NASA launches mission to explore the frozen frontier of Jupiter’s moon Europa

“We’re interested in whether Europa could support simple life—single-celled organisms.”

NASA’s Europa Clipper mission began with a fiery launch on SpaceX’s Falcon Heavy rocket.

Credit:

SpaceX

NASA’s Europa Clipper spacecraft lifted off Monday from Kennedy Space Center in Florida aboard a SpaceX Falcon Heavy rocket, kicking off a $5.2 billion robotic mission to explore one of the most promising locations in the Solar System for finding extraterrestrial life.

The Falcon Heavy rocket fired its 27 kerosene-fueled engines and vaulted away from Launch Complex 39A at 12:06 pm EDT (16:06 UTC) Monday. Delayed several days due to Hurricane Milton, which passed through Central Florida late last week, the launch of Europa Clipper signaled the start of a five-and-a-half year journey to Jupiter, where the spacecraft will settle into an orbit taking it repeatedly by one the giant planet’s numerous moons.

The moon of Jupiter that has most captured scientists’ interest, Europa, is sheathed in ice. There’s strong evidence of a global ocean of liquid water below Europa’s frozen crust, and Europa Clipper is going there to determine if it has the ingredients for life.

“This is an epic mission,” said Curt Niebur, Europa Clipper’s program scientist at NASA Headquarters. “It’s a chance for us not to explore a world that might have been habitable billions of years ago, but a world that might be habitable today, right now.”

The icy surface of Europa could hide life below.

Credit:

NASA

Europa has been near the top of the to-do list for planetary scientists since NASA’s Voyager probes returned the first up-close images of Jupiter’s moons in 1979. A follow-up mission, named Galileo, orbited Jupiter for nearly eight years in the late 1990s and early 2000s. The Galileo probe discovered a signature that Europa hides a watery ocean below its icy sheen.

But concepts for a dedicated Europa mission had trouble gaining political momentum, and for the last quarter-century, projects studying a Europa probe were canceled almost as quickly as they started. Then, a Texas congressman with a lifelong interest in space science took the chairmanship of an appropriations subcommittee that oversees NASA’s budget.

Former Rep. John Culberson, a Republican representing a district in suburban Houston, became Washington’s most powerful patron for a Europa mission. He tucked funding for a Europa probe in several NASA budgets that went through his subcommittee, until NASA and the Obama administration formally backed the mission that became Europa Clipper in 2015.

Speedy departure
For a while this summer, NASA officials worried the mission might not be ready to fly this year due to concerns about resilience of the spacecraft’s transistors to radiation around Jupiter. But engineers concluded the hardware was good to go, and last month, senior NASA officials gave the green light to proceed with final launch preparations.

Europa Clipper, weighing in at more than 12,500 pounds (5.7 metric tons) at launch, is the largest spacecraft NASA has ever sent to explore another planetary body. Its two big power-generating solar arrays, sized to absorb faint sunlight five times farther from the Sun than Earth, extended from the spacecraft soon after launch to reach a wingspan of 100 feet (30.5 meters).

It’s also the most expensive planetary science mission in NASA history, coming in at roughly half the cost of the James Webb Space Telescope, or twice the cost of the agency’s most recent Mars rover.

Europa Clipper rode into space on the world’s most powerful operational rocket, but it needed all of Falcon Heavy’s oomph to reach a trajectory that will eventually take the spacecraft to Jupiter. SpaceX disposed of all three of the rocket’s first stage boosters, devoting all of Falcon Heavy’s propellant to give Europa Clipper the speed it needed to escape Earth. This left no fuel to recover the boosters.

SpaceX’s Falcon Heavy rocket flew without its landing legs and other components needed for recovery.

Credit:
SpaceX

SpaceX’s Falcon Heavy rocket flew without its landing legs and other components needed for recovery.

Credit:

SpaceX

Around an hour after Europa Clipper’s midday liftoff from Florida, the Falcon Heavy’s upper stage deployed Europa Clipper on the opposite side of the world. It attained a speed of 28,364 mph (45,648 kilometers per hour) relative to Earth, the fastest velocity ever achieved by a SpaceX rocket, according to Jon Edwards, SpaceX’s vice president of Falcon launch vehicles.

The voyage to Jupiter will span 1.8 billion miles (2.9 billion kilometers), taking the spacecraft by Mars next March, then back near Earth again in 2026. These flybys will use each planet’s gravity to slingshot Europa Clipper farther from the Sun, allowing the spacecraft to take aim on Jupiter.

Europa Clipper will fire its engines for six to eight hours, consuming more than half of its propellant, to brake into orbit around Jupiter on April 11, 2030. That will set up the spacecraft to begin a series of 49 close encounters with Europa.

“To be clear, we’re not landing on Europa. We’ll make no attempt to land there,” said Jordan Evans, the mission’s project manager at NASA’s Jet Propulsion Laboratory (JPL), referring to a line in Arthur C. Clarke’s novel 2010: Odyssey Two. “We do get as close as 25 kilometers above the surface. That’s about 16 miles. These flybys cover both hemispheres of the moon and a variety of latitudes to get us near global coverage of the moon for the science instruments.”

Searching for an oasis
NASA’s Galileo spacecraft zoomed by Europa a dozen times, but it carried scientific instruments from the 1980s. Europa Clipper boasts a 21st century payload package with nine instruments to probe Jupiter’s icy moon, from its ocean to the space around it.

“Europa Clipper carries the most sophisticated suite of instruments that we’ve ever sent to the outer solar system,” said Bob Pappalardo, the mission’s project scientist at JPL. “It carries a radar that can penetrate through ice like a CT scan to find liquid water, super high-resolution imaging. We’ll be able to look for warm spots and plumes at Europa—all these wonderful techniques that combine together to tell us could Europa be the kind of place that could support life today.”

Europa Clipper’s best camera will resolve features on the moon’s surface as small as 1.5 feet, or 50 centimeters, in certain areas. These views will be 12 times sharper than the most detailed images captured by Galileo.

Other sensors on Europa Clipper will measure the composition of Europa’s crust and tenuous atmosphere, search for erupting plumes of water escaping through cracks in the moon’s ice shell, and scan for small pools of water that might be on or near Europa’s surface.

Europa Clipper also carries an ice-penetrating radar to investigate the structure and thickness of Europa’s ice shell, and measure the topography of the moon’s outer crust. A mass spectrometer is mounted on the front of the probe to sniff gases in the moon’s faint atmosphere, or potentially sample material from a plume shooting high above Europa, if scientists are lucky enough to guide the spacecraft through one.

The Hubble Space Telescope found evidence for jets of water vapor coming from Europa, and while the Galileo spacecraft didn’t see these eruptions, scientists went back through the mission’s data archive and found signatures consistent with the existence of plumes. Steering Europa Clipper through such a plume would make for a scientific gold mine, allowing researchers to study material coming from Europa’s watery abyss.

Scientists will use magnetic and gravity field measurements from Europa Clipper to determine the depth and salinity of Europa’s ocean. Bonnie Buratti, the mission’s deputy project scientist at JPL, said rough estimates put the ocean’s depth at 60 to 80 miles, and the ice shell’s thickness is probably on the order of 10 to 20 miles.

Artist’s concept of the Europa Clipper spacecraft orbiting Jupiter.

Credit:
NASA/JPL-Caltech

Artist’s concept of the Europa Clipper spacecraft orbiting Jupiter.

Credit:

NASA/JPL-Caltech

Europa is about size of Earth’s Moon, but is considerably more interesting. Unless Europa Clipper sails through a plume, the only part of Europa directly observable is its fractured surface, where there are few large craters, suggesting the icy crust is repaving itself through tectonic activity.

“When we look close up at Europa, we see its icy surface is just bizarre,” Pappalardo said. “It looks like no landscape seen anywhere on Earth, the surface has shifted and crumbled in ways that we really don’t understand.”

Buratti said Europa Clipper will provide a “deluge of scientific data” about the moon’s environment. The mission’s focus will be on finding out whether Europa could support primitive organisms, which need water, organic compounds, and an energy source to sustain themselves. Europa Clipper is suited to finding all three.

Scientists are pretty sure Europa has the water, perhaps twice as much as the water in all of Earth’s oceans. Jupiter’s strong gravity field constantly tugs on Europa as it orbits its parent planet every three-and-a-half days, squeezing and flexing the moon’s insides, and generating heat through tidal forces. These forces could drive hydrothermal vents where the bottom of Europa’s ocean meets the moon’s rocky interior.

This is what separates Europa, Earth, and Saturn’s small moon Enceladus—which also has a buried ocean and erupting plumes—from every other object in the Solar System, according to Cynthia Phillips, planetary geologist and Europa Clipper project staff scientist at JPL.

“In these worlds, you have an ocean layer on top of a rock layer,” she said. “That’s important because that’s what we have here on the Earth, and at the bottom of Earth’s oceans, where that ocean layer touches the rock, you can have all sorts of interesting chemical reactions take place, and hydrothermal systems.”

Scientists’ findings suggest that the interior of Jupiter’s moon Europa may consist of an iron core, surrounded by a rocky mantle in direct contact with an ocean under the icy crust. New research models how internal heat may fuel volcanoes on the seafloor.

Credit:
NASA/JPL-Caltech/Michael Carroll

Credit:

NASA/JPL-Caltech/Michael Carroll

At the bottom of Earth’s oceans, like at Europa, organisms must rely on an energy source other than the Sun. Hydrothermal vents in Earth’s oceans provide a heated environment teeming with primitive life forms, even in harsh conditions several miles deep.

“We don’t expect fish and whales that kind of thing, but we’re interested in whether Europa could support simple life—single-celled organisms,” Pappalardo said.

Of course, Europa Clipper won’t be able to burrow down the dozens of miles to reach these theorized vents. Scientists will have to deduce their presence through other data. And a direct detection of any living organism on Europa will have to wait for a future mission. Scientists don’t think life could survive on Europa’s surface because it is bathed in extreme radiation from Jupiter’s magnetosphere.

“If there is life on Europa, in this habitable environment that we’re exploring, it would be underneath the ocean, so we wouldn’t be able to see it,” Buratti said. “We’re looking for chemicals on the surface, organic chemicals that are the precursors to life. There are dream things we could observe like DNA or RNA, but we don’t expect to see those.”

If Europa Clipper turns up something truly surprising, scientists will, no doubt, be eager to send a lander to Europa. A Europa lander would be a challenging and expensive undertaking. NASA studied how it would execute such a mission nearly a decade ago, but progress on a lander has stalled since then.

Two other long-sought missions achieved top ranking in the most recent decadal survey of planetary scientists: a Uranus orbiter and a mission to Saturn’s icy moon Enceladus, a smaller, more volatile analog to Europa. NASA typically follows the decadal survey’s edicts. In the previous report from 2011, scientists put a Mars Sample Return mission and a Europa probe at the top of their list. NASA followed through with the Perseverance rover that launched in 2020 to collect samples on Mars for eventual return to Earth, and then Europa Clipper.

The Europa Clipper spacecraft, with its high-gain communications antenna prominently visible, is prepared for encapsulation inside SpaceX’s payload fairing at Kennedy Space Center.

Credit:
SpaceX

The Europa Clipper spacecraft, with its high-gain communications antenna prominently visible, is prepared for encapsulation inside SpaceX’s payload fairing at Kennedy Space Center.

Credit:

SpaceX

It would likely take an alluring discovery at Europa for a lander to leapfrog the Uranus and Enceladus missions currently in NASA’s queue. But Europa, perhaps more than any other place in the Solar System, has the potential to give scientists such a discovery.

“First, we’re going to ask the straightforward question: Are the proper ingredients there for life to exist?” Niebur said. “And you can bet your bottom dollar that if Europa Clipper tells us that, yes, those ingredients are there, we are going to be knocking on the door fighting for a second mission to go looking for life.”

A secondary objective of Europa Clipper is to find places on its tortured surface that might be worth the commitment of sending a lander, and safe enough to give the lander a reasonable chance of success. For some regions on Europa, the spacecraft’s instruments will be sensitive enough to detect boulders and measure the hardness or fluffiness of the ice a future mission might have to land on.

“Sometimes, I’m asked what I would want to see at Europa? What would be the greatest outcome?” Pappalardo said. “To me, it would be to find some sort of oasis, if you like, on Europa where there’s evidence of liquid water not far below the surface, evidence of organics on the surface. Maybe it would be warm. Maybe it would be the source of a plume.

“That could be somewhere that in the future, maybe, NASA could send a lander to scoop down below the radiation-processed surface and literally search for signs of life.”

Stephen Clark is a space reporter at Ars Technica, covering private space companies and the world’s space agencies. Stephen writes about the nexus of technology, science, policy, and business on and off the planet.

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