Science education is key to creating a successful future, but the challenges have never been greater. I'm Matt Kaplan, host of Safeguarding Sound Science, Climate Change Edition. Join us for outstanding conversations with the leading researchers, policy experts, and teachers.
who are fighting to keep misinformation and pseudoscience out of our classrooms and off our screens. Subscribe to Safeguarding Sound Science on Apple, Spotify, Amazon or wherever you like to listen. Hello and welcome to New Scientist Weekly. where we discuss the most fascinating science news of the week. I'm Penny Sartre. And I'm Rowan Hooper. Penny, I'm quite excited about today's show. Me too. Life on Mars.
The biggest discovery about dark energy for 25 years. Amazing. And a unique new way that bacteria could produce oxygen. And that could explain the dark oxygen phenomenon that we've talked about on the pod before, produced by Metal Nod. Yeah, we're getting into it. This is, you know, biggest mysteries of the universe, the solar system and the deep ocean. But let's start with, you know, the casual discovery of life on Mars, is it? OK, I will rein in touch.
So it's not life on Mars, but let's say it's intriguing suggestions for past life on Mars. And this is all from the ongoing mission of the Perseverance rover that's there on Mars now, right? Yeah, so it landed in 2021 at a place called the Jezero Crater. That's an impact crater they spent... months searching different possible locations on Mars and settled on this one. It was once a river delta and a lake. And right now...
The rover is just trondling across part of this ancient lake bed called Bright Angel. So how did they work out that it used to be a lake? Well, it looks like one. You can see where the river has once run out and spread out in a delta and spread these sediments out there. So they took a really good look at it and decided, OK, this looks... This looks like the best place to go. And because it's an ancient river delta, it looks like a really good place to look for where you might have had life.
thrashing around in the shallows. And so what sort of timescale are we talking about here? How long ago? Yeah, three and a half billion years ago, which is intriguingly around the same time that life got going on on Earth. Yeah, kind of kind of spooky that. But it's just the river system and the water. Yeah, yeah. So that's so much is established. Right, OK. But what's been building up over the last about year is...
more evidence of what we're finding, what the rover is finding through digging around the sediments on this lake. So last year the rover found... minerals that could only form in water. And there were some hints of organic compounds as well, but we couldn't confirm that. I guess quite tricky to determine when things are 3.5 billion years old. Yeah, and you're a rover.
had to only have a limited amount of stuff to work with and actually that's why one of the strands of this mission is called collect and cache and that's to sample to collect samples leave them on mars for potentially to be return to Earth later when we can use all our flashy Earth-based laboratories. The other objectives are to seek signs of past microbial life, to study the habitability of Mars and to prepare for future human missions.
But look, this week's news. The rover found these markings on a rock. in this area that they're calling bright angel and they're little speckles or some of they call leopard spots some are called poppy seeds they've called them and what's interesting is that they're similar to the patterns that we get on Earth that are associated with microbial action. So these little block, the millimetre size, you've got calcium sulphate.
around them and typically you only get that in the presence of water you get that forming in the presence of water and this latest analysis also suggests that there is evidence of organic compounds as well so when you get this on earth these marks and this composition of minerals they're either formed by microbes or by a sort of inorganic
chemical reactions, but that you only get at high temperatures. Right. And Mars is not especially hot. No. So on Earth, you need temperatures of 120 degrees Celsius. And if the Martian rocks... had been subjected to that kind of high temperature, that you'd get these large crystals that would have formed from melting and re-solidifying the rock. But there's no evidence of that. And that suggests that the low temperature, the microbial scenario...
is more likely. So it's really starting to look like maybe tiny little microbial Martians a long time ago. Yeah, it's starting to look... like that um so to tell you a bit more about the evidence for it um this has all been done by um two research groups one Joel Horowitz at Stony Brook University another one Mike Tice at Texas A&M University and they found
phosphate and sulphide minerals that appear to have oxidised and reduced as they formed. That means gaining and losing electrons. And so they believe that the organic... molecules that are around they assist in this reduction reaction and I asked someone about this Janice Bishop from the SETI Institute she's a planetary scientist and works a lot on the minerals on Mars and she's done experiments that try and recreate
the conditions on Mars in the past to make the minerals we see there today. And basically she's done these similar things, made reduced forms of minerals in the presence of organic. compounds at low temperatures. And I asked her about this latest work, and this was presented at the Lunar and Planetary Science Conference in Texas, and here she is. I don't think they know yet how much organics are present or what type of organics.
but their work provides more clues that some of the same chemistry needed for life on early Earth likely occurred on Mars as well. Of course, it is still a big stretch from the current results to finding actual evidence of prebiotic chemistry. In other words, finding molecules like amino acids on Mars. And from there, it would be another big stretch to actually find evidence of life.
Fortunately, Perseverance did collect a sample from the intriguing Bright Angels site, so eventually, once the samples return to Earth, we can investigate this in detail and with more sophisticated instruments in the lab. Something else that I find interesting is that amino acids were recently identified in samples returned from the asteroids Bennu and Ryugu.
And these rocks also contain clays, carbonates, phosphates, and sulfides, similar to the intriguing site Joel and Mike are investigating on Mars. However, we don't have the geologic context for these tiny asteroid pieces as we do for the samples collected at Mars. Still, this appears to indicate it... that asteroids also harbor prebiotic molecules and minerals indicative of liquid water and active geochemistry.
It is surely a fascinating time for exploration of our planetary neighbours and collecting evidence of prebiotic chemistry in our solar system. That's really interesting. isn't it? The bit, the point that she makes there that even asteroids have a lot of really intriguing chemistry going on. It really made me wonder about how common life could be if you've got a lot of this prebiotic... precursors to life you know basically all over the place and as we're understanding that
Life started on Earth probably a lot earlier than we originally thought. It's starting to seem like it could pop up and then go away. Janice mentioned they're getting the Mars samples back to Earth. That's super exciting. When is that likely to happen? Don't hold your breath. Well, on Mars, you don't want to breathe either. It's going to be in the 2030s. So a little while to wait.
So quite a big week for Mars then, but it's also been a big week for something much bigger, all of cosmology, with the release of data from multiple telescopes telling us something really quite dramatic about the universe, including how it might end. So, you know, quite major. Yeah, happy days. To talk us through all of that, we've got news editor Jacob Aaron here. Jacob, tell us more.
Yes, it all began on Tuesday when researchers using the Atacama Cosmology Telescope in Chile released our best ever map of the cosmic microwave background. So this is the remnants of the first light in the universe. It was released 380... 80,000 years after the Big Bang quite swift in cosmological terms and Cosmologists use this for all sorts of things They can measure the age of the universe and even how fast objects are moving as the universe expands
Wow. So this best picture yet, have they discovered lots of new exciting things? Well, no. So it turns out that the data is a pretty excellent match for our best existing model of the universe, which is called Lambda CDM. On the one hand, it's nice to get that confirmed, but it's also left cosmologists slightly scratching their heads as to what they should do next, since we know that Lambda CDM is not a complete picture. But thankfully, they didn't have to wait very long.
Yeah, it's a bit like buses. The second one came along. Yes, so on Wednesday, we got results from the Dark Energy Spectroscopic Instrument, DESI, which is in Arizona. And Dark Energy is the name we give to the mysterious forces thought to be driving the...
expansion of the universe but we know very little about it and what's exciting about this result is that one researcher told us that it could be the biggest hint about the nature of dark energy since we first discovered it around 25 years ago. That's amazing and exciting. What was it that they found? So using data from millions of galaxies and other cosmic objects, they found that dark energy might actually be weakening over time.
That matters because a fixed strength for dark energy gives a fixed rate of acceleration for the expansion of the universe, in turn meaning that it's expanding faster and faster. That's huge, isn't it? Because we've thought... The universe was expanding and that expansion was accelerating, as you say. We've thought that for ages. And if that's not the case, that's a huge deal, isn't it? And as a side note, if dark energy is weakening, does that mean we're doomed?
Well, so if it's weakening, it means that we might eventually reach a state where the universe is only expanding at a constant rate rather than faster and faster. So that's not necessarily a doomed scenario. But other more drastic scenarios are possible. so if dark energy weakens too much, the entire universe could begin collapsing in on itself, leading to what's called a big crunch.
That sounds bad. Is it? I'm guessing it's not going to happen anytime soon. Sounds like confectionery. Big crunch. Big crunch. Tasty. Yeah, so it's difficult to say exactly when it would happen, but we're talking billions of years, so not something to immediately worry about.
about, I mean, really what's got cosmologists excited is the idea that if we have got something about dark energy wrong, that could start poking holes in lambda CDM and give us clues to coming up with a new theory. So this is something, you know, whenever I talk to physicists... There's this real love-hate relationship with the standard model, isn't there? So it's the best explanation we've got. It works really well.
They really want to tear it up and sometimes they say, I want to kill it, kill it with fire. You know, if we find out we don't have a cosmological constant, isn't that more than just a little poking hole in it? Well, it depends because you could replace the constant with a function that evolves over time. So it wouldn't necessarily be rewriting the whole thing. It would just be... this sort of small component of the large model. Fudging it, yes. I mean, that's what physics generally is, really.
And we've had another, a third big sort of announcement this week. Yes, so also on Wednesday we got the first data from the European Space Agency's Euclid Space Telescope, which was images of 26 million galaxies. And the hope is actually that Euclid might one day be able to weigh in on this dark energy question with all its images of galaxies once they've gathered more data. But for now, it's just some very pretty pictures which you can find on our website.
You might not even know you had, but once you hear the answer, you'll want to share it with everyone you know. Why do rivers curve? Why do the T-Rex have such tiny arms? And why do so many more kids need glasses now than they used to? Spoiler alert, it isn't screen time. Our team of scientists digs into the research and breaks it down into a short, entertaining explanation, jam-packed with science facts and terrible puns. Subscribe to MinuteEarth wherever you like to listen.
Now, last year, it was reported that metallic nodules found deep down in the oceans on the abyssal plains appear to produce oxygen. And that was a huge deal, partly because these nodules are the target for several mining companies that want to harvest them and use them.
for things like batteries and wind turbines but also on a sort of biological ecological level because we had no idea at all how these nodules could be making this oxygen and also how significant it might be for the ecosystem down there and so that's got Everyone really excited about dark oxygen, as it's called. And now a team in China may have discovered what's going on. Michael LePage, you reported on this. You're here with us to tell us about it today. What's going on?
Yeah, so obviously this claim that there's lots of oxygen being made in a deep ocean was really controversial. We thought all the oxygen down there came from the surface, from photosynthesis. So if it's been made down there, that's quite something. And also the quantity... seem to be big enough to affect ecosystems. So we're not just talking a little oxygen, we're talking quite significant amounts. So enough to support sort of...
complex animal ecosystem. Well, we're not talking Godzilla. Let's be fair. We're not talking Godzilla. We don't know. I didn't think we were, but now I am. But we're talking sort of, you know, little things. and round and mud animals like that. But also that the sea floors is really, really, really big place. And so, you know, if this is widespread, then it adds up to quite a lot overall. It is vast. It makes me think, you know, that cliche about we know more about the...
than we do the deep sea. Apparently that's not. True. You'll be shocked here. But anyway, we have only explored a tiny fraction of the depths. What did the team from China discover then? How is this oxygen being made? Well, the most obvious source of oxygen in the deep is water. So photosynthesis, you split water.
But that takes a lot of energy. So then they thought, well, you've also got nitrates down there, which contain oxygen as well as nitrogen. And there's also a lot of nitrates in the sediment. So they tried sort of taking various deep sea bacteria.
ingrained them in the presence of nitrates, and they found two species that produced a lot of oxygen in the presence of nitrates, but not when there were no nitrates present. And this is a totally new process? Yeah, no one's discovered this before. Now, to be clear, we did know... that there are a few bacteria that could produce oxygen in ways that don't involve substances, but...
The quantities are tiny and it doesn't explain what was found last year. So this is something new and different and more significant. Okay. And just to reiterate, this is in the dark, right at the bottom of the sea. It's chemosynthesis. not photosynthesis, and the bacteria are turning nitrate into ammonia and getting energy. And we mentioned reduction reactions on Mars. This is another reduction and getting energy from that and releasing oxygen.
in the process yeah and what's amazing is we're still discovering lots of these new reactions there's a lot more to be discovered we don't know half of what microbes are capable of doing yet probably I love all the biochemistry, but where did the metallic nodules come in? You know, we thought that the oxygen was related to these things. Yes, so this finally could explain that too. These nodules contain manganese oxide.
other things. And so the Chinese team also tried growing these bacteria in the presence of nitrates and manganese. And what they found is you had manganese oxide precipitating out. Now That suggests that the nodules might actually form as a result of the bacterial action. And so the bacteria could be forming these nodules as a byproduct of the oxygen they're producing. Now, that hasn't been, we don't know that for sure yet, but it's certainly...
Suggestive. It reminds me of those flowers that they were growing in Arizona on a... The flowers sequester metals from the soil, so you can grow metals in the flower farm. Very small amounts of metals, but you need lots of flowers. But very cool.
So this is a team in China that's suggesting this. What did the team who found the dark oxygen... at the bottom of the sea what do they think do we know yeah so i spoke to andrew sweetman who's the key researcher behind that and he's actually really enthusiastic so he's he's saying yes this this could explain my findings he's not saying it's a definite explanation but he was he was enthusiastic
There was a lot of intrigue about it, wasn't there, as you know. So what happened was Sweetman's study was part-funded by the Metals Company, which is a deep-sea mining company, looking to harvest those metallic... from the clarion clipperton zone. And last year, the metals company, well, they weren't happy when Sweetman found this dark oxygen, and they put out a rebuttal.
to those findings saying they thought the oxygen was due to contamination from external sources. So very interesting now that we're finding a real mechanism. a bacterial mechanism from deep sea bacteria that could produce this oxygen. So I'd be interested to see what they come back with.
Yeah, definitely watch this space. You know, we often think about the strange things that microbes do at the bottom of the sea might tell us about what they might do on other planets. Does this have implications for life beyond Earth? Absolutely. I spoke with the leader of the team in China, Xiaoming San, and he told me that this could happen on other planets. And in particular, he mentioned that they've, we were talking about Mars earlier, they've discovered nitrates.
Mars. So if you had the right microbes there, they could be making oxygen from those nitrates. In fact, the team has actually suggested in their paper that if you wanted to terraform Mars, you could put these microbes there and they could turn those nitrates. into oxygen of you, and this would be a way to terraform Mars. Don't let Elon Musk hear that. Yeah, I think we're getting slightly ahead of ourselves. And also, I mean, I am a fan of terraforming, but you do need a magnetic field.
and Mars hasn't got one and anything formed will just get stripped away immediately. There's a whole host of problems. But, you know, it's something. It could definitely, if there are nitrates on other planets and there are microbes that can do this, then you could get... oxygen there. Yeah, you get local sort of caves of oxygen. Exactly, yeah.
OK, that's all the revolutionary science news we have for you this week. Thanks to our guests, Michael O'Page, Jacob Aaron, and thanks to you for listening. Do you tell your friends about us? Give us a five-star rating and review on Spotify, Apple Podcasts, wherever you listen, and subscribe to us on YouTube. we'll be back next week bye for now bye