NASA’s asteroid-smashing DART mission snapped a photo of Jupiter and its four largest moons to test the autonomous navigation system that will guide the spacecraft to an asteroid collision next week.
The image, released by NASA on Tuesday (September 20), was actually taken in the summer when ARROW was about 16 million miles (26 million kilometers) away Earth and is cruising toward its destination, the binary asteroid system of Didymos and Dimorphos. DART operators used Jupiter and its four Galilean moons to validate how close together objects appear to the DRACO camera, which is DART’s sole instrument and the heart of DART’s Small-Body Maneuvering Autonomous Real Time Navigation (SMART Nav) system.
The team focused specifically on Jupiter’s moon Europethe moon closest to Jupiter on the right side of the planet in the image that DRACO visually observed separately from that gas giant while DART traveled. Similarly, the small asteroid Dimorphos separates from the larger Didymos it orbits during DART’s final approach to crash into Dimorphos. Conducted on July 1st and August 2nd, the test on Europa was the first validation of DRACO’s capabilities in space.
Related: NASA’s DART mission to hit an asteroid will be a key test of planetary defenses
“The Jupiter tests gave us an opportunity for DRACO to image something in our own solar system,” Carolyn Ernst, DRACO instrument scientist at Johns Hopkins University’s Applied Physics Laboratory (APL), which is leading the mission, said in a NASA statement expression (opens in new tab). “The images look fantastic and we can’t wait to see what DRACO will reveal about Didymos and Dimorphos in the hours and minutes leading up to impact!”
The team analyzed the intensity of the objects and the number of pixels each object occupied in the image as it moved across the field of view. (The image shows, from left to right, Ganymede, Jupiter, Europa, Io, and Callisto.)
The DRACO camera, which is based on technology originally developed for the New Horizons Mission that explores Pluto, DART will lead to Dimorphos fully autonomously, NASA officials wrote in the statement. The ground control team may only intervene in the event of “significant and mission-threatening deviations from expectations,” NASA said. Optimizing camera performance therefore helps teams to better interpret the situation just before impact.
“Every time we run one of these tests, we tweak the displays, make them a little bit better and a little bit more responsive to what we’re actually going to be looking for during the real terminal event,” Peter Ericksen, SMART Nav Software Engineer at APL said in the NASA statement.
DART will impact Dimorphos on Monday (September 26) in a unique experiment designed to alter the orbit of a celestial body. The intent is to slightly accelerate Dimorphos’ orbit around Didymos, a technique that could one day be used to protect Earth from a threatening space rock.
Coincidentally, on Sunday (September 25) Jupiter makes his closest approach to Earth in 59 years. And on the day of DART’s impact, the planet is directly on the opposite side of Earth from the Sun, in what astronomers call opposition. The combination means skygazers don’t need a spacecraft to get stunning views of the gas giant, just binoculars or a telescope.