NASA’s Lucy spacecraft is about to zoom past Earth

This gravity assist will place Lucy on a new trajectory for a two-year orbit, at which time it will return to Earth for a second gravity assist. This second assist will give Lucy the energy it needs to cross the main asteroid belt, where it will observe asteroid Donaldjohanson, and then travel into the leading Trojan asteroid swarm. There, Lucy will fly past six Trojan asteroids: Eurybates and its satellite Queta, Polymele and its yet unnamed satellite, Leucus, and Orus. Lucy will then return to Earth for a third gravity assist in 2030 to re-target the spacecraft for a rendezvous with the Patroclus-Menoetius binary asteroid pair in the trailing Trojan asteroid swarm.

NASA’s Lucy spacecraft will make an exceptionally close flyby of Earth on October 16, 2022. Photo credit: NASA’s Goddard Space Flight Center

For this first gravity assist, Lucy appears to be approaching Earth from the direction of the Sun. While this means observers on Earth won’t be able to see Lucy in the days leading up to the event, Lucy will be able to take pictures of the nearly full Earth and moon. Mission scientists will use these images to calibrate the instruments.

Lucy’s trajectory will bring the spacecraft very close to Earth, even lower than the International Space Station (ISS), meaning Lucy will pass through a region full of Earth-orbiting satellites and debris. To ensure spacecraft safety, NASA has developed procedures to anticipate potential hazards and, if necessary, perform a small maneuver to avoid a collision.

“The Lucy team prepared two different maneuvers,” said Coralie Adam, deputy leader of the Lucy navigation team at KinetX Aerospace in Simi Valley, California. “If the team determines that Lucy is in danger of colliding with a satellite or a piece of debris, the spacecraft will – 12 hours before closest approach to Earth – execute one of them, shifting the time of closest approach by either two or four seconds.” . This is a small correction, but it is enough to avoid a potentially catastrophic collision.”

Illustration of the Lucy spacecraft near a large asteroid with Jupiter in the distant background. Photo credit: Southwest Research Institute

Lucy will pass Earth at such a low altitude that the team had to take the effect of atmospheric drag into account when designing this flyby. Lucy’s large solar arrays amplify this effect.

“The original plan was for Lucy to fly about 30 miles closer to Earth,” says Rich Burns, Lucy project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “However, when it became clear that we might need to do this flyby using one of the solar arrays, we decided to use some of our fuel reserves to allow the spacecraft to pass Earth at a slightly higher altitude, thereby reducing the disruption to atmospheric pollution of the spacecraft’s solar arrays.”

At approximately 6:55 am EDT, Lucy will be visible for the first time to ground observers in Western Australia (6:55 pm for those observers). Lucy will fly quickly overhead and be clearly visible to the unaided eye for a few minutes before disappearing at 7:02 a.m. EDT as the spacecraft enters Earth’s shadow. Lucy will continue flying in the dark over the Pacific Ocean, emerging from Earth’s shadow at 7:26 am EDT. If the clouds cooperate, skywatchers in the western US should be able to see Lucy with the help of binoculars.

The trajectory of Lucy during the Earth flyby as seen from above the Earth’s North Pole, a red dot every 10 minutes. Location at some key times shown in white. Photo credit: SWRI

“The last time we saw the spacecraft, it was encased in the payload fairing in Florida,” said Hal Levison. He is the Lucy Principal Investigator at the Southwest Research Institute (SwRI) office in Boulder, Colorado. “It’s exciting to be able to stand here in Colorado and see the spacecraft again. And this time Lucy will be in heaven.”

Lucy will then quickly pull out of near Earth, sweep past the Moon and take a few more calibration images before heading out into interplanetary space.

“I’m particularly excited about the final images Lucy will be taking of the moon,” said John Spencer, associate project scientist at SwRI. “Counting craters to understand the collision history of the Trojan asteroids is key to the science that Lucy will be conducting, and this will be the first opportunity to calibrate Lucy’s ability to detect craters by comparing them with previous observations of the Moon.” compared by other space missions.”

Ride-along view of Lucy’s first Earth Gravity Assist (EGA). The camera follows Lucy as the spacecraft approaches the sunlit side of Earth before fading into Earth’s shadow as it tumbles around the planet. Photo credit: NASA Scientific Visualization Studio

The public is invited to participate in the #WaveToLucy social media campaign by posting pictures of yourself waving at the spacecraft and tagging the @NASASolarSystem account. Also, if you are in an area where Lucy will be visible, take a picture of Lucy and post it on social media with the hashtag #SpotTheSpacecraft. For instructions on how to watch Lucy from your location, click here.

Hal Levison of the Southwest Research Institute (SwRI) in its Boulder, Colorado office is the lead investigator. Headquartered in San Antonio, SwRI also leads the science team and the mission’s scientific observation planning and data processing. NASA Goddard provides all mission management, systems engineering, safety and mission assurance for Lucy. Lockheed Martin Space of Littleton, Colorado built the spacecraft, primarily designing the orbit and providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the Lucy spacecraft. Lucy is the thirteenth mission in NASA’s Discovery program managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama.