0:00:05 > 0:00:06Mars...
0:00:07 > 0:00:09..the Red Planet.
0:00:11 > 0:00:14Many scientists believe that the first person to set foot
0:00:14 > 0:00:17on its surface is alive today.
0:00:20 > 0:00:22Perhaps it's someone watching this film?
0:00:24 > 0:00:26Perhaps it's you!
0:00:30 > 0:00:33If it is you, then welcome to your traveller's guide...
0:00:34 > 0:00:37..a guide in which we will show you where to land,
0:00:37 > 0:00:41where to live, and, most importantly of all,
0:00:41 > 0:00:43what to see and do while you're there...
0:00:46 > 0:00:48..from towering volcanoes...
0:00:50 > 0:00:53..to unfathomably large canyons...
0:00:55 > 0:00:58..and mysterious features etched on the landscape.
0:01:01 > 0:01:03We'll even take you deep underground.
0:01:06 > 0:01:10Horizon has gathered together the world's leading experts on Mars.
0:01:12 > 0:01:15I've been interested in space exploration since I was seven years old.
0:01:15 > 0:01:19We asked each of them where would they go if they got the chance.
0:01:19 > 0:01:23We don't have anything like this on Earth.
0:01:23 > 0:01:26And what they would need to survive.
0:01:26 > 0:01:29You need something to protect you from essentially exploding,
0:01:29 > 0:01:33or at least having your skin all stretched out and the blood boiling.
0:01:33 > 0:01:35Using real images and data,
0:01:35 > 0:01:38we will take you to some of the most jaw-dropping landscapes
0:01:38 > 0:01:40discovered in our solar system...
0:01:42 > 0:01:44Standing on the rim,
0:01:44 > 0:01:47I wonder, "Could I pick up the rock that actually came from
0:01:47 > 0:01:49"the object that formed this enormous feature?"
0:01:49 > 0:01:53..places that may change the way you think about our own world...
0:01:56 > 0:01:58Is there life beyond the Earth?
0:01:58 > 0:02:00This is probably one of the most profound questions
0:02:00 > 0:02:02that's ever been asked by the human mind.
0:02:02 > 0:02:06..on a journey that will test the endurance of any traveller.
0:02:06 > 0:02:10Travelling to Mars, the idea sounds romantic,
0:02:10 > 0:02:13but, you know, the journey is not for the faint of heart.
0:02:13 > 0:02:16At the dawn of the next golden age of exploration,
0:02:16 > 0:02:19we'll take you to the Martian frontier.
0:02:20 > 0:02:22I cannot wait for the day
0:02:22 > 0:02:25I get to see people walk on Mars for the first time.
0:02:25 > 0:02:29This is your traveller's guide to Mars.
0:02:46 > 0:02:47The red glow of Mars
0:02:47 > 0:02:50is an omnipresent feature of our night sky.
0:02:51 > 0:02:53But it's only when viewed up close
0:02:53 > 0:02:57that this rusty planet really begins to reveal its secrets.
0:03:02 > 0:03:04It promises to wow any visitor
0:03:04 > 0:03:07who's spent the past seven months onboard a spaceship
0:03:07 > 0:03:08travelling to get there.
0:03:11 > 0:03:15Other than our home planet, there is no world we know in such detail.
0:03:19 > 0:03:22That's thanks to the numerous successful satellites and rovers
0:03:22 > 0:03:25we've sent there over past 50 years.
0:03:27 > 0:03:32And the landscapes they've looked down upon tell astonishing stories.
0:03:33 > 0:03:36Vast plains, riddled with hundreds and thousands of craters.
0:03:37 > 0:03:40Deep canyons and strange rock formations.
0:03:42 > 0:03:44And scenery not seen anywhere on Earth.
0:03:46 > 0:03:49We've photographed every corner of the planet
0:03:49 > 0:03:54and plans are now underway to send the first humans to Mars.
0:03:54 > 0:03:56But what does it take to get there?
0:03:56 > 0:03:59How can we survive on the surface?
0:03:59 > 0:04:02And where are the best places to explore?
0:04:02 > 0:04:06We'll start with the Martian landmark we know best.
0:04:09 > 0:04:11Gale Crater,
0:04:11 > 0:04:14a vast scar on the planet
0:04:14 > 0:04:18and home to NASA's flagship rover Curiosity since 2012.
0:04:21 > 0:04:25Arguably the most ambitious explorer sent to the Red Planet so far.
0:04:28 > 0:04:31The crater itself dwarfs any similar features here on Earth.
0:04:34 > 0:04:37Every day, Curiosity sends back detailed images
0:04:37 > 0:04:39from within the crater.
0:04:40 > 0:04:43This is one of them.
0:04:43 > 0:04:45And here, at the Data Science Institute,
0:04:45 > 0:04:49Professor Sanjeev Gupta is part of the team studying them.
0:04:49 > 0:04:51This is the crater remote here.
0:04:51 > 0:04:56This is 150km in diameter, so a really big feature.
0:04:56 > 0:05:01And there, in this view over here, what we can see is Mount Sharp.
0:05:01 > 0:05:03That's 5km high.
0:05:03 > 0:05:05That sits in the centre of the crater,
0:05:05 > 0:05:09so it's really amazing here being able to look at this image
0:05:09 > 0:05:12at such a scale because you really get a sense of this mountain
0:05:12 > 0:05:15that's sort of towering high above us.
0:05:15 > 0:05:18But Professor Gupta isn't simply enjoying the view.
0:05:20 > 0:05:23Today, we know Mars is a dry, desolate world,
0:05:23 > 0:05:27but some images suggest that wasn't always the case.
0:05:29 > 0:05:32Gale Crater was chosen as the landing site for Curiosity
0:05:32 > 0:05:35after a very lengthy selection process.
0:05:35 > 0:05:39Orbiters had discovered evidence that the rocks
0:05:39 > 0:05:40at the base of Mount Sharp,
0:05:40 > 0:05:46so the rocks that we can see over here, had evidence for hydration.
0:05:51 > 0:05:55Long before Curiosity left Earth, satellite images like this
0:05:55 > 0:05:58hinted there was more to this crater than meets the eye.
0:06:01 > 0:06:03What's beautiful in this image
0:06:03 > 0:06:07is that you can see these canyons or valleys carved into the crater rim,
0:06:07 > 0:06:13and this is really suggestive that water flowed down the crater rim
0:06:13 > 0:06:15and eroded these canyons.
0:06:15 > 0:06:18Secondly, we can see all these beautiful layers here
0:06:18 > 0:06:21that form the base of Mount Sharp.
0:06:21 > 0:06:24These layers are enriched in hydrated minerals,
0:06:24 > 0:06:28so those are minerals that contain water.
0:06:28 > 0:06:29Curiosity's mission?
0:06:29 > 0:06:33To follow the elusive trail of water on Mars.
0:06:33 > 0:06:39So, essentially, the orbital images provide us clues on where to go,
0:06:39 > 0:06:41but we really need to be on the ground,
0:06:41 > 0:06:44looking carefully at these rocks
0:06:44 > 0:06:47from a few metres away, and that's why we send rovers to Mars.
0:06:50 > 0:06:55Once the rover touched down, it quickly began picking up more clues.
0:06:55 > 0:07:00These are actually pebbles that are a few centimetres in diameter.
0:07:00 > 0:07:03What you can see, when you look at the pebble outlines,
0:07:03 > 0:07:06is that they have rounded shapes,
0:07:06 > 0:07:10so they've been basically rounded during a transport process.
0:07:10 > 0:07:15And they're too large to have been moved and rounded by wind processes,
0:07:15 > 0:07:21and so the only way we can actually get this rounding is by water flow.
0:07:21 > 0:07:23And I remember when this image first came up and we were all
0:07:23 > 0:07:26huddled around a giant screen looking at this,
0:07:26 > 0:07:30it actually took us a while to really hit home, oh, gosh,
0:07:30 > 0:07:33actually, this is the first evidence
0:07:33 > 0:07:36from on the ground of water flow on Mars.
0:07:37 > 0:07:40This was just one in a long list of features Curiosity discovered
0:07:40 > 0:07:43within the crater that are reminiscent of features
0:07:43 > 0:07:46shaped by water here on Earth.
0:07:46 > 0:07:49I think it's irrefutable that there was once water flowing
0:07:49 > 0:07:53at the surface on Mars, based on the geological evidence.
0:08:03 > 0:08:07Rovers haven't just shown us the surface of Mars in detail,
0:08:07 > 0:08:10they've also shown us how difficult it is to land.
0:08:12 > 0:08:15Spacecraft structures engineer Abbie Hutty
0:08:15 > 0:08:19is responsible for making sure Europe's first rover, ExoMars,
0:08:19 > 0:08:20stays in one piece.
0:08:22 > 0:08:24Landing's always going to be one of the trickiest parts
0:08:24 > 0:08:27of getting a mission to Mars safely.
0:08:27 > 0:08:28It's very hard to predict
0:08:28 > 0:08:31exactly what you're going to be dropping down through
0:08:31 > 0:08:33because the wind speeds vary dramatically.
0:08:33 > 0:08:38You get dust storms, which really change the atmospheric density.
0:08:38 > 0:08:41And fundamentally, you don't have that much thickness of atmosphere
0:08:41 > 0:08:44between entering it at the top and hitting the ground at the bottom,
0:08:44 > 0:08:47so you've not got very much to actually slow yourself down.
0:08:47 > 0:08:50When you first hit the top of Mars' atmosphere,
0:08:50 > 0:08:53you are going so fast that really
0:08:53 > 0:08:56all you can do is just hide behind a heat shield and hope for the best.
0:08:58 > 0:09:00During atmospheric entry,
0:09:00 > 0:09:01the lander will need to withstand
0:09:01 > 0:09:05temperatures reaching up to 1750 Celsius.
0:09:06 > 0:09:08So eventually you'll get to the point
0:09:08 > 0:09:12where you can deploy a much larger parachute,
0:09:12 > 0:09:16so you have a lot more acting to slow yourself down
0:09:16 > 0:09:19and, at this point, you're going slow enough
0:09:19 > 0:09:21that you don't really need this heat shield any more,
0:09:21 > 0:09:24so you jettison your heat shield.
0:09:24 > 0:09:27The next stage is you can fire retrorockets,
0:09:27 > 0:09:30so they're rockets that fire in the direction of travel.
0:09:30 > 0:09:34These retrorockets can bring it to a hover about a metre,
0:09:34 > 0:09:36a metre and a half above the planet's surface,
0:09:36 > 0:09:41and then you can drop that final metre down onto the surface,
0:09:41 > 0:09:44until you're landing there on the surface of Mars.
0:09:45 > 0:09:48This is an aluminium prototype.
0:09:48 > 0:09:51But the final version of ExoMars will be made of carbon fibre,
0:09:51 > 0:09:56an incredibly tough, lightweight material that is thermally stable -
0:09:56 > 0:10:01all qualities needed for a safe landing and successful mission.
0:10:01 > 0:10:04As with any really grand challenge like this,
0:10:04 > 0:10:08there's so many different stages the rover has to go through successfully
0:10:08 > 0:10:11for the whole mission to be declared a success.
0:10:11 > 0:10:15I think the things that really are concerning are things that are
0:10:15 > 0:10:16completely out of your hands.
0:10:16 > 0:10:20So the rocket launch, it's one of those kind of split-second things
0:10:20 > 0:10:23that it's either going to work or it's going to go up in flames.
0:10:23 > 0:10:24And then the landing as well
0:10:24 > 0:10:28is another really challenging aspect and that's where a lot of missions
0:10:28 > 0:10:29have failed in the past,
0:10:29 > 0:10:32so definitely, when you get that safe landing confirmed,
0:10:32 > 0:10:35that's going to be a big relief.
0:10:36 > 0:10:38Engineers like Abbie
0:10:38 > 0:10:43will one day design vehicles to take the first human travellers to Mars.
0:10:43 > 0:10:47But the question remains, where should you land?
0:10:49 > 0:10:51Seven months after leaving Earth behind,
0:10:51 > 0:10:55Martian visitors will be met with astounding views of the Red Planet
0:10:55 > 0:11:00and vast landscapes calling out to be explored.
0:11:00 > 0:11:03But the perfect spot may surprise you.
0:11:08 > 0:11:13This is Valles Marineris, named after Mariner 9,
0:11:13 > 0:11:15the NASA mission that discovered it.
0:11:15 > 0:11:17The scale of the canyon is breathtaking.
0:11:19 > 0:11:22It is like the Grand Canyon on Earth, but super-size.
0:11:24 > 0:11:28In places, its walls plunge 10km down,
0:11:28 > 0:11:32a unique geological formation not matched anywhere else on the planet.
0:11:33 > 0:11:36And it's thanks to this geology that this vast canyon system
0:11:36 > 0:11:39makes the ideal landing site on Mars...
0:11:43 > 0:11:47..as astro geologist Dr Jim Rice can testify to.
0:11:48 > 0:11:52He's been involved in selecting Mars landing sites for every NASA mission
0:11:52 > 0:11:56since Mars Pathfinder in 1994.
0:11:57 > 0:12:01You want something fairly flat, not too rocky, not too dusty.
0:12:01 > 0:12:04And because we use parachutes to help slow us down
0:12:04 > 0:12:06in the entry into the Martian atmosphere,
0:12:06 > 0:12:07a little bit lower in elevation.
0:12:09 > 0:12:11And the views would be breathtaking, too.
0:12:12 > 0:12:14Valles Marineris is a great spot
0:12:14 > 0:12:16because it's basically kind of like the Grand Canyon here,
0:12:16 > 0:12:20it's like someone's taken a giant surgeon with a scalpel and made
0:12:20 > 0:12:22an incision and opened up the crust of the planet,
0:12:22 > 0:12:26allowing you to see deeper down and deeper down in geology
0:12:26 > 0:12:28is further back in history.
0:12:28 > 0:12:32It's this view inside the planet that is the big draw for Dr Rice.
0:12:32 > 0:12:37But for most of us, the epic scale alone would be enticing enough.
0:12:37 > 0:12:42Now, that canyon is ten times longer than the Grand Canyon here.
0:12:42 > 0:12:46It's four times deeper and about 12 times wider.
0:12:46 > 0:12:50Another way to think about it is the vast expanse of this canyon,
0:12:50 > 0:12:54the length of it, would be from New York City to Los Angeles,
0:12:54 > 0:12:56so that truly is the Grand Canyon of the solar system.
0:13:00 > 0:13:03Valles Marineris would provide the ultimate draw
0:13:03 > 0:13:04for any Martian visitor.
0:13:06 > 0:13:08But it's not just the views that are attractive.
0:13:13 > 0:13:15Touching down inside Valles Marineris
0:13:15 > 0:13:17could help answer long-held questions
0:13:17 > 0:13:19about the chasm's formation.
0:13:20 > 0:13:25Images like this, taken from orbit, give us some clues to its history.
0:13:27 > 0:13:31One theory is that ancient volcanoes ripped apart the surface,
0:13:31 > 0:13:34creating a rift that running water continued to carve.
0:13:37 > 0:13:41But it's only by landing there we can gather the conclusive proof.
0:13:42 > 0:13:45What you want to do, as a geologist is get to outcrop,
0:13:45 > 0:13:46like we see right here.
0:13:46 > 0:13:50A slab of rock that you can interrogate and taste, so to speak,
0:13:50 > 0:13:51with your instruments.
0:13:53 > 0:13:56If you were a Martian coming to Earth, you'd probably come here
0:13:56 > 0:13:59because you get a good idea of the geological history of the Earth,
0:13:59 > 0:14:01from the rim all the way down to the floor.
0:14:01 > 0:14:05Most of these rocks record oceans that came and went,
0:14:05 > 0:14:07mountain changes that came and went, deserts that came and went.
0:14:07 > 0:14:10You know, on Mars, it would be safe to say you go back three,
0:14:10 > 0:14:12three and half, maybe even four billion years
0:14:12 > 0:14:14at the floor of the canyon down there.
0:14:14 > 0:14:16I'd go in a heartbeat.
0:14:17 > 0:14:20Like many of us, perhaps even you,
0:14:20 > 0:14:24Dr Rice also dreams of walking on Mars.
0:14:24 > 0:14:27I mean, on Mars, we don't know what there is to learn yet.
0:14:27 > 0:14:31It's this open book waiting for us to go there and sample it
0:14:31 > 0:14:33and to decipher the geological history.
0:14:33 > 0:14:36In a canyon system like Valles Marineris,
0:14:36 > 0:14:38the book is open right there for you.
0:14:38 > 0:14:41You've just got to get there and start collecting samples.
0:14:42 > 0:14:47Many think Valles Marineris is the perfect landing zone.
0:14:47 > 0:14:51Not only are there last flat areas to touch down,
0:14:51 > 0:14:55but it would also give a tantalising hint into Mars's geological past.
0:14:57 > 0:15:01And, of course, stood at the edge of the grandest canyon
0:15:01 > 0:15:04of the solar system, the view would be jaw-dropping.
0:15:15 > 0:15:18So, now you know how to get there and where to land.
0:15:19 > 0:15:22But travelling around Mars is not just about seeing the sights.
0:15:24 > 0:15:28No guide would be complete without advice for visitors
0:15:28 > 0:15:30on how to survive once they get there.
0:15:32 > 0:15:35Mars is a barren world,
0:15:35 > 0:15:38with its water and atmosphere long lost to the hands of time.
0:15:40 > 0:15:44For humans, it would be an inhospitable environment.
0:15:46 > 0:15:49That is why researchers have descended upon the volcanoes of Hawaii...
0:15:51 > 0:15:54..an environment on Earth that closely matches Mars
0:15:54 > 0:15:56in terms of landscape, at least.
0:15:58 > 0:16:00They're working out how we can survive
0:16:00 > 0:16:02on this desolate and hostile planet.
0:16:05 > 0:16:08Michael Lye and his team have designed a spacesuit
0:16:08 > 0:16:11to simulate Mars missions here on Hawaii.
0:16:13 > 0:16:16Once you land on Mars, you're basically living in a vacuum.
0:16:16 > 0:16:19It's got an atmosphere, but not much.
0:16:19 > 0:16:20And, while you're there,
0:16:20 > 0:16:23you won't be able to go outside and breathe naturally.
0:16:25 > 0:16:29Temperature-wise, it's going to be extremely cold at many times
0:16:29 > 0:16:32and it's generally a pretty hostile environment.
0:16:32 > 0:16:36Solar flares, UV radiation, alpha particles,
0:16:36 > 0:16:40other kinds of radiation from the sun as well as cosmic radiation
0:16:40 > 0:16:43that's coming from all over the solar system and beyond.
0:16:43 > 0:16:46You have to wear a spacesuit the entire time
0:16:46 > 0:16:48you're on the surface of Mars.
0:16:53 > 0:16:59Temperatures on Mars can plummet below minus 126 degrees Celsius near the poles.
0:17:02 > 0:17:04Containing virtually no oxygen,
0:17:04 > 0:17:09the wispy atmosphere has a pressure of just 0.6% of what can be found at
0:17:09 > 0:17:10sea level here on Earth.
0:17:13 > 0:17:17This is why spacesuits will be one of the critical components
0:17:17 > 0:17:19for any future human missions.
0:17:21 > 0:17:24So you need something to protect you from essentially exploding,
0:17:24 > 0:17:27or at least having your skin stretched out
0:17:27 > 0:17:30and the blood boiling and getting the bends, things like that.
0:17:31 > 0:17:33The way spacesuits are designed now,
0:17:33 > 0:17:36they're mostly pressurised spacecraft.
0:17:36 > 0:17:39Essentially, they're almost like a mini spaceship.
0:17:46 > 0:17:49Martian visitors will require a full face helmet,
0:17:49 > 0:17:51permanent oxygen supply,
0:17:51 > 0:17:53life support and electrical systems...
0:17:54 > 0:17:58..just like astronauts on board the International Space Station.
0:18:03 > 0:18:06The microgravity environment aboard the Space Station
0:18:06 > 0:18:10makes the 130-kilogram spacesuits effectively weightless.
0:18:13 > 0:18:16The suit itself is a little bit top-heavy,
0:18:16 > 0:18:18so it makes it a little hard to negotiate.
0:18:18 > 0:18:20It's actually pretty comfortable walking,
0:18:20 > 0:18:22even though it weighs quite a bit.
0:18:22 > 0:18:26Unfortunately, this won't be the case on Mars.
0:18:26 > 0:18:28Mars is a much smaller planet.
0:18:28 > 0:18:32The gravity field on Mars is roughly about a third of Earth's gravity,
0:18:32 > 0:18:37so if something weighs 150 pounds on Earth it would weigh about 50 pounds
0:18:37 > 0:18:39in a Martian gravity field.
0:18:39 > 0:18:43The volcano looks pretty impressive over the hill.
0:18:44 > 0:18:48I'm just going to take a breather here for a moment.
0:18:48 > 0:18:51We're going to be doing field tests all summer on this suit,
0:18:51 > 0:18:54starting with short ones like today
0:18:54 > 0:18:56and going onto longer duration ones
0:18:56 > 0:18:58to get it ready for the HI-SEAS mission.
0:19:02 > 0:19:07HI-SEAS stands for the Hawaii Space Exploration Analog And Simulation program.
0:19:08 > 0:19:12Teams of researchers regularly enter this facility to simulate
0:19:12 > 0:19:15a long duration planetary surface mission to Mars.
0:19:18 > 0:19:21Hidden about 2,500 metres above sea level,
0:19:21 > 0:19:25inhabitants are completely cut off from the outside world
0:19:25 > 0:19:27for between four and 12 months at a time.
0:19:29 > 0:19:33This is footage specially filmed by the teams.
0:19:34 > 0:19:37It reveals the extent of the habitat.
0:19:38 > 0:19:41There are sleeping quarters, a kitchen,
0:19:41 > 0:19:45laboratory, bathroom, simulated air lock and work area.
0:19:49 > 0:19:51Research into food, crew dynamics,
0:19:51 > 0:19:54behaviours, roles and performance are all analysed.
0:19:56 > 0:20:00But it's when researchers step outside the habitat on EVAs,
0:20:00 > 0:20:02or extravehicular activities,
0:20:02 > 0:20:06that this Martian simulation really comes to life.
0:20:15 > 0:20:19Thanks to the research being conducted in places like this,
0:20:19 > 0:20:21any future travellers will be prepared
0:20:21 > 0:20:24to brave the harsh Martian environments.
0:20:26 > 0:20:31But you'll also need a place to shelter, a place to call home.
0:20:31 > 0:20:32And if you're really clever,
0:20:32 > 0:20:37Mars has some peculiar geology that you could find astonishingly useful.
0:20:45 > 0:20:48Our next location is one that could provide some much-needed refuge
0:20:48 > 0:20:50for the weary traveller.
0:20:52 > 0:20:55The flanks of the Pavonis Mons volcano.
0:20:58 > 0:21:02It may not look like a home that you or I recognise,
0:21:02 > 0:21:06but buried just beneath the surface of this volcano is a unique feature
0:21:06 > 0:21:08that offers protection from the elements.
0:21:12 > 0:21:16And remarkably, similar features can be found right here on Earth
0:21:16 > 0:21:18if you know where to look for them.
0:21:24 > 0:21:27We're out here on an a'a flow in Hawaii.
0:21:27 > 0:21:30This lava flow originated towards the summit of Mauna Loa
0:21:30 > 0:21:35and has flowed about 20km, you know, towards the ocean here.
0:21:35 > 0:21:40But what you don't see is that this lava flow is covering a vast network
0:21:40 > 0:21:42of lava tubes that is now below us.
0:21:42 > 0:21:44That's what we want to get to.
0:21:47 > 0:21:51Vulcanoes are cool cos we find them all over the solar system.
0:21:51 > 0:21:55Volcanism is a fundamental process for shaping planetary bodies,
0:21:55 > 0:21:58for shaping moons, so, the more we can learn about it,
0:21:58 > 0:22:01the more we can understand our solar system and our universe.
0:22:04 > 0:22:08The surface of Pavonis Mons is riddled with lava tubes like this.
0:22:09 > 0:22:11Natural caverns that formed
0:22:11 > 0:22:14when the planet was still volcanically active.
0:22:14 > 0:22:18NASA volcanologist Dr Brent Garry has dedicated his career
0:22:18 > 0:22:21to understanding these features.
0:22:21 > 0:22:23As the lava flow is coming down,
0:22:23 > 0:22:27these tube systems can form underneath a solid crust.
0:22:27 > 0:22:30So, you have a hard crust on the outside,
0:22:30 > 0:22:34and the interior will be the lava, the liquid rock flowing through it.
0:22:34 > 0:22:36Think of the London Underground,
0:22:36 > 0:22:39it's like a subway system of lava going through there.
0:22:39 > 0:22:40And, as the lava drains out,
0:22:40 > 0:22:44that's when we're left with these, you know, giant cavern systems
0:22:44 > 0:22:46that we see here, that we're inside right now.
0:22:48 > 0:22:53Today, Dr Garry is using light detection and ranging technology,
0:22:53 > 0:22:57or LiDAR, to create a 3-D model of this lava tube in Hawaii.
0:22:59 > 0:23:03What we're building with all the LiDAR scans is a map of a lava tube.
0:23:03 > 0:23:05LiDAR is an optimal system to use
0:23:05 > 0:23:07because it doesn't need its own light source.
0:23:07 > 0:23:09It can see in the dark.
0:23:09 > 0:23:13Until we land on the Red Planet, mapping lava tubes on Earth
0:23:13 > 0:23:15is Dr Garry's best chance at understanding
0:23:15 > 0:23:17their Martian equivalents.
0:23:20 > 0:23:23This is a map created on one of his previous expeditions.
0:23:25 > 0:23:28Here we're flying through one of the collapsed pits
0:23:28 > 0:23:32and what we're capturing is the shape, the dimensions,
0:23:32 > 0:23:35the morphology of the whole entire lava tube system,
0:23:35 > 0:23:38but we're also capturing the details of all the different textures
0:23:38 > 0:23:40that are on the inside of the lava tube.
0:23:45 > 0:23:48Travelling to Mars is not for the faint-hearted.
0:23:48 > 0:23:51You need to be prepared for a harsh, dynamic environment.
0:23:53 > 0:23:55Micro meteorites rain down,
0:23:55 > 0:23:58dust storms rage for weeks at a time
0:23:58 > 0:24:02and radiation levels are up to 250 times higher than on Earth.
0:24:04 > 0:24:07Lava tubes would provide much-needed sanctuary
0:24:07 > 0:24:11for any travellers weary of the ferocious Martian climate,
0:24:11 > 0:24:16but visitors needn't be entirely cut off from the outside world.
0:24:16 > 0:24:17Behind me is a skylight
0:24:17 > 0:24:22and that is an opening that goes into the lava tube.
0:24:22 > 0:24:25We have satellites that are orbiting Mars right now
0:24:25 > 0:24:27and they have these very powerful cameras
0:24:27 > 0:24:31that can image the surface with extreme resolutions
0:24:31 > 0:24:34that we can actually find and observe pits on Mars
0:24:34 > 0:24:36that look just like the skylight.
0:24:38 > 0:24:41The view outside would be dramatic, seeing the stars.
0:24:41 > 0:24:45Maybe if you're lucky you could maybe see Phobos or Deimos,
0:24:45 > 0:24:47the moons of Mars, transit past the skylight.
0:24:47 > 0:24:50Trying to watch a Martian sunrise or Martian sunset,
0:24:50 > 0:24:52that would be pretty cool to see.
0:24:52 > 0:24:58If you're down there, it just gives you this little window to the outside world on the Red Planet.
0:25:01 > 0:25:06This skylight on the western slopes of Pavonis Mons is a cavernous hole
0:25:06 > 0:25:09about 35 metres wide and 30 metres deep.
0:25:16 > 0:25:19Perhaps this will be the window that you will look out
0:25:19 > 0:25:21from your subterranean refuge.
0:25:22 > 0:25:24Maybe one day, you know,
0:25:24 > 0:25:26we can have the technology to get us to these areas.
0:25:26 > 0:25:30First we have to get to the surface, then we have to get inside these lava tube systems,
0:25:30 > 0:25:32so it's definitely going to be a challenge
0:25:32 > 0:25:36and we'll need some innovative engineering to get us into these tube systems.
0:25:36 > 0:25:39Explorers staying in the Pavonis Mons lava tubes
0:25:39 > 0:25:43would get much-needed respite from the relentless Martian climate...
0:25:48 > 0:25:50..and escape from the radiation and fine dust
0:25:50 > 0:25:52that coats much of the planet.
0:25:54 > 0:25:58They may even get access to underground water resources.
0:25:59 > 0:26:02Surely, a destination not to be missed.
0:26:08 > 0:26:11But for those clamouring for more of the great outdoors,
0:26:11 > 0:26:17the lava tubes provide the perfect base from which to explore the rest of the region.
0:26:21 > 0:26:26Home to 12 vast volcanoes and stretching across 4,000km,
0:26:26 > 0:26:28this is the Tharsis region.
0:26:36 > 0:26:39The volcanoes here are record-breaking,
0:26:39 > 0:26:41up to 100 times larger than anything on Earth.
0:26:44 > 0:26:48The most spectacular of all is Olympus Mons,
0:26:48 > 0:26:51the largest volcano in our solar system.
0:27:03 > 0:27:05With so many stunning images,
0:27:05 > 0:27:09it's easy to forget just how isolated Mars is from Earth.
0:27:11 > 0:27:14Intrepid travellers will need a way to keep in touch with home.
0:27:16 > 0:27:19NASA engineer Dr Kara Beaton is part of the team
0:27:19 > 0:27:23investigating how future Mars explorers will be able to communicate.
0:27:24 > 0:27:27The shortest journey that you would have for a Mars mission
0:27:27 > 0:27:28is close to three years.
0:27:28 > 0:27:30It's about six months of transit time there,
0:27:30 > 0:27:33and then you need to wait for about a year or a year and a half on the
0:27:33 > 0:27:37surface before you can begin your return journey back to Earth.
0:27:39 > 0:27:42Three years in isolation with a very small crew
0:27:42 > 0:27:45of just a couple of people and limited communication
0:27:45 > 0:27:50with family and friends on Earth is a big challenge that NASA is currently looking into.
0:27:55 > 0:28:00Today, Dr Beaton and her colleagues are testing prototype communications backpacks.
0:28:02 > 0:28:05So, because of the very large distances between Earth and Mars,
0:28:05 > 0:28:09anywhere from 35 to 225 million miles,
0:28:09 > 0:28:15there is a communication delay between someone talking on Earth to someone on Mars and vice versa.
0:28:17 > 0:28:21So, if I were to have a conversation with you and I'm on Mars and you're on Earth,
0:28:21 > 0:28:24and I speak over a voice com loop,
0:28:24 > 0:28:27it would take anywhere from four to 22 minutes to get to you,
0:28:27 > 0:28:28and then for you to respond,
0:28:28 > 0:28:30it would take another four to 22 minutes
0:28:30 > 0:28:32for me to hear that response.
0:28:33 > 0:28:37By seeing how these sorts of delays impact upon real fieldwork,
0:28:37 > 0:28:42Dr Beaton and the team are able to develop solutions.
0:28:42 > 0:28:46So, we've come up with different techniques for how to best communicate.
0:28:46 > 0:28:50So, obviously, voice is one way, and certainly that's a viable option,
0:28:50 > 0:28:53but we've also found that text messaging is good
0:28:53 > 0:28:56because that allows the crewmembers to do something else on the side
0:28:56 > 0:28:58while they're waiting to hear a response.
0:29:00 > 0:29:02But in a real Mars mission,
0:29:02 > 0:29:06how would you actually send and receive these messages?
0:29:06 > 0:29:10To begin, you'll need one of these -
0:29:10 > 0:29:12a 70-metre radio telescope.
0:29:14 > 0:29:16Richard Stephenson is a radio engineer
0:29:16 > 0:29:20here at the Canberra Deep Space Communication Complex in Australia.
0:29:24 > 0:29:28The deep space network is capable of sending and receiving high-frequency
0:29:28 > 0:29:32radio signals billions of miles away,
0:29:32 > 0:29:34even to the very edges of our solar system.
0:29:35 > 0:29:40The deep space network has three complexes around the globe
0:29:40 > 0:29:44and they're spaced around about 120 degrees apart,
0:29:44 > 0:29:47so, as the Earth rotates,
0:29:47 > 0:29:48we can provide 24/7 coverage
0:29:48 > 0:29:51to any of the missions that we're supporting.
0:29:52 > 0:29:55These radio dishes are our eyes and ears on the planet,
0:29:55 > 0:30:00and any information we get back from Mars is received right here.
0:30:00 > 0:30:01This antenna,
0:30:01 > 0:30:04Deep Space Station 43, is our 70-metre antenna.
0:30:04 > 0:30:07It's a very heavy-duty antenna.
0:30:07 > 0:30:10We're looking at 4,000 tonnes of steerable metal,
0:30:10 > 0:30:12so regardless of wind, weather,
0:30:12 > 0:30:16we can support the spacecraft that need to communicate to Earth.
0:30:16 > 0:30:22As we prepare to send the first human explorers to the Red Planet,
0:30:22 > 0:30:26building up a Martian communication infrastructure is going to be key.
0:30:26 > 0:30:31The deep space network's motto is, "Don't leave Earth without us."
0:30:31 > 0:30:33We're the traffic control of the solar system.
0:30:34 > 0:30:38It's going to be up to Richard and the deep space network team
0:30:38 > 0:30:41to juggle communications with future Mars travellers
0:30:41 > 0:30:44and, more importantly, prevent their spacecraft
0:30:44 > 0:30:47from slamming into one another in a Martian traffic jam.
0:30:48 > 0:30:51So today the team are testing how this might work.
0:30:52 > 0:30:55Over there, on the work station,
0:30:55 > 0:30:58John is just about to commence a Multiple Spacecraft Per Aperture.
0:30:58 > 0:31:01RADIO CHATTER
0:31:01 > 0:31:04Essentially, what we do is we point the antenna
0:31:04 > 0:31:07right in the middle of Mars and, using the beam,
0:31:07 > 0:31:10we can incorporate any spacecraft orbiting Mars.
0:31:10 > 0:31:13John will be supporting four.
0:31:13 > 0:31:16What makes it particularly difficult is they're all orbiters,
0:31:16 > 0:31:19so we have to make sure that we capture them
0:31:19 > 0:31:21as they come around Mars.
0:31:26 > 0:31:31This is the first glimpse of the future of our Martian communications network,
0:31:31 > 0:31:36the very same one that will support the first human travellers to the Red Planet.
0:31:36 > 0:31:38In two years' time,
0:31:38 > 0:31:43we start possibly launching humans beyond our atmosphere
0:31:43 > 0:31:47and my ambition is to be able to talk to somebody
0:31:47 > 0:31:49who is on a pathway to Mars.
0:31:50 > 0:31:53Thanks to radio telescopes like these,
0:31:53 > 0:31:55strategically positioned around the globe,
0:31:55 > 0:31:58travellers to Mars needn't worry about being isolated
0:31:58 > 0:32:00from everyone back on Earth.
0:32:00 > 0:32:03If you're one of them, you'll be able to communicate
0:32:03 > 0:32:06with your loved ones every day, if you want,
0:32:06 > 0:32:09waxing lyrical about the epic wonders you have seen.
0:32:11 > 0:32:16These telescopes will be the sorting offices of the most spectacular postcards in the universe.
0:32:20 > 0:32:22With a plan for how to get there,
0:32:22 > 0:32:24and armed with everything we need to survive,
0:32:24 > 0:32:28we can now start to explore some of the mysteries of Mars.
0:32:34 > 0:32:37This is Orcus Patera crater.
0:32:40 > 0:32:44Nearly 400km long, it dwarfs any features nearby.
0:32:47 > 0:32:51No-one quite knows how this unusual teardrop crater was formed.
0:32:54 > 0:32:57The latest in a long line of mysteries,
0:32:57 > 0:33:00it would prove an intriguing stop on any Martian adventure.
0:33:10 > 0:33:14Mars has a lot of craters, yet most of them are circular.
0:33:14 > 0:33:17You can see these craters, 40 or 50km across,
0:33:17 > 0:33:21they tend to be circular, but there are some that are not.
0:33:21 > 0:33:22If I were going to Mars,
0:33:22 > 0:33:25the one I would like to go to the most is the whopper.
0:33:25 > 0:33:27It looks like a whale.
0:33:27 > 0:33:30In fact, it's called Orcus Patera - "orcus" means "whale".
0:33:30 > 0:33:32So there's something odd. Look at all the other craters -
0:33:32 > 0:33:34they're round.
0:33:34 > 0:33:36What formed this?
0:33:36 > 0:33:38Until we go there ourselves,
0:33:38 > 0:33:42our best shot at answering that question
0:33:42 > 0:33:45is to recreate the impact here on Earth
0:33:45 > 0:33:48and Professor Peter Schultz has just the experiment.
0:33:49 > 0:33:52This is the NASA Ames Vertical Gun Range...
0:33:53 > 0:33:59..a unique facility that simulates high-speed celestial body impacts on a small scale.
0:34:02 > 0:34:07Today, Professor Schultz is going to try to recreate the Orucs Patera crater.
0:34:09 > 0:34:13This is a case of trying to simulate what happens
0:34:13 > 0:34:17when you have a giant projectile, an asteroid,
0:34:17 > 0:34:19or even a moon, collide with Mars,
0:34:19 > 0:34:23so we're trying going to try that here by impacting into sand.
0:34:24 > 0:34:28The target sits inside a large pressure-controlled impact chamber.
0:34:30 > 0:34:33So, with the chamber, we can control the atmosphere conditions
0:34:33 > 0:34:36and we have a projectile that will be launched
0:34:36 > 0:34:38to go through this hole, this launch tube,
0:34:38 > 0:34:42and is going to hit right here where this laser is hitting,
0:34:42 > 0:34:46maybe about eight times the velocity of a speeding bullet.
0:34:46 > 0:34:51So now all we have to do is, really, lock and load.
0:34:54 > 0:34:56Professor Schultz has rigged the gun
0:34:56 > 0:35:00so that it fires at just 15 degrees from the horizontal,
0:35:00 > 0:35:03simulating an oblique meteor strike.
0:35:03 > 0:35:07With everything in place, all it takes now is to fire the projectile.
0:35:08 > 0:35:09JP, are you ready?
0:35:09 > 0:35:10We're good. Ready.
0:35:10 > 0:35:12Yeah, ready to go.
0:35:14 > 0:35:15It's charged.
0:35:15 > 0:35:17Lights are green.
0:35:19 > 0:35:20Here we go.
0:35:22 > 0:35:23Rolling.
0:35:28 > 0:35:31Oh! Sweet.
0:35:31 > 0:35:345.53 kilometres per second.
0:35:34 > 0:35:36Well done.
0:35:39 > 0:35:43To see if Professor Schultz has recreated Orcus Patera,
0:35:43 > 0:35:45he needs to analyse the footage.
0:35:46 > 0:35:50And now we watch the evolution of the plume...
0:35:50 > 0:35:54and you can see this vapour, this plasma.
0:35:54 > 0:35:56This is 6,000 Kelvin.
0:35:56 > 0:35:59This is really hot. It's like the surface of the sun.
0:36:05 > 0:36:08In this perspective, all this brightness here is because of the projectile
0:36:08 > 0:36:12that has sheared off at the moment of impact and is impacting this
0:36:12 > 0:36:15aluminium plate that's lying down on the surface.
0:36:18 > 0:36:21At the same time, the crater is beginning to form.
0:36:21 > 0:36:23Right now, the crater looks like it's a gash.
0:36:23 > 0:36:26It begins as a gash.
0:36:26 > 0:36:28But, as it progresses,
0:36:28 > 0:36:30it begins to be circular.
0:36:32 > 0:36:36The sand shows how an oblique meteor strike throws material
0:36:36 > 0:36:39downstream of the impact, just like in Orcus Patera.
0:36:41 > 0:36:43But it's not the perfect Mars analogue.
0:36:43 > 0:36:45The fluid, loose nature of sand
0:36:45 > 0:36:49means the original impact crater shape is not preserved.
0:36:49 > 0:36:54Professor Schultz must repeat the experiment with a tougher target -
0:36:54 > 0:36:56an aluminium block.
0:36:56 > 0:36:57JP, are you ready?
0:36:57 > 0:37:00- Ready.- Get it to reset.
0:37:06 > 0:37:07Rolling.
0:37:11 > 0:37:14Oh, good! We got it, we got it, we got it.
0:37:14 > 0:37:15Let me see. Let me see, let me see.
0:37:15 > 0:37:176.0 kilometres per second.
0:37:17 > 0:37:18Well done, sir.
0:37:19 > 0:37:21Oh!
0:37:24 > 0:37:25Whoa!
0:37:25 > 0:37:28It looks like it worked.
0:37:28 > 0:37:30So, instead of getting a round crater,
0:37:30 > 0:37:32we have an oblong crater
0:37:32 > 0:37:36and we have an oblong crater that has multiple impacts downrange.
0:37:36 > 0:37:41There's a really low rim here, high rim there, and a shelf,
0:37:41 > 0:37:45and it requires a very low angle impact -
0:37:45 > 0:37:47and I think that's what has happened on Mars.
0:37:51 > 0:37:54The crater is almost a mirror image of Orcus Patera,
0:37:54 > 0:37:56scoured lengthways across the landscape.
0:37:58 > 0:38:01And Professor Schultz has a theory for how it was formed.
0:38:05 > 0:38:09A moon going around Mars is in her orbit and eventually that orbit
0:38:09 > 0:38:12decays, gets closer and closer to Mars.
0:38:12 > 0:38:16In fact, the moon Phobos going around Mars right now
0:38:16 > 0:38:20will collide with Mars in something like 28, maybe 30 million years.
0:38:20 > 0:38:24So, when that happens, it will come in at an extremely low angle,
0:38:24 > 0:38:28grazing, just like a spacecraft trying to come in for landing,
0:38:28 > 0:38:30except it's not going to land so well.
0:38:30 > 0:38:34It's going to collide and form a crater very similar to Orcus Patera.
0:38:36 > 0:38:39Mars has two small potato-shaped moons -
0:38:39 > 0:38:42Phobos and Deimos -
0:38:42 > 0:38:44but Peter's audacious thought
0:38:44 > 0:38:47is that there was once another lost moon orbiting the planet.
0:38:49 > 0:38:52The theory makes sense, but the jury remains out.
0:38:55 > 0:38:59Situated close to some of Mars's largest volcanoes,
0:38:59 > 0:39:03other scientists argue that volcanic forces could have created the crater
0:39:03 > 0:39:05by stretching and compressing the ground.
0:39:09 > 0:39:12If we are to discover the crater's true origins,
0:39:12 > 0:39:14we must go there ourselves...
0:39:16 > 0:39:19..because it's only by studying landscapes up close
0:39:19 > 0:39:21that we can fully understand them.
0:39:21 > 0:39:24We can look at the San Andreas Fault, it's right there.
0:39:24 > 0:39:27But to understand how old it is,
0:39:27 > 0:39:30and understand what's on both sides of the Fault,
0:39:30 > 0:39:31you've got to be there.
0:39:31 > 0:39:33I think we need to be on Mars.
0:39:33 > 0:39:36Standing on the rim of Orcus Patera,
0:39:36 > 0:39:39I'd probably find the entire history of the solar system
0:39:39 > 0:39:42spread across the surface in different places.
0:39:44 > 0:39:48I wonder, could I pick up a rock that actually came from the object
0:39:48 > 0:39:50that formed this enormous feature?
0:39:50 > 0:39:52Could it be an ancient moon on Mars?
0:39:52 > 0:39:55Could it be just another big, giant asteroid?
0:39:55 > 0:39:56This is the advantage of being there.
0:39:56 > 0:40:00You identify the rock, you make a decision, your choice.
0:40:00 > 0:40:02You look, you study.
0:40:03 > 0:40:06It's different when you actually hold the sample
0:40:06 > 0:40:08and that is the next step.
0:40:11 > 0:40:14For now, Orcus Patera remains a mystery,
0:40:14 > 0:40:17but what a beautiful mystery it is.
0:40:17 > 0:40:20Imagine standing atop the crater rim,
0:40:20 > 0:40:24rising 1,800 metres above the surrounding plains,
0:40:24 > 0:40:28looking into the depths of the crater almost 2.5km below.
0:40:30 > 0:40:35What an incredible and enigmatic stop on your adventure across Mars.
0:40:39 > 0:40:42Our technology has allowed us to map Mars in unprecedented detail.
0:40:44 > 0:40:49Some of the landscapes we discovered look eerily like those on Earth,
0:40:49 > 0:40:52while others are completely alien.
0:40:59 > 0:41:01And there is no better place to explore these strange,
0:41:01 > 0:41:04ever-changing, mysterious landscapes
0:41:04 > 0:41:07than at the southernmost reaches of the planet.
0:41:08 > 0:41:10It may be well off the beaten track,
0:41:10 > 0:41:14but the extra effort required to get there will be worthwhile.
0:41:22 > 0:41:25This is Mars's southern polar cap.
0:41:25 > 0:41:27One of the coldest places on the planet,
0:41:27 > 0:41:31temperatures here can drop below minus 120 Celsius.
0:41:31 > 0:41:38It's an icy destination for which planetary scientist Dr Meg Schwamb has long held a fascination.
0:41:39 > 0:41:43So we're standing on a dormant volcano on the big island of Hawaii,
0:41:43 > 0:41:47and so this is where we have some of the world-class telescopes that are
0:41:47 > 0:41:48observing the night sky.
0:41:49 > 0:41:53I'm a planetary astronomer and a planetary scientist,
0:41:53 > 0:41:58and I study both using telescopes and spacecraft around planets,
0:41:58 > 0:42:01studying what they're made of and how they formed,
0:42:01 > 0:42:03both in our solar system and outside.
0:42:05 > 0:42:08I'm really interested in the South Pole of Mars
0:42:08 > 0:42:13and how that can tell us more about Mars's past and its current history.
0:42:15 > 0:42:18On a clear night, the poles of Mars can even be seen
0:42:18 > 0:42:20through small telescopes from here on Earth.
0:42:25 > 0:42:28Amateur images like these show the bright ice caps
0:42:28 > 0:42:30against the red disc of the planet,
0:42:30 > 0:42:35but their wonder is only truly revealed with images taken from orbit.
0:42:39 > 0:42:43Over 400km wide and 3km thick,
0:42:43 > 0:42:48the southern polar cap is a freezing vision of swirling white
0:42:48 > 0:42:51on an otherwise rust-coloured planet.
0:42:51 > 0:42:54Though it may look much like the South Pole on Earth,
0:42:54 > 0:42:56it has one crucial difference.
0:42:58 > 0:42:59So, as you can see behind me,
0:42:59 > 0:43:01there's some white dotting the surface
0:43:01 > 0:43:04and that's actually some snow left after one of our recent snowfalls.
0:43:04 > 0:43:07But on Mars, on the South Pole,
0:43:07 > 0:43:10there isn't water ice that's exposed, or snow -
0:43:10 > 0:43:13it actually snows carbon dioxide.
0:43:13 > 0:43:17Often referred to as dry ice, during the Martian winter,
0:43:17 > 0:43:21this frozen carbon dioxide blankets the southern reaches of the planet.
0:43:22 > 0:43:26Come spring, when it melts, it transforms straight into a gas,
0:43:26 > 0:43:28dramatically changing the landscape
0:43:28 > 0:43:31and creating a remarkable phenomenon.
0:43:31 > 0:43:35So what happens on the South Pole of Mars is you have this layer
0:43:35 > 0:43:39of semi-translucent ice on top of the dirt
0:43:39 > 0:43:42and, when the sun comes up in the spring and summer,
0:43:42 > 0:43:47the sunlight penetrates through down to that dirt layer and heats up.
0:43:47 > 0:43:53Because it's warm, the carbon dioxide ice in contact with it starts to turn into gas
0:43:53 > 0:43:57and so now you have a layer of gas trapped underneath a layer of ice.
0:43:58 > 0:44:02The consequences of this thaw are quite spectacular.
0:44:02 > 0:44:05So when this gas is trapped underneath this ice sheet,
0:44:05 > 0:44:08it breaks through in any way it can through the ice.
0:44:08 > 0:44:11And when it gets to the surface, it creates these jets or geysers
0:44:11 > 0:44:14on the surface of the South Pole of Mars.
0:44:14 > 0:44:18Gas is rushing out maybe a few metres, not much further, we think.
0:44:18 > 0:44:22It brings up this dust and dirt from below that ice sheet.
0:44:23 > 0:44:25If I was standing on the surface of Mars,
0:44:25 > 0:44:29you'd see these dark jets coming up and it's the local surface winds
0:44:29 > 0:44:33that blow these material into these dark streaks.
0:44:33 > 0:44:37And then, when there's no more carbon dioxide ice, it disappears.
0:44:41 > 0:44:45Seen from space, this windblown dust creates breathtaking landscapes.
0:44:47 > 0:44:49But these images aren't simply pretty,
0:44:49 > 0:44:51they tell us about the Martian climate, too.
0:44:53 > 0:44:57If we can study how these geysers form, these jets,
0:44:57 > 0:45:01and how the wind blows these materials,
0:45:01 > 0:45:04we can learn more about the Martian atmosphere.
0:45:04 > 0:45:06This process is completely alien.
0:45:06 > 0:45:09We don't have anything like this on Earth.
0:45:12 > 0:45:15These features disappear each year,
0:45:15 > 0:45:18but they leave behind another wonder in their wake -
0:45:18 > 0:45:21the real spiders from Mars.
0:45:21 > 0:45:24If we look a little deeper into these images,
0:45:24 > 0:45:29what we find that when there's no carbon dioxide ice any more, the fans go away.
0:45:29 > 0:45:32And what's left in many of these areas
0:45:32 > 0:45:36are these kind of dendritic-like, spiderlike features,
0:45:36 > 0:45:39which have been informally dubbed spiders.
0:45:42 > 0:45:45These erosion channels meet in the central pit,
0:45:45 > 0:45:49resembling the body and long legs of a spider -
0:45:49 > 0:45:52legs that can stretch for hundreds of metres
0:45:52 > 0:45:55and can take more than 1,000 Martian years to grow.
0:45:58 > 0:46:00I'd be really excited to be able to walk around
0:46:00 > 0:46:04and see what these spiders look like on the surface in the summer,
0:46:04 > 0:46:08and maybe even tentatively kind of explore there in the spring and summer,
0:46:08 > 0:46:11when these carbon dioxide jets break through the surface,
0:46:11 > 0:46:15creating these brilliant bands that we see on the service.
0:46:17 > 0:46:21Explorers lucky enough to be stood at the South Pole during a Martian
0:46:21 > 0:46:25summer would gaze upon these alien spiderlike features
0:46:25 > 0:46:27stretching across the landscape.
0:46:28 > 0:46:31They would be offered a taste of Martian weather
0:46:31 > 0:46:35and witness the dramatic proof that Mars is far from the dead
0:46:35 > 0:46:38and unchanging planet that many people assume.
0:46:45 > 0:46:49Mars's icy poles provide some respite from the desert landscapes
0:46:49 > 0:46:51that cover most of the planet.
0:46:52 > 0:46:54And the more adventurous traveller,
0:46:54 > 0:46:57they also choose to follow the elusive trail of liquid water
0:46:57 > 0:46:58on the Martian surface.
0:46:59 > 0:47:04In doing so, they will uncover the hidden story of ancient Mars.
0:47:10 > 0:47:12Thanks to the curiosity rover,
0:47:12 > 0:47:17we now know that Gale Crater was once the site of an ancient lake.
0:47:17 > 0:47:19But where did all that water go,
0:47:19 > 0:47:22and how did it shape the landscape we see today?
0:47:24 > 0:47:27To see that, Dr Gupta needs to look at Gale Crater
0:47:27 > 0:47:323.8 billion years ago, just after it was formed by a meteor impact.
0:47:33 > 0:47:35So, this is really cool.
0:47:35 > 0:47:37Here we've got an augmented reality sandbox
0:47:37 > 0:47:41and so what I'm doing now is I'm creating the crater rim.
0:47:41 > 0:47:44There would have been a mountain in the centre of the crater,
0:47:44 > 0:47:49formed during that impact process, that forms the core of Mount Sharp.
0:47:51 > 0:47:53When Gale Crater first formed,
0:47:53 > 0:47:57it's thought Mars had a much more substantial atmosphere,
0:47:57 > 0:48:01making the planet warmer and so wetter than today.
0:48:01 > 0:48:05And the water fell across the planet's surface as rain and snow.
0:48:05 > 0:48:09You see, now it's raining on the crest of that crater rim, and look at that.
0:48:09 > 0:48:13We've got rain forming on the crater rim and then gushing out
0:48:13 > 0:48:16into the centre of Gale Crater and building up.
0:48:19 > 0:48:21As it poured down into the crater,
0:48:21 > 0:48:24this water shaped many of the features we see today.
0:48:27 > 0:48:31Imagine if you have heavy rainfall, rainfall over hundreds of years,
0:48:31 > 0:48:35the landscape gets progressively eroded and what happens is all that
0:48:35 > 0:48:38rushing water erodes into the landscape
0:48:38 > 0:48:40and carves deep canyons and valleys.
0:48:40 > 0:48:44The sediment eroded from those gullies
0:48:44 > 0:48:46would have washed into Gale Crater,
0:48:46 > 0:48:50forming those river deposits that we can see so beautifully
0:48:50 > 0:48:51in the images that Curiosity takes.
0:48:55 > 0:48:56Surprisingly, though,
0:48:56 > 0:49:00it's not the dried river beds but the towering Mount Sharp
0:49:00 > 0:49:04that provided the definitive proof of Gale Crater's watery past.
0:49:05 > 0:49:08So we think that the basal parts of Mount Sharp
0:49:08 > 0:49:14are actually the deposits of erosion of that crater rim.
0:49:14 > 0:49:16They're recording that water story,
0:49:16 > 0:49:21water erosion and deposition within Gale Crater over here.
0:49:22 > 0:49:27Deposits that were exposed when the Martian climate eventually dried up.
0:49:28 > 0:49:31So this is Gale Crater, in a wet and warm period,
0:49:31 > 0:49:33and then the climate changed.
0:49:33 > 0:49:38It lost its atmosphere and became arid and hyper cold,
0:49:38 > 0:49:40and all that water evaporated,
0:49:40 > 0:49:46and we were left with a crater infilled with sediment.
0:49:46 > 0:49:53So imagine my hand here is actually wind erosion over millions of years,
0:49:53 > 0:49:57progressively carving out the moat,
0:49:57 > 0:50:01leaving Mount Sharp, this 5km high mountain, in the centre,
0:50:01 > 0:50:04and the eroded crater rim to the sides.
0:50:07 > 0:50:11The next generation of explorers stepping foot inside the crater
0:50:11 > 0:50:15will build on the body of evidence collected by Curiosity
0:50:15 > 0:50:18and paint in even more detail about Mars's past.
0:50:20 > 0:50:22And just as Curiosity has done,
0:50:22 > 0:50:24travellers visiting Gale Crater and Mount Sharp
0:50:24 > 0:50:27will be able to explore a breathtaking landscape.
0:50:28 > 0:50:30They'll gaze upon a vast mountain,
0:50:30 > 0:50:35where it appears to have burst from the base of an impact crater,
0:50:35 > 0:50:39but, more than that, they'll peer into an ancient watery world,
0:50:39 > 0:50:43a world that has long since been lost to the winds.
0:50:52 > 0:50:57The rusty, ancient surface of Mars has enigmatic landscapes at every turn...
0:50:59 > 0:51:05..from towering sculpted peaks to hidden underground caverns.
0:51:05 > 0:51:08And if you're one of the first explorers,
0:51:08 > 0:51:10you will need to study every detail.
0:51:11 > 0:51:15Each landmark holds its own clues to Mars's mysteries...
0:51:16 > 0:51:21..and there is no greater mystery than whether life exists beyond the Earth.
0:51:26 > 0:51:29To stand a chance of finding it on Mars,
0:51:29 > 0:51:31travellers will need to journey to a region of the planet
0:51:31 > 0:51:34hitherto unexplored by landers or rovers.
0:51:37 > 0:51:39Perched in the removed Southern Highlands,
0:51:39 > 0:51:42Terra Sirenum is a land of cratered terrain
0:51:42 > 0:51:44capped in crystalline mineral deposits.
0:51:47 > 0:51:50It's thought that if we're going to find signs of local wildlife,
0:51:50 > 0:51:53past or present, then this will be the best spot...
0:51:57 > 0:52:01..a theory that Professor Charles Cockell believes is entirely viable.
0:52:02 > 0:52:04I'm an astrobiologist,
0:52:04 > 0:52:07which means that I study life in extreme environments on the Earth
0:52:07 > 0:52:10and then I use that to try and understand
0:52:10 > 0:52:13whether there might be habitable conditions or even life elsewhere.
0:52:13 > 0:52:17Of all the questions astrobiology asks, probably its biggest one is -
0:52:17 > 0:52:19is there life beyond the Earth?
0:52:19 > 0:52:21This is one of the most profound questions
0:52:21 > 0:52:23that's ever been asked by the human mind.
0:52:23 > 0:52:26The first step in looking for life on Mars
0:52:26 > 0:52:28is figuring out where to look.
0:52:30 > 0:52:32When we're assessing whether a planet is habitable,
0:52:32 > 0:52:34we're looking for some basic things.
0:52:34 > 0:52:38We need some liquid water, for all those chemical reactions to happen in,
0:52:38 > 0:52:42we need a source of energy, like sunlight or chemical energy,
0:52:42 > 0:52:44and we also need some basic elements,
0:52:44 > 0:52:46like carbon and phosphorus.
0:52:46 > 0:52:48All those things have to come together in one place
0:52:48 > 0:52:52for life as we know it at least to be able to grow.
0:52:55 > 0:52:58Before our first spacecraft arrived in the 1960s,
0:52:58 > 0:53:02the idea of visitors to Mars setting foot on a lush living planet
0:53:02 > 0:53:05seemed like a perfectly reasonable idea.
0:53:05 > 0:53:06In the early history of Mars,
0:53:06 > 0:53:10the planet would have looked quite a lot like early Earth.
0:53:10 > 0:53:12There would have been liquid water on the surface -
0:53:12 > 0:53:14maybe it would have been warmer.
0:53:14 > 0:53:17Perhaps during that period of time it could have sustained biology
0:53:17 > 0:53:21and maybe it could do, even today, deep underground.
0:53:21 > 0:53:23But about three and a half billion years ago,
0:53:23 > 0:53:27that water froze up and the planet became what we know today -
0:53:27 > 0:53:29pretty much a desert world.
0:53:30 > 0:53:35Because of that, it was never able to sustain the sort of evolutionary
0:53:35 > 0:53:37developments that you can see around you here.
0:53:38 > 0:53:41We would probably, if we were looking for life on Mars,
0:53:41 > 0:53:43be looking for something quite primitive
0:53:43 > 0:53:45that was able perhaps to take hold
0:53:45 > 0:53:47in that early period of Martian history.
0:53:49 > 0:53:51So we need to look in places on Mars
0:53:51 > 0:53:54that could give primitive life a fighting chance.
0:53:56 > 0:53:58There are two types of places.
0:53:58 > 0:54:00We might look in briny, salty solutions,
0:54:00 > 0:54:03those brines could still be liquid on the surface of Mars today,
0:54:03 > 0:54:06and we are looking at ancient salt deposits.
0:54:06 > 0:54:10In those salts, maybe we might try and look for signs of past life.
0:54:11 > 0:54:13So, with that in mind,
0:54:13 > 0:54:17astrobiologists like Professor Cockell started searching
0:54:17 > 0:54:19for the perfect spot to hunt for life.
0:54:26 > 0:54:28And, in time, images taken from orbit
0:54:28 > 0:54:32revealed more than 200 places in the Terra Sirenum region
0:54:32 > 0:54:34where thick salt layers exist.
0:54:37 > 0:54:42The Terra Sirenum region of Mars has salt deposits from ancient ponds
0:54:42 > 0:54:45and lakes that essentially evaporated -
0:54:45 > 0:54:48the last remnants of liquid water on Mars.
0:54:48 > 0:54:53If we want to test the hypothesis that Mars was habitable,
0:54:53 > 0:54:54maybe even hosted life,
0:54:54 > 0:54:57it's to places like these that we need to go.
0:54:59 > 0:55:01Any salts in Terra Sirenum
0:55:01 > 0:55:05could preserve or record the existence of life on Mars and,
0:55:05 > 0:55:09to support this theory, Professor Cockell has been investigating
0:55:09 > 0:55:12some of the most remote and inhospitable places on Earth.
0:55:13 > 0:55:17We go to extreme environments around the world and we collect samples,
0:55:17 > 0:55:21and what we want to do is try and isolate the microbes
0:55:21 > 0:55:25that live in those samples and study their ability to survive in extremes.
0:55:25 > 0:55:28So here we've got some examples from the Negev Desert.
0:55:28 > 0:55:32Microbes that live in those environments are very tolerant
0:55:32 > 0:55:35of both high temperatures and extreme dryness.
0:55:35 > 0:55:38And then these microbes are from a lake in Canada
0:55:38 > 0:55:41that has very high concentrations of sulphate
0:55:41 > 0:55:44similar to the sorts of salt that we find on Mars.
0:55:45 > 0:55:49Finding living bacteria in places like this tells Charles and his team
0:55:49 > 0:55:54that Mars-like environments here on Earth can support life.
0:55:54 > 0:55:56But that's only half the picture.
0:55:56 > 0:55:59So this is a sample from a very extreme environment.
0:55:59 > 0:56:03It comes from a kilometre underground in a salt mine.
0:56:03 > 0:56:09This is a sort of sample you might be able to find in Terra Sirenum if you dug down beneath the surface.
0:56:09 > 0:56:15You can collect these samples and you can culture microbes and have a look at them under the microscope.
0:56:16 > 0:56:22The question is, could these microbes also survive under the conditions on the present day Mars?
0:56:22 > 0:56:27We've subjected these microbes to similar sorts of environments
0:56:27 > 0:56:30that you might find on Mars - so no oxygen,
0:56:30 > 0:56:31very low amounts of energy,
0:56:31 > 0:56:34very low concentrations of nutrients -
0:56:34 > 0:56:36and in those sorts of environments,
0:56:36 > 0:56:39these microbes can not only survive, they can also grow.
0:56:39 > 0:56:43What these results show us is that some of these salty environments
0:56:43 > 0:56:46on Mars may well have been habitable.
0:56:46 > 0:56:48It may not look like much,
0:56:48 > 0:56:52but this is the closest thing to life on Mars anyone has seen.
0:56:52 > 0:56:55I often joke that, if you send me to Terra Sirenum
0:56:55 > 0:56:57with a microscope and a shovel,
0:56:57 > 0:57:01I can tell you within a few hours whether there's life on Mars.
0:57:01 > 0:57:04I think the simplest thing to do is to collect samples.
0:57:04 > 0:57:08If you could grow something from a sample taken from Mars
0:57:08 > 0:57:11and just look at your microbes under a microscope,
0:57:11 > 0:57:13it would probably look a bit like this.
0:57:15 > 0:57:18Astrobiologists like Professor Cockell are building a case
0:57:18 > 0:57:22that the salt plains on Mars are potentially habitable.
0:57:23 > 0:57:26The inquisitive traveller prepared to dig deep
0:57:26 > 0:57:28might just find some of the local wildlife
0:57:28 > 0:57:31sheltered beneath the subsurface.
0:57:31 > 0:57:33It would be the discovery of the century
0:57:33 > 0:57:36and prove that life probably exists elsewhere in the universe, too.
0:57:38 > 0:57:41And it would be the perfect end to an epic journey.
0:57:48 > 0:57:51Mars, the Red Planet.
0:57:52 > 0:57:57A world similar to ours in so many ways, yet also totally alien.
0:57:57 > 0:58:00A world waiting to be explored.
0:58:02 > 0:58:08Many scientists believe that the first person to set foot on its surface is alive today.
0:58:10 > 0:58:12Someone, somewhere,
0:58:12 > 0:58:17looking up into the night sky and glimpsing the small, rusty planet
0:58:17 > 0:58:20may one day make the journey there.
0:58:20 > 0:58:24They may even discover the first alien life.
0:58:24 > 0:58:26Perhaps it's someone watching this film.
0:58:27 > 0:58:29Perhaps it's you.