A Natural History of Mars

around 3.7 billion years ago a little north of the equator a flash flood swept up a large Boulder into a fast running River it was carried Downstream into a Delta Where the River met a lake that had formed inside a huge crater 45 kilometers wide the impact site of an asteroid that had hit long ago finally the boulder splashed into the Crater Lake sinking to the bottom floods like this were fairly common on Ancient Earth but this was not Earth this was Mars but at a time in the Deep past when it was much more Earth-like it had big bodies of liquid water on its surface it had a protective and insulating atmosphere it had a warmer climate and maybe just maybe it had life as far as we can tell though it doesn't have any of those things anymore here on eons we often talk about the radical changes and countless revolutions that our planet has gone through over deep time but while Earth's natural history has been playing out over the last few billion years another epic planetary Saga has been unfolding right next door even though we've been asking questions of that red dot in the night sky for a long time we've only just recently begun to figure out some answers thanks in large part to our curiosity and perseverance so what happened on Mars how and why did it go from that warm wet potentially habitable planet to the cold dry inhospitable one that we know today well the core reason seems to be that while we had some surface level similarities at one point internally Our Two Worlds were on very different trajectories foreign things to lots of different people over human history this strange mobile point of light was counted by the ancient Greeks as one of the planetes or Wanderers and its foreboding reddish tinge meant that several ancient cultures interpreted it as a Divine symbol of War violence and conflict but it wasn't until Galileo first gazed at the planet through a telescope in the early 1600s that Mars started to mean something very different as astrology gave way to astronomy our views of Mars transformed from a mystical Celestial body to an actual physical place an entire other world complete with geologic features and vast Landscapes that we could observe map out and dream of visiting and it opened the door to another tantalizing possibility too as we gazed at Mars was anything gazing bad it was a question that we could only speculate about from a distance and boy did we but we didn't have the technology to actually get any good answers it would take until the second half of the 20th century when our relationship with Mars transformed yet again for us to finally investigate this possibility because Mars went from being a place that we could only observe from far away to a destination that we could actually travel to or at least send machines to on our behalf orbiters Landers and now Rovers have revealed to us a dry Rocky Barren world with no obvious signs of life and they've also offered us the long sought after opportunity to gain new insight into the natural history of the planet take the perseverance Rover for example our most recent robotic representative to arrive on the red planet since 2021 perseverance has been working on a very important mission to explore and study the now dried up lake bed of that crater we mentioned earlier here it's looking for evidence of any ancient life that might have called that Crater Lake home billions of years ago and the data that perseverance has collected has also allowed us to trace ancient geological events from that more Dynamic period of Mars's history like the story of that flood nearly 4 billion years ago back then the planet had a thicker atmosphere and was much warmer wetter and suitable for life but to understand how and why Mars changed into what it is today we need to go back to its formation see Mars's origin story was very similar to Earth's with a few important differences both planets formed around 4.6 billion years ago from clouds of dust and Rocky debris orbiting our sun at their centers were partially molten cores of iron that gave both planets powerful magnetic fields this was a result of the Dynamo effect the generation of a magnetosphere by the rotating convection acting and electrically conducting liquid iron in the outer core now we are lucky enough to still have an active and Powerful magnetosphere here on Earth more than 4 billion years later it acts as in invisible shield protecting our atmosphere from being eroded by solar wind charged particles belched out from the Sun but Mars has lost its magnetosphere and with it protection from those solar winds over time they Stripped Away its thick atmosphere its warmth its protection from radiation it's liquid water and it seems any life it might have once had too because Mars's Dynamo switched off sometime after 3.7 billion years ago we can tell because those are the youngest Martian rocks that are still magnetized which happens when lava cools in the presence of a magnetic field we're still figuring out exactly why it switched off but a big part of it may have simply come down to size see Mars is only around half the diameter of Earth so its core cooled down much faster after the planets formed this shut off the Dynamo effect and exposed the atmosphere to the full force of the solar winds the planets rivers lakes and perhaps even an ancient ocean all vanished as the water either froze got trapped in rocks or was lost to space without a thick atmosphere to retain it though they left Behind The Valleys Lake beds and shorelines that they carved into the planet's surface Prime Targets in our search for past or present Martian life because the question is if life had emerged during that long gone age of habitability could some especially resilient lineages have stuck around maybe by moving underground or to the polar ice caps where some amount of liquid water still exists after all if studying life on Earth has taught us anything it's that life finds a way and species especially microbes can often adapt to thrive and even the most extreme of environments or if not could any evidence of past life have survived after all those billions of years while we haven't found any definitive evidence of Martian life yet we have found some clues in 2018 for example perseverance is older sibling curiosity made an intriguing Discovery it collected data showing that the concentration of methane in Mars's thin atmosphere a gas which on Earth is primarily produced by living organisms seemed to cycle seasonally this suggested that the gas might be seeping out from underground reservoirs which could potentially be a byproduct of microbial Life below the surface where there might be liquid water and where there's better protection from radiation plus both curiosity and perseverance have also found a variety of organic molecules in Martian rocks on the surface that are over 3 billion years old all life that we know of is carbon based so organic molecules are the necessary raw materials for and potential trace of ancient carbon-based life now to be clear neither of these discoveries means that life either definitely used to exist on mars or still does today both could also just be a result of chemical and geological processes rather than biological ones we still don't know that for sure but there are basically three possible options Mars never had life Mars had life at some point but it died out or Mars had life and still has it today and figuring it out might even require another transformation in our relationship with the red planet we may need to bring Mars To Us by returning some of the most promising samples to Earth we could study them in much more detail than our Rovers alone can on the planet itself so in late 2022 perseverance carried out one of its most important orders it collected a rock sample from the crater packaged it in a titanium tube and left it at an assigned spot nearby this was the first of many samples of rock sediment and atmosphere that perseverance has been tasked with carefully collecting and in the early 2030s a robotic Mission will arrive retrieve some of the samples and return them to Earth for analysis scientists hope that studying actual samples of Mars in our Labs from that ancient Crater Lake and other promising sites could be the key to figuring out the question of life on the planet whatever the answer is it will radically change how we understand the nature of life itself is by biology common or rare in the universe is Life on Mars related to life on Earth is that life based on the same underlying biochemistry and genetics or a totally different system in other words are there other ways of being alive and is life infinitely resilient capable of adapting to even the most difficult times and persisting in some form or can a planet lose its entire biosphere right down to the last microbe if conditions get bad enough and you can see how answering these questions especially those last two with the data from Mars's past might be important for the future of life on Earth curious about the microcosmos join host Hank Green and devoki shock rivardi on another show produced by our team Journey to the microcosmos if you haven't watched their videos yet you are really missing out each episode uses incredible footage to take you on a dive into the tiny Unseen World that surrounds us check them out at youtube.com microcosmos we know that Mercury Venus and Mars are all super low on water so why do we have so much of it find out in our episode where did water come from and thanks to this month's a Marsing eontologists Raphael Huss Jake heart 1M Annie and Eric Higgins John Davidson ing Melody lamb Carnival and Colton become an ionite at patreon.com eons and you can get fun perks like submitting a joke for me to read here's one from Sarah W what are the basil animals favorite herb basil and as always thanks for joining me in the Adam low Studio subscribe at youtube.com eons for more prehistoric stories [Music] both planets formed around 4.6 billion years ago from clouds of dust in Rocky debris or to wow see Marge's March

Channel: PBS Eons

Views: 1,091,168

Keywords: mars, mars water, precambrian, jezero crater, red planet, life, planetes, orbiters, landers, rovers, space exploration, Perseverance, Curiosity, dynamo effect, Martian, rock samples, natural history, search for life, biology, evolution

Id: 70Qi4Nk3aJc

Length: 12min 27sec (747 seconds)

Published: Tue May 09 2023