NASA’s asteroid-smacking spacecraft will give us all some dramatic visuals next week.Â
The live show from space will require a degree of coordination never seen before, as the agency’s Double Asteroid Redirection Test (DART) probe zooms toward the asteroid moonlet Dimorphos on Sept. 27 to try to change its orbit around its parent body, the asteroid Didymos.Â
The broadcast will feature images from DART’s DRACO instrument, which is the only scientific instrument the spacecraft is carrying. (The acronym stands for “Didymos Reconnaissance and Asteroid Camera for Optical navigation.”)
“The DRACO images, I just want to stress, are going to be pretty spectacular,” Nancy Chabot, DART coordination lead at the Johns Hopkins University Applied Research Laboratory, said during a press conference on Sept. 12.Â
“You’re going to be coming into an asteroid that nobody’s ever seen before,” Chabot continued. “You’re going to see things that are tens of centimeters in size for that final image and then it’s going to cut off. I think that’s going to be pretty cool.”
Related: NASA’s DART mission will move an asteroid and change our relationship with the solar systemÂ
The images will flow back to Earth at a rate of one per second, and we’ll see them in real time via NASA Television. Officials anticipate the real show will happen about two minutes before impact, when the asteroid begins filling the view of the camera. “We’re honestly super-excited to see what it looks like,” said Michelle Chen, lead engineer for a DART algorithm known as SMART Nav.
Given Earth will be nearly seven million miles (11 million km) from the asteroid pair at impact, engineers can’t exactly steer DART by hand. Rather, SMART Nav will independently guide the spacecraft to the asteroid and get the systems all set up for the big crash.
The goal is to have the spacecraft figure out the last four hours of its mission without any human directing the way. With DRACO, the spacecraft will find its target, make corrections to its trajectory by itself, and make its way to Dimorphos’ surface for a one-way trip.
This all is valuable practice for a method of asteroid deflection called kinetic impacting. Should some asteroid of the future be on a collision course with Earth, perhaps an impactor like this could knock it out of the way. That said, NASA officials have emphasized that there is no known asteroid threat to human civilization for at least the next 100 years, and scientists conduct searches constantly to verify that.Â
Related: Just how many threatening asteroids are there? It’s complicated.
The most “sweaty” time for the engineers watching will be about 50 minutes before the impact, said Evan Smith, DART deputy mission systems engineer at APL.
“Both objects will still be in the field of view, but we’re going to go straight for Dimorphos and go for impact,” he said. “We have a lot of contingencies built right around that 50 minute transition. We’re going to be watching the telemetry like a hawk. We’ll be very scared, but excited.”
Key stages after that point will include a precision lock at 20 minutes to impact, and then the moment when thrusters cut off on the spacecraft roughly 2.5 minutes before impact.Â
“We’re going to be streaming images the whole time,” Smith said. The images will move from DRACO through the avionics of the spacecraft and then beam back to Earth via radio. NASA’s Deep Space Network of satellite dishes will pick up the signal to send it to broadcasts live on Earth.
Meanwhile, a little cubesat called LICIACube that launched with DART will be taking images of its own, safely away from the site of the impact. That footage should beam back to Earth in the following days.Â
NASA will also watch for the impact via a network of ground telescopes, and officials said they would share that information as soon as feasible. That said, it may take several weeks to get all the information out, as verifying whether Dimorphos’ orbit has changed could take time.
Related: A small asteroid’s orbit is changed forever after super close Earth flyby
What we will actually see right after the impact remains a big unknown, despite the number of simulations that NASA has run. “The amount of ejecta, if you wanted to ballpark it, we don’t know specifically, which is why we’re doing this test. But it’s something like a million kilograms,” Chabot said.Â
While that sounds like a lot, she noted that’s roughly a tenth of the mass of Dimorphos and that the spacecraft is of course very small in comparison. At most, the orbit of the moonlet will shift by only 1%, DART team members think.
“We describe it as running a golf cart into the Great Pyramid,” Chabot said. “This isn’t going to blow up the asteroid. It isn’t going to put it into lots of pieces.”
Future space missions will benefit not only from the asteroid-nudging demonstration but also from the advances that will allow DART to guide itself on its final plunge.Â
“I just want to geek out for a second,” Chen said. “From an engineer’s perspective, with the technology demonstration of smartness, we are super-excited about the idea of doing more autonomous control and navigation of future spacecraft.”Â
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