Everything you need to know about NASA's groundbreaking Lucy mission to explore Trojan asteroids

Star Trek fans have heard this ad nauseam, but space really is the final frontier — and the Trojan asteroids are one of the many final frontiers within it.

NASA’s Lucy mission is literally going where no spacecraft has gone before. It wouldn’t be science fiction to say that by venturing out to the Trojan asteroids, Lucy will be flying back in time to the emergence of the solar system over 4 billion years ago. The spacecraft was named after a prehistoric human skeleton that gave us insight into the evolution of homo sapiens like never before. The Trojans are the cosmic bones that will reveal more about the early solar system.

“There’s been a revolution in our ideas about how the solar system formed in the first 10 million years or so,” Hal Weaver, principal investigator for Lucy’s L’LORRI instrument, told SYFY WIRE. “Instead of the objects in the solar system being where they are now there was a lot of migration, which is the reason why we think we have such diversity in the Trojans.”

Lucy is not only going to be the first spacecraft ever to explore the Trojans, which lurk in Jupiter’s orbit, but also the first to perform flybys of eight asteroids and the solar-powered spacecraft to wander furthest from the Sun. There is a Trojan swarm ahead of Jupiter and one behind it. These leftovers of solar system formation may have been held there by Jupiter’s gravity for eons, but are actually further from the gas giant than they appear. Lucy will be flying by seven Trojan asteroids and one main belt asteroid after it reaches their vicinity in 2033.

The Trojans are around 5.05 and 5.35 AU from Jupiter. Just one AU (astronomical unit) is almost 93 million miles, so they aren’t exactly as close as a diagram would have you believe. They could also be made of just about anything. Some may be pieces of planets that never started to form but never made it. The early solar system was a dangerous place where just about everything was smashing into everything else. These collisions, along with gravitational forces, flung many objects far away from where they had formed; some were even ejected form the solar system.

“The Trojans are a collection of objects that probably formed at multiple distances from the Sun, and that is the primary reason why they are so interesting,” Weaver said.

It took years of planning and conceptualizing by some 500 scientists, engineers and other specialists, along with 14 intense months of building and testing, to bring Lucy into reality. 2.5 months were dedicated to final checks and hardware integration alone. The spacecraft has now been rolled out to its launchpad at Kennedy Space Center in Cape Canaveral, Florida, standing 4 stories high and weighing around 3,300 pounds (close to your average car). It will launch on the first day of its short window of opportunity; Saturday, October 16, at 5:34 a.m. ET.

How it works

On board Lucy is a suite of hypersensitive instruments that will allow it to observe the Trojans like never before. They were inspired by the New Horizons mission to Pluto and beyond, which also discovered the bizarre object known as Arrokoth, and the OSIRIS REx mission to the asteroid Bennu.

Lucy boasts impressive solar panels that will use sunlight to power it all the way to the Trojans. Its L’Ralph camera, an upgrade of New Horizons’ Ralph, is capable of multi-spectral imaging that can show what he asteroids are made of. It’s L’Lorri or Long Range Reconnaissance Imager was also inherited from New Horizons. This panchromatic camera will beam back incredibly detailed images. L’TES is the next generation of the OSIRIS Rex TES instrument, and will look into the properties of the Trojans to give those of us back on Earth more insight about their distant past.

Lucy will also be equipped with an advanced antenna, the High Gain Antenna, which will be able to tell how much mass an asteroid has by using radio signals. It also has another camera. The T2Cam is a terminal tracking camera that will image the asteroids with a wide field of view so their shapes can be better understood.

“There are lots of indicators about where objects formed in the solar system,” Lucy deputy principal investigator Cathy Olkin told SYFY WIRE. “Some ices are a great indicator that the Trojans formed further away, and so is density, but there is no single measurement that will tell us exactly. That’s why we need a suite of instruments.”

The mission will be in space for at least the next 12 years, possibly more, so long as the spacecraft remains healthy enough to perform repeated flybys of the Trojans. Even the pandemic was not enough to stop the determined Lucy team from getting this spacecraft off the ground. In space, it will experience several gravity assists from Earth’s orbit that will send it off to the Trojan swarms. That means drastic temperature changes. Lucy has undergone test after test to make sure it can withstand these extreme shifts, as well as the power of its own launch.

Like those fossilized human bones that are its namesake, Lucy will be looking back into the evolution of the solar system through the Trojans. What it finds could make us see our region of space like never before. It could even shatter and and rebuild previous assumptions about how objects formed during that primordial epoch and how that ended up impacting the only known star system in which any sort of life-forms actually exist.

“It is really all about putting together clues and getting all the data we can,” Lucy project scientist Keith Noll also told SYFY WIRE. “Some objects that formed early on got trapped in the Trojans, and we want evidence that supports or rejects hypotheses about them. That’s what we’re looking for.”