Space, Aliens, Planets, and Moons – oh my!
Time to read: Under four minutes
Astrobiologist, planetary scientist, and general expert on everything alien, Kevin Peter Hand is out to change the way we think about life on other planets. No, we’re not talking about big-eyed, grey-skinned men from Mars, but what we are talking about is the infinite possibilities for life outside of our safe, blue sphere.
“Astrobiology is the study of life in the universe. People assume that this is the search for life beyond earth, which is correct - that’s certainly part of astrobiology - but what’s also central to the study of astrobiology is study of the origin, evolution, and future of life on earth. Where did we come from? Where are we going? How did life originate?” asks Hand. “When you think about the living universe, right now, all we know of is life on Earth. We have yet to find even a speck of life beyond Earth.”
When Kevin is looking at the night sky, imagining the possibility of life on other heavenly bodies, his attention is fixed closer to home than you might expect. “I focus most of my time, both from a research standpoint and a mission standpoint, on Jupiter's moon Europa. And to a slightly lesser extent, Saturn's moon Enceladus.” The reason for this comes down to the age-old Goldilocks scenario. You need to find a planet that’s not too hot, or close to its star, and not too far, or too cold to have liquid water. In this scenario, Europa is just right.
“Europa, in particular, we think occupies this new Goldilocks sweet spot where it's got just the right amount of tidal energy dissipation so as to sustain a global salty liquid water ocean that's 100 kilometers or 60 miles in depth,” says Kevin. As a quick comparison, the Mariana Trench, the deepest oceanic trench on Earth in the western Pacific Ocean, is 11km deep. That makes Europa’s ocean 10 times as deep. An ocean that deep could be hiding all kinds of secrets, and perhaps, even life.
So why not Mars? It’s our closest neighbour and there’s strong evidence to support that theory that it once had flowing water on its surface. And for anyone tuned into the news, the Mars Perseverance Rover is sending back some of the most interesting information to date about our red planet neighbour. Though that water seems to be long gone, it could have been a source for life before it disappeared. “Mars is fantastic. Mars is still a wonderful place to look for evidence of past life and potentially life that's alive today. We'll just have to dig a lot deeper,” say Kevin.
“When it comes to the search for extant life, I really prioritize Europa and Enceladus for extant life similar to life as we know it. And then if we go one layer deeper, I prioritize Europa over Enceladus. Europa, we have good reason to predict, has had an ocean for the history of the solar system. So, it's an ocean that's been around for a while.” Saturn’s moon, Enceladus, also has surface water, but it’s hard to know how long it has been there as the rings of Saturn suggest a climactic collision in the not-so-distant past which could have given birth to the moon. The older the planet or moon, the more likely that it has had time to develop life.
This month, NASA announced October 2024 as the launch date of the new Europe Clipper spacecraft which will give scientists on Earth their first close-up view of Enceladus.
In so many ways, the possibilities for life in our universe is endless, but for the time being we are limited in how far we, and our robotic probes, can travel to search for this life. In 2005, the spacecraft Cassini orbited Saturn and landed a probe on Titan, the largest moon of Saturn and the second-largest natural satellite in the solar system. In 2017, Cassini flew into the atmosphere of Saturn, and burned up completely, concluding its 20-year mission. Unfortunately, Cassini found no life on its journey through our solar system. Kevin isn’t discouraged though, especially when faced with a universe of possibility.
“I certainly am excited about the prospect of discovering life elsewhere. And that's in part because, at a more philosophical and human level, and taking off my science brain, biology is beautiful. I love life forms and seeing how life works,” says Kevin. “I'm excited by the prospect of biology being out there and different ecosystems, different planets. So, I do hope it is a when, but there again, the universe doesn't care what we want.”
You can hear Kevin Peter Hand speak live along with his colleague Kobie Boykins at Arts Commons Presents National Geographic Live Virtual – Life on Other Worlds on March 22, 2021. Tickets are free, but registration is required.
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