NASA launches its Lucy spacecraft to study Jupiter Trojan asteroids

NASA's Lucy space probe successfully launched from Cape Canaveral in Florida early Saturday, beginning a 12-year mission to study Jupiter's Trojan asteroids.

The spacecraft took off at 5:34 a.m. ET aboard a United Launch Alliance Atlas V rocket. Lucy sent her first signal to Earth from her own antenna to NASA's Deep Space Network at 6:40 a.m. ET. Scientists believe that Trojan asteroids, which orbit the Sun along a path similar to Jupiter, may offer clues about the formation of our solar system. This is NASA's first single-spacecraft mission to explore so many different asteroids, the agency said.

Lucy is named for a fossilized human skeleton discovered in Ethiopia in 1974, which provided important insights into human evolution. The fossil gets its name from the Beatles song "Lucy in the Sky with Diamonds" where the diggers found it. NASA says the Lucy spacecraft will provide insight into our evolution the way its fossil counterpart did, only this time on a planetary scale.

Lucy is on a complex trajectory that will involve three trips toward Earth thanks to a gravity assist. First, Lucy will orbit the Sun and then return to Earth the following year for a gravity assist. It will accelerate and direct the craft's trajectory beyond the orbit of Mars, when Lucy heads back toward Earth again in 2024 for another gravity assist. This will help carry the craft to the Donaldjohansson asteroid in 2025; Lucy will then head to the incoming Trojan asteroids in 2027. Then, after four targeted fly-bys, Lucy will return to Earth in 2031 for a third gravity assist, which will propel it to the Trojans for another encounter in 2033.

"We started working on the Lucy mission concept in early 2014, so it took a long time to launch," said Hal Levison, Lucy's principal investigator from the Southwest Research Institute (SRI). "It will still take years for us to reach the first Trojan asteroid, but these objects are worth the wait and all the effort because of their enormous scientific value. They are like diamonds in the sky."