Next Monday, NASA will issue its first attempt at modifying the orbit of an asteroid, a capability that will be critical if we detect an asteroid that poses a collision threat with Earth. The planetary defense effort is centered around a craft called DART, for Double Asteroid Redirection Test, which will target a small asteroid called Dimorphos that orbits the larger 65803 Didymos, forming a binary system. If all goes according to plan, DART will be headed for a head-on collision that will slow down Dimorphos, upsetting its orbit around Didymos. NASA has repeatedly stressed that there is no way the asteroid or any material released from the collision poses a threat to Earth.
Ars will be in mission control at the Johns Hopkins Applied Physics Laboratory (APL) for the planned collision, which will also be broadcast live on NASA’s YouTube channels. While we’ll know right away if the collision went as planned, it may be several months before we’re sure Dimorphos’s orbit was successfully altered.
To prepare you for Monday’s festivities, we’ve compiled information about the DART mission and planned follow-up observations.
DART and its final approach
The DART spacecraft itself weighs just over 600kg and is notable primarily for its lack of instruments. Its solar arrays include an experimental concentrating solar cell that takes up less space to generate the same amount of power as existing space hardware, and its main transmitter is testing a new antenna configuration. Its ion engine is also a next-generation evolution of previous NASA hardware.
But all the action is handled through a single camera, the Didymos Asteroid and Reconnaissance Camera for Optical Navigation, or DRACO, a 2,560×2,160-pixel single-color camera. DRACO and the transmission hardware are capable of sending an image to Earth every second. During its final approach to Didymos, DART will be far enough away that round-trip transmissions will take more than a minute. As such, the asteroid’s final approach and orientation will be handled by an onboard navigation system called SMART Nav (Small-Body Maneuvering Real-Time Autonomous Navigation).
Right now, Dimorphos is so small that DRACO can’t figure it out and will stay that way until about an hour and a half before impact. As described by Evan Smith, DART’s deputy mission system engineer, the system will switch to onboard navigation approximately four hours before impact, with SMART Nav tracking the larger Didymos and using it for navigation until approximately 50 minutes before impact. of the collision. or about half an hour after it can be resolved. 2.5 minutes before the collision, the ion engine will shut down and DART will enter a collision at about 6 kilometers per second.
Although Dimorphos is only about 120 meters wide, it will completely fill the view from DRACO about two minutes before the collision. “We don’t know what Dimorphos looks like,” said APL planetary scientist Nancy Chabot. “This will be the first time we’ve seen what this asteroid looks like.” In the final image, sent back a second before impact, it will resolve features that are only tens of centimeters wide, according to Chabot.
And then if all goes well, the transmissions will stop.
