Although I had Europa on my mind yesterday, I hadn’t thought to find a connection between the icy Jovian moon and the DART mission. Yet it turns out the Double Asteroid Redirection Test imaged Jupiter and Europa in July and August as the spacecraft moved toward yesterday’s encounter with the binary asteroid Didymos. Controllers used the spacecraft’s DRACO imager (Didymos Reconnaissance and Asteroid Camera for Optical navigation) to examine the visual separation between moon and planet, homing in on variations in the pixel count and intensity as the targets moved across the detector. All this in anticipation of the spacing that would soon be detected between the larger asteroid Didymos and its tiny companion Dimorphos.

Says Peter Ericksen, SMART Nav software engineer at APL:

“Every time we do one of these tests, we tweak the displays, make them a little bit better and a little bit more responsive to what we will actually be looking for during the real terminal event.”

Image: This is a cropped composite of a DART Didymos Reconnaissance and Asteroid Camera for Optical navigation (DRACO) image centered on Jupiter taken during tests of DART’s SMART Nav system. DART was about 435 million miles (700 million kilometers) from Jupiter, and about 16 million miles (26 million kilometers) from Earth, when the image was taken. Two brightness and contrast stretches, made to optimize Jupiter and its moons, respectively, were combined to form this view. From left to right are Ganymede, Jupiter, Europa, Io and Callisto. Credit: NASA/Johns Hopkins APL.

Jupiter and Europa were only part of the extensive testing before last night’s event, involving thousands of pictures of stars. A successful impact was the result. Nice work by the DART team!

It will take time to determine how well the experiment worked, which means measuring the impact’s effect on the tiny asteroid, but the data will help enormously as we continue to assess strategies for adjusting the trajectory of any future objects that may pose a danger to the Earth. We’ll be getting imagery from the Italian LiciaCube spacecraft within days, and further information from ESA’s Hera mission, which will make follow-up studies at Didymos and Dimorphos in four years.

I’ve long believed that efforts like these, necessary to ensure planetary security, will be a powerful driver for space technologies going forward. The threat of a catastrophic collision with an asteroid is small, but the image below, likewise from JHU/APL, gives us a sense of the possibilities. I think of Arthur C. Clarke’s Rendezvous with Rama (1972), where an impact in 2077 causes catastrophic damage to parts of Europe, leading to the development of the protective system of technologies that eventually spots Rama, the enigmatic alien vessel entering our Solar System.

Let’s hope we’re far enough ahead in the game to have the technologies in place to avoid that kind of impact in the first place. DART is an early step in that direction.