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NASA’s Lucy Days Away from Asteroid Encounter

NASA’s Lucy spacecraft will soon reach the small main belt asteroid Donaldjohanson. In this image, created by stacking images that the Lucy spacecraft took during its approach, the asteroid appears as a series of points in front of the static background of stars and galaxies. In addition to the asteroid brightening as the spacecraft approaches it, Donaldjohanson can also be seen to periodically brighten and dim on a roughly 10-day cycle. This indicates the asteroid is likely a slowly rotating elongated object, appearing brighter when its longer sides face the spacecraft.

Image of asteroid Donaldjohanson moving across the sky from Feb. 20 to April 5, 2025. The image was created from a series of stacked optical navigation images taken by the L'LORRI instrument on NASA's Lucy spacecraft. The sky is black with bright white dots of varying sizes scattered across. Asteroid Donaldjohanson appears in a slightly diagonal line going through the center of the image.
Stacked optical navigation images taken by the L’LORRI instrument from Feb 20 to April 5, 2025, as NASA’s Lucy spacecraft approaches the asteroid Donaldjohanson. 
Credit: NASA/Goddard/SwRI/Johns Hopkins APL

Using these and other images, the spacecraft navigation team has ensured that Lucy is on target for its closest approach of the asteroid at 1:51 pm EDT on Sunday, April 20. The spacecraft carried out a small trajectory correction maneuver April 13, changing the spacecraft’s velocity by an estimated 0.15 mph (6.9 cm/s) to precisely reach the planned aimpoint.

The team will remain in communication with the spacecraft until its autonomous tracking system is able to lock onto the asteroid, approximately 30 minutes before its closest approach. At that time, the spacecraft will use its terminal tracking system to rotate the spacecraft in order to keep the asteroid in the instruments’ field of view. This movement will also rotate the spacecraft’s antennae away from Earth, so communication with the ground team will pause. The spacecraft will reestablish contact with Earth in the hours after closest approach, though it will take up to a week to downlink the data collected during the encounter.