NASA’s Lucy to fly past thousands of objects for Earth gravity assist

Mission engineers will monitor NASA’s Lucy spacecraft nonstop because it prepares to swoop near Earth on Oct. 16 to make use of this planet’s gravity to set itself on a course towards the Jupiter Trojan asteroids.

However additionally they can be carefully monitoring one thing else: greater than 47,000 satellites, particles, and different objects circling our planet. A larger than 1-10,000 probability that Lucy will collide with one among these objects would require mission engineers to barely modify the spacecraft’s trajectory.

Though an adjustment is unlikely, and collisions are uncommon, the possibilities are growing because the variety of objects in Earth’s orbit grows, NASA specialists say.

The Worldwide House Station, as an example, has maneuvered out of the best way of space particles 31 occasions since 1999, together with thrice since 2020.

“Low-Earth orbit is getting extra crowded, in order that must be a part of the consideration these days, particularly for missions that fly low, like Lucy,” stated Dr. Dolan Highsmith, chief engineer for the Conjunction Evaluation Danger Evaluation group at NASA’s Goddard House Flight Middle in Greenbelt, Maryland. The group determines the chances of collisions between NASA’s robotic spacecraft and Earth-orbiting objects. NASA’s Johnson House Middle in Houston does the identical for crewed spacecraft, such because the space station.

Launched on Oct. 16, 2021, Lucy is on a 12-year-journey to review a number of Trojan asteroids up shut. It’s going to be the primary spacecraft to go to these remnants from the early solar system, serving to scientists hone their theories on how the planets shaped 4.5 billion years in the past and why they ended up of their present configuration.

However Lucy has a protracted method to go earlier than it arrives on the Trojans in 2027. The upcoming gravity help is one among three the spacecraft will depend on to catapult itself to its deep-space targets.

When Lucy comes nearest to Earth for its first gravity help it would cruise 220 miles (350 km) above the floor. That is decrease than the altitude of the space station and low sufficient that the spacecraft can be seen with the bare eye from western Australia for a couple of minutes beginning at 6:55 p.m. native time (10:55 UTC). On its means down, Lucy will fly via probably 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 establish shut approaches.

Engineers started collision evaluation for Lucy per week earlier than the spacecraft’s Earth strategy. Beginning the method any earlier would render collision predictions futile, Highsmith stated: “The additional you are predicting into the longer term, the extra unsure you’re about the place an object goes to be.”

Figuring out the positions of spacecraft, plus orbiting satellites and particles, is difficult, notably when attempting to anticipate the longer term. Largely that is as a result of the Solar performs a significant function in pulling or pushing objects round, and future solar exercise is tough to foretell. For instance, the Solar’s exercise—how a lot plasma and radiation it shoots out—impacts ambiance density, and thus how a lot friction will tug on a spacecraft and gradual it down.

So the nearer the collision evaluation is to the Earth flyby time, the higher. NASA sends Lucy’s whereabouts to the House Pressure squadron day by day. If the squadron determines that Lucy may intersect with one thing, Highsmith’s group will calculate the likelihood of a collision and work with the mission crew to maneuver the spacecraft, if mandatory.

With such a excessive worth mission, you actually need to just be sure you have the potential, in case it is a unhealthy day, to get out of the best way,” Highsmith stated.

Lucy navigation engineers have two maneuver choices prepared in case the spacecraft must keep away from an object. Each maneuvers require engine burns to hurry up the spacecraft, which is touring about 8 miles (12 km) per second. Every maneuver can transfer Lucy’s closest strategy to Earth up by 2 seconds or 4 seconds, respectively.

“That is sufficient to keep away from anybody factor that could possibly be in the best way,” stated Kevin E. Berry, Lucy’s flight dynamics crew lead from NASA Goddard.