NASA’s Lucy spacecraft says hello to Earth en route to study Trojan asteroids

A year after launch, NASA’s Lucy spacecraft flew past Earth capturing images of our home planet as it continued a 12-year journey to study asteroids thought to be fossils in our solar system.

Lucy will perform three flybys of Earth, each providing a gravitational boost into deep space to study a group of objects known as the Trojan asteroids. These asteroids are made of the same materials as the giant planets of our solar system: Jupiter, Saturn and Uranus.

Associated with Jupiter because the asteroids are on the same orbital path, two groups of Trojan asteroids are hurtling past Jupiter and trailing behind the gas giant.

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Lucy was named after fossils found in Ethiopia in 1974. The skeleton, one of the oldest known ancestors of man, was named after the Beatles song “Lucy In The Sky With Diamonds” after a night of celebrating discovery while listening to the band’s songs. .

United Launch Alliance successfully launched Lucy into orbit just before sunrise on October 16, 2021, launching the Atlas V rocket from Cape Canaveral Space Force Station in Florida.

According to NASA, Lucy flew past Earth a year later, coming close to 220 miles above the surface. This maneuver launches Lucy into space into a two-year orbit before the spacecraft returns for a second gravity assist. The spacecraft will encounter its first Trojan asteroids in 2027 before a final slingshot by Earth in 2030.

The close encounter was a chance for Lucy’s team on Earth to calibrate the spacecraft’s instruments by photographing Earth and the Moon. The images were taken by Lucy’s Terminal Tracking Camera (T2CAM) system, a pair of cameras operated by Lockheed Martin that would later track Trojan asteroids during Lucy’s encounters.

On October 13, 2022, NASA’s Lucy spacecraft captured this image of the Earth and Moon from a distance of 890,000 miles with the Lucy Terminal Tracking Camera System (T2CAM), a pair of identical cameras that are responsible for tracking asteroids. The T2CAM system was designed, built and tested by Malin Space Science Systems; Lockheed Martin has integrated the T2CAMs on the Lucy spacecraft and operates them. (Image: Credit: NASA/Goddard/SwRI)

Lucy’s body is about the size of a large freezer and has two massive solar wings spread out 24 feet each to power the mission. However, shortly after launch NASA engineers discovered that one of Lucy’s wings was not opening properly and crews had to fix the problem. The wing is now open about 355 degrees over 360 degrees, but even the small difference meant changing Lucy’s game plan for the ground sling.

“In the original plan, Lucy was actually going to pass about 30 miles closer to Earth,” said Lucy’s project manager, Rich Burns, of NASA’s Goddard Space Flight Center. “However, when it became clear that we might have to execute this flyby with one of the solar panels unlocked, we elected to use some of our fuel reserves to have the spacecraft pass Earth at an altitude slightly higher, reducing atmospheric drag disturbance on the spacecraft’s solar panels.”

Lucy’s trajectory took the spacecraft through a crowded area in low Earth orbit full of satellites and debris. The team prepared two different maneuvers in case Lucy was in danger of colliding with space junk. About 12 hours before the closest approach, the spacecraft executed one of the maneuvers to avoid any potentially catastrophic collision.

A graph shows the distribution of space debris around the Earth. Credits: European Space Agency

Lucy’s Earth photo happens to include Hadar, Ethiopia, home to the 3.2 million year old fossils the spacecraft was named for.

Lucy’s flyby of Earth was closer than the orbit of the International Space Station and was even visible to people on Earth in Western Australia and parts of the United States.