One of the biggest planetary stories from last week was the announcement by NASA of the preliminary results of the DART mission’s impact of asteroid Dimorphos. With much fanfare and a press conference, NASA shared that the spacecraft altered the asteroid’s orbit, successfully completing the first full-scale demonstration of this particular form of planetary protection.

I’m pretty sure most of the science community expected that we managed to alter an asteroid’s orbit after witnessing the amazing puff of material and 10,000-kilometer-long trail of dust. What was not expected was the degree to which Dimorphos’s orbit was altered. The minimum success for this mission was a whopping change of at least 73 seconds. Seconds. Dimorphos orbits Didymos in 11 hours and 55 minutes, which means 73 seconds isn’t a very big difference.

However, after careful measurements by the investigation team using a variety of ground telescopes, Dimorphos’s orbit was calculated to be 11 hours and 23 minutes – a change of 32 minutes. Minutes, not seconds. Lori Glaze, director of NASA’s Planetary Science Division, notes: This result is one important step toward understanding the full effect of DART’s impact with its target asteroid. 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 if we ever discover one headed our way.

Pretty impressive for a first demonstration. We look forward to more results over the coming months and years as the data is analyzed and when ESA’s Hera spacecraft arrives to conduct detailed surveys of the system.

More Information

NASA press release