0:00:03 > 0:00:05Mars, the Red Planet.
0:00:06 > 0:00:09For millennia, an object of mystery,
0:00:09 > 0:00:12intrigue and fantasy.
0:00:13 > 0:00:15But now it's more than that.
0:00:15 > 0:00:19It's the next target in the human exploration of space.
0:00:23 > 0:00:27It's a thrilling prospect, but how likely are we to succeed?
0:00:28 > 0:00:31And is it a journey we should even be attempting?
0:00:33 > 0:00:37With a career spanning medicine, astrophysics and aeronautics,
0:00:37 > 0:00:42Dr Kevin Fong is uniquely placed to explore the incredible challenges
0:00:42 > 0:00:44that a human mission to Mars would pose.
0:00:44 > 0:00:48This is going to be the most risky human expedition in the history of our species.
0:00:48 > 0:00:52The Red Planet, Mars. For over 2,000 years, the symbol for war.
0:00:55 > 0:00:58Now, with the help of the BBC's archive...
0:00:58 > 0:01:01We've just had some amazing photographs sent back by the American probe
0:01:01 > 0:01:03to Mars, Mariner 6.
0:01:03 > 0:01:07..Kevin is going to explore what we'll need to do if we are to succeed.
0:01:07 > 0:01:11It cannot happen without your ability to integrate stuff in low Earth orbit.
0:01:11 > 0:01:15It cannot happen without international cooperation.
0:01:15 > 0:01:20It's a journey that will test technology and human survival to their limits.
0:01:20 > 0:01:21No-one knows if it's possible.
0:01:23 > 0:01:26That isolation, that feeling of isolation,
0:01:26 > 0:01:29partly because of the delay in communications, will be quite intense.
0:01:33 > 0:01:38It's a debate that, for Kevin, pushes the limits of technology,
0:01:38 > 0:01:43the extremes of human endurance and explores the very idea of what it is
0:01:43 > 0:01:44to be human.
0:01:56 > 0:01:58Go, Atlas. Go, Centaur.
0:02:04 > 0:02:07We're in the early days of a new space race.
0:02:07 > 0:02:09This time, the target is Mars.
0:02:11 > 0:02:14But it isn't the Russians going toe to toe with Nasa,
0:02:14 > 0:02:17it's private companies taking their first steps into space.
0:02:19 > 0:02:22No-one is better qualified to explore the challenge of our first
0:02:22 > 0:02:25human expedition to Mars than Dr Kevin Fong.
0:02:26 > 0:02:29He's trained and worked with Nasa,
0:02:29 > 0:02:33and he's researched human survivability in extreme environments to better
0:02:33 > 0:02:36understand the challenges of human space missions.
0:02:37 > 0:02:40The effects of altitude are pretty obvious.
0:02:43 > 0:02:47With the race to Mars well and truly under way,
0:02:47 > 0:02:51Kevin will dissect the unique challenges such a mission would face,
0:02:51 > 0:02:54explore the reasons for going,
0:02:54 > 0:02:58encounter powerful arguments against a human mission to Mars and,
0:02:58 > 0:03:05in so doing, make his case for the toughest journey humanity will have ever attempted.
0:03:19 > 0:03:23The first problem with Mars is that history is against us.
0:03:23 > 0:03:26Our robotic spacecraft have been there many times already,
0:03:26 > 0:03:28with decidedly mixed results.
0:03:34 > 0:03:39We've been firing stuff at Mars for more than half a century now.
0:03:39 > 0:03:43The first missions went in the 1960s.
0:03:43 > 0:03:48And we've slowly been building up this collage of evidence about what
0:03:48 > 0:03:49Mars is like.
0:03:49 > 0:03:54The very first spacecraft to reach the Red Planet was Nasa's Mariner 4 probe.
0:03:57 > 0:04:00As Mariner 4 swept past Mars,
0:04:00 > 0:04:04its black and white television camera snapped 22 close-up pictures of the planet.
0:04:07 > 0:04:10These images, the first-ever digital television pictures,
0:04:10 > 0:04:12were stored on a tape recorder.
0:04:12 > 0:04:14Then they had to be radioed back to Earth.
0:04:18 > 0:04:23But the early successes of the Mariner probes paint a false picture,
0:04:23 > 0:04:25because Mars is littered with the wreckage of failure.
0:04:27 > 0:04:31The history of Mars exploration is pretty chequered.
0:04:31 > 0:04:34It's actually worse than 50/50, our success rate there.
0:04:34 > 0:04:38It's more like one in every three objects that we throw at Mars actually
0:04:38 > 0:04:40gets there and completes its mission.
0:04:45 > 0:04:51Nasa's Mariner 3 and Mariner 8 probes were both destroyed shortly after launch.
0:04:51 > 0:04:54But the Russians suffered the worst losses,
0:04:54 > 0:04:59failing with every attempt they made to reach Mars between 1960 and 1971.
0:05:00 > 0:05:04Then, in the 1990s, it was the Americans' turn to hit trouble again.
0:05:06 > 0:05:08Two high-profile missions went wrong,
0:05:08 > 0:05:11the first in an almost comically inept way.
0:05:12 > 0:05:14Now, it's a mistake many of us have made,
0:05:14 > 0:05:17but then most of us aren't in charge of missions into space.
0:05:17 > 0:05:20Scientists at Nasa couldn't work out why the Mars Orbiter,
0:05:20 > 0:05:24worth a small £78 million, got lost in space,
0:05:24 > 0:05:28until someone pointed out that they'd planned everything in feet and inches
0:05:28 > 0:05:30rather than metres and centimetres.
0:05:30 > 0:05:35Only three months later, another mission, and more bad news.
0:05:35 > 0:05:39American space agency Nasa is on the verge of having to admit to another
0:05:39 > 0:05:41embarrassing failure.
0:05:41 > 0:05:44The Mars Polar lander would be the second spacecraft that it's lost in
0:05:44 > 0:05:49- just two months.- Three days on, and still no sign of their lost lander.
0:05:49 > 0:05:52Nasa engineers had thought it was just a case of a misdirected
0:05:52 > 0:05:54communications antenna.
0:05:54 > 0:05:58Now it looks likely that the spacecraft could be seriously damaged.
0:06:00 > 0:06:05The 21st century has brought little improvement in our success rate.
0:06:05 > 0:06:09In 2003, the British Beagle 2 lander was lost,
0:06:09 > 0:06:12apparently destroyed on impact with the Martian surface.
0:06:13 > 0:06:19And in 2016, the Schiaparelli lander came to an even more violent end,
0:06:19 > 0:06:22its remains now smeared across the Martian landscape.
0:06:25 > 0:06:30Given this patchy and, at times, embarrassing track record,
0:06:30 > 0:06:34should we really be planning to send humans to Mars?
0:06:34 > 0:06:35To travel to Mars,
0:06:35 > 0:06:38you're talking about crossing hundreds of millions of miles of
0:06:38 > 0:06:40interplanetary space,
0:06:40 > 0:06:45screaming into a re-entry at thousands of kilometres an hour, and then trying
0:06:45 > 0:06:49to land on the surface of a planet on your own with no real direct input
0:06:49 > 0:06:52from Earth, after months and months of journeying.
0:06:54 > 0:06:57That's hard enough to do with unmanned vehicles.
0:06:57 > 0:07:01So it's going to be a significant challenge for human crews.
0:07:03 > 0:07:08Superficially, our record of sending humans into space gives cause for optimism.
0:07:10 > 0:07:12Apollo was a triumph.
0:07:22 > 0:07:25But since Apollo, it can be argued that we've regressed.
0:07:37 > 0:07:39Since December 1972,
0:07:39 > 0:07:43when Apollo 17 blasted off from Taurus-Littrow crater,
0:07:43 > 0:07:48no human has ventured more than 250 miles from the surface of the Earth.
0:08:00 > 0:08:04Britain's first astronaut, Helen Sharman, disagrees.
0:08:04 > 0:08:07She feels our experiences with the International Space Station and
0:08:07 > 0:08:12the space shuttle have been the perfect preparation for sending humans to Mars.
0:08:12 > 0:08:16We've learnt technically how to create more reliable spacecraft,
0:08:16 > 0:08:18how to create better cooling systems,
0:08:18 > 0:08:22how to generate energy in different ways.
0:08:22 > 0:08:25So there's lots that we've learnt, and it will provide us in good stead
0:08:25 > 0:08:27for the future.
0:08:27 > 0:08:30Despite the failure of many robotic missions to Mars,
0:08:30 > 0:08:34we have made some progress in human space flight.
0:08:34 > 0:08:36But there's no getting away from the scale of the challenge.
0:08:37 > 0:08:40The first big problem happens right at the start of the mission.
0:08:41 > 0:08:45Sending humans to Mars will require some seriously heavy lifting.
0:09:07 > 0:09:11Putting Apollo into space required the biggest and most powerful rockets
0:09:11 > 0:09:15ever built. But they're puny compared to what will be needed for Mars.
0:09:18 > 0:09:22When you're talking about exploring Mars, it's all about how much you want to take with you,
0:09:22 > 0:09:24what you want to pack to go there, who you want to go.
0:09:24 > 0:09:28It's about the mass that you want to deliver to the surface of Mars.
0:09:28 > 0:09:33And so every kilo you want to take to Mars requires tens - if not hundreds -
0:09:33 > 0:09:36of kilos of equipment to move it to low Earth orbit.
0:09:37 > 0:09:41It's estimated that even a modest crewed mission to Mars will require
0:09:41 > 0:09:43a payload of 40 tonnes.
0:09:43 > 0:09:47That's 40 times what was needed to send the Curiosity rover to Mars.
0:09:48 > 0:09:53And just getting that off the ground would be a mammoth task.
0:09:53 > 0:09:55Climbing out of the deep gravity well,
0:09:55 > 0:09:59that huge force of attraction around a planet like Earth,
0:09:59 > 0:10:00is the most difficult bit.
0:10:00 > 0:10:04It requires an explosive release of energy, massive energy,
0:10:04 > 0:10:07energy comparable to the size of a small nuclear weapon,
0:10:07 > 0:10:11to get a vehicle and her crew into low Earth orbit.
0:10:11 > 0:10:14And so in human space flight, in all of space flight,
0:10:14 > 0:10:18the first 250 miles are the hardest 250 miles.
0:10:21 > 0:10:24Several different approaches are being planned.
0:10:25 > 0:10:27We have lift-off at the Falcon 9.
0:10:27 > 0:10:30Miraculous. That's first-stage acceleration.
0:10:30 > 0:10:34SpaceX, brainchild of South African entrepreneur Elon Musk,
0:10:34 > 0:10:36is banking on small,
0:10:36 > 0:10:41lightweight reusable rockets that can shuttle payload into orbit
0:10:41 > 0:10:44and then come back to pick up more,
0:10:44 > 0:10:46though early test results have been mixed.
0:10:51 > 0:10:53And then there's Nasa.
0:10:53 > 0:10:57With the Apollo programme Saturn V rocket as their template,
0:10:57 > 0:11:02they've decided to take an unashamedly American route
0:11:02 > 0:11:03by going large.
0:11:04 > 0:11:09Nasa's rocket is called the Space Launch System or SLS.
0:11:09 > 0:11:14And when it's complete, it will be the largest and most powerful rocket ever built.
0:11:15 > 0:11:18It's so much larger than what we did here before, so much taller.
0:11:18 > 0:11:23The best way to assemble something this complex and this big is to
0:11:23 > 0:11:24assemble it vertically.
0:11:29 > 0:11:31This is as high as we can go using the elevator.
0:11:31 > 0:11:33The rest is on foot.
0:11:39 > 0:11:42It's hard to tell, with this big of a space,
0:11:42 > 0:11:45how big the actual vehicle's going to be, the rocket.
0:11:45 > 0:11:48You can actually already see some signs emerging.
0:11:48 > 0:11:51You can see that blue circle forming.
0:11:51 > 0:11:53That is the actual diameter of the rocket.
0:11:54 > 0:11:57And even at this height, we cannot contain the entire rocket.
0:12:05 > 0:12:07In Stennis, Mississippi,
0:12:07 > 0:12:11Nasa test the rocket engines that will power the SLS into space.
0:12:22 > 0:12:27An engine like this will be just one of six which will help propel the SLS into orbit.
0:12:33 > 0:12:37So when the time comes to test the much bigger SLS rocket,
0:12:37 > 0:12:39it must be at the largest stand they have.
0:12:42 > 0:12:44Like so much in the mission to Mars,
0:12:44 > 0:12:47they'll be standing on the shoulders of Nasa's previous missions,
0:12:47 > 0:12:53borrowing and repurposing the best from Apollo and the shuttle.
0:12:53 > 0:12:55- How's it going, man? - It's going good.- All right.
0:12:56 > 0:13:00B Stand was built over 50 years ago to test the Saturn rockets that
0:13:00 > 0:13:02carried the Apollo missions to space.
0:13:04 > 0:13:09Gary Benton and his team will be reshaping and upgrading this stand
0:13:09 > 0:13:12so that it can cope with the next generation of rockets.
0:13:12 > 0:13:16This is the same crane that we used to lift those Saturn V core stages,
0:13:16 > 0:13:17and we're going to use that very same crane
0:13:17 > 0:13:20to lift up the SLS core stage and place it
0:13:20 > 0:13:23in this facility, anchor it down really good,
0:13:23 > 0:13:26fire off about two million pounds of thrust, and that's going to be
0:13:26 > 0:13:30the biggest test we've done out here since we did the Saturn V.
0:13:32 > 0:13:34There's a palpable sense of excitement here,
0:13:34 > 0:13:36because, for the first time in decades,
0:13:36 > 0:13:40they're thinking of using these rockets to send people beyond Earth's orbit.
0:13:44 > 0:13:48For now, this is Nasa's best vision of what a rocket bound for Mars
0:13:48 > 0:13:54- would look like.- T-minus ten, nine, eight, seven, six, five...
0:13:54 > 0:13:59But the first complete SLS rocket is still a distant dream,
0:13:59 > 0:14:01and it gets worse.
0:14:01 > 0:14:05Nasa estimates they will need seven SLS launches for a single Mars
0:14:05 > 0:14:10mission so the huge Mars spacecraft can be pieced together in space.
0:14:11 > 0:14:15But at least this problem is just a question of brute strength.
0:14:15 > 0:14:18Throw enough money at it, and solutions should be found.
0:14:20 > 0:14:24But the next stage of the journey poses a very different set of challenges.
0:14:43 > 0:14:46There's an uncomfortable truth about the journey to Mars.
0:14:47 > 0:14:53At a minimum of 34 million miles, 120 times more distant than the moon,
0:14:53 > 0:14:58it's two orders of magnitude further than any journey humans have ever made before.
0:14:59 > 0:15:04With existing technology, if you're using chemical propulsion,
0:15:04 > 0:15:08then a journey to Mars is between six and nine months in one direction,
0:15:08 > 0:15:10so from Earth to Mars.
0:15:10 > 0:15:14And then you have to sit on Mars and wait for the right planetary alignments
0:15:14 > 0:15:18to be able to get back, and those come up at about 30 days or so,
0:15:18 > 0:15:21and then again about a year and a half later.
0:15:21 > 0:15:25So the shortest mission that you could hope for for Mars is just over
0:15:25 > 0:15:28a year. The longest ones are approaching three years.
0:15:29 > 0:15:32A three-year mission would be nearly triple the length of anything we've
0:15:32 > 0:15:37done before, and spending that long in space poses some serious risks.
0:15:39 > 0:15:41The first problem is radiation.
0:15:47 > 0:15:51Just how much radiation you would be exposed to on a mission to Mars was
0:15:51 > 0:15:55quantified by the recent Curiosity mission,
0:15:55 > 0:15:59and they found it to be several hundred times more intense than on Earth.
0:16:00 > 0:16:02And that's a problem.
0:16:02 > 0:16:05One important factor of life on Earth and how we were able to evolve
0:16:05 > 0:16:07is that we're protected from the radiation
0:16:07 > 0:16:09of galactic cosmic rays and from the radiation
0:16:09 > 0:16:11of the sun by the magnetic field of the Earth,
0:16:11 > 0:16:13which is caused by the iron core of the Earth.
0:16:15 > 0:16:19That magnetic field creates a protective shield around our planet called
0:16:19 > 0:16:22the magnetosphere, which deflects radiation.
0:16:22 > 0:16:26The more dangerous solar particles don't get through.
0:16:26 > 0:16:29Those that do create the spectacular light show of the aurora.
0:16:31 > 0:16:34But out in space, everything is different.
0:16:36 > 0:16:42Out here, the bubbling surface of the sun occasionally builds to a huge explosion.
0:16:42 > 0:16:46These solar flares throw out massive bursts of radiation and high-energy
0:16:46 > 0:16:49protons which might damage your DNA,
0:16:49 > 0:16:52causing mutations and cancer later in life.
0:16:56 > 0:16:59Protecting against radiation will be crucial if we are to successfully
0:16:59 > 0:17:00send people to Mars.
0:17:02 > 0:17:06What we need is a material that can shield astronauts in the event of a
0:17:06 > 0:17:10solar storm, but doesn't add extra weight to the spacecraft.
0:17:12 > 0:17:16Nasa's answer is to use something they will already be carrying,
0:17:16 > 0:17:19a material known for its ability to absorb solar radiation...
0:17:21 > 0:17:22Water.
0:17:27 > 0:17:29So we're looking at taking a garment and filling it with water,
0:17:29 > 0:17:35which you see a first concept of here, of this astronaut
0:17:35 > 0:17:39with a water wall built into its wearable garment.
0:17:39 > 0:17:42So this is something that you'd fill for an event.
0:17:42 > 0:17:46So he gets protection in maybe a different form,
0:17:46 > 0:17:48but with a lot less mass penalty to it.
0:17:50 > 0:17:52Unfortunately for Martian astronauts,
0:17:52 > 0:17:55radiation will only be the start of the problems.
0:17:57 > 0:18:01An even more pernicious threat begins only minutes after launch.
0:18:03 > 0:18:05Now let's try backwards.
0:18:05 > 0:18:10Your body starts to experience weightlessness
0:18:10 > 0:18:11as soon as you get into low Earth orbit,
0:18:11 > 0:18:16and that starts modifying your body from the moment you deploy in space.
0:18:16 > 0:18:20And that has effects on your bones and your muscles,
0:18:20 > 0:18:21because those go to waste very quickly.
0:18:23 > 0:18:28The answer, for now, is exercise - and lots of it.
0:18:31 > 0:18:36Something that Libby Jackson knows only too well from her days as flight director
0:18:36 > 0:18:40of the International Space Station's Columbus science module.
0:18:40 > 0:18:43The crew on board the International Space Station have to exercise for
0:18:43 > 0:18:45about two hours every day.
0:18:45 > 0:18:47That's about an hour of cardio
0:18:47 > 0:18:49and an hour of what we would call weights.
0:18:49 > 0:18:51They're not lifting weights, you can't do that in a weightless
0:18:51 > 0:18:55environment, but they have a hydraulic ram that gives them resistance.
0:18:55 > 0:18:57You need to keep your body in a condition
0:18:57 > 0:19:01that allows you to function when you get to Mars.
0:19:02 > 0:19:06But Kevin favours a different approach to the problem of zero gravity...
0:19:07 > 0:19:10..one that will require a major technological leap.
0:19:10 > 0:19:14We take our light, our heat, our power, our water, our food,
0:19:14 > 0:19:16we take even our atmosphere with us.
0:19:16 > 0:19:19So why don't we take gravity?
0:19:19 > 0:19:22Now it turns out that that's not as sci-fi as it sounds.
0:19:22 > 0:19:26You can do that by building a large rotating vehicle.
0:19:26 > 0:19:29I'm talking about a vehicle about the size of the London Eye that would spin
0:19:29 > 0:19:31about four times a minute.
0:19:35 > 0:19:38That would be enough to provide this level of gravity,
0:19:38 > 0:19:41a 1G Earth gravitational load.
0:19:41 > 0:19:43And that would wash away an awful lot of our problems.
0:19:45 > 0:19:49An artificial gravity device of this kind may have its benefits,
0:19:49 > 0:19:53but it would add huge cost and weight to an already difficult mission.
0:20:01 > 0:20:06The third huge challenge is that sense of isolation from the world,
0:20:06 > 0:20:09not being able to get back easily.
0:20:13 > 0:20:17Unlike the physical threats that have the potential to be managed with technology,
0:20:17 > 0:20:21the psychological dangers of a journey to Mars are much harder
0:20:21 > 0:20:22to quantify.
0:20:25 > 0:20:28Astronauts will have to deal with the twin challenges of isolation from
0:20:28 > 0:20:30their loved ones on Earth
0:20:30 > 0:20:33and close confinement with their fellow crewmates.
0:20:35 > 0:20:38One of my favourite quotes is from Valery Ryumin,
0:20:38 > 0:20:41who was a Russian who flew their Salyut space station missions
0:20:41 > 0:20:44in the 1970s, I think in 1976.
0:20:44 > 0:20:47He said all the conditions necessary for murder were met
0:20:47 > 0:20:51if you lock two people in a cabin for three months.
0:20:52 > 0:20:57These missions are going to be up to 30 months, a very testing time.
0:20:57 > 0:21:02Engines on. Five, four, three, two, one.
0:21:02 > 0:21:05All engines running.
0:21:05 > 0:21:07Liftoff! We have liftoff.
0:21:07 > 0:21:10Picking a crew for a journey of this length will be tricky.
0:21:11 > 0:21:15Back in the days of Apollo 11, astronaut recruitment was straightforward.
0:21:16 > 0:21:19It was clear who had the right stuff.
0:21:20 > 0:21:22Neil Armstrong,
0:21:22 > 0:21:26Buzz Aldrin and Michael Collins were the cream of US supersonic flight.
0:21:28 > 0:21:31They were drawn from the elite world of fighter and test pilots,
0:21:31 > 0:21:36and with that came supreme hand-eye coordination and physical daring.
0:21:36 > 0:21:40But these may not be the same skills you'd need to go to Mars.
0:21:41 > 0:21:44I noticed that a lot of the astronauts were of the old school.
0:21:44 > 0:21:46"I hunt, I fish, I climb mountains."
0:21:46 > 0:21:48You know, lots of outdoor stuff.
0:21:48 > 0:21:50But think about a mission to Mars.
0:21:50 > 0:21:53Is it outdoor stuff, or is it confinement?
0:21:54 > 0:21:57And then I see somebody that says "I have a stamp collection,
0:21:57 > 0:22:00"I do a lot of reading, I enjoy watching movies,"
0:22:00 > 0:22:03and I'm thinking, "That might be good for confinement."
0:22:04 > 0:22:07Dr David Dinges is interested in how you select a crew
0:22:07 > 0:22:10and safeguard their psychological welfare in space.
0:22:13 > 0:22:17The key issue is understanding who's going to develop a problem
0:22:17 > 0:22:20and when it will develop. Will all the crew develop it?
0:22:20 > 0:22:21How do we detect it?
0:22:21 > 0:22:24How do we prevent it to begin with?
0:22:24 > 0:22:28To date, the only answers come from a Russian study,
0:22:28 > 0:22:32an earthbound simulation of the approximately 520 days in isolation
0:22:32 > 0:22:36it would take for a return trip to the Red Planet.
0:22:40 > 0:22:44As the Russian study was gearing up, Dr Dinges set himself a challenge.
0:22:44 > 0:22:47Could he use his expert knowledge to anticipate
0:22:47 > 0:22:49who would fare best in confinement?
0:22:49 > 0:22:53In the Mars 520 mission, I watched the crew intensively.
0:22:53 > 0:22:57I wanted to see them during the maelstrom of media attention
0:22:57 > 0:23:00before they went into the chamber and how they interacted
0:23:00 > 0:23:01in that environment and body posture -
0:23:01 > 0:23:03where they were looking, what they said.
0:23:03 > 0:23:07I wrote down a variety of things. I made predictions,
0:23:07 > 0:23:10and this is true - I sealed it up in an envelope and put it
0:23:10 > 0:23:12in the drawer and waited till the mission was over.
0:23:12 > 0:23:14In this footage,
0:23:14 > 0:23:18released by the European Space Agency, the astronauts look well.
0:23:18 > 0:23:22But by the end, deep troubles were brewing.
0:23:22 > 0:23:24The bottom line is that, out of six people who went,
0:23:24 > 0:23:27only two didn't have significant behavioural problems
0:23:27 > 0:23:28of one kind or another.
0:23:31 > 0:23:33A couple of them experienced insomnia.
0:23:33 > 0:23:35One experienced some depression.
0:23:35 > 0:23:38Um, another was more socially isolated.
0:23:38 > 0:23:43But the two I predicted would make it just fine, made it just fine.
0:23:45 > 0:23:48It seems that all the problems of putting astronauts on Mars
0:23:48 > 0:23:53return to one thing - the mission's delicate payload of human beings.
0:23:53 > 0:23:56And even if they survive the perils of the journey,
0:23:56 > 0:24:00the most dangerous 15 minutes of the trip would still be ahead.
0:24:29 > 0:24:32After nine months of psychological and physical discomfort,
0:24:32 > 0:24:34the final few minutes of the journey to Mars
0:24:34 > 0:24:37present some of the biggest challenges.
0:24:38 > 0:24:41The first is communication.
0:24:42 > 0:24:45Earth and Mars are both in orbit around the sun,
0:24:45 > 0:24:48and so the time delay between them when we're at our closest, when
0:24:48 > 0:24:51we're at the same points in our orbit, is only about four minutes.
0:24:51 > 0:24:55But if we're on one side of the sun and Mars is on the other side
0:24:55 > 0:24:58of the sun, that can be as much as 24 minutes one-way,
0:24:58 > 0:25:01which means that if mission control are sending a message
0:25:01 > 0:25:06to the astronauts, it can take 48 minutes for the answer to come back.
0:25:06 > 0:25:11And that just completely changes how your astronauts are supported
0:25:11 > 0:25:13by your teams on the ground.
0:25:13 > 0:25:15When we went to the moon,
0:25:15 > 0:25:18there was a delay of about a second or two in the communication.
0:25:19 > 0:25:21The crew had to fire their engines
0:25:21 > 0:25:24to go into lunar orbit behind the moon,
0:25:24 > 0:25:28and all mission control can do is say, "Your computers are loaded.
0:25:28 > 0:25:31"Good luck. We'll see you on the other side."
0:25:35 > 0:25:39And what will happen with Mars will be like that, but a hundredfold.
0:25:42 > 0:25:46The challenges of communication might make landing on Mars tricky.
0:25:46 > 0:25:49But for Kevin, there's a far bigger problem,
0:25:49 > 0:25:53and that's the Red Planet's thin atmosphere.
0:25:59 > 0:26:02The Martian atmosphere is the worst of all worlds when it comes to
0:26:02 > 0:26:04stopping in space exploration.
0:26:04 > 0:26:07It's too thick to let you through safely,
0:26:07 > 0:26:10but it's too thin to provide you with enough deceleration
0:26:10 > 0:26:12to get you down to a useful speed.
0:26:13 > 0:26:16It's not like landing on the moon. It's not like re-entry on Earth.
0:26:16 > 0:26:19It requires a lot of novel solutions.
0:26:19 > 0:26:21And we've seen some of that in our history
0:26:21 > 0:26:23of robotic exploration of that planet.
0:26:33 > 0:26:37The most audacious landing in the history of Martian exploration came
0:26:37 > 0:26:41in 2012, when the Curiosity rover touched down in Gale Crater.
0:26:44 > 0:26:49It was a cosmic ballet choreographed by Nasa engineer Dr Adam Steltzner.
0:26:59 > 0:27:01Landing Curiosity, a tonne -
0:27:01 > 0:27:04the biggest thing we've landed on Mars to date.
0:27:04 > 0:27:10A challenge, but not nearly as much of a challenge as landing humans.
0:27:10 > 0:27:12Humans are sensitive, they're delicate.
0:27:12 > 0:27:14They don't like a lot of Gs.
0:27:14 > 0:27:16They like to carry water with them.
0:27:16 > 0:27:18They're heavy.
0:27:18 > 0:27:22So we think that landing humans might be something
0:27:22 > 0:27:26like 40 metric tonnes, or maybe more.
0:27:26 > 0:27:30Once again, for the spacecraft carrying humans,
0:27:30 > 0:27:33it's the bigger size that raises challenges.
0:27:33 > 0:27:37There's this interesting pit of physics that occurs
0:27:37 > 0:27:39as you scale up things.
0:27:39 > 0:27:42Imagine scaling up a drop of water.
0:27:42 > 0:27:46As it gets small or big,
0:27:46 > 0:27:51its weight goes up with the size of it...
0:27:53 > 0:27:56..cubed, raised to the third power.
0:27:56 > 0:28:02But its aerodynamic drag gets larger based on its area,
0:28:02 > 0:28:06which is its diameter squared.
0:28:06 > 0:28:11What that means is the bigger the self-similar thing gets,
0:28:11 > 0:28:13the more easily it falls.
0:28:13 > 0:28:16The same thing happens with spacecraft.
0:28:16 > 0:28:19So if you think about Curiosity,
0:28:19 > 0:28:23she came in going very, very fast, slowing down,
0:28:23 > 0:28:27slowing down and eventually making contact with the surface.
0:28:28 > 0:28:32The smaller size of Curiosity meant that it was successfully slowed
0:28:32 > 0:28:35by aerodynamic drag as it fell.
0:28:35 > 0:28:37But scaling up the size for a human lander
0:28:37 > 0:28:40changes the physics of landing radically.
0:28:41 > 0:28:43I've got this self-similar shape.
0:28:43 > 0:28:47I'm not going to not put Curiosity on the surface,
0:28:47 > 0:28:52but I'm going to put TWO Curiosities, OK, three, four, five.
0:28:52 > 0:28:53Getting a little challenging.
0:28:53 > 0:28:5740. Now all of a sudden, I can't fly that shape.
0:28:57 > 0:28:59It's the same shape it was before.
0:28:59 > 0:29:02It's packed at the same densities of spacecraft,
0:29:02 > 0:29:05but now it ends up flying a trajectory
0:29:05 > 0:29:11that intersects the surface of Mars when it's moving Mach 20.
0:29:11 > 0:29:13Not good.
0:29:13 > 0:29:17Perhaps to get really big things to the surface of Mars,
0:29:17 > 0:29:20what we need to do is...
0:29:23 > 0:29:29We need to make our shape like this, which regular rockets look like,
0:29:29 > 0:29:32but when we come flying in, we don't put the pointy end in
0:29:32 > 0:29:35or the back end in - we come in sideways.
0:29:35 > 0:29:37By coming in sideways,
0:29:37 > 0:29:40the drag on the spacecraft is increased significantly,
0:29:40 > 0:29:44slowing the rocket from hypersonic to supersonic.
0:29:44 > 0:29:46To slow it down further,
0:29:46 > 0:29:50you need something else to push against the gravity of Mars.
0:29:50 > 0:29:53It's called supersonic retro-propulsion.
0:29:53 > 0:29:56Imagine motorbiking with your mouth open at 60mph.
0:29:56 > 0:29:58Waah! It fills your mouth with air
0:29:58 > 0:30:01and it's actually sometimes hard to breathe out against it.
0:30:01 > 0:30:04Well, that is the challenge of supersonic retro-propulsion.
0:30:04 > 0:30:08You can light a rocket off into the flow,
0:30:08 > 0:30:10but it's going to be supersonic flow.
0:30:10 > 0:30:12Well, Nasa's working on that.
0:30:12 > 0:30:15And it's likely to take those rockets from a supersonic condition
0:30:15 > 0:30:17all the way down to the surface.
0:30:20 > 0:30:22If Dr Stelzner's idea is developed,
0:30:22 > 0:30:26it would pave the way for astronauts to land on the Martian surface
0:30:26 > 0:30:27for the first time.
0:30:29 > 0:30:31But even if they arrive safely,
0:30:31 > 0:30:35they will face an immediate and potentially deadly challenge.
0:30:35 > 0:30:38One of the most difficult things for those of us who imagine what it's
0:30:38 > 0:30:40going to be like for a human crew
0:30:40 > 0:30:43arriving at Mars is what shape they're going to be in
0:30:43 > 0:30:45and how they're going to look after themselves,
0:30:45 > 0:30:48because they're going to arrive after six, maybe nine months
0:30:48 > 0:30:50of flight with all the deconditioning of their bodies
0:30:50 > 0:30:52that we know is going to have happened.
0:30:52 > 0:30:56And they're not going to be met by a huge army of medical professionals
0:30:56 > 0:31:00and scientists who can then scoop them into
0:31:00 > 0:31:02a state-of-the-art hospital.
0:31:02 > 0:31:05Helen Sharman spent only eight days in space during her mission
0:31:05 > 0:31:08to the Mir space station in 1991.
0:31:09 > 0:31:13But she was completely reliant on the welcoming committee waiting
0:31:13 > 0:31:14for her on landing.
0:31:14 > 0:31:18Once we landed, the spacecraft was uprighted by the rescue crew.
0:31:18 > 0:31:21The rescue crew pulled us out of the spacecraft,
0:31:21 > 0:31:26glided us down a little sort of ramp into seats,
0:31:26 > 0:31:30and then doctors came to monitor our blood pressure and other bodily
0:31:30 > 0:31:35functions before they decided that we were fit and healthy.
0:31:36 > 0:31:39There will be no such luxuries for astronauts landing on Mars.
0:31:41 > 0:31:45They're going to be on their own and have to fend for themselves.
0:31:45 > 0:31:48And so it is down to the crews who plan the missions,
0:31:48 > 0:31:51down to the clinicians and the physicians who prepare them
0:31:51 > 0:31:55to deliver them in as good medical condition as they possibly can.
0:31:57 > 0:32:01If we can solve the challenges of landing safely on Mars,
0:32:01 > 0:32:02it would set the stage for humans
0:32:02 > 0:32:07to walk on the surface of another planet for the first time.
0:32:07 > 0:32:10But what could WE achieve that robotic landers couldn't?
0:32:12 > 0:32:15And how would we deal with the challenges of working on the surface
0:32:15 > 0:32:16of another planet?
0:32:33 > 0:32:36WIND WHISTLES
0:32:43 > 0:32:45Over the last five decades,
0:32:45 > 0:32:48robots have been our only way of exploring the surface of Mars.
0:32:50 > 0:32:52They've been our cosmic emissaries,
0:32:52 > 0:32:55gathering data and imagery for us to digest back on Earth.
0:32:57 > 0:33:00But for Kevin, their limitations are too great.
0:33:01 > 0:33:03For me, Mars is all about life,
0:33:03 > 0:33:06and when you look at the history of our exploration
0:33:06 > 0:33:09of early forms of life on this planet,
0:33:09 > 0:33:13it was found in rocks by teams of geologists bashing on rocks and
0:33:13 > 0:33:15examining them and coming up with thoughts
0:33:15 > 0:33:16about where to explore next.
0:33:16 > 0:33:21It was not and it could not have been found by parachuting something
0:33:21 > 0:33:24that looked like R2-D2 into that territory.
0:33:24 > 0:33:26That's the scale of the challenge,
0:33:26 > 0:33:29and that's why you need humans in situ on Mars.
0:33:29 > 0:33:33But if we get there, working on Mars will be no cakewalk.
0:33:35 > 0:33:39Unlike Earth, Mars has no protective magnetic field.
0:33:39 > 0:33:42So radiation continues to be an astronaut's biggest enemy.
0:33:45 > 0:33:48Wild variations in temperature,
0:33:48 > 0:33:52from minus 150 degrees in winter to 20 degrees in summer,
0:33:52 > 0:33:55are another potential killer.
0:33:55 > 0:33:56And with this comes another risk...
0:33:59 > 0:34:03Powerful dust storms which can shroud the entire planet.
0:34:05 > 0:34:09So for astronauts to live and work comfortably on the Martian surface,
0:34:09 > 0:34:11they're going to need a new form of protection.
0:34:15 > 0:34:19And scientists working on the next generation of spacesuits are taking
0:34:19 > 0:34:22inspiration from a notorious incident
0:34:22 > 0:34:24during the Apollo 16 mission.
0:34:24 > 0:34:26Whilst walking on the lunar surface,
0:34:26 > 0:34:30astronaut Charlie Duke dropped his hammer.
0:34:30 > 0:34:33But the restrictive nature of his spacesuit meant
0:34:33 > 0:34:34he couldn't pick it up.
0:34:34 > 0:34:37He has real trouble retrieving the hammer.
0:34:37 > 0:34:40So he just resorts basically to falling on it.
0:34:40 > 0:34:44You can see we've progressed quite a ways.
0:34:44 > 0:34:47So our crew members now, and our subjects now can now do a lot
0:34:47 > 0:34:50of those functional, realistic tasks that you need to do
0:34:50 > 0:34:54in a much more normal fashion that didn't scare spacesuit engineers
0:34:54 > 0:34:56like Charlie did on Apollo.
0:34:57 > 0:35:01Remarkably, spacesuits have changed little since the Apollo days.
0:35:01 > 0:35:06And those worn on the Space Station are just as bulky.
0:35:06 > 0:35:09So scientists are looking to slim down and add flexibility
0:35:09 > 0:35:11in any way they can.
0:35:11 > 0:35:15This suit was built so it can allow a flexing extension joint,
0:35:15 > 0:35:19a waist bearing, and allows him a pretty wide range of motion,
0:35:19 > 0:35:21very natural.
0:35:21 > 0:35:23And you move your waist a lot when you walk and you don't realise that,
0:35:23 > 0:35:26so that's an important joint to have.
0:35:26 > 0:35:28And then we can watch him squat.
0:35:28 > 0:35:29Touch the ground.
0:35:33 > 0:35:35Seemingly small developments like this
0:35:35 > 0:35:38take us closer to the prospect of sending humans to Mars.
0:35:38 > 0:35:42You can see the joints work as he's doing these functional tasks.
0:35:43 > 0:35:46If we can get working conditions for Martian astronauts right,
0:35:46 > 0:35:50the scientific rewards would be huge.
0:35:50 > 0:35:54Today, Martian science can only be conducted remotely by vehicles that
0:35:54 > 0:35:57slowly trundle around the surface, gathering data and imagery.
0:35:58 > 0:36:02For Curiosity mission planner and geologist Professor Sanjeev Gupta,
0:36:02 > 0:36:05it's just no match for what a human scientist could do.
0:36:07 > 0:36:10As a scientist working on the Curiosity mission,
0:36:10 > 0:36:14the biggest challenge we have is how to pick where to go in the time
0:36:14 > 0:36:16period we have to work.
0:36:16 > 0:36:20Robots are simply not very efficient and they can't get everywhere.
0:36:20 > 0:36:23When we command Curiosity, the tasks it conducts
0:36:23 > 0:36:25in maybe a couple of days,
0:36:25 > 0:36:30I could probably do in a few minutes by myself if I was there.
0:36:30 > 0:36:34That time-saving element is crucial.
0:36:34 > 0:36:38With Curiosity now, we skim at the surface of the science we can do.
0:36:38 > 0:36:40We can do a bit of it,
0:36:40 > 0:36:44but a human could just do it so much better and so much faster.
0:36:45 > 0:36:49But for Kevin, it's not a choice between machines and humans -
0:36:49 > 0:36:52it's about both working together.
0:36:52 > 0:36:55The Pathfinder rovers took many years
0:36:55 > 0:36:57to cover just a few kilometres.
0:36:57 > 0:37:01The distance they covered in three or four years of exploration was the
0:37:01 > 0:37:05same as that distance covered in a single afternoon
0:37:05 > 0:37:07by the Apollo 15 lunar rover.
0:37:07 > 0:37:11So you can see there how much more rapidly you can take on
0:37:11 > 0:37:13an environment with human explorers
0:37:13 > 0:37:17partnering with machinery than you can with robots on their own.
0:37:23 > 0:37:26Helen Sharman prefers to concentrate on something else,
0:37:26 > 0:37:30and that's giving astronauts like her the ability to think and act
0:37:30 > 0:37:31for themselves.
0:37:45 > 0:37:48Robots are totally reliant on the plans that were made
0:37:48 > 0:37:51leading up to the launch.
0:37:51 > 0:37:55So pretty much, the robot will do what you planned it to do
0:37:55 > 0:37:59years before it got sent, whereas humans can do new things.
0:38:02 > 0:38:05Humans can also take a look around.
0:38:05 > 0:38:09And, "Actually, there's a bit of black earth over there
0:38:09 > 0:38:11"or a bit of white rock over there.
0:38:11 > 0:38:14"And although we'd only intended getting samples from this area,
0:38:14 > 0:38:16"to get a good representative sample,
0:38:16 > 0:38:19"we need to take a bit of black and white as well, thank you very much."
0:38:19 > 0:38:21So humans can make those decisions.
0:38:29 > 0:38:32The prize of putting humans in a position to do meaningful science
0:38:32 > 0:38:35on the surface of Mars would be huge.
0:38:39 > 0:38:42Our understanding of our nearest neighbour would be transformed
0:38:42 > 0:38:45even with only a few short hours on its surface.
0:38:45 > 0:38:47And there's one question in particular
0:38:47 > 0:38:49that we are desperate to answer,
0:38:49 > 0:38:53one that has consumed our thoughts more than any other.
0:39:05 > 0:39:08- Gentlemen.- The idea of astronauts stepping out of their capsule
0:39:08 > 0:39:11and being greeted by little green men may be a hangover
0:39:11 > 0:39:13from 1950s B-movies...
0:39:14 > 0:39:16Are you here?
0:39:18 > 0:39:23..but the question of whether there is or WAS life on Mars is creeping
0:39:23 > 0:39:25towards a meaningful answer.
0:39:25 > 0:39:32This is a location for great joy and peace on the planet.
0:39:39 > 0:39:42Here's the thing. If it IS there,
0:39:42 > 0:39:45it means that when you look up at the night sky,
0:39:45 > 0:39:48it is a universe teeming with life, it's a jungle up there.
0:39:48 > 0:39:51If you go to Mars and you find not only is there not any life there
0:39:51 > 0:39:54now, but there never has been and it's a sterile planet,
0:39:54 > 0:39:58then when you look at the night sky, it's a desert.
0:40:00 > 0:40:04Many scientists put the odds at better than 50-50,
0:40:04 > 0:40:07and landing astronauts on the surface of the Red Planet
0:40:07 > 0:40:11should finally provide concrete evidence one way or another.
0:40:11 > 0:40:13I don't know what the answer
0:40:13 > 0:40:18to the question "is there life on Mars?" is. That's why we have to go.
0:40:18 > 0:40:22As a scientist, I think it would be highly surprising
0:40:22 > 0:40:25that life only arose on Earth.
0:40:25 > 0:40:29I find that quite an incredible concept.
0:40:30 > 0:40:33The biggest barrier to the existence of life on Mars
0:40:33 > 0:40:35is the presence of water.
0:40:35 > 0:40:38On Earth, all life is based on water.
0:40:38 > 0:40:41It's the main constituent of every cell,
0:40:41 > 0:40:44and it's thought that water is an essential ingredient for life
0:40:44 > 0:40:45anywhere in the universe.
0:40:45 > 0:40:49It's been known for almost a century that there are icecaps
0:40:49 > 0:40:51at the Martian poles.
0:40:51 > 0:40:54But with temperatures of minus 150 degrees,
0:40:54 > 0:40:56these aren't good places to search for life.
0:40:58 > 0:41:00What you need is liquid water.
0:41:01 > 0:41:05And the first hint of that on Mars came in the mid-1970s.
0:41:08 > 0:41:12These photographs taken by the Viking space probe in 1976
0:41:12 > 0:41:15showed what looked like dried-up river valleys.
0:41:17 > 0:41:19You can see one here.
0:41:19 > 0:41:21You can see there's a valley through here.
0:41:21 > 0:41:23You can see it branches.
0:41:23 > 0:41:24There are tributaries.
0:41:24 > 0:41:27Here's one branch going off here with tributaries.
0:41:27 > 0:41:32So this looks very much like a terrestrial river system.
0:41:32 > 0:41:35If these WERE dried-up riverbeds,
0:41:35 > 0:41:38it meant that Mars must once have had the perfect conditions for life.
0:41:42 > 0:41:46For Mars to have rivers, it must once have had streams, rain,
0:41:46 > 0:41:48clouds and an atmosphere.
0:41:48 > 0:41:51But for 20 years, they couldn't be sure.
0:41:59 > 0:42:02The answers would come in 1998,
0:42:02 > 0:42:06with the launch of the Mars Global Surveyor.
0:42:06 > 0:42:09Sections of the valleys were revealed in fantastic detail.
0:42:14 > 0:42:17Then, after they'd searched through thousands of images,
0:42:17 > 0:42:19they found this.
0:42:19 > 0:42:23A winding valley 2km wide and, at a bend in the canyon,
0:42:23 > 0:42:27a tiny channel - the unmistakable trace of an ancient river.
0:42:29 > 0:42:33In 2015 came confirmation of something even more remarkable.
0:42:42 > 0:42:46Images sent back by the Mars Reconnaissance Orbiter showed
0:42:46 > 0:42:50dark streaks that seemed to follow the contours of the landscape.
0:42:50 > 0:42:52These streaks of moisture and salt
0:42:52 > 0:42:55were incontrovertible proof that liquid water
0:42:55 > 0:42:58still flows on the surface of Mars.
0:42:59 > 0:43:02Follow that water, perhaps as it flows underground,
0:43:02 > 0:43:05and maybe we'll find life.
0:43:05 > 0:43:10If life is on Mars, it's most likely deep within the planet,
0:43:10 > 0:43:14and that means having to dig down,
0:43:14 > 0:43:19tunnel down very considerable distances. Many metres, if not more.
0:43:19 > 0:43:23And that requires an effort
0:43:23 > 0:43:27that isn't really doable by robotic platforms on their own.
0:43:27 > 0:43:29You need human infrastructures.
0:43:30 > 0:43:33But sending human life to Mars to hunt for alien life
0:43:33 > 0:43:36presents another problem.
0:43:36 > 0:43:38It's a bit of a paradox, actually.
0:43:38 > 0:43:40If you want to discover life on Mars
0:43:40 > 0:43:43or answer the question "is there life on Mars?",
0:43:43 > 0:43:47sending life to Mars to try and discover that
0:43:47 > 0:43:49might put Mars at risk.
0:43:49 > 0:43:52The question of planetary protection -
0:43:52 > 0:43:56protecting both Mars and Earth from cross-contamination -
0:43:56 > 0:43:59is a central part of 21st century mission planning,
0:43:59 > 0:44:02so much so, it's even enshrined in law.
0:44:03 > 0:44:06Because Mars could still have life,
0:44:06 > 0:44:11there are very strict UN rules on going and protecting the planet.
0:44:11 > 0:44:16You need to make sure that you don't disturb any life on Mars
0:44:16 > 0:44:19or introduce anything to it.
0:44:19 > 0:44:22You need to make sure that if you were to bring anything back
0:44:22 > 0:44:26to Earth, we don't put life on Earth at risk.
0:44:26 > 0:44:32If we cannot promise to protect Mars, then maybe we shouldn't go.
0:44:33 > 0:44:35But Kevin disagrees.
0:44:35 > 0:44:39He thinks planetary protection is something we've already solved
0:44:39 > 0:44:41with our experience closer to home.
0:44:41 > 0:44:45We have had to think about that here on Earth, when we drilled recently
0:44:45 > 0:44:50in Antarctica. There were efforts to drill many, many metres through ice
0:44:50 > 0:44:54to ancient lakes that had been sealed off from the rest
0:44:54 > 0:44:56of the world for over a million years.
0:44:56 > 0:44:57And those protection issues,
0:44:57 > 0:45:00protecting one system from another, had to be broached then.
0:45:00 > 0:45:04So it's not like we don't have some quite mature thinking in this.
0:45:04 > 0:45:06And this isn't an insurmountable problem.
0:45:07 > 0:45:10Assuming we can solve the contamination issue
0:45:10 > 0:45:12and do meaningful science,
0:45:12 > 0:45:15the next question that will arise is even more challenging
0:45:15 > 0:45:16than the journey to Mars.
0:45:37 > 0:45:40When the Apollo astronauts returned to Earth,
0:45:40 > 0:45:42it was to a heroes' welcome.
0:45:44 > 0:45:46But for the astronauts going to Mars,
0:45:46 > 0:45:50there's rather more uncertainty about their homecoming,
0:45:50 > 0:45:53and that's because coming back from Mars will be just as challenging
0:45:53 > 0:45:55as getting there.
0:45:58 > 0:46:01Nasa and SpaceX are investing significant research
0:46:01 > 0:46:02into the problem.
0:46:04 > 0:46:09In particular, how to carry enough fuel for a return journey,
0:46:09 > 0:46:13or even to mine it from deep under the Martian surface.
0:46:15 > 0:46:19But the Dutch Mars One project scheduled for 2032
0:46:19 > 0:46:23has a starkly simple solution to this conundrum.
0:46:23 > 0:46:26Their astronauts will stay on Mars,
0:46:26 > 0:46:28and never come home.
0:46:29 > 0:46:31There are organisations out there
0:46:31 > 0:46:34who are promoting the idea of a one-way trip.
0:46:34 > 0:46:37There is an enormous amount of public interest in those
0:46:37 > 0:46:40and, for me, it's fascinating to see the range of people
0:46:40 > 0:46:43who are willing to go on such a trip.
0:46:43 > 0:46:47But the idea of sending astronauts to their certain eventual death
0:46:47 > 0:46:49poses serious moral questions
0:46:49 > 0:46:53and has led to harsh criticism from across the space flight community.
0:46:54 > 0:46:58I think any mission that only sends people one way
0:46:58 > 0:47:01is just morally indefensible.
0:47:01 > 0:47:04Even though the individuals might themselves accept
0:47:04 > 0:47:07that they're only going to go one way,
0:47:07 > 0:47:10it's just not right morally.
0:47:11 > 0:47:14But for Kevin, the idea of a one-way journey to Mars
0:47:14 > 0:47:16isn't so controversial.
0:47:16 > 0:47:18It's just the latest in a long tradition
0:47:18 > 0:47:20of risky frontier expeditions
0:47:20 > 0:47:23in which coming home isn't guaranteed.
0:47:25 > 0:47:28When you look at human history and the history of exploration of THIS
0:47:28 > 0:47:31planet, people did often undertake very long journeys that were more
0:47:31 > 0:47:35hazardous in many ways than the proposed trips to Mars,
0:47:35 > 0:47:37that were going to be one-way.
0:47:39 > 0:47:44If you were around 100 years ago and you saw Scott and Amundsen race to
0:47:44 > 0:47:47the Pole and you watched the news come in of Scott's team perishing,
0:47:47 > 0:47:51you must have thought, "For what? For what value?"
0:47:51 > 0:47:53And yet, by the end of that same century,
0:47:53 > 0:47:56the ice cores we were pulling out of Antarctica,
0:47:56 > 0:47:58the paleoatmosphere that we were pulling out of the bubbles
0:47:58 > 0:48:01in those ice cores, was giving us the most convincing
0:48:01 > 0:48:03evidence yet that our climate was
0:48:03 > 0:48:07warming at a rate never before seen in history.
0:48:07 > 0:48:09And so, what started out as a meaningless adventure
0:48:09 > 0:48:13that no-one could understand, by the end of the same century,
0:48:13 > 0:48:18became knowledge that was literally the key to saving the planet.
0:48:18 > 0:48:21There's no reason to expect that that might not happen on Mars.
0:48:22 > 0:48:26Permanent settlement of Antarctica would have seemed like a pipe dream
0:48:26 > 0:48:29to Scott and Amundsen.
0:48:29 > 0:48:31Yet in the space of 100 years,
0:48:31 > 0:48:35we've made this inhospitable corner of the Earth a place
0:48:35 > 0:48:39where we can live and work safely for long periods.
0:48:39 > 0:48:41Could we do the same on Mars -
0:48:41 > 0:48:44make it a place not just to visit,
0:48:44 > 0:48:46but somewhere to call home?
0:49:06 > 0:49:08Mars!
0:49:08 > 0:49:12Permanent human habitation on a planetary body other than the Earth
0:49:12 > 0:49:15is one of science fiction's most prevalent themes.
0:49:15 > 0:49:18TRANSLATION:
0:49:25 > 0:49:28The relatively kind surface conditions on Mars
0:49:28 > 0:49:30and the presence of water
0:49:30 > 0:49:33make it the only place in the solar system other than Earth
0:49:33 > 0:49:35we could even consider doing it.
0:49:36 > 0:49:39The ultimate goal is to terraform Mars -
0:49:39 > 0:49:42to transform its atmosphere and surface into a second Earth
0:49:42 > 0:49:45that could support terrestrial life.
0:49:45 > 0:49:47But it's a distant dream.
0:49:48 > 0:49:52The romantic in me loves the idea of going to Mars
0:49:52 > 0:49:57and terraforming it and greening it and colonising it eventually,
0:49:57 > 0:50:01because it's testament to technological progress
0:50:01 > 0:50:03that would mean that we had moved
0:50:03 > 0:50:06beyond the so-called cradle of Earth.
0:50:08 > 0:50:12Terraforming Mars may remain the stuff of science fiction,
0:50:12 > 0:50:14but alternative ways to sustain life
0:50:14 > 0:50:17are being given serious consideration.
0:50:19 > 0:50:22These images, released at the beginning of 2017,
0:50:22 > 0:50:24shown Nasa's concept for how it might be done.
0:50:26 > 0:50:31These futuristic domes are built from an unexpected material - ice.
0:50:33 > 0:50:37With water now thought to be in plentiful supply and water molecules
0:50:37 > 0:50:40offering excellent protection from harmful cosmic rays,
0:50:40 > 0:50:42maybe the first long-term settlers
0:50:42 > 0:50:46will live in the Martian equivalent of igloos.
0:50:46 > 0:50:47I can see that happening.
0:50:47 > 0:50:52I can see us developing technologies that allow us to persist on Mars
0:50:52 > 0:50:54for much longer periods of time than we imagine at the moment,
0:50:54 > 0:50:57without having to go through the rigmarole
0:50:57 > 0:50:59of terraforming the atmosphere.
0:50:59 > 0:51:01We may reach that point that we may do that,
0:51:01 > 0:51:05but it will take a fairly enormous effort.
0:51:05 > 0:51:08To some, the question of a permanent settlement
0:51:08 > 0:51:12on the Red Planet has more urgency.
0:51:12 > 0:51:14As we continue to deplete the resources
0:51:14 > 0:51:18and alter the delicate balance of Earth, many people argue
0:51:18 > 0:51:21that we will need to settle on Mars as an escape route
0:51:21 > 0:51:23from our dying planet.
0:51:24 > 0:51:28Ultimately, the Earth will not be habitable. Whether or not we...
0:51:29 > 0:51:32..we mess it up, it will not be habitable at some point.
0:51:32 > 0:51:36And long-term, if we want humans to be able to continue,
0:51:36 > 0:51:38we do have to learn to survive elsewhere,
0:51:38 > 0:51:40but not at the detriment of our own planet.
0:51:43 > 0:51:45At some level or another,
0:51:45 > 0:51:47it has to be morally reprehensible
0:51:47 > 0:51:52to be a species whose behaviour is that it trashes one planet
0:51:52 > 0:51:55and then moves along to another one and then trashes that one.
0:51:55 > 0:51:56That's not the way we should be.
0:51:56 > 0:51:59That's not what we should strive for. We should look after
0:51:59 > 0:52:01the very precious jewel that is our Planet Earth
0:52:01 > 0:52:04and we should explore Mars responsibly.
0:52:04 > 0:52:07Um, there may come a time when, inevitably, we have to move planet,
0:52:07 > 0:52:10but that's, I think, much further in the future.
0:52:12 > 0:52:15Whatever form our long-term relationship with Mars takes,
0:52:15 > 0:52:18several things are clear.
0:52:18 > 0:52:21Going to Mars will be astronomically expensive,
0:52:21 > 0:52:25incredibly dangerous and highly controversial.
0:52:25 > 0:52:29Can the benefits really outweigh the vast costs?
0:52:31 > 0:52:34Or would we be better spending that money on something else?
0:52:52 > 0:52:55I think in some quarters of the public,
0:52:55 > 0:52:59there's this temptation to think that when you send people and things
0:52:59 > 0:53:02into space, you load the payload bays
0:53:02 > 0:53:05and you cram in these dollar bills and then you shut
0:53:05 > 0:53:07the payload bay doors, and as it launches,
0:53:07 > 0:53:10you sort of spread that money out into space
0:53:10 > 0:53:13and it burns up on re-entry. Of course, that's not what happens.
0:53:14 > 0:53:18Money casts a dark shadow over our hopes of going to the Red Planet.
0:53:18 > 0:53:20Just landing a robot on a comet
0:53:20 > 0:53:24for the Rosetta mission cost 1.5 billion.
0:53:24 > 0:53:28But that's nothing compared to the expected 100 billion cost
0:53:28 > 0:53:29of a mission to Mars.
0:53:31 > 0:53:33In a world of fiscal austerity,
0:53:33 > 0:53:35surely this money could be better spent?
0:53:35 > 0:53:37Helen Sharman disagrees.
0:53:37 > 0:53:40For her, the only way human space research
0:53:40 > 0:53:44can continue to attract funding is to tell people compelling
0:53:44 > 0:53:48human stories, and that means sending people.
0:53:48 > 0:53:51It's often been said that you'll have two to three orders
0:53:51 > 0:53:53of magnitude more value from a human mission
0:53:53 > 0:53:56than you will from a robotic mission,
0:53:56 > 0:53:58although a human mission will only be
0:53:58 > 0:54:01one to two orders of magnitude more costly.
0:54:01 > 0:54:06So actually, the value of humans on Mars is so much better
0:54:06 > 0:54:10than the value of robots and rovers on Mars.
0:54:12 > 0:54:14Humans relate to other humans.
0:54:14 > 0:54:19So when humans go places and talk about what it's like there,
0:54:19 > 0:54:22the rest of the world realises that actually,
0:54:22 > 0:54:26there really IS benefit in us exploring further
0:54:26 > 0:54:29something about that particular place.
0:54:31 > 0:54:36Our exploration of the moon, with its six landings, cost 25 billion.
0:54:38 > 0:54:42And its value has been the subject of endless debate.
0:54:42 > 0:54:46To some, it was a colossally expensive vanity project.
0:54:46 > 0:54:50But to others, the benefits were wide-ranging.
0:54:50 > 0:54:52Many of the technologies we use today
0:54:52 > 0:54:54were originally developed for Apollo.
0:55:01 > 0:55:04We also learned a huge amount about the moon -
0:55:04 > 0:55:06a legacy that continues today.
0:55:13 > 0:55:16The third of a tonne of moon rock we brought back to Earth will keep
0:55:16 > 0:55:18scientists busy for decades to come.
0:55:18 > 0:55:23Those samples are still yielding new science results -
0:55:23 > 0:55:25and major new science results -
0:55:25 > 0:55:28changing our understanding of the evolution of the moon.
0:55:28 > 0:55:33And, so, that legacy is just win-win-win continuously.
0:55:39 > 0:55:44Who knows what a mission to the Red Planet will teach us about Mars...
0:55:44 > 0:55:46about Earth...
0:55:46 > 0:55:48and even about ourselves?
0:55:54 > 0:56:00For Kevin, the question of money is secondary to a much bigger idea,
0:56:00 > 0:56:03and that's the importance of exploration itself.
0:56:04 > 0:56:08For him, without exploration of destinations like Mars,
0:56:08 > 0:56:11we simply might not survive as a species.
0:56:14 > 0:56:17The future of our species does depend in a very fundamental way
0:56:17 > 0:56:20on exploration. It always has. It's what we've always done.
0:56:35 > 0:56:39I think if we cease in our exploration now,
0:56:39 > 0:56:43we are calling a halt to us as...
0:56:43 > 0:56:47as a species that persists indefinitely.
0:56:47 > 0:56:48You have to explore.
0:56:48 > 0:56:52You know, it's a truism that to explore, you have to survive,
0:56:52 > 0:56:58but the opposite is also true - that to survive, you have to explore.
0:56:59 > 0:57:03The necessity of exploration, to go to Mars and beyond,
0:57:03 > 0:57:06is a sentiment shared by some of the planet's greatest thinkers.
0:57:06 > 0:57:10If the human race is to continue for another million years,
0:57:10 > 0:57:16we will have to boldly go where no-one has gone before.
0:57:16 > 0:57:20Spreading out into space will have an even greater effect.
0:57:20 > 0:57:24It will completely change the future of the human race
0:57:24 > 0:57:28and maybe determine whether we have any future at all.
0:57:28 > 0:57:32We could have a base on the moon within 30 years,
0:57:32 > 0:57:34reach Mars in 50 years,
0:57:34 > 0:57:38and explore the moons of the outer planets in 200 years.
0:57:40 > 0:57:45The idea of putting human astronauts on Mars is no longer an idealistic
0:57:45 > 0:57:49dream, but one that may finally be on the verge of becoming a reality.
0:57:49 > 0:57:52If we succeed,
0:57:52 > 0:57:55it will be the most perilous and expensive journey
0:57:55 > 0:57:57humans have ever made.
0:57:57 > 0:57:59We're already well on the way to overcoming
0:57:59 > 0:58:02the key technical obstacles to getting there safely,
0:58:02 > 0:58:05but whether the cost and risk to human life are worth it
0:58:05 > 0:58:08will continue to spark lively debate.
0:58:11 > 0:58:15There's a lovely quote from Arthur C Clarke, where he says that we could
0:58:15 > 0:58:16stop in these endeavours,
0:58:16 > 0:58:20but to do so would be to turn your back
0:58:20 > 0:58:22on billions of years of progress,
0:58:22 > 0:58:25millions of years of human evolution
0:58:25 > 0:58:27and to have begun to descend what he calls
0:58:27 > 0:58:31"the slopes that end at the shores of the primordial sea."
0:58:31 > 0:58:34And I think that's true.