A spacecraft named Lucy is on its way to a part of space that’s never been explored after being rocketed into the sky from Cape Canaveral before Saturday’s sunrise.
The probe launched on time at 5:34 a.m. aboard United Launch Alliance’s Atlas V rocket, beginning a 4-billion-mile journey to explore the Trojans, two clusters of asteroids that lead and trail Jupiter, stuck in its orbit around the sun. The mission will span 12 years, during which Lucy will visit seven Trojan asteroids, hoping to find clues to the solar system’s formation.
Although the asteroids are fixed in Jupiter’s orbit, scientists don’t believe they’ve always been there, explained Hal Weaver, a principal investigator from Johns Hopkins University who worked on the $981 million mission.
Like the hominid fossil the Lucy spacecraft is named after, the Trojans are “fossils,” so to speak, fragments leftover from when the outer planets formed. Scientists hypothesize they could be from all over the solar system, scattered around by the gravitational pulls of Saturn, Uranus and Neptune during the earliest days of the solar system billions of years ago.
“The giant planets came in toward the sun and back out again, really mixing everything up. That’s the reason why we think we have such diversity in the Trojans. It collected in these gravitational ruts, so to speak, objects that formed in multiple different distances from the sun,” Weaver said. “That’s the primary reason why the Trojans are so interesting.”
Lucy won’t touch down or gather samples from any of the asteroids, but this first scout mission will take high-resolution photos and collect data about their surfaces, their composition temperate, density and mass, which NASA will use to determine their ages and origins.
The spacecraft, which weighs about 3,300 pounds and is about the size of the car, will come within 500 miles of the targeted asteroids and use a set of cameras and telescopes. It is similar to the ones on NASA’s New Horizons probe that flew by Pluto and the OSIRIS-REx probe that recently touched down on the asteroid Bennu.
“There are lots of indicators about where objects formed in the solar system,” Cathy Olkin, deputy principal investigator from the Southwest Research Institute. “So if were to, say, look inside a fresh crater, a crater that’s less than 100 million years old, and we were to see specific ices, that would be a great indicator that the Trojan asteroids formed further away (from the sun).”
But it will be a long time before Lucy reaches the first Trojan asteroid, and to get there the spacecraft will have to pull off a complicatedly precise flight plan consisting of three and a half wild loops around the sun to fling it in the right direction.
First, it’ll perform fly-bys of the Earth in 2022 and 2024 to pick up speed, slingshotting the spacecraft out to the leading cluster of asteroids, Eurybates, Polymele, Leucus and Orus. It’ll reach Eurybates, the largest of the seven asteroids, in 2027.
Six years and one more gravity assist from Earth later, Lucy will arrive at the trailing cluster of asteroids, which includes Patroclus, Menoetius and Queta, stopping by the last one in 2033.
Never has a mission attempted to travel so far into space using only solar power instead of nuclear energy. Without those boosts from Earth, it would require five times the fuel to pull off the mission, making it unfeasible.
cglenn@orlandosentinel.com
