Could life exist on a faraway moon?
Millions of miles from our planet, scientists think that one planetary body could harbor life.
Europa is an icy moon, with an ocean underneath its surface. It’s one of Jupiter’s 95 moons, and it’s slightly smaller than Earth’s.
Within Europa’s icy waters is where scientists think they may find habitable conditions, or even signs that life once existed there.
That’s why NASA launched the Europa Clipper mission back in 2024. The probe will reach Europa in 2030, hoping to observe and find potential evidence of life. The spacecraft will orbit Jupiter and conduct 49 flybys of Europa.
Before Europa Clipper reaches Jupiter, scientists are already thinking about the potential for life on Europa both in the past and in the present. One of those scientists is Paul Byrne, a planetary scientist at Washington University in St. Louis. Byrne is one of the authors in a recent study that models Europa’s ocean.
In this study, Byrne explained that some of the processes that have happened on Earth to create new life may not be happening on Europa. If new life is happening on the distant moon, Byrne explained it won’t be the same way that Earth has created life.
“What we find is that geologically, there's probably not a lot happening on Europa’s ocean floor today,” Byrne said. “Which means if there is going to be some kind of life ecosystem there, it's going to have to be reliant on processes that aren't quite the same as what we know on Earth. We're not saying we're not ruling out life. We can't rule out life on Europa. What we can say is that the processes that certainly we recognize on Earth are probably not operating.”
Will there be signs of life on Europa? Byrne said we won’t know until we get there with Europa Clipper and study it, and until we can send a spacecraft into its icy ocean for a closer look.
“If we found that there were no life in Europa today, for example, that doesn't mean that there wasn't there originally, and even if we find that there was nothing there originally, that's still a really important data point,” Byrne said ,“because it tells us, well, maybe these aren't the conditions that we need for life, or maybe these environments aren't as potentially habitable or as encouraging as we once thought they were.”
Byrne said even if Europa Clipper and potential future missions don’t find signs of life or the conditions that could harbor life, it’s still important to explore.
“Let’s say these future missions ultimately show us that Europa is dead as a doornail. That doesn't mean it's not an important or exciting place to continue exploring,” Byrne said. “Clipper is going to definitely give us new information, very important information, on the potential, astro-biological potential of Europa, but it's also going to give us core information as to how these kinds of worlds form.”
A new look at lunar radiation
Scientists will soon examine cosmic radiation on the surface of the moon thanks to the agency’s Commercial Lunar Payload Services program.
SELINE, or Site-agnostic Energetic Lunar Ion and Neutron Environment, will look at cosmic rays coming in and bouncing off the lunar surface, hopefully uncovering possible safety issues for moon-bound astronauts and narrowing the understandings of how lunar bodies form.
Drew Turner, heliophysicist and astrophysicist at Johns Hopkins University Applied Physics Laboratory, said the microwave-sized payload will advance simulated experiments into something more physical.
“Currently, our best understanding of the entire environment is from these models that we have,” Turner said. “There's never been a ground truth measurement of the comprehensive incident radiation coming in from space and then the comprehensive secondary radiation right there at the surface.
The moon is far more exposed to space than Earth because it lacks an atmosphere, resulting in temperatures dropping to near absolute zero at night. This shortens the window in which SELINE can do science to less than two weeks – just one lunar day.
“We're not guaranteed with this opportunity to be able to survive lunar night, which gets extremely cold, like that the electronics fail, right? We're not putting any survival heaters or anything onto SELINE,” Turner said. “We'll be able to close our mission criteria and our success criteria with one hour of data. Everything else is gravy and bonus in terms of the statistics that we can build up, plus the chances of being hit by something from the sun.”
SELINE is being sent to the lunar surface with two other missions. EMILIA-3D, or Emission Imager for Lunar Infrared Analysis in 3D, will create a 3D thermal map of lunar terrain. LISTER, or Lunar Instrumentation for Subsurface Thermal Exploration with Rapidity, will measure the moon's internal heat flow by drilling beneath the lunar surface.
In addition to informing safety procedures in lunar travel and a potential lunar or Martian base, SELINE will hopefully provide narrower insight on planetary formation and weathering.
"Think about asteroids, right? Think about other moons, about other planets, other worlds, and that lack of constraint right now is one of the major barriers in terms of understanding some of these other worlds and how they formed,” Turner said. “With the data we get from SELINE, that will actually help inform our understanding of other airless bodies throughout the solar system.”
