NASA’s Lucy mission puts Hal Levison ’81 on a collision course with Jupiter’s Trojan Asteroids. Can it unlock the earliest secrets of our solar system?
How do you build a spacecraft that will attempt to answer questions about the earliest history of our solar system?
Hal Fromberg Levison ’81, a renowned planetary scientist, is in the process of finding out. Levison is the principal investigator for one of two projects recently selected by NASA that have the potential to unlock secrets about the formation and evolution of giant planets—a process occurring less than 10 million years after the birth of the sun. His mission, titled “Lucy,” will perform the first reconnaissance of the Jupiter Trojan Asteroids, astronomical objects thought to hold vital clues to deciphering the origins of the solar system.
Just another day at the office? Hardly.
“This is not what I normally do,” Levison says in his office at the Southwest Research Institute in Boulder, Colo. Instead, the astronomer typically spends his days building large-scale computer simulations to study the theoretical formation of planetary systems and their evolution over time.
Now, he’s planning to make contact with some of the very same astronomical bodies he’s long studied from a distance. Appropriately named after the prehistoric human fossil discovered in east Africa and dating back 3.2 million years, Lucy is the first mission to the Trojan Asteroids.
“My argument is that [the Trojans] are the leftovers… the fossils of planet formation,” Levison says. “Lucy revolutionized our understanding of how the human race came to be. Our hope is that this mission will revolutionize our understanding of where the solar system came from and how it came to be.”
To do that, Levison first has to plan an interplanetary excursion involving a robotic spacecraft that will spend more than a decade transmitting data to him and his team. While this may sound like a daunting process, it’s not at all unlike planning a road trip here on Earth.
First, determine why you’re going.
Adventure is part of the call to the Trojan Asteroids, groupings of which lead and follow Jupiter’s orbit by 60 degrees during its 12-year journey around the sun. But the trip has implications that extend far beyond the thirst for exploring uncharted territory.
“Lucy came out of the realization that the theories of planet formation were moving ahead of the data,” Levison says. “[Scientists] had a lot of ideas about what could have happened, but didn’t have enough information to know which ideas were right. The population we’re going to visit will supply important information to understand which of our models is closer to being reality.”
While the average person’s astronomy focuses on the solar system’s eight planets, it’s the decidedly less publicized asteroid belts that provide lasting clues into how these planets formed in the first place.
“Probably the objects that glommed together and formed the planets were objects like [these] asteroids,” says Michael Seeds, F&M’s John W. Wetzel Emeritus Professor of Astronomy and a former professor of Levison’s. “Asteroids trapped in the orbit of Jupiter have been pretty well preserved. They haven’t collided nearly as often as regular asteroids have, so there’s some hope that they are more pristine. Those are the ones you want to study.”
In addition to its scientific implications, the mission is something of a dream come true for Levison.
“I decided I wanted to do what I’m doing when I was about 12,” he says. His passion for astronomy led him first to F&M, where he majored in physics and was an active presence at the planetarium of the North Museum, which sits on the southern edge of the F&M campus. Upon graduation, Levison went on to earn his master’s and doctorate in astronomy at the University of Michigan. He then pursued jobs all over the country before joining the Southwest Research Institute.
Levison will be 75 when the Lucy mission is complete, and the project represents the cherry on top of his successful career.
“He’s done so many things,” says Seeds. “I’ve always been impressed with him. It’s not fair to say I have favorite students. But there are some who are kind of impressive, and I’ll always enjoy following his career and seeing his name in print.”
Levison’s name appears frequently in scientific literature and astronomy publications when the origins of the solar system are being discussed, and he has written a number of computer programs that are used in the planetary sciences today. The NASA grant is simply the latest in a long series of career accomplishments.
Next, plan your route.
After years of development, Lucy will launch from Cape Canaveral in October 2021. If all goes to plan, the spacecraft will pass a main belt asteroid in 2025. Two years later, it will encounter the Trojans for the first time. The spacecraft will begin its explorations in the Trojan’s “L4 swarm” (the grouping of asteroids traveling ahead of Jupiter) before orbiting around the sun and then entering the second, “L5” swarm (which follows Jupiter’s orbit) in 2033. The mission will end in 2034 after Lucy has visited a total of six Trojan Asteroids.
That might sound like a painfully slow journey. But the spacecraft will actually travel at a whopping 5 to 7 kilometers per second for the full 12 years of the mission. To put that in perspective, says Levison, a bullet flies at less than a kilometer per second.
“These [asteroids] are far away,” says Levison. “And we want to go to a lot of them—which means the spacecraft needs to be hauling ass, because it has to cover a lot of real estate.”
Because of the spacecraft’s speed, the encounter with each asteroid will last for just under an hour (the Lucy team will collect data for several days in advance). During each encounter, Lucy will use remote sensing instruments to observe the object’s shape, geology, surface composition, gravitational pull (which will be used to determine the object’s mass), and number of craters (which provides insight into the object’s age). After each encounter, it will spend the next several weeks beaming back the data to ground stations on Earth.
Once the mission is complete, Lucy will enjoy a long retirement in the solar system. “There’s a small chance [the spacecraft] will hit the sun in a couple million years,” says Levison. “More likely it will float around the galaxy and last forever—even after the sun and Earth are dead.”
Work out a budget.
It’s not cheap to send a spacecraft to Jupiter’s orbit. So several years ago, after conceiving this journey, Levison and his team set about applying for the Discovery Grant from NASA. The open competition accepts a wide range of proposals relevant to planetary science.
Levison submitted his first proposal, which clocked in at 250 pages, along with 27 other competitors. From those, five were selected as finalists. Each finalist received $3 million with which to prove the proposed engineering would work. The last stage of the competition took place at the end of 2016. It consisted of a 1,000-page proposal, a 10-hour site visit and oral exam conducted by dozens of NASA representatives.
All told, the application process spanned multiple years and countless man hours. “It was probably the most stressful thing I’ve ever done in my life,” says Levison.
In the end, the team’s efforts paid off. Lucy earned one of the two final selections and a budget of approximately $980 million to go along with this distinction. The other mission, titled “Psyche,” will explore a giant metal asteroid in the main asteroid belt known as 16 Psyche. Scientists believe the asteroid could be an exposed core of an early planet that lost its rocky outer layers due to violent collisions billions of years ago.
“These are true missions of discovery that integrate into NASA’s larger strategy of investigating how the solar system formed and evolved,” said NASA’s Planetary Science Director Jim Green. “We've explored terrestrial planets, gas giants, and a range of other bodies orbiting the sun. Lucy will observe primitive remnants from farther out in the solar system, while Psyche will directly observe the interior of a planetary body. These additional pieces of the puzzle will help us understand how the sun and its family of planets formed, changed over time, and became places where life could develop and be sustained—and what the future may hold.”
“It’s a ton of money,” Levison says. “I’m a little intimidated by the fact that they’re making me responsible for making sure [it] is spent responsibly.”
Levison may be humble, but those who know him believe in his ability to see the project to fruition.
“I have a lot of confidence in him,” says Seeds. “He’s just a really ingenious guy who can do it.”
Gather your crew.
Having never been part of a mission to space, Levison has encountered a number of lessons even at this early stage in the process.
“The thing that shocked me is how much effort and how many people are involved,” he says.
From project managers who take care of scheduling and budgeting to the engineers in charge of conceiving viable technology, it takes a village to design, build, and manage the development of a spacecraft that will spend more than a decade exploring astronomical objects.
“We only have four and a half years to design and build this thing,” says Levison. “This is an extremely complicated machine that has to be robust, very sophisticated, and very smart.”
So far, it appears the combined efforts of the engineers at Lockheed Martin, his own team at the Southwest Research Institute, and many other contributors are up to the task.
Keep the faith.
As with any excursion, when it comes to launching a spacecraft into the solar system, uncertainty is guaranteed.
“There are many fears that keep me up at night,” says Levison. These include encountering a technical problem that the team is unable to solve, going over budget, the risk that the spacecraft will blow up on the launch pad, or a mechanical failure happening during the spacecraft’s flight. Still, Levison remains committed to taking the project one step at a time.
“You get satisfaction at the end of every phase,” he says. “First of all, I got tremendous satisfaction winning the competition. Now we’re in Phase B—at the end of which everything will be designed.”
Then it’s on to the rocket launch, which Levison anticipates will be an “amazing event” in its own right. After all those successes, Lucy’s journey into the solar system will be the icing on the cake. More than anything, Levison looks forward to the impact his mission could have on humanity’s understanding of our solar system’s origins.
“Human beings have this need to figure out how we got here,” says Levison. “From a solar system point of view, the thing that we now realize is planets do not form independent of one another. To understand where the Earth came from, we have to understand the whole system.”
Thus, this journey to outer space serves much the same function as any trip on Earth. In traveling far from home, we learn more than we ever could have imagined about ourselves and the place we are from.