Mission engineers will observe NASA’s Lucy spacecraft nonstop because it prepares to swoop close to 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 might 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 alter the spacecraft’s trajectory.
Though an adjustment is unlikely, and collisions are uncommon, the probabilities 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 house particles 31 occasions since 1999, together with thrice since 2020.
“Low-Earth orbit is getting extra crowded, in order that needs to be a part of the consideration these days, particularly for missions that fly low, like Lucy,” mentioned Dr. Dolan Highsmith, chief engineer for the Conjunction Evaluation Threat Evaluation group at NASA’s Goddard House Flight Heart in Greenbelt, Maryland. The group determines the possibilities of collisions between NASA’s robotic spacecraft and Earth-orbiting objects. NASA’s Johnson House Heart in Houston does the identical for crewed spacecraft, such because the house 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 photo voltaic system, serving to scientists hone their theories on how the planets fashioned 4.5 billion years in the past and why they ended up of their present configuration.
However Lucy has a protracted option 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’ll cruise 220 miles (350 km) above the floor. That is decrease than the altitude of the house station and low sufficient that the spacecraft might 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 approach down, Lucy will fly by probably the most crowded layer of Earth’s orbit, which is monitored by the U.S. House Power’s 18th House Management Squadron. The squadron helps NASA establish shut approaches.
Engineers started collision evaluation for Lucy every week earlier than the spacecraft’s Earth method. Beginning the method any earlier would render collision predictions futile, Highsmith mentioned: “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, significantly 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 photo voltaic exercise is difficult to foretell. For instance, the Solar’s exercise — how a lot plasma and radiation it shoots out — impacts environment 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 Power squadron every day. If the squadron determines that Lucy might intersect with one thing, Highsmith’s group will calculate the chance of a collision and work with the mission staff to maneuver the spacecraft, if vital.
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 mentioned.
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 method to Earth up by 2 seconds or 4 seconds, respectively.
“That is sufficient to keep away from anyone factor that could possibly be in the best way,” mentioned Kevin E. Berry, Lucy’s flight dynamics staff lead from NASA Goddard.