Mark Megahan
There’s something about NASA’s DART project which caught the world’s attention like one of those high school lab demos. One where everyone has to put their safety goggles on first, because it’s going to explode. Like dropping a hunk of sodium in a beaker full of water. Now that the experiment has been run, it’s time to collect the data and see if it matched the theory. Not only did the impact have a bigger result than expected, it gave astronomers and physicists a whole bunch of unexpected bonus data to work with.
DART destroyed on impact
The multi-million dollar DART satellite was on a suicide mission from the beginning, designed to go splat against the surface of micro-moon Dimorphos, which orbits asteroid Didymos.
Everything went perfectly according to plan despite all the things which could have gone wrong. The project engineers were thrilled because there’s so much at stake for the human race.
DART is the first test of our one and only planetary defense option. Asteroids which haven’t previously been detected have been whizzing past annoyingly close to home. A couple went by that we didn’t see until they were right on top of us.
That’s not a good thing because with current state of the art there isn’t much we can do. This experiment works on the tried and true Newtonian formula of force equals mass times acceleration.
DART may only weigh a few pounds but it was moving really fast when it hit, so should have delivered one heck of a wallop. It did. The general idea is to see if the impact could nudge the space rock enough that the technique could form the basis of our planetary defense network.
Along the way to it’s predetermined fate, the one and only onboard instrument managed to get some work done. After months in flight, it sponged up about 10 minutes of hard to get data. Then, on September 26 it went splat.
Some instant observations
The technicians in charge of the project are quick to explain that some of the answers will take a while to confirm but there are a few things they can point out already.
“There’s a lot of instant observations you can make, but there’s a lot of careful things you have to put together before you go too far down any road,” Carolyn Ernst with Johns Hopkins University Applied Physics Laboratory announces. She’s the instrument scientist for the only one on DART.
For much of the journey, “the asteroids appeared as one bright dot, but by about 10 minutes before impact, that dot began to transform into two small but unique worlds.” The camera sent back the last few moments of DART with crystal clarity.
The world was thrilled to see “the rocky surface strewn with boulders, dust and everything in between” just before the screen went black. Prior to impact, it jettisoned another cubesat device which imaged the aftereffects. The close timing meant that the camera flew right through all the debris, which clutters the images.
Earth and space based telescopes also focused on the effects and captured first one tail then a second one, making the asteroid a temporary comet.
As for the effects, careful measurements reveal that “Dimorphos’ orbit previously lasted 11 hours and 55 minutes; in the wake of the impact, that period has decreased by 32 minutes. That was on the high end of scientists’ expectations before launch.” In other words, DART worked even better than expected. Now, we can ramp up construction on something big and heavy we can throw at any “planet killer” we see coming in at us. Provided we can catch it in time, that is.
