NASA's Lucy launches to Trojan asteroids

5:34 AM Est atop an Atlas V in the 401 configuration from SLC-41 at CCSFS

Taking its name from the fossilized human remains of one of our ancestors whose skeletal remains provided insight into humanity’s evolution the Lucy Mission hopes to do the same with our solar system. This will be the first space mission to venture into and study the Trojans. Associated with the planet Jupiter, the swarm of Trojan asteroids are thought to be remnants of the primordial material which formed the outer planets, a time capsule from their birth so to speak. The Trojans orbit the Sun in two groups, one group ahead of Jupiter, leading directly in it’s path. The other trailing behind.

Launching this morning with a boost from Earth’s gravity the spacecraft has started it’s twelve year journey to eight different asteroids, one Main Belt asteroid, and seven of the Trojans. Lucy’s difficult path will take it to both clusters of the asteroid belt and give us the first close up look at all three of the major types of bodies in the clusters of asteroids (C-, P-, and D- types). There has been no other mission in history where so many destinations were on the agenda. Lucy will have to cross the solar system returning near Earth to use it’s gravitational pull to reach the far side of the Trojans, and for the first time show us the diversity of the primordial bodies that built the planets.

Lucy will use it’s tools to study the asteroids, some the size of cities, detailing their shapes, structures, surface features, composition and temperature. If the Trojans were made from the same materials as Jupiter’s moons, it would suggest they formed at the same distance from the sun, but this is not the expectation. It’s expected that the asteroids were made from the sort of materials seen much further out into space and later pulled into what is called the Kuiper Belt. The prevailing theory is that there was a big “re-juggle” of objects early on in our solar systems history, when some things gravitationally got thrown out of balance.

As long as the spacecraft remains healthy it will continue to loop through the swarms of asteroids. Though focused on the Trojans it will also visit a different type, an object called the Donald Johansson (named after the paleoanthropologist who discovered the Ethiopian Human remains named Lucy in 1974). The craft itself shares much of the same engineering as the NASA’s New Horizon’s Mission, which made the first and only flight by Pluto back in 2015. The biggest difference is the power source. New Horizons drew its power from a nuclear battery where Lucy is flying with two solar panels. Over seven meters in diameter they have to generate sufficient electricity to drive the spacecraft at the less lit depths of space of Jupiter’s orbit. When it’s near Earth the craft will have about 18,000 watts of power which is equivalent of powering up a few residential houses. When Lucy gets near Jupiter it will be down to about 500 watts of power, which is enough for a few lightbulbs, but not enough for a microwave to heat your coffee. This is no worry however as the spacecraft only needs 82 watts of power to do its job.

Launching atop an Atlas V in the 401 configuration Lucy was ready to go, and all systems were cleared for the mission to launch on the first attempt. A weather forecast of 90% was given hours before the T-Zero mark and held true through the night. Some low level clouds rolled into Cape Canaveral before the launch, but nothing significant enough to delay the launch. When the engines ignited, the moonless night lit up the surrounding area as onlookers were bathed in light as the rocket lifted higher and higher. For brief moments the flames were lost behind clouds would would reappear again until finally MECO (Main Engine Cut Off) was called out and the rocket’s first stage burn was complete. Launching on time this morning means Lucy will encounter her first asteroids of the Trojan system in the year 2027 or 2028, then reach the trailing cluster around the year 2033.