The Red Planet - Professor Carolin Crawford

and we're going to be talking about the red planet which is of course Mars I hope you realize that it's the fourth planet out from the Sun and it's one of the four rocky planets of our solar system and in many ways is your discover it quite resembles the earth and because of that and also the fact that is our most accessible planet it's the one that comes nearest to us it's the planet that I feel has really kind of captured a lot of the human imagination through the centuries and not just that it also means it's a very easy focus for our space exploration and there are many ways in which we know an awful lot about the surface of the planet Mars so it's a terrestrial planet its fourth out from the Sun so it's an x1 out from the earth which means is a colder planet because it's that much further away from the warmth and the heat of the Sun and it's about half the size of Earth just to scale here which means it's still bigger than the moon and Mercury but packed in that volume it's only good about a tenth the Earth's mass so the gravity of Mars is a lot weaker it's about a third of that of the earth so when you look at Mars with your naked eye it just looks like a star you can see that distinct red color obviously it's what lends its name to bitly being the red planet you need a telescope to resolve it into a disk and despite that it wasn't until like 50 years after Galileo first enter telescope to the heavens that people actually began to see features on the surface of the disk so in 1659 Christian Huygens Dutch astronomer first notice are going to regular come a Bloch mark on the disk of southerner he'd looked three years earlier and Sutton Mercer he looked at the planet three years earlier and he'd not seen any features on it completely blank this time it was a slightly closer apparition of Mars it was closer to the Earth in its orbit around the Sun and he saw the first time this dark blocked we now know this is a feature we call syrtis majors and a regular patch that he's going to tried to sketch in the story and just by watching how that patch rotated into and then out of you over the next few days and weeks he calculated that the day on Mars was just slightly longer than the one on earth this was confirmed a little bit later a few years later by gentlemen jammed on domenico cassini the Italian astronomer who also followed these features on the surface of Mars and confirmed Huygens result that the day on Mars is only 37 minutes longer than no one on earth so the first similarity of day length is very similar and both Huygens in letcher observations and you can see you can see in these drawings notice the ight the white caps at each end of Mars a hundred years later the English astronomer William Herschel showed demonstrated that the tilt of the rotational axis of Mars again is very similar to the earth it's 25 degrees or just slightly larger and this is an important point because if you just solar tilt that means that you get seasons you get the same seasonal changes on Mars then you do on earth so go through all the same seasons winter summer spring and autumn the in a catcher courses that they last twice as long because it takes Mars 1.9 earth year to go once around it's all bet of course it's not that similar to earth in terms of its seasons not only do they last twice as long but they're a lot more extreme and there's a big disparity between the north and the southern hemispheres and this is because Mars orbit around the Sun is also slightly more squash than that of the earth so this is the Sun and this is the orbit of the earth and the orbit of Mars not accurately scared cause you find that when Mars is at perihelion so that's the posh word for point in its orbit closest to the Sun it's a 207 in the in kilometers distance when it's at axion so the other side of its orbit furthest away from the Sun it's a full 42 million kilometers further away now when ice is combined with that tilt in the axis that means that the southern hemisphere which experiences the summers where it's close to the Sun the winters when Mars is farthest from the Sun had a greater seasonal variation it has the most extreme summers the hottest summers most extreme winters the coldest winters compared to the northern hemisphere so already there's quite a disparity in a seasonal change between the north and south hemisphere this is also this kind of squash enos of the orbit relative to the earth tells you why sometimes Mars is easier to both observe and to get to at different times of of the year or it's yet you imagine the earth is going where this a little bit and Mars is going around this orbit every so often they coincide so the distance between them can be as low as 35 million miles other times if you cross in the earth or one side here a bit and miles on the other so the best observations so like when we cancel that dark patch that the surface major happened when they're close together and also when they're close together that's when his Space Agency so the whole barrage of space missions off to Mars there are some times when it's a lot more economic to send a spacecraft to another planet and this schematic details 2003 don't you you remember the bats when things like the Spirit and Opportunity Rovers were sent the ill-fated people lambda there was a whole flooring activity and so you get these bursts of missions to Mars when it's at the favorable point and it's all but relative to the earth okay Mars unlike the earth has got two moons and as you can see there's moon don't look anything like our moon first of all they're all irregular in shape they're very small they're very dark colored and for those reasons they weren't discovered till 1877 relatively later on in the study of Mars and they're created they're very small this is the largest moons called Phobos is longest dimension is less than 30 kilometers it doesn't have enough gravity to pull it into a spherical shape you got craters you got marks all over the surface and the other nodes called Deimos which is substantially smaller now the thing about Phobos the larger though not only is it irregular but both of these asteroids look on/off sorry up in again way most of these moons look an awful lot like the asteroids in the asteroid belt and if that we think they were stolen from the asteroid belt by Mars maybe they'd just be nudged closer to it by the gravity of Mars or gravity of Jupiter but they've been pulled into orbit and they're now captured asteroids which have become the moons of Mars now Phobos this while it's spinning steadily here is very closer it only orbits about 6,000 kilometers above the surface of the planet and that's above the equator that means if you're at the poles you can't actually see Phobos and if you're an equator you see it rise and set three times every day because it's orbital period is seven hours 39 minutes so it's kind of whizzing round the planet here's a very nice it's not really an eclipse but as a set of Phobos moving in front of the Sun as seen from one of the land land is currently on Mars so it's very close to the surface which is not good news for Phobos it's all bit is shrinking at a rate of about 1.8 metres per century it's not going to stay in orbit around Mars for an awful lot longer well yeah astronomical terms worrying about half a billion years which is you know not long in a lifetime of our solar system it'll either be shuttered into bits you don't by the tidal gravitational forces of Mars maybe that will create a temporary ring around the planet or you can even crash onto the planet's surface so it's not going to be a long-lived moon the other little moon Deimos which can you just see one moon eclipse and yeah there's a lot further away and it's probably about as far away as you can get from the surface of Mars and still be retained by its gravity Mars has been the subject of its own space race were all familiar with the idea of the space race between Russia and America to get to the moon there was a parallel space race to send missions to Mars and even though the Russians were the first ones to launch a spacecraft to Mars Mars one unfortunate communication with that seas and it wasn't until the Mariner program a little bit later from the Americans that we began to learn more about the planet Mariner for did the first fly past of the planet it went within about 9,500 kilometers of the surface and took 22 photographs and this was later followed by Mariner six and seven which is closer flyer bus and sent back about 200 photographs of the surface and then Mariner 9 which was sent into orbit around the planet and all of these revealed there's a wealth features on the surface that you cannot observe from Earth you've got craters show you some of these things you've got craters you've got volcanoes you've got a huge canyon all of these that were under hitherto unknown the first Lander from the first spacecraft to actually land on Mars was again a Russian one Mars 3 I think the early 70s which had the misfortune to land on Mars in the middle of a huge dust storm and so communication was again rapidly lost from it so again the first successful Landers didn't happen till a few years late in 1976 the Viking landers which I'm sure we all remember incredibly successful missions and they were monitoring the composition of the atmosphere the weather in the sky the property the chemical and mineralogical comet and properties of the soil monitoring seismic activity you can see in this lower picture even had a scoop which would scoop down into the soil and one of the things they were looking for was to test whether any organic compounds in the surface layers of the soil a test which proved unsuccessful and so that meant that certainly life on Mars if it is there wasn't going to be easy to find it wasn't sitting on the surface just waiting for us to discover it of course now we have moved to a completely new phase of Martian exploration there's a whole host of new Rovers on the surface and orbiters mapping it from the sky this for example is a drawing of the Spirit and Opportunity Rovers they landed on surface of Mars in 2004 and have returned a huge amount of information we now have also had several satellites such as the Global Surveyor or Mars Express and most recently the Mars Reconnaissance Orbiter which are mapping the surface of Mars in fabulous detail resolving structures only a few meters across so you can set beautiful current rippling sand dunes and really understanding the geology of Mars from these orbiters this is what it would be like if you stood in the surface of Mars and you could fool yourself you were somewhere in an African Oh Sahara Desert or some sandy desert somewhere there are a lot of differences in Mars I've told you OD the gravity will not be a lot weaker that would be the first thing you feel but one of the main differences is one that is not apparent from any of the images I'm going to show you and that is that Mars does not have a global magnetic field like the earth we think it used to the oldest rock on the surface of the planet shows some residual magnetism suggesting that Mars once had in a strong magnetic field about four billion years ago but more recent terrain on on the planet does not have any of this residual magnetism so about 3.8 3.9 billion years ago Mars lost its magnetic field we don't know how it could be a particularly heavy bombardment or impact during that time and there's a lot of debris left over and the planets was still forming in the early solar system maybe that disrupted the core and you know removed the magnetic field but this lack of magnetic field leads Mars very vulnerable first of all you are fully exposed and surface of Mars to all the dangerous radiation that comes from the Sun in terms of what we call the solar winds is this stream of charged particles that bombard the surface not only is the surface runnable but so is the atmosphere Mars has an atmosphere is had volcanoes in the past it we think it had a lot thicker atmosphere in the past but as soon as the magnetic field was stripped away it leaves the outer layers of the atmosphere very vulnerable to themselves being stripped away remember they're not so strongly tied to Mars because the weak of gravity and the solar wind and radiation has blasted the atmosphere and stripped a lot of it away until what is left is a very tenuous very thin sparse atmosphere these are most ferric pressures about 1% of that on earth so it's more or less a vacuum on the surface of Mars not just that but the atmosphere is poisonous would be poisonous to us it's mainly carbon dioxide with a bit of nitrogen and a tiny bit of argan and maybe slight smattering of oxygen and car monoxide you're not going to have an ozone layer because you don't have enough oxygen so again that doesn't protect you from the harsh UV radiation from the Sun and that affects the chemistry of the soil so it's a very thin very tenuous quite poisonous atmosphere mainly carbon dioxide so this atmosphere means that the you don't get Mitch Wright's burning up so readily is you do enough so you get a lot more impacts from the surface of Mars as well now between the atmosphere and also the temperature Mars okay it's cold the Mars it's quite nice outside in London this morning wasn't it yeah you probably get to that temperature on a Midsummer's day on the equator at midday and Mars that would be your very best bet most of Mars is going to be around minus 60 degrees C at the poles you're going to drop down to minus 150 degrees C okay so you can immediately see one problem is that the carbon dioxide will fall out of the atmosphere it'll you'll actually get precipitation the atmosphere will freeze during them especially those extreme southern winters and if you're removing carbon dioxide from the air as snowfall that means you get huge variations near pressure so it's weak to begin with then you get seasonal variations as up to a third of the carbon drives and dioxide in the atmosphere kind of sudden and it condenses out as snow for during the winters so you get huge variations in this this pressure and these cold temperatures and this absence of any real air pressure means there is no liquid water on the surface of Mars now any liquid water in any quantity is either going to freeze or sublimate away it is combination of the lack of atmosphere and the cold temperatures that does for it now the surface of Mars is red because it's rusty one of the chemical that there's a lot of iron in that surface soil it gets oxidized to give that characteristic red color it's very dry there isn't a lot of water and so the motor service of Mars is covered with a very fine dust kind of desert grains and even finer particles there's also a lot of weather on Mars there's a lot of wind I've told you there are these huge temperature changes there was a huge pressure changes and especially at the turn of the seasons these differences in pressure can drive enormous winds across the surface of the planet winds of up to 200 kilometers an hour and this can redistribute this dust and it carries it around the planet first of all you will see perhaps on a photo like this that the sky Mars is pink it's not blue now it's because a lot of these dried dust grains get carried up into the atmosphere and are suspended there in the air and they color the sky pink and this has complications because they can absorb the sunlight and heat up the atmosphere you can begin to see ways quite difficult to land something on the surface of Mars when the atmosphere is kind of growing expanding according to how much dust there is and you've got strong winds that pepper the surface so the answer is Mars is kind of variable quantity so first of all you get dust whisked into the air and hanging there all the time and then these strong winds can also shape dust on the surface the sand and surface there are clear pictures of large desert dunes and ripple structures that we can see changing from these winds on a small scale the dust gets whipped up in small tornadoes again as the ground heats up and heats the air above it you can get little sort of vortices there that whip up dust with them to create what are known as dust devils here's one seen from orbit from one of these orbiters after you're looking down on it and it's shadow here and these can stretch up to a few kilometers above the ground and some of the Landers have even seen them studying across the surface of Mars so think these don't last long but they're pretty vicious they scour the surface underneath them and they they remove any lightweight material and behind them they leave tract so again when you look from orbit there are these fabulous patterns just etched all over the surface of Mars and every time it's these dust devils that only last perhaps a few minutes a very short time but they just leave these huge whirling tracks behind them as they've lifted material and erased it from the surface those are the small scale dust storms masters things on an even bigger scale and particularly the turn of the seasons when you've got that change in atmospheric pressure you can drive even bigger wings and these whip up more material into the air and then start getting a feedback process if the more dust you have in the air the more it observe more it absorbs the sunlight warms up the air more drives this differential strengthening the wind whipping more stuff into the air and you get a feedback processes which results in global dust storms they can obscure the whole surface of the planet at a time living lasts for weeks or months they will only ever stop when you get so much material in the atmosphere that actually starts blocking the sunlight and the air begins to cool and then it ceases so here's the start of one you can see just beginning but just show you the effect of one of these global dust storms on Mars so here we are June the 10th 2001 and then just about a month later you can barely see any surface features so remember those only astronomers try and map out early surface features on Mars here one of these dust storms there's no chance even in a close apparition of the planet where you're going to be able to make out any of those features and so these can just completely scour the surface and remember they're redistributing with the sand and the material the whole time is a lot of weathering on Mars from the winds the ice caps are mean well they have two layers to them I've told you that during the the winters it gets so cold that the carbon dioxide condenses out a snowfall and this stop and builds up the icecap until you get variations in the size of icecap now this is the northern hemisphere in winter in fact there's a dust storm just beginning down here this is what it looks like in summer you can see that shape just perhaps embedded in there try to do them to the same scale this is water ice and then all of this is an extra layer of carbon dioxide which falls out of the atmosphere and just builds up that ice cap it's even greater in the southern hemisphere again you have a permanent layer of water ice which then is supplemented by a much larger cap of and temporary cap of that carbon dioxide and so the size of the polar caps waxes and wanes with the seasons and because you have this continual deposition and then falling and then you have the season of dust storms one of the things the features that we can map from orbit are layering layering of deposits where you have ice and then dust and then ice and all this seasonal cycle leads these layers of how far the ice is expanded or retreated each time and Martian geologists can read this much like we read the width of tree rings and they can tell us something about the seasonal variation of Mars over you know the last few millions of years and they can tell us about any long-term trends any long-term variation in the weather of the seasons and Mars perhaps due to a change in the axial tilt of the rotation or the way that the orbit of Mars shape might change slightly around the Sun so again you can start to tell something about Martian weather history from these deposits the inside of Mars we think it's fairly similar to the earth there's been some differentiation which means that you know metals have settled out you've got a core mainly iron core that was molten originally and then you've got a lot of silica rich crust and mantle overlaying that there's a lot more there's an iron at the core a lot more in the surface then there is an earth and they cause a lot smaller because Mars is smaller that core did not stay warm for as long it cools down more quickly because it's got a small volume a small volume and a large surface area the surface of Mars has got craters all over it they can sometimes be obscured by the storms or filled in by the storms but some of them are very large I'm quite partial to this one on the left you see the smiley face and this is a this is also a nice bullseye you've got a crater within a crater I don't quite Haven to get two impacts so completely lined up so all over the surface of Mars you have craters but there are other spectacular geological features and indeed in just a simple geology of Mars is a bit weird because you have a huge difference between the south and the north now this is an elevation map it apocrypha map of Mars unraveled so you have the lower part here these are the southern lands and this the Northlands and the first thing you can see because red is up is higher and blue is lower that the southern hemisphere is an average about five kilometers and higher in elevation in the Northern Hemisphere and southern hemisphere is heavily cratered is the older terrain and so it looks like something happened in the north which either recoated the surface maybe there was a lopsided upwelling of magma that came out and lava recoated the surface or maybe very early on in Mars history something tore off maybe a big impact with another protoplanet tore off the crust in the northern hemisphere leaving you need to resurface itself but this is called the crustal dichotomy a big difference between the north and the southern hemisphere and again we don't quite understand the origin for that it happened when Mars was um you know it was a few million years into its history so perhaps about 3.8 billion years ago or even slightly more recent so if I just put that color on to glows you can see the southern hires again was created these are all craters from most them from that very heavy bombardment that happened early on in the solar system and there was a lot of debris left that was falling onto all the inner planets providing the craters that you see a mercury on Mars and on the moon there there's one crater years 2300 kilometers across as a very early very massive impact but lots of them are much older you can see it here filled with snow this is the dark syrtis major future editor William Herschel observed what open up Android is and in the move well just straddling this low North miss high cell there's a bulge it's a strange part of the planet that sort of swirls out about ten kilometers above the surrounding thing and it's about five thousand kilometers across and this underlies where there are volcanoes on the surface of Mars you have this large bulge and it seems like there's always been again an upwelling of volcanic magma which is not broken through the surface just push the mantle out slightly and the fact that it's associated with the position of these volcanoes and Mars suggests there could be the explanation so you've got this kind of bulge on one side of Mars which again we don't see on other planets near to us the volcanoes themselves are large you've got weaker gravity on Mars so if you have a continual vent of magma coming up then to the gradually accumulating a volcano it can get an awful lot bigger and still support its own weight these are what we call shield volcanoes where we see them on earth is placed like the Hawaiian Islands and you have an upwelling of magma creating volcano no an earth we've got tectonic plates that slip until you get a China violence you don't know how tectonic plates on the surface of Mars yet welling all cabins continuing one place and you build up these huge mountains now this is the largest volcano Mars is called Olympus Mons you could fit the whole of Britain from to the other here it's about 600 kilometers across 25 kilometers above the surrounding terrain so that's effectively three times higher than Mount Everest these are massive volcanoes now most of them that are just wandering that fascist bode region on the side of Mars they're all dormant now Mars is no longer volcanic Li active but it clearly went through a period where there was volcanic material outgassing and creation of these volcanoes and has connected with the creation of that bulge there's an enormous fracture in the surface of Mars it's called the Valles Marianas and it's named off the Mariner spacecraft because they they effectively discovered it so the 4,000 kilometers long it's a canyon it's up to 8 kilometers deep it wasn't created by water it is it literally a split along some kind of fracture or some kind of fault line in the crust and it could be connected with this this bulge on the side when it was created so again Martha's fantastic geology which seems a lot more extreme than what we have on earth now there is water on Mars the underlying ice cap and both the North and the South Poles is of water there's a trace amount of water vapour in the air here you've got clouds hanging around just the summit of those volcanoes so if you do get water vapor clouds as well as carbon dioxide clouds in the air and we do see water ice elsewhere on the planet for here's a picture from Viking where one morning in 1976-77 a frost just covered the surrounding rocks similarly from orbit we can see craters and you can test obviously the reflective properties of this ice this is a creative 35 kilometers across and this is a giant puddle of water ice many of you planning to go to Mars that could be very good place to land somewhere you can go get water for your cup of tea from and they've also water ice frost around shaded regions of this predator so there are areas where they're in shadow is particularly cold you do get pockets of water ice now we know that there's also regions where there was a water on the surface of the planet now this is just a map of Mars a glob of Mars taken by Mars Express and it's just detailing all this site they found evidence for mineral salts now you can see every one of those dots is where they have a detection of what they call hydrated salts so these are things that require water liquid water to form usually have evaporation of water that leaves behind these minerals and they are all heavily concentrated to the south all those kind of old Highlands and anywhere there's a depression in the old Highlands you find evidence for a kind of smattering of this this mineral salt so we know that there was once liquid water on the surface of Mars is left behind it's back right away and left behind this material so we know that something's chained from the past to today now obviously Mars has got colder and another of the things we know is there's a lot of ice below the surface again two different spacecraft had gone and looked at the surface of Mars with a neutron spectrometer and also a ground-penetrating radar and they discover there are an enormous reservoirs of ice beneath the soil and this is true even at the equator as at the poles there are aquifers of frozen water ice below the surface now we don't know how deep they go the ground penetrating radar and it goes back a metre down and it's possible these could be up to a kilometer or more deep within the soil but there's clearly water ice locked in the soil of Mars it's all frozen in there where it becomes apparent could be when you have a later meteoritic impact such as these here I hope you'll agree when you look at them they kind of look a bit sludgy then excuse me you can see ring round here when were to you is more like you can I dropped a pebble in the muddy sludge or here again a very sludgy kind of splatter where you get the senses watering the material that has melted during impact and then refrozen and these overlapping lobes round be the crater so we see indications wear a hat because this frozen water this frozen ice has melted and then refrozen suggesting again you've got a lot of water ice locked beneath below the surface layers of Mars kind of permafrost if you like and one of the key things about permafrost on earth that we see near the poles is we see a polygon pattern and this has also been seen on Mars this is the Phoenix lander that landed in the northern regions of Mars near the polar regions and this is a view it took of the terrain stretching way into the distance and you can see it's cracked into what they call polygons as far as you can see this is characteristic on earth of permafrost reasons where you've got that more trice locked into the soil but with the changing seasons that ice falls and then freezes and that the soil and look at the ground but it's locked into will then swell and expand and then contract and that sees no expansion and contraction breaks and fractures the ground into this characteristic pattern we see it right next to the Phoenix lander in those northern polar regions we also see it from space looking down at surface of Mars so this is just a black-and-white picture showing you these kind of Ridge polygons and within them polygons within polygons and different scales again very indeed indicative of all that water ice deep within the soil the evidence for flowing water and Mars is also apparent from mainly from the orbital image mocking the geological surfaces when the Mars Global Surveyor orbited Mars one of the most exciting things they had they saw looking at the crests at a lot of these sand dunes and the the rims of crota walls and a lot of detail were gullies you can see here they look for all the world like some kind of flow has happened these were originally touted as perhaps from melting of that water ice within the soil it may still be due to some melting of carbon dioxide and indeed we saw these gullies being created over a period of six years new fresh deposits would occur within in this case it's a crater wall suggesting material of perhaps tripled down now most of these now attributed to melting of carbon dioxide ice within the rim of the crater perhaps landslips a little bit of seismic activity or meteoritic and impact nearby loosening material to scatter down the slope there are few of these studies that we think could be due to melting of water ice they tend to be in the parts and craters that are shattered for most most of the time and so you can get a buildup of water ice there and maybe they only see the Sun occasioning then you get a rapid flood but that isn't the key these dollies are not the key evidence for water and Mars instead you're looking for features that resemble valley networks drainage systems again similar to what we see on earth and here's an example from one of the Viking orbiters when you get tribute trees braiding together and coming together to form deeper channels and this is an example of such a structure that we feel is very clearly formed by water on the surface of Mars now to develop a network like this you need a continual and steady flow you know trickle of water almost so this could be perhaps from melting of the groundwater ice some kind of seepage from some kind of gradual seepage and maybe at the bottom of a canyon and feeding a temporary flow that spreads across the surface of the planet for a short while crazies channels and dies away there are channels like this and surface that are due to water and then there are much more dramatic events we think that have happened in the sort of continuous studies seepage so for example here is a patch of of Mars it's at a large Valley where we see evidence of a much more torrential flood of water across the surface and need to see in various patches all over Mars and if you look you see the scale 70 kilometers so the width of these features they can be tens of kilometers wide they can last thousands kilometers long and if you look in detail at the structures within these large outflow channels you can see stream line stretches see here where are they seeing a crater or something it's like water has flowed around it and piled up sediment to form this kind of this teardrop shape is very streamlined effect there's some there there's some up here and all of this shows perhaps a torrential flood a very temporary flood of a lot of water again just from the geology and other structures within these outflow channels and the question is you know where does this water go and where does it come from now so where it goes we think once you've initiated a sudden current of water it'll flow very rapidly until it reaches some kind of low-lying basin maybe a crater it'll flood the crater and create a temporary lake or sea now those are the lengths of sees that evaporate away and leave behind the mineral salts that we see from orbit how its created probably goes back to that subsurface ice some of these flows he's an example you can see it big flow Chau stretching the way down here seem to originate in cracked fractured land there's another example with false colors here is an elbow that weekend you got a very clear flow that goes on and marries up with the one I've shown you earlier but again it originates in very sort of crack and French Egeland and the the origin we think is again from subsurface water layers where perhaps the weight of the overlying material prices down heats the eyes and so there's a huge collapse when it melts the top layers crashed down and ice itself melts and creates these temporary torrent is flooding across the landscape which lasts for a while creates these ancient lakes and seas which they need the sublimate away evaporate away or sink down and become again part of the frozen ice the permafrost in soil so you get this cycle which was mainly early on in the history of Mars could still potentially happen today we see no evidence of it being very recent and I'll come back to that the cellulose liquid water flowing across the surface of Mars so there's evidence from orbit by looking at these geological structures comparing them to what we know of water flow on earth but of course we have the luxury of exploring the surface of Mars remotely through our little remote control spacecraft so in 2004 two rovers Spirit and Opportunity will land by Nasser and opposite sides of the planet sort of fairly near the equator and in both cases they chose locations that we knew from orbital matting orbital Madi there was likely to have been water on the surface so the first one spirit landed in this crater look at the crows you can immediately see it's indicative of a water Chow that then filled this crater again orbital matting subject and mapping suggested that there's a stronger pond Durance of those those hydrated minerals within that Basin spirit has explored or you know a good fraction of this basin it landed over here it went there how to look at this crater over here the view of that crater from the vantage point of the the rover and then it crawled across here and went up into husband Carroll's and down here down to Columbia Hills and this is the view from the hills there's the flat basins the crater in the distance and you're up in these hills you can see the tracks of the rover here now as it did not it was examining the soil again it confirms by doing an analysis it's got that scoop er mechana analyze what's in the soil it can even its wheels turning over the soil exposing countries it there's a little bit smattering of white chemicals here again these salts it confirmed the presence that this looked like it was an ancient water bed that there had been mortar on this side of Mars to the other side of Mars Opportunity was landed in another region which from orbit they detected high levels of a mineral called hematite now this is something that requires it takes a long while to form and it forms from again in a body standing water very slow evaporation process and this is the view from the opportunity Rover a kind of pavement stretching away of rock and scattered all over the surface little bubbles when you look at them in detail these are blueberries what they call they call them blueberries and you get microscopic imaging can see them in more detail all of these are little hematite granules and again they suggest their standing body of water that evaporated slowly away so both sides of the planet evidence different kinds of evidence for liquid water and not just any liquid water I should stress it would be something to be very acidic very salty not actually very nice water compared to stuff we're used to on earth there's more evidence from other Landers Phoenix was a said lime dude in the pole of northern polar regions of Mars it didn't move it didn't Rove around surface it just explored its immediate environment in great detail but again it had a scoop and this scoop could dig trenches down to about 15 centimeters down into the first layer of soil and he if one of the scooped the trenches it dug this is the first image of it you can see white material here my hope you can see there are some white blobs there three days later it looks like this okay spot the difference these cubes are --here disappear on some of this though the rapidity with which this is sublimating way shows its water eyes so again clear evidence for water ice within the surface of the soil but not just bad things could do very detailed analysis of the soil this scoop picked up surface layers and delivered it to the belly of the rover with so another over the lander ate not only did this microscopic imaging of the the soil he also baked it since what was in the soil and it detected the presence of some mineral salt could have perchlorate and the key thing about this is that it is incredibly soluble if you detect that as Phoenix dig within the soil of Mars it means there has not been liquid water for millions of years over that patch of Mars so the fact is this per crate is sitting there have there been any water salt you know water around recently it would have all been washed away the fact is there means that Mars has been dry for a long time so the presence of this percolate has also been confirmed by our latest rover Curiosity here is unlike the lab on earth for NASA missions back size of a large mini car you can see it's got a a camera here it's also got scoops it's got lasers it's got drills it can do a lot of remote exploration and testing of the surface of Mars for us alone did last summer in August 2012 and since then is driven too short three kilometers over the surface of Mars and it's sent back tens of thousands of images so we really are looking at things on Mars in great detail and like both the spirit opportunity and the Phoenix it has the potential to investigate both at microscopic levels but also the chemical makeup of the soil and just examine curious features it seems now is the line did in a crater this is it this just a selfie it's taken okay it's landing in Gusev crater here's a kind of 3d relief picture from some of the orbital imaging there's the crater wall here the land is the road is about there and you've got the central peak of the crater now looking at that edge when you look at this selfie you can see the crater wall in the distance here and you can see the beginning of the central mountain mount sharp at the core of the crater now again you land your spacecraft where you think it's going to be something interesting to look at now curiosity's not looking for life on Mars none of the current Rovers and planned missions are doing that what they're looking for other kind of trying to be scared of the water history of Mars when was Mars warmer when was it wet it is their true evidence for water liquid water flowing across the surface of Mars and in fact it's already solved that very near where it landed but okay just to say that why it landed in this crater is that the again you've got from all bit the idea you've got these minerals salts within the crater and there's also a cut in the crater rim which suggests that water flow is just kind of flooded that's one of those surges has flooded over the rim and filled the crater sometime in the past so right near the landing site the Curiosity notice some eroded rocks so you can see layers of rock here if we just zoom in on this little narrow region and then or perhaps some of these outcrops looking at that and examining it in great detail already provides evidence for liquid water on Mars so here's a picture of this region now really close and this is a similar region on earth this kind of odd conglomerate is when you've got air gravel small pebbles and it's all cemented together by fineness and where we see that on earth is on riverbeds and dry riverbeds when you look at the conglomerate on Mars and these outcrops first thing you notice is that it looks like river gravel the pebbles are too large to have been transported there by the wind they're rounded so they've experienced erosion and they're all different colors which suggests they've come from a variety of sites being brought together by one mechanism presuming liquid flow and in comparison to rivers on earth and river deposits on earth we you know the scientists suggest that they could have been delivered there within a strict you know liquid flow there's not traveling awfully fast and isn't particularly deep you know probably bit somewhere between ankle and waist height you've got a fair stream just eroding and depositing material and perhaps carrying it up to ten to fifteen kilometers away from source and this fits with the idea that this crater was once flooded curiosity is there there's the cut in the rim and indeed when you look at it in detail the structures is the idea of some kind of material that just spills over and it could flow and fans out over the surface of the crater so it's already found that there were lots of evidence for there being flowing water on the Mars but remember a long time ago because it doesn't find a plug perchlorates within the soil now curiosity is going to explore Mars for a while yet it's now moving towards its main target which is that central mountain and this again is one of the key reasons for going to this particular crater is the mountain at the center it is surrounded by sediment you can see some of the deposits down here if i zoom in on this region on a slightly enhanced picture you can see there's a sort of difference between the and this picture they're just drawn dots to delineate the boundary between different kinds of of sedimentary layers within the rock not just that but if you zoom in even further you can see sculptured sediment and here the ideas of more erosive activity and more deposition it looks like there's an interesting water history there to examine and that is where curiosity is headed it can't take a direct route there are big kind of sound dunes within the way it's going to have to take a circuit us route and this is are going to get distracted they'll be interesting rocks or outcrops that it'll go and look at in detail but it's clear is going to be turning up fantastic images and more detail from the surface of Mars for a while to come I'm sure we're going to see it in our in our news headlines it's already shown that Mars has a complex and interesting water history so the key thing is why was Mars much warmer and wetter in the past and now it's not by the way sonars impression when discovery liquid water on Mars it's going to give an impression of what it might be like in the past now Mars was obviously warmer it had volcanic activity but that cooled out a lot more quickly than it did on earth but the volcanoes will have delivered material to form a nice thick atmosphere if you have a thick atmosphere you have a greenhouse effect you might have a warmer surface of the planet the whole planet could have been a lot warmer in the past the thing we think is important is the removal of the magnetic field whatever did that so 3.9 4 billion years ago that then change the whole nature of the atmosphere it was then free to evaporate away and get stripped off into space and at that point Mars began to cool down and it began to become a very different planet and that's probably that's probably the key factor in whether or not it now has with washing services what impact will what event stripped away magnetic field and then left the atmosphere vulnerable to exposure of course if Mars was once warmer and wetter in the past it could Harbor life now Mars is the one planet that springs to mind when everybody talks about aliens you think about Martians I'm afraid I'm not going to announce any great discovery I'm going to counteract the idea that there's intelligence of Mars but a lot of this human fascination came from when astronomers so this is the the notebook of Schiaparelli from 1877 who when he was observing Mars this telescope he could see dark structures and he turned these Canali which is the talent for channels but it kind of got misrepresented when translated to the English as canals and some astronomers like their imagination run away of themselves and suggesting this was an artificial origin I mean here's a mothership ray mapping out these structures on the surface of Mars now he wasn't stupid he was doing really good observations and in fact when he compares some of the drawings made by people like no all around the turn of the century to perhaps modern pictures of Mars but you just got a scream and blow your eyes you can see that they are represent you mowing through not a great telescope you are representing what you see now already by 19 you know well 1910 telescopic images and observation had ruled out these dark linear structures being real okay they're in more optical illusion where the I kind of draw if you have dark blotches it kind of draws a line between them it's a bit of an optical illusion but it raised the idea I mean there were whole flights of fancy where these were canals bringing water to irrigate the desert from the polar regions and the dark that you would see changes in the canals which they attributed to seasonal growth but we know is probably more likely due to the dust storms they would obscured features or recoat features so again it was embedded in the human imagination this idea of Martians we now know of course it's not true cently not far martians we haven't found any onset player but you still can't rule out that somewhere there could be microbes there is life on Mars it would be what we turn an extreme afar we get them on earth these are the bacteria that can grow in very acidic very salty very harsh very cold conditions now they will not exist in the surface layers of Mars because you've got you've got no ozone layer so you've got harsh UV radiation from the Sun the whole surface of all is oxidized you are not going to get anything surviving that environment for millions of years from when it was warm and wet to the present of day now where we think it could be if there is life it would be down deep underground after all we have discovered extremophiles on earth up to a kilometer below the surface but it's going to be a while before we send a mission that does dig down into the surface that far and examine it ideal what we want to do is to bring samples of miles back to look at in the laboratory now we haven't done that yet occasionally Mars obligingly sends us samples remember this week of gravity of Mars and if you have a really big impact some of the ejecta from the impact will fly off and escape the gravity of Mars you need to get five kilometres per second to escape the gravity of Mars and every so often wanted they'll go into orbit around Mars then around the Sun and maybe intersect with the earth and land is a meteorite on earth now there aren't that many of them only about 20 Martian meteorites we know they're from Mars from look of bubbles of air in the rocks that exactly March match the composition of Martian atmosphere from the isotopic composition of the rock in fact ever there's a bit of Mars here by the way delivered from a one of these Martian meteorites and you will remember 1996 those one particular meteorite where microscopic examination showed what was thought at the time to be like tiny nano fossils of early bacteria the consider consensus now a long time later is that these are probably mineral structures and we even if they were fossils you couldn't rule out termination from from earthlife they're a lot smaller than any kind of Earth Earth form of life were expected but nonetheless it does it it raised the idea from you at that time that life could have traveled from Mars to earth some of you may read just recently in the last month this is again being revived with again analysis of the composition of the soil and Mars and the idea that actually Mars could have been hospitable to life long before it was an earth much earlier it would have cooled down more rapidly and there are certain elements in the soil so difficult of burano my that are in soil and Mars in a good state to prove - these are crucial to how you make those molecular components for life such as RNA DNA and proteins and in fact maybe they're in a much more favorable form on Mars and much earlier in Mars than they were in earth where they weren't necessary in the right chemical form in the right quantity or they were dissolved in the oceans so this has really recently got a resurgence that life might have started even earlier in Mars than on the earth but if we really want to test that we don't have to rely on those meteorites come from Mars we want to go there we want to bring back samples and we are a long way of that yet there are missions planned to Mars they're going to carry on this this mineralogical this chemicals physical analysis of the soil it's going to be a long time before we start digging deep under the soil and ideally as I say we want to bring samples back and bring them back to earth and that's considered really the next important step you're going to prove you can bring things back from Mars before you can send astronauts there it's not easy to bring things back from Mars so do people because not only do you need all the fuel to get them to Mars and all their their supplies to Mars you then need to sender the fuel to Mars that you need to bring them back and it's a kind of runaway effect it becomes you know very expensive very unwieldy to do now president Obama has challenged NASA to put astronauts on Mars in the 20 tee's but over the summer you may have heard of other initiatives where they try and get round the issue of bringing people back and there is one initiative it's called Mars one that's been in the news lately where they're offering some successful candidates your chance for a one-way ticket to Mars and you have to think about this as you are the first settler it's not different from only people settling Australia and the Americas you don't know that you're never going to see your homeland again but the idea is that we've had over 200,000 applicants okay so they're plenty you don't have to be an astronaut to apply and if you miss that round there will be other rounds later but they're looking to spend 4-pin first crew of four people to Mars in 2023 well launch them 2020 to get to Mars in 2023 and they're gonna be all kinds of missions to deliver stars and set Scout that landing site but this is you know quite an exciting possibility but they in fact it could be a private company it's not for profit company who you're going to finance all this by selling the media right guess it's going to be Big Brother on Mars right weird seriously which of the astronauts get chosen that first crew on Mars is going to be by popular choice popular involvement and it's a completely different way of going about choosing your astronauts to Mars and most of it I haven't signed up I think I know too much about the surface of Mars to know it's not a nice place it's not just the atmosphere the dangerous radiation from the Sun the the cold the lack of water that you know it's the weaker gravity would destroy bone and muscle mass there's a lot of negative things about the surface of Mars so I've got apply but I believe me I will be cheering those astronauts all the way yeah very very pleased some peaches to go but I'll just sit in the surfer and watch I said I'm gonna go for the first crew anyway however as I say there will be further round so if any of you are inspired by my later to go in service Mars you will get other opportunities to join subsequent crews for this colony on Mars so thank you very much I'll just end and tell you that in a month's time I should be talking about quasars a completely other end of the astronomical spectrum thank you

Channel: Gresham College

Views: 65,144

Rating: 4.7313433 out of 5

Keywords: mars, curiosity, mars rover, mars lander, mariner, red planet, space travel, space exploration, tharsis bulge, olympus mons, phobos, deimos, astronomy, solar system, astrophysics, mars geology, Space, Gresham College (Organization)

Id: eveN3AUu2UA

Length: 59min 6sec (3546 seconds)

Published: Thu Oct 03 2013