Mission engineers will monitor 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 will likely be carefully monitoring one thing else: greater than 47,000 satellites, particles, and different objects circling our planet. A higher than 1-10,000 likelihood 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 possibilities are growing because the variety of objects in Earth’s orbit grows, NASA consultants say.
The Worldwide Area Station, as an example, has maneuvered out of the way in which of area 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,” mentioned Dr. Dolan Highsmith, chief engineer for the Conjunction Evaluation Threat Evaluation group at NASA’s Goddard Area Flight Middle in Greenbelt, Maryland. The group determines the chances of collisions between NASA’s robotic spacecraft and Earth-orbiting objects. NASA’s Johnson Area Middle in Houston does the identical for crewed spacecraft, such because the area station.
Launched on Oct. 16, 2021, Lucy is on a 12-year-journey to check 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 approach 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 area station and low sufficient that the spacecraft will likely 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 manner down, Lucy will fly by means of probably the most crowded layer of Earth’s orbit, which is monitored by the U.S. Area Drive’s 18th Area 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 long run, 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 long run. Largely that is as a result of the Solar performs a serious position 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 Area Drive 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 group to maneuver the spacecraft, if essential.
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 way in which,” 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 anybody factor that may very well be in the way in which,” mentioned Kevin E. Berry, Lucy’s flight dynamics group lead from NASA Goddard.
