NASA is about to crash a spacecraft into an asteroid


The Double Asteroid Redirection Test is about to reach its final destination

Bright stars on a back background. A blue inset highlights the location of Didymos, which appears as a white speck.

DART’s view of the Didymos system
NASA JPL DART Navigation Team

Bracing for impact

During its final approach, DART will be driving itself. There will be about 44 people in a control room watching telemetry and data, but starting about four hours before impact, “the spacecraft has to do everything,” said Elena Adams, DART mission systems engineer at John Hopkins Applied Physics Laboratory during a press conference. It has a smart navigation system on board that is guiding it to the Didymos/Dimorphos system. It spotted Didymos earlier this summer, but it won’t be able to see Dimorphos, the actual target, until about an hour before impact.

When it spots Dimorphos, the 163-meter-wide (530 feet) asteroid will only appear as a pixel. That will be enough for the navigation system to begin tracking toward the rock itself, instead of its companion asteroid. Two and a half minutes before impact, the navigation systems that brought the spacecraft to that point will switch off, Adams says. “We’re just going to point the camera, and take the most amazing pictures of this asteroid that we’re going to see for the first time.”

It’s not every day that scientists get to crash a $250 million spacecraft, as Adams told The Verge last November, ahead of DART’s launch. Because it’s such a once-in-a-lifetime experience, the team will be documenting the collision in detail.

In addition to the observatories in space and on Earth that will be watching, DART’s own camera will be sending back images until the last minute, beaming them back to Earth so that people can watch as the mission reaches its dramatic conclusion.

In addition, a small companion spacecraft will be documenting the action in space. The Italian LICIACube (Light Italian CubeSat for Imaging Asteroids) launched with DART and separated from the larger spacecraft on September 11th. It is following its companion, and will document the experiment’s aftermath, flying by Dimorphos about three minutes after impact. It will also have the chance to see the other side of Dimorphos, which the larger spacecraft will never get to see.

What comes next?

“This mission has two parts. The first part is hitting the asteroid, the next part is actually measuring what happens afterwards,” Adams said. The team expects the asteroid to run faster after the collision, and will be tracking that over time.

“It’s just like if you dropped your wristwatch and damaged it. It’s not going to keep necessarily the same time,” said Tom Statler, DART’s program scientist. “You might not notice it right away, but in the weeks and days and weeks to follow you will notice that your watch is running fast — and we will notice that the binary asteroid system is running fast.” Statler said.

While Statler and the other researchers have a good idea of what might happen after the crash, one of the big reasons for this test is that we don’t know exactly what will happen when we crash into an asteroid. Information about how the asteroid reacts to an impact could help calibrate future tests, and eventually inform how we might approach a threatening asteroid.

“As a scientist I fully hope to be surprised by the results of the experiment.” said Statler. “Although as a planetary defender, I don’t want to be too surprised.”

How to watch NASA’s DART Mission

NASA will begin its coverage of the DART impact at 6PM ET on Monday, September 26th. The collision is expected at 7:14PM ET. People can tune in to live coverage on NASA’s website or YouTube channel, or follow along on Facebook and Twitter.

Go to Publisher: The Verge – All Posts
Author: Mary Beth Griggs