NASA’s DART Spacecraft To Smash Into Target Asteroid

NASA’s Double Asteroid Redirection Test (DART) spacecraft recently acquired its first image of Didymos, the double-asteroid system that includes its target, Dimorphos. On September 26, DART will purposefully collide with Dimorphos, the moonlet of the asteroid Didymos. This is humanity's first attempt to use a spacecraft to deflect an asteroid for planetary defense, even though the asteroid poses no threat to Earth. This composite of 243 photos taken on July 27, 2022, by the Didymos Reconnaissance and Asteroid Camera for Optical Navigation (DRACO) aboard DART shows the light from the asteroid Didymos and its orbital moonlet Dimorphos. The Didymos system is still quite weak from this distance—roughly 20 million miles from DART—and navigation camera scientists weren't sure if DRACO would be able to see the asteroid yet. However, by combining the 243 images that DRACO captured during this observation series, the team was able to improve it and discover Didymos and identify its precise location. Elena Adams explained that "this initial collection of photos is being utilized as a test to establish our imaging techniques." She works as the DART mission systems engineer at the Laurel, Maryland-based Johns Hopkins Applied Physics Laboratory (APL). The image quality is comparable to that which we could obtain from ground-based telescopes, but it is crucial to demonstrate that DRACO is operating correctly and seeing its target in order to make any necessary adjustments before using the images to guide the spacecraft into the asteroid autonomously. The team has already carried out a number of navigation simulations using non-DRACO photos of Didymos. However, DART's ability to direct the spacecraft toward the asteroid, particularly in the final four hours before impact, will ultimately rest on its capacity to view and interpret photographs of Didymos and Dimorphos, once it too can be detected. DART will then need to independently self-navigate in order to successfully impact with Dimorphos without any assistance from humans. “Seeing the DRACO images of Didymos for the first time, we can iron out the best settings for DRACO and fine-tune the software,” said Julie Bellerose, the DART navigation lead at NASA’s Jet Propulsion Laboratory in Pasadena, California. “In September, we’ll refine where DART is aiming by getting a more precise determination of Didymos’ location.” The DART team will carry out three trajectory correction procedures over the following three weeks using observations made every five hours. Each of them will further limit the spacecraft's needed impact trajectory's margin of error. The navigation crew will be able to pinpoint the target Dimorphos within two kilometers after the final maneuver on September 25, roughly 24 hours before impact (1.2 miles). DART will then be left to maneuver itself to intercept the asteroid moonlet on its own. DART will collide with Dimorphos at a speed of 4 miles per second (7 km/h). Following that, Didymos was spotted by DRACO on August 12, August 13, and August 22 during scheduled observations. The DART mission is managed by the Johns Hopkins Applied Physics Laboratory (APL) for NASA's Planetary Defense Coordination Office as a project of the office's Planetary Missions Program. DART, the first planetary defense test mission ever, deliberately impacts Dimorphos in order to gently alter its path through space. The DART mission will show that a spacecraft can travel to a kinetic impact on a relatively tiny asteroid autonomously and that this is a possible method to divert an asteroid from colliding with Earth if one is ever discovered, even though the asteroid poses no threat to Earth. The target date for DART is September 26, 2022.