DART deflected Dimorphos from its natural orbit: we can sleep better in the face of a possible asteroid impact on Earth

On September 27, during a live broadcast, we witnessed how the DART spacecraft, after a long journey of almost 10 months, finally collided with the asteroid Dimorphos.

This was the beginning of a race against time to understand and decipher what happened at that moment.

The hard days of relentless work began, as well as great excitement and enthusiasm among the members of the DART mission science team.

Observatories around the planet studied the impact in detail

Dozens of astronomical observatories located on all continents and at different latitudes observed in detail the moment when the DART spacecraft collided with the surface of little Dimorphos.

Some of these observatories recorded a large amount of material that was burned at the same time.

Determining the velocity and composition of this material was the first challenge the team faced, as the correct interpretation of this data is critical to the subsequent impact assessment.

LICIAcube images left us breathless

Literally a few hours later, at a press conference, the first image of the impact, taken by one of the cameras aboard the LICIAcube, was shown. This Italian device separated from the DART spacecraft 15 days before the collision to capture high-resolution images of Didymos and his companion Dimorphos.

The image really left us speechless: an explosion of filamentous structure and impressive size on Dimorphos, illuminated and directed (or so it seemed) at his satellite Didyma.

As a result of these images, new questions have flooded the social networks: what are these threads? Did the explosion on Dimorphos have the desired effect? Was material deposited from the Didymos explosion? Could some of this material ever intercept the Earth?

Meanwhile, the mission’s research team continued to analyze data and make calculations in an attempt to answer these and other questions in record time.

“Comet” Dimorphos

A couple of days after the impact, several observatories confirmed the formation of a long tail behind the small colliding asteroid. The gas, dust and small particles ejected after the collision formed a trail that gives Dimorphos the appearance of a small comet.

Although the models predicted this behavior, experimental confirmation of this fact provides interesting information about the dynamics of the system.

Influence efficiency

The deviation of Dimorphos from its natural orbit has to be measured using observatories on Earth, calculating the change in the period of revolution, that is, measuring how long it takes Dimorphos (the moon of a larger asteroid) to complete a revolution around its companion. , and comparing it with the time before impact (11 h 55 min). If this time after impact had been shorter, this would have meant that Dimorphos had moved into a shorter inner orbit than before, and the mission would have reached its goal.

A few days after the impact, the first data on the change in the orbital period began to arrive, but, like everything in science, scattered data is not enough, and it would take more than two weeks for there to be enough measurements to draw reliable conclusions. .

Finally, on October 11, two weeks after the DART crash, NASA officially announced that the planetary-scale experiment had succeeded: Dimorphos’ orbit changed in about half an hour, and now it takes about 32 minutes less to complete one revolution around Didymos. .

The DART impact dislodged Dimorphos, bringing it closer to the larger asteroid by a distance equivalent to the length of a tennis court. To date, Dimorphos has driven an extra lap around his partner as a result of the impact.

The initially ejected material captured in the first images from Earth appears to be only gas and dust, and of course, some of this material will not intercept us here on Earth.

The filamentous structures shown in the LICIAcube images may be nothing more than a grouping of ejected material in the form of “rays”, a consequence of the difference in size between rocks and regolith (finer material) on the asteroid’s surface, as the CAB team predicted in our work before the impact .

It seems that at the moment the most important and pressing issues have already been resolved. From now on, we will all sleep a little more peacefully, safe from those 20,000 small asteroids like Dimorphos, which just 10 months ago posed a big risk to our survival.

M. Isabelle Herreros, PhD, Research Fellow at the Center for Astrobiology, Specializing in Numerical Models for Planetary Sciences, Center for Astrobiology (INTA-CSIC) and Jens Orme, PhD in Geology. Research Fellow at the Public Research Organizations Center for Astrobiology (INTA-CSIC)

This article was originally published on The Conversation. Read the original.

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