonlet off its orbit by 10 minutes would have been considered a success.
“Let’s all just kind of take a moment to soak this in. We’re all here this afternoon because for the first time ever NASA has charged the orbit of a planetary body, a planetary object,” said Lori Glaze, director of NASA’s Planetary Science Division. “The first time ever.”
Astronomers using telescopes on Earth have confirmed that the impact altered the orbit by 32 minutes, NASA officials said.
“This is a watershed moment for planetary defense and a watershed moment for humanity, and that’s why it was fitting that DART was an international endeavor. Science benefits humanity. This is a unifying mission,” NASA Administrator Bill Nelson said.
DART included an Italian Space Agency craft, the Light Italian CubeSat for Imaging of Asteroids (LICIACube), that tagged along to capture the impact.
“All of us have a responsibility to protect our home planet. After all, it’s the only one we have, and this mission shows that NASA is trying to be ready for whatever the universe throws at us,” Nelson said.
Nancy Chabot, the DART coordination lead from the Johns Hopkins Applied Physics Laboratory in Maryland, called the results exciting, but also noted that the 4% change in the orbital period amounted to a small nudge. To use kinetic energy to deflect an asteroid would need to occur years in advance, Chabot said.
“Warning time is really key here in order to enable this sort of deflection to be potentially used in the future, and it is part of a much larger planetary defense strategy,” Chabot said.
The analysis of DART’s rendezvous will continue as scientists hope to learn more about the other effects of the impact.
“The learning is going to continue for a long time to come,” Glaze said.
In about four years, the European Space Agency’s Hera project will conduct detailed surveys of both Dimorphos and Didymos, with a particular focus on the crater left by DART’s collision and a precise measurement of Dimorphos’ mass.
“We’re opening new windows of understanding, looking deeper and deeper and deeper to gain a better understanding of not just how to defend our planet against this natural hazard of asteroid impact but also to understand how our solar system works and how we got to be where we are now,” said Tom Statler, a NASA program scientist.