NASA’s Lucy spacecraft has successfully completed its first gravity-assisted flyby of Earth, dodging tens of thousands of satellites and debris.
The probe is named for the incomplete female skeleton of an early human ancestor discovered in Ethiopia in 1974, which is more than three million years old. The spacecraft is on a 12-year mission to an even older type of relic: Jupiter’s Trojan asteroid. NASA described the rocks as “fossils of planet formation,” left over when the largest planets in the solar system began forming more than 4.5 billion years ago.
To get Lucy closer to the Trojans, Mission Control will have the spacecraft perform multiple gravity assists around Earth to get it on a path to Jupiter. NASA successfully completed the first on October 16. Lucy came just 351 kilometers from Earth’s surface, bringing it closer than most orbiting spacecraft, such as the International Space Station.
At those distances, Lucy faced a dangerous environment littered with more than 47,000 satellites, debris, and other objects orbiting the earth. Scientists had to monitor and track these pieces while predicting the spacecraft’s position to figure out how to avoid collisions. If the probability of impact with any of the objects was more than one in 10,000, Lucy’s trajectory had to be adjusted before the orbital burn.
The spacecraft managed to turn off gravity assist without hiccups. However, the team had to account for an increase in Earth’s atmospheric drag on the probe as it approached our planet: one of Lucy’s solar panels had failed to latch, forcing the spacecraft to fly by at a higher altitude.
“In the original plan, Lucy was supposed to fly about 30 miles (48 km) closer to Earth,” Rich Burns, Lucy’s project manager at NASA’s Goddard Space Flight Center, said in a statement.
“However, when it became clear that we might need to do this flyby using one of the solar arrays, we decided to use some of our fuel reserves to allow the spacecraft to pass Earth at a slightly higher altitude, thereby reducing the disruption to atmospheric pollution of the spacecraft’s solar arrays.”
The gravity assist with Earth increased Lucy’s speed and the spacecraft is now on a path to Mars. It must make a second support in 2024 to go to Jupiter. Lucy will fly past 52246 Donaldjohanson, an asteroid in the inner main belt of our planetary system, and then visit seven other Trojan asteroids during its 12-year journey.
Four of these rocks are binary systems, while the other three are dark red-type asteroids resembling Kuiper Belt objects beyond Neptune. These seven targets will give scientists a good representation of the three main C, P and D types of asteroids. Trojan asteroids are believed to be rich in dark carbon compounds and may contain water and other volatile substances.
“This is a unique opportunity,” said Harold Levison, senior investigator for the Lucy mission at the Southwest Research Institute in Boulder, Colorado. “Because the Trojans are remnants of the primordial material from which the outer planets were formed, they hold important clues to unlocking the history of the solar system. Lucy, like the human fossil it is named after, will revolutionize understanding of our origins.” ®
https://www.theregister.com/2022/10/17/nasas_lucy_spacecraft_successfully_dodged/ NASA’s Lucy successfully conducts a gravity-assisted Earth flyby • The Register