An intrepid explorer is about to set out to one of the places in our solar system likeliest to host life. NASA’s Europa Clipper spacecraft, the agency’s latest flagship mission, will head to Jupiter’s icy moon Europa and determine whether it’s a hospitable place for life.
“This is the biggest spacecraft ever sent into outer space, with the most sophisticated instruments,” Bonnie Buratti said at a 17 September event for reporters. Buratti is a deputy project scientist for Europa Clipper at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
“There will be 49 flybys of Europa to study the moon from pole to pole,” Buratti added. “We have pretty much complete coverage, and it will not only realize the main goal of this mission, which is to search for a habitable environment where possibly life could thrive, but it will also address the three major objectives of understanding the geology of the surface, the composition, and then to characterize the interior.”
Europa Clipper’s launch window is open from 10 October to 6 November and it will launch once the launch facilities have been assessed for damage caused by Hurricane Milton. The craft is set to arrive at Jupiter in April 2030.
Ice Dancer
Europa is one of Jupiter’s four Galilean moons. Past missions to the Jovian system discovered that Europa, along with fellow icy moons Ganymede and Callisto, have vast liquid water oceans sloshing around beneath icy shells.
“Ocean worlds have been considered potentially habitable environments for a while,” said Monica Vidaurri, a doctoral student in planetary modeling at Stanford University in California. “This is the first time we’re really dedicating a spacecraft to [exploring] it.”
Europa Clipper aims to measure the thickness of the ice shell, analyze the composition of the surface and any outgassed material, and characterize the geology. The craft is equipped with nine scientific instruments that will work together to answer these questions.
The visible and infrared cameras will create high-resolution maps of Europa’s surface and track thermal variations that might be caused by the movement of water within or beneath the ice. Infrared and ultraviolet spectrometers will trace the chemistry of the icy surface and the wispy transient atmosphere to analyze the mineralogy and salt content of the ocean.
A magnetometer and plasma instrument will decipher Jupiter’s magnetic field at Europa and how it induces a magnetic field on the moon. Scientists will use those measurements to further constrain the ice shell’s thickness and the ocean’s salinity. A radar instrument will probe the ice shell to understand how its thickness varies and whether there are any imperfections or fractures, as well as search the moon’s atmosphere for outgassed plumes.
“Not only is there thought to be this liquid water ocean, but there could also be liquid water within the ice shell itself.”
“Not only is there thought to be this liquid water ocean, but there could also be liquid water within the ice shell itself,” explained Krista Soderlund, a planetary scientist at the University of Texas at Austin and part of the radar instrument team for Europa Clipper. “The radar instrument is really excellent at detecting water, especially if it’s within the first few kilometers of the surface.”
A mass spectrometer and dust analyzer will analyze the chemistry of Europa’s atmosphere as well as material in the space between Jupiter and Europa that falls onto the moon’s surface. In addition, the spacecraft’s communication and navigation hardware will be used to map Europa’s gravity field, track its tides, and create a geodetic map during nearly 50 flybys.
“Repeated flybys of a moon can improve our understanding of its gravity field through the minute changes in acceleration that the spacecraft experiences as it travels,” said Adeene Denton, a planetary scientist at the Southwest Research Institute in Boulder, Colo. “As we get more and more finer information about Europa’s gravity field, it can tell us about where mass is distributed…. Those mass distributions will reflect changes in density, potential, [and] compositional layering.”
All Things Europa…
Planetary scientists consider Europa one of the most promising locations in the solar system to look for extraterrestrial life. But Europa Clipper won’t be the mission to find it.
“We’re not a life detection mission,” Buratti emphasized. “We’re just looking for the conditions for life. That is, water, some type of chemicals, specifically organic compounds that can serve as food for any primitive organisms, and then finally, energy.”
“If there is life on Europa in this habitable environment that we’re exploring, it will be underneath the ocean, so we wouldn’t be able to see it,” she added.
However, the suite of measurements will contribute to a better understanding of the ocean dynamics taking place beneath the ice.
“How thick the ice shell is, if there’s any variations in ice shell thickness, how salty the ocean is; those are really fundamental constraints,” said Soderlund, who researches planetary fluid dynamics across the solar system. These measurements will improve upon existing models of ocean circulation and fluid dynamics and allow scientists to use those models to understand the new data, she added.
“The radar will give much finer detail about the ice shell structure, and then the gravity data will tell us a lot more about how the ice shell, the ocean, and the core all relate to each other,” Denton added.
“This mission will really be able to tell us how complex an ice shell of an icy world really is.”
Denton, who models planetary impacts on icy bodies, said that the new data on Europa’s ice shell “could potentially make my life as an impact modeler a lot more difficult because we’ll probably have to finally stop approximating the ice shells of icy bodies as just a pure block of ice.”
In this case, more difficult is a good thing. “This mission will really be able to tell us how complex an ice shell of an icy world really is,” they added. “And I think it will be really fun to try to adapt our models to keep up with the science that Clipper is bringing us.”
…And Beyond
In April of last year, the European Space Agency (ESA) launched its Jupiter Icy Moons Explorer (JUICE) spacecraft, which will arrive in the Jovian system not long after Europa Clipper. The two missions will spend several years cruising around the Jovian system at the same time.
“The synergy between Europa Clipper and JUICE will be really exciting,” Denton said. “The fact that ESA is planning to target [Jupiter’s] other two icy moons, Ganymede and Callisto, means that we will be able to put the information that we’re getting from Europa in context.”
“It’s a great time to be working in the outer solar system.”
“It’s a great time to be working in the outer solar system,” they added.
With new data coming in about three very different icy worlds at the same time, planetary scientists are excited about learning how the three worlds compare, with the hope of applying new understanding to other ocean worlds. The formation of Europa’s chaos terrain could provide new insight into the jigsaw surface of Uranus’s moon Miranda. The fluid dynamics inferred for Europa could provide additional context for when the Dragonfly mission visits Saturn’s moon Titan.
Better understanding of how tides generate Europa’s internal heat could also help astronomers finally answer whether exoplanets around small red stars can be habitable environments, Vidaurri said.
“A lot of the exoplanets that astrobiologists are interested in exist around M dwarf stars and are super close to the star,” she explained. “You’re going to get these tidal forces. You might even get some similar magnetic activity” as what Europa experiences around Jupiter, Vidaurri said.
If Europa can sustain the conditions for life in such a harsh environment, then maybe there’s hope for exoplanets around M dwarf stars, too.
Because of these similarities, Jupiter and its Galilean moons are often thought of as scaled-down versions of M dwarf exoplanetary systems. If Europa can sustain the conditions for life in such a harsh environment, then maybe there’s hope for exoplanets around M dwarf stars, too.
Europa Clipper is scheduled to spend at least 4 years studying Europa before ending its mission in a planned crash onto Ganymede’s surface. By the end of the mission’s lifetime, scientists hope to have an answer about whether the moon has the right stuff to host life.
“I’m over the moon about it,” Soderlund said.
—Kimberly M. S. Cartier (@AstroKimCartier), Staff Writer
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Citation: Cartier, K. M. S. (2024), Clipper sets sail for an ocean millions of miles away, Eos, 105, https://doi.org/10.1029/2024EO240448. Published on 11 October 2024.
Text © 2024. AGU. CC BY-NC-ND 3.0
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