Team members of NASA’s Double Asteroid Redirection Test (DART) have filled the spacecraft with fuel, have performed many of the final tests, and are running rehearsals as they approach DART’s scheduled launch on Nov. 23.
DART will be the world’s first planetary defense test mission, heading for the small moonlet asteroid Dimorphos, which orbits a larger companion asteroid called Didymos, and intentionally crashing into the asteroid to slightly change its orbit. While neither asteroid poses a threat to Earth, DART’s kinetic impact will prove that a spacecraft can autonomously navigate to a target asteroid and kinetically impact it. Then, using Earth-based telescopes to measure the effects of the impact on the asteroid system, the mission will enhance modeling and predictive capabilities to help us better prepare for an actual asteroid threat should one ever be discovered.
“DART will be the first demonstration of the ‘kinetic impactor’ technique in which a spacecraft deliberately collides with a known asteroid at high speed to change the asteroid’s motion in space,” said Lindley Johnson, NASA’s Planetary Defense Officer. “This technique is thought to be the most technologically mature approach for mitigating a potentially hazardous asteroid, and it will help planetary defense experts refine asteroid kinetic impactor computer models, giving insight into how we could deflect potentially dangerous near-Earth objects in the future.”
Over the last year and a half, while following pandemic health and safety protocols, engineers built DART from a collection of parts to a fully assembled spacecraft. Engineers outfitted the spacecraft with the various technologies that the mission will test, including NASA’s NEXT-C ion propulsion system that was designed to improve performance and fuel efficiency for deep-space missions, and a flat, slotted high-gain antenna for efficient communication between Earth and the spacecraft.
During the summer and early September, engineers installed the spacecraft’s onboard camera DRACO (its only instrument), its two roll-out solar arrays that each unfurl to 28 feet, and the Italian Space Agency’s miniature satellite LICIACube that is designed to capture images of DART’s kinetic impact and its immediate aftereffects.
“It’s a miracle what this team has accomplished, with all of the obstacles in the way like COVID and the development of so many new technologies,” said Elena Adams, DART mission systems engineer at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland. “But the reason why we succeeded so far is because our team is excited, extremely sharp, and they genuinely want to show that if an asteroid was coming toward Earth, we could prevent a catastrophe.”
The spacecraft arrived at Vandenberg Space Force Base (VSFB) near Lompoc, California, in early October after a cross-country drive. DART team members have since been preparing the spacecraft for flight, testing the spacecraft’s mechanisms and electrical system, wrapping the final parts in multilayer insulation blankets, and practicing the launch sequence from both the launch site and the mission operations center at APL.
DART headed to the SpaceX Payload Processing Facility on VSFB on Oct. 26. Two days later, the team received the green light to fill DART’s fuel tank with roughly 110 pounds (50 kilograms) of hydrazine propellant for spacecraft maneuvers and attitude control. DART also carries about 130 pounds (60 kilograms) of xenon for the NEXT-C ion engine. Engineers loaded the xenon before the spacecraft left APL in early October.
Starting on Nov. 10, engineers will “mate” the spacecraft to the adapter that stacks on top of the SpaceX Falcon 9 rocket. A day before launch, the rocket will roll out of the hangar and onto the launch pad at Space Launch Complex 4 East (SLC-4E), where it will propel the spacecraft into space and kick off DART’s journey to the Didymos system.
“I’m both amazed and grateful that DART has gone from a twinkle in the eye to a spacecraft in final preparation for launch within 11 years,” said Andy Cheng, DART investigation team lead at APL and the one who came up with the idea of DART. “What made it possible was a great team that overcame all the challenges of building a spacecraft to do something never done before.”
DART’s first launch opportunity is scheduled for Nov. 23 at 10:20 p.m. PST. If weather or other issues prevent a launch on the first night, the team will have an additional opportunity to launch the next day. If necessary, subsequent launch attempts can take place through February 2022.