NASA’s Lucy spacecraft will swoop near Earth today Oct. 16 to use this planet’s gravity to set itself on a course toward the Jupiter Trojan asteroids.
Launched on Oct. 16, 2021, Lucy is on a 12-year-journey to study multiple Trojan asteroids up close. It’ll be the first spacecraft to visit these remnants from the early solar system, helping scientists hone their theories on how the planets formed 4.5 billion years ago and why they ended up in their current configuration.
When Lucy comes nearest to Earth for its first gravity assist it will cruise 220 miles (350 km) above the surface. That’s lower than the altitude of the space station and low enough that the spacecraft will be visible with the naked eye from western Australia for a few minutes starting at 6:55 p.m. local time (10:55 UTC). On its way down, Lucy will fly through the most crowded layer of Earth’s orbit, which is monitored by the U.S. Space Force’s 18th Space Control Squadron. The squadron helps NASA identify close approaches.
Lucy navigation engineers have two manoeuvre options ready in case the spacecraft needs to avoid an object. Both manoeuvres require engine burns to speed up the spacecraft, which is traveling about 8 miles (12 km) per second. Each manoeuvre can move Lucy’s closest approach to Earth up by 2 seconds or 4 seconds, respectively.
There are more than 47,000 satellites, debris, and other objects circling our planet.