image of asteroid moonlet Dimorphos

Photo courtesy NASA/John Hopkins APL “The last complete image of asteroid moonlet Dimorphos, taken by the DRACO imager on NASA’s DART mission from about seven miles (12 km.) from the asteroid and two seconds before impact. The image shows a patch of the asteroid that is 100 ft. (31 m.) across. Ecliptic north is toward the bottom of the image. This image is shown as it appears on the DRACO detector and is mirror flipped across the x-axis from reality.” (NASA/John Hopkins APL)

The DART spacecraft slammed into the surface of a distant asteroid at 6:14 p.m. Central Daylight Time on Monday, September 26. The spacecraft, valued at $325 million, was completely destroyed. NASA’s DART project has an expected additional cost of $16.5 million to complete the project. So what exactly went wrong with the project? Get ready for the shocking news, nothing! DART was designed to crash into the remote asteroid as part of the Double Asteroid Redirection Test (DART) mission.

It was 5:14 p.m. Monday and the target asteroid, Dimorphos, was not even visible from the cameras on the spacecraft. The first images barely showed the larger companion of Dimorphos, Didymos. Didymos looked like a single dot on a sea of blackness. It is one of those scenarios where avoiding the asteroid would have been much easier than hitting it at full speed. DART hurled toward the unseen target at 14,000 miles per hour, so details of the twin asteroids quickly came into view. DART darted past Didymos and into a dense cloud of boulders before the screen went bright red and DART was no more.

The first detailed views of Dimorphos were seen by the scientists driving the mission for the first time; they knew by predictive models where the pair of asteroids should be and were relying heavily on mathematical models in hopes of reaching the target.

Elena Adams, DART Mission Systems Engineer said, “We didn’t really know the shape of the asteroid, but we knew we’re going to hit. So I think all of us were kind of holding our breath. I’m kind of surprised none of us passed out actually, for a second there.”

This was the first experiment in a series of tests designed to determine the most practical way to protect Earth from high speed asteroid impacts.

Lori Gaze, Director of NASA’s Planetary Science Division was quoted, “We’re embarking on a new era of humankind, an era in which we potentially have the capability to protect ourselves from something like a dangerous, hazardous asteroid impact. What an amazing thing. We’ve never had that capability before.”

Just to be clear, neither Dimorphos not Didymos posed any threat to Earth and neither do any known asteroids today, but NASA is playing the long game, knowing that someday we may have to defend the planet against a dangerous asteroid. Dimorphos was a relatively small asteroid and was impossible to see from earth. So how did we know where to find it and what did we expect to see change? This is where the really interesting science comes in. We were able to guess the size and position of Dimorphos based on seeing the shadow it cast in the light reflected from Didymos. You see Dimorphos was orbiting Didymos and we could observe Dimorphos crossing between us and Didymos.

Through very complex mathematical models, scientists were able to predict exactly when to strike Dimorphos; the plan was to strike it as it was moving away from earth in hopes of speeding up its orbit. The expectation is to see an increase in the speed of the orbit. In other words, we should see Didymos dim more frequently following the collision. Scientists were not able to calculate the amount of difference the collision would create due to several unknown factors, such as the exact size, shape and weight of Dimorphos. It will take a few months of observation to get a full answer on the success of the mission, but you can see some of the early images from the mission at https://www.nasa.gov/feature/dart-s-final-images-prior-to-impact

The DART spacecraft was carrying a smaller satellite, LICIACube, built by the Italian space agency. The sole job of LICIACube was to drop in behind DART and capture the final images of the craft as it impacted Dimorphos. Seven telescopes from around the globe were also focused on the event and will remain focused on the twin asteroids to capture the data of the next several weeks. In addition to the earth bound telescopes, the James Webb Space Telescope, Hubble, and the spacecraft Lucy will remain focused on the scene. In 2024, the European Space Agency will join the game and send another observation spacecraft to the asteroid pair in hopes of getting a closeup look at the planned space accident. Until next week, stay safe and learn something new.

Scott Hamilton is an Expert in Emerging Technologies at ATOS and can be reached with questions and comments via email to shamilton@techshepherd.org or through his website at https://www.techshepherd.org.

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