Uploaded May 2026 | Updated September 2026, 2 weeks ago
I don’t think we should send humans to Mars. At least, not if we want to know: is there life on Mars? Modern day Mars might be dry and dusty, but the features we see on its surface leave clues to how it looked very different in the past. We think Mars once had liquid water on its surface that flowed along rivers, carved out canyons, and met oceans at big deltas. But over time, the Sun’s radiation bombarded Mars, slowly stripping away its atmosphere so that the water evaporated and was lost to space. All that’s been left behind is some ice at Mars poles. Now on Earth at least, where we find water is where find we life. So the big question for us scientists has always been, is there life on Mars? Or perhaps, more likely, was there life on Mars in the past? Back when it had a cosy atmosphere and water on its surface. If there was, or is life on Mars, we should be able to find evidence of that in the Martian rocks. Either as fossilised or living bacteria (because not to break any hearts, but its likely that any Martian life is tiny microbes, not "little green men"). But if we send humans there, with all the waste that humans naturally generate, and all the bacteria that make their home in our gut and on our skin, and then after that we do find evidence for life on Mars, how do we know what we’ve found isn’t from human activity on Mars? And then we can’t even ask the coolest question of all, is Martian life the same or different from Earth life? Did it evolve from the same bacterial ancestor, or did it evolve completely independently? All these questions tie in to our understanding of life in the Universe as a whole, and whether its likely that we’re truly alone, or whether the Universe is teeming with life...
Video filmed on a Sony ⍺7 IV
Video edited and produced by Dr Becky Smethurst
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📚 My book, "A Brief History of Black Holes", out NOW in hardback, paperback, e-book and audiobook (which I narrated myself!): lnk.to/DrBecky
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👕 My merch, including JWST designs, are available here (with worldwide shipping!): dr-becky.teemill.com
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🎧 Royal Astronomical Society Podcast that I co-host: podfollow.com/supermassive
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🔔 Don't forget to subscribe and click the little bell icon to be notified when I post a new video!
---
👩🏽💻 I'm Dr. Becky Smethurst, an astrophysicist at the University of Oxford. I love making videos about science with an unnatural level of enthusiasm. I like to focus on how we know things, not just what we know. And especially, the things we still don't know. If you've ever wondered about something in space and couldn't find an answer online - you can ask me! My day job is to do research into how supermassive black holes can affect the galaxies that they live in. In particular, I look at whether the energy output from the disk of material orbiting around a growing supermassive black hole can stop a galaxy from forming stars.
drbecky.uk.com
I don’t think we should send humans to Mars. At least, not if we want to know: is there life on Mars? Modern day Mars might be dry and dusty, but the features we see on its surface leave clues to how it looked very different in the past. We think Mars once had liquid water on its surface that flowed along rivers, carved out canyons, and met oceans at big deltas. But over time, the Sun’s radiation bombarded Mars, slowly stripping away its atmosphere so that the water evaporated and was lost to space. All that’s been left behind is some ice at Mars poles. Now on Earth at least, where we find water is where find we life. So the big question for us scientists has always been, is there life on Mars? Or perhaps, more likely, was there life on Mars in the past? Back when it had a cosy atmosphere and water on its surface. If there was, or is life on Mars, we should be able to find evidence of that in the Martian rocks. Either as fossilised or living bacteria (because not to break any hearts, but its likely that any Martian life is tiny microbes, not "little green men"). But if we send humans there, with all the waste that humans naturally generate, and all the bacteria that make their home in our gut and on our skin, and then after that we do find evidence for life on Mars, how do we know what we’ve found isn’t from human activity on Mars? And then we can’t even ask the coolest question of all, is Martian life the same or different from Earth life? Did it evolve from the same bacterial ancestor, or did it evolve completely independently? All these questions tie in to our understanding of life in the Universe as a whole, and whether its likely that we’re truly alone, or whether the Universe is teeming with life...
Video filmed on a Sony ⍺7 IV
Video edited and produced by Dr Becky Smethurst
---
📚 My book, "A Brief History of Black Holes", out NOW in hardback, paperback, e-book and audiobook (which I narrated myself!): lnk.to/DrBecky
---
👕 My merch, including JWST designs, are available here (with worldwide shipping!): dr-becky.teemill.com
---
🎧 Royal Astronomical Society Podcast that I co-host: podfollow.com/supermassive
---
🔔 Don't forget to subscribe and click the little bell icon to be notified when I post a new video!
---
👩🏽💻 I'm Dr. Becky Smethurst, an astrophysicist at the University of Oxford. I love making videos about science with an unnatural level of enthusiasm. I like to focus on how we know things, not just what we know. And especially, the things we still don't know. If you've ever wondered about something in space and couldn't find an answer online - you can ask me! My day job is to do research into how supermassive black holes can affect the galaxies that they live in. In particular, I look at whether the energy output from the disk of material orbiting around a growing supermassive black hole can stop a galaxy from forming stars.
drbecky.uk.com
