NASA's Lucy spacecraft will skim the Earth's atmosphere, passing a mere 220 miles above the surface. The flyby is scheduled for Oct. 16, which marks the first anniversary of its launch.
NASA Lucy to Flyby on Earth
According to Phys.org, by swinging past Earth, Lucy will gain some of the orbital energy it needs to travel to this never-before-visited population of asteroids. The spacecraft is the first mission to the Jupiter Trojan asteroids.
The Trojan asteroids are trapped in orbits around the sun at the same distance as Jupiter, either far ahead of or behind the giant planet.
Lucy's Twelve-Year Voyage
Currently, Lucy has almost completed its first year of its twelve-year voyage. The spacecraft will be placed on a new trajectory for a two-year orbit. At this point, Lucy will come back to Earth for a second gravity assist. With the help of this second assistance, Lucy will have the energy necessary to traverse the main asteroid belt and observe the asteroid Donaldjohanson.
Eurybates and its satellite Queta, Polymele and its unnamed satellite Leucus, and Orus are three of the six Trojan asteroids that Lucy will fly past, according to Space.com. To re-target the spacecraft for a rendezvous with the binary asteroid pair Patroclus-Menoetius in the trailing Trojan asteroid swarm, Lucy will then make a third gravity-assistance trip to Earth in 2030.
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NASA Lucy's First Gravity Assist
Lucy will appear to be traveling toward Earth from the direction of the sun for this first gravity assist. As a result, Lucy will not be visible to observers on Earth in the days leading up to the event. The nearly full moon and Earth will be visible in images taken by Lucy. These images will be used by mission scientists to calibrate the instruments.
Due to Lucy's trajectory, it will pass very close to Earth. It will be lower than the International Space Station. It implies that Lucy will pass through an area populated by debris and satellites in Earth's orbit. NASA created procedures to foresee any potential threat and, if necessary, carry out a small maneuver to avoid a collision in order to ensure the safety of the spacecraft.
According to Coralie Adam, Lucy deputy navigation team chief at KinetX Aerospace in Simi Valley, California, said that the Lucy team has prepared two distinct maneuvers. The spacecraft will carry out one of these maneuvers 12 hours prior to its closest approach to Earth if the team determines that Lucy is in danger of colliding with a satellite or piece of debris, which will move the closest approach time by two or four seconds. Even though this is a minor adjustment, it is sufficient to prevent a potentially disastrous collision.
Rich Burns, Lucy project manager at NASA's Goddard Space Flight Center in Greenbelt, Maryland said that in the original plan, the spacecraft was actually going to pass about 30 miles closer to the Earth.
However, they realized that they might have to execute the flyby with one of the solar arrays unlatched. So they chose to use a bit of the fuel reserves to make it possible for the spacecraft to pass the Earth at a slightly higher altitude. This will reduce the disturbance from the atmospheric drag on the solar arrays of Lucy.
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