NASA’s Lucy spacecraft skimming Earth’s atmosphere today!
Lucy’s second slingshot of Earth. The Lucy spacecraft will perform its second Earth gravity assist on December 12, 2024. Video via NASA Goddard.
- Our planet Earth will give NASA’s Lucy spacecraft its 2nd gravity assist today (December 12, 2024). This close flyby will give Lucy a boost, placing it on a new trajectory that’ll carry the spacecraft through the main asteroid belt and out to Jupiter’s Trojan asteroids.
- Observers in the Hawaiian Islands might be able to catch a glimpse of Lucy as the spacecraft approaches Earth, before it passes into Earth’s shadow. Lucy will then be visible to observers with a telescope in western regions of Africa and eastern regions of South America.
- Lucy’s next encounter will be with asteroid Donaldjohanson on April 20, 2025.
This article by Erin Morton was published originally at the NASA Lucy Mission blog. Edits by EarthSky.
NASA’s Lucy spacecraft prepares for 2nd Earth gravity assist
On Thursday, December 12, at 11:15 p.m. EST (04:15 UTC on Dec. 13), NASA’s Lucy spacecraft, currently in a two-year orbit around the sun, will skim Earth’s atmosphere. It will pass only about 220 miles (350 kilometers) above the surface. This close flyby will result in a gravity assist. This puts the spacecraft on a new trajectory that travels through the main asteroid belt and out to the never-before-explored Jupiter Trojan asteroids.
Trojans orbit the sun at the same distance as Jupiter.
This 2nd Earth gravity assist occurs three years into the Lucy spacecraft’s 12-year voyage. Its 1st gravity assist was on October 16, 2022, one year after launch. It boosted the spacecraft from an initial one-year orbit onto the present two-year orbit. That orbit reached into the inner limits of the main asteroid belt.
This enabled Lucy’s 1st asteroid encounter, with the small asteroid Dinkinesh and its satellite Selam.
Through the asteroid belt and on to the Trojans
Then, the upcoming gravity assist will boost the spacecraft into a six-year orbit. That one that will carry Lucy through the main asteroid belt (where it will fly past the asteroid Donaldjohanson). It will then go into the Trojan asteroid swarm that leads Jupiter in its orbit, for the 1st Trojan asteroid encounter in 2027.
Lucy spacecraft’s approach invisible in the glare of the sun
During the gravity assist, the Lucy spacecraft, from Earth’s perspective, will approach from the direction of the sun. This means that observers on Earth will not be able to see Lucy approaching, as it will be lost in the sun’s glare. Lucy’s trajectory will bring the spacecraft very close to the Earth. In fact, it will be even lower in altitude than the International Space Station.
Also, to ensure the safety of the spacecraft as it passes through this region full of Earth-orbiting satellites and debris, NASA has procedures to anticipate and avoid potential collisions. If needed, the spacecraft will execute a small trajectory correction maneuver 12 hours before closest approach. This will alter the time of closest approach by one or two seconds, enough to avoid a potential collision.
Probe might be visible in early evening for Hawaiians
Shortly after sunset, keen observers in the Hawaiian Islands may be able to catch a glimpse of Lucy as the spacecraft approaches Earth before it passes into Earth’s shadow at 6:14 p.m. HST (04:14 UTC on December 13). Lucy will speed over the continental U.S. in darkness, travelling over 33,000 miles per hour (14.8 kilometers per second). It will then emerge from Earth’s shadow 20 minutes later at 11:34 p.m. EST (04:34 UTC).
At that time, Lucy may be visible to observers with a telescope in the western regions of Africa and the eastern regions of South America. Sunlight reflects off the spacecraft’s large solar panels (observers in the eastern United States will be looking at the much dimmer “back” side of the solar panels, making Lucy harder to see. Go here for more information about observing Lucy during this gravity assist). Lucy will then rapidly recede from Earth and return to interplanetary space. The gravity assist increased the spacecraft’s speed with respect to the sun by over 16,000 miles per hour (7.2 kilometers per second).
During the 1st Earth gravity assist in 2022, the spacecraft imaged the Earth and the moon as part of an instrument calibration. As no further calibrations are needed at this time, the instruments will be off during this encounter. Lucy’s next asteroid encounter will be with the small main belt asteroid Donaldjohanson on April 20, 2025.
Bottom line: The Lucy spacecraft will make a close approach to Earth today. Its six-year mission will carry it through the main asteroid belt and into the orbit of Jupiter.
Read more: Lucy spacecraft update: And then there were 3!
The post NASA’s Lucy spacecraft skimming Earth’s atmosphere today! first appeared on EarthSky.