When a spacecraft collided with an asteroid last month, it pushed it closer to its companion and accelerated its orbit by about 32 minutes. It’s a huge milestone in planetary defense; it finds that it may be possible for humans to significantly alter the path of a potentially dangerous asteroid — especially if we have a warning that one is on the way.
When the Double Asteroid Redirection Test (DART) mission crashed a spacecraft onto the surface on Sept. 26, telescopes on Earth and in space watched the action. Now the first data from those observatories has shown that DART has achieved its goal. Before the impact, the asteroid Dimorphos took about 11 hours and 55 minutes to orbit its much larger companion asteroid Didymos. The same journey now takes 11 hours and 23 minutes.
Skipping an asteroid’s orbit for half an hour is a huge victory for the mission, which… would even have categorized a 73 second change as a success. Researchers think one of the reasons for the big change in the orbit is that the impact displaced tons of material, creating a dramatic-looking plume of debris in the process. This “kickback” gave the impact an extra boost, nasa said:.
There’s still a lot about the impact that scientists need time to figure out. They will pour out many more observations to answer questions like: Is there a new shape in the orbit? Does Dimorphos wobble? How much debris came off the asteroid when we collided with it at 14,000 miles per hour?
Once they have that information, the modeling becomes even more intense; they will take the information from the observatories and run it through physics simulations over and over until they have a pretty good idea of what happened. That way, when the Hera spacecraft of the European Space Agency arrives at the asteroid system in a few years, researchers will have a pretty good idea of what it will find.
“All of this information plays into our understanding of what really happened in the experiment. How effectively did the kinetic impact change the asteroid’s motion? How efficiently was the momentum transferred? It’s too early to say; there are many moving parts in this calculation,” Tom Statler, NASA DART program scientist, said at a news conference.
That’s all important information for any future mission to reroute an asteroid to our planet – the base tenant of planetary defense. Dimorphos and Didymos posed no threat to Earth, but researchers are looking for other asteroids and near-Earth objects that could be dangerous.
As exciting as these early results of the DART mission are, knowing how to move an asteroid is only part of future efforts to defend our planet from space rocks. The much bigger problem is knowing what dangers there are – and being aware of them as soon as possible.
“This is a four percent change in Dimorphos’ orbital period around Didymos — and it just gave it a little push,” said Nancy Chabot, DART coordination leader at the Johns Hopkins University Applied Physics Laboratory.
A similar “little nudge” to a potentially dangerous asteroid could be enough to keep it out of Earth’s path, but timing would be vital. “If you wanted to do this in the future, it could potentially work. But you might want to do it years in advance. Warning time is really key here,” Chabot said.
“The single most important factor we need to know is which ones are potentially dangerous and when they can be potentially dangerous,” said Lori Glaze, director of NASA’s Planetary Science Division. NASA is working on the Mission of a near-Earth surveyor, who would specifically look for these kinds of dangers. The mission, which had to deal with financing problems in the latest congressional budget cyclesis considered a top priority of the planetary science community.
