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This Might Actually be Happening

2025-09-12 · explainer · Hank · 20:20 · watch on YouTube

Topic: Science & nature · mode: News analysis · tags: timely hook

Hank explains that Perseverance found iron and sulfur chemistry in a Jezero Crater mudstone that is hard to explain without past life on Mars, surveys earlier Mars evidence, the tests that could settle it and what a yes would mean, and argues that big scientific claims become consensus slowly, so even a huge discovery can feel anticlimactic.

What is said

The parts of the video and what is said in each (★ — how much it matters to the video).

00:00:00 — Hank does not feel up to the moment, so he talks about life on Mars: NASA and a paper report Perseverance findings hard to explain without life

  • ★★ Hank says he doesn't feel up to the moment, one where everything seems possible and there are no good answers, so instead he wants to talk about life on Mars. — 00:00:00 · Mars
  • ★★★ Hank reports that NASA and a paper announced that after a year of work Perseverance found things on Mars that we do not know how to explain without past life there. — 00:00:30 · Mars
  • ★★ Hank stresses that this is very different from saying there definitely was life on Mars, and even more different from saying there is life there now. — 00:00:30 · Mars

00:01:00 — The past: Viking's biology experiments, the ALH 84001 meteorite, Curiosity's organics, methane and evidence of ancient water

  • ★★ Hank thinks the recent discovery could be quite a big deal. (hedged) — 00:01:00
  • ★★ Hank says the first spacecraft sent to the surface of Mars, Viking 1 and 2 in the 1970s, carried a little biology lab with experiments designed to detect life. — 00:01:00 · Mars
  • ★★ Hank says Viking's soil experiment first released gas, but other experiments found no organic molecules and reactive compounds could mimic metabolism, so the verdict shifted from maybe yes to probably not. — 00:02:03
  • ★★★ Hank says Viking was set up as one big experiment to decide everything, which is rarely how science works: it is drips that get interrogated, through measurements, countermeasurements, arguments and revisions. — 00:02:03
  • ★★ Hank says that in 1996 the Martian meteorite ALH 84001, found in Antarctica, looked under an electron microscope like a fossil of a bacterium, which was very big news. — 00:02:33 · Mars
  • ★ Hank recalls that in 1996, at 16, he was at summer camp when the Mars meteorite news broke, and was frustrated that he had no computer to blog about it. — 00:03:02 · Mars
  • ★★ Hank says geology can make bacteria-shaped structures on its own, so ALH 84001 remains in limbo, probably forever a maybe, not a check in either column for him. — 00:03:02
  • ★★ Hank notes, among skipped evidence, that Curiosity discovered some organic molecules in mudstone. — 00:03:02

  • ★★ Hank explains that 'organic' here is the chemistry definition: part of the large family of carbon-centred chemistry, not made by life. — 00:03:48

    “that's the chemistry definition of organic, which does not mean made by life.”

  • ★★ Hank says a huge amount of planetary science has proved that Mars once had a lot of running water, something not known when he was a kid. — 00:03:48 · Mars

00:04:17 — The present: the Jezero Crater mudstone spots, vivianite and greigite, redox energy and chemosynthesis

  • ★★★ Hank says that in 2024 Perseverance drilled into a rock in Jezero Crater, part of a dried-up river delta that once fed a Martian lake; the rock formed from mud. — 00:04:17
  • ★★ Hank says the mudstone is covered in spots with differently coloured rock inside and at the edge: something happened in the middle and changed the rock as it spread out. — 00:04:46
  • ★★★ Hank says Perseverance found organic compounds plus two minerals, vivianite (iron phosphate) and greigite. — 00:05:08
  • ★★★ Hank explains that the iron and sulfur sit in a stable high-energy state that normally needs heat to escape, yet inside the spots they seem to have spontaneously dropped to a lower-energy state. (hedged) — 00:06:07
  • ★★ Hank says everything else about the environment shows it was not hot, and the chemicals formed where they are rather than being deposited from elsewhere. — 00:06:36
  • ★★★ Hank says that on Earth microbes capture the energy of such drops to power metabolism: Geobacter with iron reduction, sulfate-reducing bacteria with sulfur; this is chemosynthesis. — 00:07:05 · Earth
  • ★★★ Hank says the compounds and matching organics are there, great heat is definitely ruled out, and an unknown third chemical path is only a maybe, which he, knowing basic biochemistry, finds super exciting. — 00:07:34

00:08:03 — The near future: how to test the rocks for life (DNA, proteins, amino-acid handedness, lipids, carbon isotopes)

  • ★★ Hank says that if the rocks were on Earth, it would not be hard to tell whether ordinary or biological chemistry made them. — 00:08:03 · Earth
  • ★★ Hank lists life's four big macromolecules, DNA, proteins, carbohydrates and lipids, and says DNA breaks down too fast to help over billions of years. — 00:08:32
  • ★★ Hank says amino acids can form without life, but a non-50/50 mix of their handedness would basically be a smoking gun for life, though the handedness might be lost over time. — 00:09:01
  • ★★ Hank says lipids are tougher and would be a pretty big hint if cell-membrane sized; lipid remnants have been found in 2-billion-year-old rocks on Earth. — 00:09:31 · Earth
  • ★★★ Hank says the big test is isotopes: life prefers lighter carbon-12 over carbon-13, so carbon ratios could determine for sure whether something was alive; this is probably how it will be done. — 00:10:00
  • ★★ Hank says evidence of Earth's earliest life rests on isotopic fractionation in 3.5-billion-year-old rocks in Australia and South Africa, the oldest rocks, since Earth constantly recycles rock. — 00:10:42 · Australia, Earth

00:11:14 — The Mars sample return mission: not launched, fraught, in limbo

  • ★★ Hank says Perseverance packages and leaves samples for a robotic return mission, which has not launched and has been fraught to get done and funded. — 00:11:14
  • ★★ Hank says the Mars sample return mission is definitely not going to happen in the 2020s. — 00:11:14 · Mars
  • ★ Hank hopes the sample return will happen in the 2030s, when he will theoretically still be alive. (hedged) — 00:11:14

00:12:02 — What a biosignature would mean: independent or shared origin, early evolution, possible living microbes, not killing them

  • ★★★ Hank says that if the rock's leopard spots are really biosignatures, Mars was inhabited, but accepting that brings new mysteries, not closure. — 00:12:02 · Mars
  • ★★★ Hank says an independent origin of life on Mars would be the most exciting version: it would mean life, though not necessarily complex life, is extraordinarily common in the universe. — 00:12:02 · Mars
  • ★★ Hank says we could probably tell whether Martian life had its own biochemistry or shared a single origin with Earth life. (hedged) — 00:12:31 · Earth
  • ★★ Hank says planets swap material through impact ejecta, so life might have moved from Earth to Mars, Mars to Earth, or from elsewhere to both. (speculative) — 00:13:00 · Earth, Mars
  • ★★★ Hank says Earth's oldest life evidence is limited by its oldest rocks; Mars could preserve early steps Earth erased and help explain how chemistry became biology. (hedged) — 00:13:37 · Mars, Earth
  • ★★ Hank says Mars still has internal heat: its most recent volcanic eruption was millions of years ago or less, not billions; there is probably still subsurface water. — 00:14:06 · Mars
  • ★★★ Hank says that if Mars once had life and has warm subsurface water, it seems entirely possible that living microbes are still in Mars, which would be so cool. (hedged) — 00:14:37 · Mars
  • ★★ Hank says we would have to make sure not to kill Martian life: extincting a whole biosphere with our well-evolved microbes, the ultimate invasive species, would be far worse than extincting a species. — 00:14:37

00:15:45 — Big scientific claims become consensus slowly: the discovery of atoms, drip by drip, data surviving skepticism

  • ★★ Hank says that if the question of life on Mars is answered yes, it becomes a trillion exciting new questions. — 00:15:45 · Mars
  • ★★★ Hank says this follows how almost every big scientific claim becomes consensus: an early hint, contradictory data, tantalizing maybes, years of debate, then settlement. — 00:15:45
  • ★★ Hank's favourite example: when were atoms discovered? With Democritus's philosophy, Dalton and Lavoisier's whole-number chemistry, Einstein's Brownian-motion math, or Max von Laue's first X-ray diffraction images? — 00:16:15
  • ★★★ Hank says science rarely ends with one look like a lander spotting moss; it is drip after drip until the flood is big enough that everyone agrees, so huge results can feel anticlimactic. — 00:16:44

  • ★★★ Hank says extraordinary claims need evidence, open data and time to answer challenges: the body of scientific knowledge is what has survived contact with intense skepticism. — 00:17:14

    “the body of scientific knowledge is the stuff that has survived contact with intense skepticism”

00:18:02 — Finding life beyond Earth will not be a big news story; the scale is tipping; Hank admits his bias

  • ★★★ Hank says finding life beyond Earth in his lifetime is totally possible, but as a slow tipping of the scales it probably won't be a big news story, though it would be the biggest story ever. (hedged) — 00:18:02 · Earth
  • ★★ Hank says viewers, with good reason given the week's competing news, may have missed one of the most important discoveries in the history of planetary geology. — 00:18:02
  • ★★★ Hank says the scale is starting to tip toward there having once been life on Mars; it could tip back, but to him, after long interest, it feels like it's going one way. (hedged) — 00:18:43 · Mars
  • ★★ Hank admits he wants there to be life on Mars, so that bias is there. — 00:18:43 · Mars
  • ★★ Hank says every round of new evidence and objection inches us toward the truth, and once samples reach Earth's labs the question might be fairly easily answered. — 00:18:43 · Earth

00:19:30 — Conclusion: a big question with a path to certainty is comforting when many questions feel unanswerable; sign-off

  • ★★ Hank says many big questions now feel unanswerable because humanity is too big and complex, and he is feeling that a lot right now. — 00:19:30
  • ★★★ Hank concludes that here a really big question has a potential path to certainty and on to the next questions, which he understandably finds comforting. — 00:20:04

In the description and comments

  • ★ The description names the Nature paper, 'Redox-driven mineral and organic associations in Jezero Crater, Mars', and says it could go down in history as a pretty important moment. (hedged) — video description · Mars
  • ★★ In a channel comment, Hank says the Great Filter is much more likely to be complex multicellularity, since life arose very early on Earth but multicellularity only about 800 million years ago. — creator comment · Earth
  • ★★ In a channel comment, Hank adds that there appears to be nothing particularly special about our solar system. — creator comment
  • ★★ In a channel comment, Hank says some water (ice) on Mars has been known since the 70s, but a long wet period only became consensus in the mid-2000s. — creator comment · Mars
  • ★★ In a channel comment, Hank concedes with 'DANGIT!' a viewer's point that pencils, his carbon-isotope comparison, are also made from once-living material. (playful) — creator comment

Threads in this video

Where the stories that moved here went next

Mentioned

Central: biosignature · extraterrestrial life · isotope · Jezero Crater · Mars · Mars 2020 · scientific consensus

Also: People: Albert Einstein · Antoine Lavoisier · Democritus · John Dalton · Max von Laue

Organizations: NASA

Concepts: abiogenesis · amino acid · Atomic theory · biochemistry · Brownian motion · carbohydrate · carbon · chemosynthesis · chirality · DNA · extinction · Geobacter · greigite · invasive species · lipid · meteorite · methane · microorganism · organic compound · panspermia · protein · scientific method · sulfate-reducing microorganism · vivianite · water on Mars · X-ray crystallography

Places: Allan Hills 84001 · Antarctica · Australia · Earth · Moon · South Africa

Events: Mars sample return · Mars Science Laboratory · Viking program

Only in the description or credits: Great Filter · Redox-driven mineral and organic associations in Jezero Crater, Mars

Also centred on extraterrestrial life: Where are the Space Aliens?! · We just had our first interstellar visitor...and it's weird. · They Say it Gets Colder · Aliens · Is it Good or Bad that we Haven't Met Aliens? · Fine, I'll Talk About the Drones…

Also centred on scientific consensus: Trust and Fire - Thoughts from the Smoke · Can You Trust Science Too Much?

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