0:00:02 > 0:00:06This month, a majestic sight in our night skies. Mars is the closest and brightest it's been for years.
0:00:06 > 0:00:09Mars captures the imagination like no other planet
0:00:09 > 0:00:12so come with us and let us take you to this amazing world.
0:00:12 > 0:00:14Let's journey to Mars.
0:00:40 > 0:00:44We're in Stevenage, where Airbus has built a small slice of Mars
0:00:44 > 0:00:49here on Earth to test out prototypes for Europe's ExoMars Rover.
0:00:49 > 0:00:53And, coming up, geologist Iain Stewart will reveal how these rocks
0:00:53 > 0:00:56help unlock the secrets of Mars.
0:00:56 > 0:01:00So this really is evidence that through here in the past
0:01:00 > 0:01:02once flowed a mighty river.
0:01:02 > 0:01:04Pete Lawrence will be showing us
0:01:04 > 0:01:07the great things we can see on Mars from right here on Earth.
0:01:07 > 0:01:10That's fantastic. There's so much detail there.
0:01:10 > 0:01:13We'll be giving one of you the chance to capture your very own
0:01:13 > 0:01:17photograph of Mars by taking control of the most powerful
0:01:17 > 0:01:18camera in Martian orbit.
0:01:20 > 0:01:24Away from Mars, could this be the scientific discovery of the century?
0:01:27 > 0:01:31But, first, our journey to Mars begins above the Red Planet.
0:01:31 > 0:01:34It's astonishing what discoveries have been made
0:01:34 > 0:01:36without even landing on the surface.
0:01:36 > 0:01:40Though we're used to thinking of Mars as a dry and dusty red desert,
0:01:40 > 0:01:44it's actually an amazingly varied and even a dynamic place.
0:01:46 > 0:01:49The HiRISE camera on NASA's Mars Reconnaissance Orbiter
0:01:49 > 0:01:52allows us to see the planet in exquisite detail.
0:01:54 > 0:01:59It reveals a series of extraordinary landscapes, from these vast
0:01:59 > 0:02:03fields of ice sculpted into varied and wonderful forms...
0:02:03 > 0:02:08To shifting seas of sand dunes, their shady sides covered in frost.
0:02:08 > 0:02:13There are areas covered in polygons where ice has thawed and cracked,
0:02:13 > 0:02:16creating these almost leaf-like structures.
0:02:16 > 0:02:18And impact craters that help tell us
0:02:18 > 0:02:21the age of the surface of the planet.
0:02:21 > 0:02:24And the HiRISE camera has revealed that this dynamic world
0:02:24 > 0:02:27can also change almost in front of our eyes.
0:02:27 > 0:02:31This is an image of spring arriving at the polar ice caps on Mars.
0:02:31 > 0:02:36Mars is tilted on its axis, just like the Earth, and so it too has seasons.
0:02:36 > 0:02:40What you can see here in this sort of brain-like image is the ground
0:02:40 > 0:02:43emerging through the ice as it begins to thaw.
0:02:43 > 0:02:47But this is actually frozen water and frozen carbon dioxide,
0:02:47 > 0:02:49otherwise known as dry ice.
0:02:49 > 0:02:50Mars's atmosphere is so thin
0:02:50 > 0:02:55it can't sustain liquid water on its surface in most circumstances,
0:02:55 > 0:02:58but have a look at these images from near the Martian equator.
0:02:58 > 0:03:01There seems to be something flowing down this slope.
0:03:01 > 0:03:04This is quite controversial because there's debate as to what it is.
0:03:04 > 0:03:07Some people think water, some people think it's salt water, which is
0:03:07 > 0:03:09actually fluid at a much lower temperature.
0:03:09 > 0:03:12Other people think it's just carbon dioxide
0:03:12 > 0:03:14or maybe some dust rolling down a slope.
0:03:14 > 0:03:18If not, though, this could be the first images to show liquid
0:03:18 > 0:03:19moving on the Martian surface.
0:03:19 > 0:03:23Now, the Martian atmosphere might be incredibly thin, but it doesn't mean
0:03:23 > 0:03:25there's no weather there, as we can see in this image.
0:03:25 > 0:03:29This spiral is a dust devil half a mile high,
0:03:29 > 0:03:31a huge tornado in the Martian atmosphere.
0:03:31 > 0:03:34Now, this is one of my favourite images.
0:03:34 > 0:03:36This is a uniquely Martian scene.
0:03:36 > 0:03:40This is the result of blocks of dry ice skidding down a slope,
0:03:40 > 0:03:43almost as if they were skiing.
0:03:43 > 0:03:45Now, we use dry ice here on Earth at room temperature
0:03:45 > 0:03:47to create nice atmospheric smoky scenes
0:03:47 > 0:03:51but on Mars the atmosphere's at minus 150 degrees C,
0:03:51 > 0:03:53and so the dry ice stays frozen.
0:03:53 > 0:03:56So what we're seeing is something that couldn't happen on Earth.
0:03:56 > 0:03:59Mars is a funny planet. Sometimes it looks so Earth-like
0:03:59 > 0:04:03and sometimes it does something like this that's uniquely Martian.
0:04:03 > 0:04:06A little later we'll be giving you an exciting opportunity
0:04:06 > 0:04:10to take control of the HiRISE camera and get your very own image of Mars.
0:04:10 > 0:04:13Thanks to HiRISE and the other orbiting cameras,
0:04:13 > 0:04:16we've been able to explore the Mars of today.
0:04:16 > 0:04:20And what's really exciting is trying to understand the Mars of the past.
0:04:22 > 0:04:26Today the Red Planet is a hostile environment for life
0:04:26 > 0:04:31but it now seems, over 3½ billion years ago, it was very different.
0:04:33 > 0:04:36This history has been uncovered by a succession of rovers
0:04:36 > 0:04:39that have travelled to Mars as our surrogate explorers.
0:04:41 > 0:04:47In 2004, two rovers, Spirit and Opportunity, arrived on the planet.
0:04:47 > 0:04:49They were designed to survive for 90 days
0:04:49 > 0:04:54but Opportunity is still going strong, 10 years later.
0:04:54 > 0:04:58And then, in 2012, the much larger Curiosity rover arrived.
0:05:00 > 0:05:03In just a single decade these missions have
0:05:03 > 0:05:06transformed our understanding of Mars by allowing us
0:05:06 > 0:05:09to read the secrets contained within its rocks.
0:05:10 > 0:05:13Geologist Iain Stewart has been investigating how
0:05:13 > 0:05:17the rocks on Mars have allowed us to search for signs of ancient water
0:05:17 > 0:05:21and recreate the planet's astonishing past.
0:05:21 > 0:05:24Inside here is something really precious.
0:05:25 > 0:05:29That...is a slice of another planet.
0:05:29 > 0:05:32This tiny rock is a bit of a meteorite
0:05:32 > 0:05:35which fell in Oman in the desert in 1999.
0:05:35 > 0:05:38But actually it's from Mars.
0:05:38 > 0:05:42It's one of about 130 or so meteorites that came from Mars,
0:05:42 > 0:05:45blasted off by asteroid impacts.
0:05:45 > 0:05:49The thing is, you can tell a lot about a place and its past
0:05:49 > 0:05:51from the rocks that it leaves behind.
0:05:51 > 0:05:56So this, I know, is an igneous rock, it's a basalt,
0:05:56 > 0:05:58which means at some point in the past
0:05:58 > 0:06:01volcanoes were erupting on Mars.
0:06:01 > 0:06:05This little rock tells us a great deal about how Mars formed
0:06:05 > 0:06:10but it doesn't help us with the really big question -
0:06:10 > 0:06:13could the planet have once harboured life?
0:06:16 > 0:06:20The Mars rovers are roaming the surface of the Red Planet,
0:06:20 > 0:06:22searching for rocks that reveal clues
0:06:22 > 0:06:25to what the environment was like in the past.
0:06:27 > 0:06:30Reading this evidence is a skill we've perfected here on earth.
0:06:32 > 0:06:36This rock face is part of the Jurassic coastline in Devon.
0:06:36 > 0:06:39It was formed around 240 million years ago
0:06:39 > 0:06:44and it provides a detailed record of different environmental conditions.
0:06:44 > 0:06:47There's a whole set of layers in this cliff, and the thing is,
0:06:47 > 0:06:49if you know how to read them properly,
0:06:49 > 0:06:52you can create these different environments.
0:06:52 > 0:06:54So here we've got a layer of cobbles,
0:06:54 > 0:06:57there's a layer of sand coming through
0:06:57 > 0:07:00and here's more of these cobbles, sand, cobbles,
0:07:00 > 0:07:02and then we get this, it's more of a soil.
0:07:02 > 0:07:03This is an ancient land surface.
0:07:03 > 0:07:08Then, above that, it's just sand blown around by the wind.
0:07:08 > 0:07:11Now, these, these are really distinctive.
0:07:11 > 0:07:14You can see how beautifully rounded all those pebbles are.
0:07:14 > 0:07:16Look at them, incredible.
0:07:16 > 0:07:19So they would have started off as just general angular rocks
0:07:19 > 0:07:23but what's made them all smooth is water.
0:07:23 > 0:07:25They've been churned around in a turbulent flow.
0:07:25 > 0:07:28Imagine a big river of debris coming along,
0:07:28 > 0:07:31knocking the edges off the clasts as they go,
0:07:31 > 0:07:34just creating these beautifully smooth pebbles.
0:07:34 > 0:07:37So this really is evidence that through here in the past
0:07:37 > 0:07:39once flowed a mighty river.
0:07:40 > 0:07:44The one key condition that most scientists agree
0:07:44 > 0:07:47is needed for life to have existed on Mars is water.
0:07:47 > 0:07:51So the rovers have been searching for rounded pebbles
0:07:51 > 0:07:53that might be signs of riverbeds.
0:07:53 > 0:07:57But just along the coast, there's a different kind of rock formation
0:07:57 > 0:08:01that shows a very different kind of evidence of contact with water.
0:08:01 > 0:08:04And potentially an even more favourable environment
0:08:04 > 0:08:06to search for life.
0:08:06 > 0:08:09What we've got in front of us here is just a wall of sand,
0:08:09 > 0:08:13just layer upon layer of sand dunes piled on top of each other.
0:08:13 > 0:08:17But in amongst it there's these little bands. There's another one.
0:08:17 > 0:08:18And they get a little bit thicker
0:08:18 > 0:08:21and they look different to the sand above.
0:08:21 > 0:08:25In fact, if you look in here, how crumbly this is.
0:08:28 > 0:08:31Because what we've got here is a deposit that's been laid down
0:08:31 > 0:08:36by really fine sediment settling out of standing water.
0:08:36 > 0:08:40Essentially this is a temporary lake among the sand.
0:08:41 > 0:08:45You only get rocks with this incredibly fine-grained structure
0:08:45 > 0:08:48if they were formed when water becomes really still,
0:08:48 > 0:08:51as it is in lakes and ponds.
0:08:51 > 0:08:53I've just taken a big dollop of sand here
0:08:53 > 0:08:55and as I swirl it around you see that, as long as I keep
0:08:55 > 0:08:59the swirl going, then most of the sediment is still in the water.
0:08:59 > 0:09:03But watch what happens if I stop the flow.
0:09:03 > 0:09:07Immediately the finer sediment, the mud and the silt, just settles out.
0:09:07 > 0:09:11So that means that whenever we see a kind of thin band of really
0:09:11 > 0:09:16fine sediment, we know that it must have fallen out from still water.
0:09:18 > 0:09:22This kind of sediment is much more likely to preserve signs of life
0:09:22 > 0:09:25because it formed in a much gentler way.
0:09:25 > 0:09:29Using these geological tricks we've built up this detailed
0:09:29 > 0:09:33and compelling picture of the history of water on Earth.
0:09:33 > 0:09:37But what does all this mean for Mars?
0:09:38 > 0:09:40NASA's Mars Curiosity rover
0:09:40 > 0:09:44has been taking close-up images of rocks on Mars
0:09:44 > 0:09:48and sending them back to Earth for scientists to analyse.
0:09:50 > 0:09:53Sanjeev Gupta is a geologist on the Curiosity team.
0:09:53 > 0:09:56So this is a photograph taken by Curiosity, is that right?
0:09:56 > 0:09:58That's right, this is Curiosity in Gale Crater.
0:09:58 > 0:10:02You can see these beautiful planes that Curiosity is driving over,
0:10:02 > 0:10:06searching for rock layers that might contain evidence for past life.
0:10:06 > 0:10:09So what kind of rocks did it encounter, then?
0:10:09 > 0:10:13So here we are, we can see these beautiful rock layers here.
0:10:13 > 0:10:16- If we zoom in, you can see... - Oh, wow.
0:10:16 > 0:10:20..that it's actually made up of lots and lots
0:10:20 > 0:10:23of small particles, pebbles.
0:10:23 > 0:10:26But what's really exciting about this rock
0:10:26 > 0:10:30- is that the pebbles themselves are actually rounded.- Mm.
0:10:30 > 0:10:34So we actually interpret this rock layer to be actually
0:10:34 > 0:10:36- an ancient stream bed. - That's so cool.
0:10:36 > 0:10:38That's the first time we've had that sort of evidence.
0:10:38 > 0:10:41Now, rivers aren't that great for looking for ancient life.
0:10:41 > 0:10:44You know, you can imagine these pebbles are being
0:10:44 > 0:10:46tumbled in these flows and it's just too high energy.
0:10:46 > 0:10:49And what geologists really look for, for searching,
0:10:49 > 0:10:52are quiet water environments, calm environments,
0:10:52 > 0:10:54where particles, sediment particles,
0:10:54 > 0:10:58can settle out of suspension and trap organic matter, for example.
0:10:58 > 0:11:02You know, the best environment would be an ancient lake.
0:11:02 > 0:11:05Now, we never dared expect to find an ancient lake,
0:11:05 > 0:11:06but this is what we saw.
0:11:07 > 0:11:10So here's one of the first-ever drill holes
0:11:10 > 0:11:13- on the surface of another planet. - That's extraordinary.
0:11:13 > 0:11:16- That's something we do all the time on Earth.- That's right.
0:11:16 > 0:11:18This is one of the first ones.
0:11:18 > 0:11:21And you can see this drill hole is about 2½ centimetres in diameter
0:11:21 > 0:11:23and you can see the rock powder
0:11:23 > 0:11:25that's resulted in the drill tailings over here.
0:11:25 > 0:11:27The next image is just fantastic
0:11:27 > 0:11:30because this is actually an angled view into that drill hole.
0:11:30 > 0:11:31Into the hole.
0:11:31 > 0:11:34And you can see the grains over here, very, very fine-grained.
0:11:34 > 0:11:38- This hole is about 2½cm across.- So these are smaller than sand grains.
0:11:38 > 0:11:41They're smaller than sand grains.
0:11:41 > 0:11:45And these layers have basically built up through time in an ancient lake,
0:11:45 > 0:11:49and this is a perfect environment to look for clues for ancient life.
0:11:51 > 0:11:54Curiosity has been able to go even further,
0:11:54 > 0:11:59creating the clearest picture yet of Mars over 3½ billion years ago.
0:11:59 > 0:12:02Using its on-board laboratory, it's analysed these samples
0:12:02 > 0:12:05to show that not only did Mars have water
0:12:05 > 0:12:08but that the water would have been fresh.
0:12:09 > 0:12:12It's amazing to think how much we've managed to learn
0:12:12 > 0:12:14by studying the rocks on another planet
0:12:14 > 0:12:17without having to actually go there ourselves.
0:12:17 > 0:12:21The picture it reveals is Mars over 3½ billion years ago,
0:12:21 > 0:12:23awash with fresh water
0:12:23 > 0:12:26and prime with the ingredients to support life.
0:12:28 > 0:12:31Not only that, but we now have a good idea about where to look
0:12:31 > 0:12:34for direct signs of past life on Mars.
0:12:36 > 0:12:38And that's exactly what the next rover will do.
0:12:46 > 0:12:50Mars has captivated us for millennia and one of the reasons is
0:12:50 > 0:12:54that as our next-door neighbour, it's an unmissable presence in our skies.
0:12:55 > 0:12:59And so Pete Lawrence begins this month's Star Guide
0:12:59 > 0:13:02with some tips on how to observe Mars.
0:13:02 > 0:13:05Now is a great time to go and view magnificent Mars
0:13:05 > 0:13:09and you can see it up there just off to the left of the moon.
0:13:09 > 0:13:12The reason why this is such a good time to look for it
0:13:12 > 0:13:15is that the Earth is currently located between Mars and the sun
0:13:15 > 0:13:18and that means that Mars is at its closest to us.
0:13:18 > 0:13:21This occurs roughly every two years or so.
0:13:21 > 0:13:24When it happens, Mars appears bright in the sky
0:13:24 > 0:13:27and is really easy to find with the naked eye.
0:13:29 > 0:13:33The motion of Mars across the night sky is extraordinary.
0:13:33 > 0:13:37It appears to wander back and forth, performing a giant loop.
0:13:38 > 0:13:41Mars isn't actually moving around the solar system
0:13:41 > 0:13:43in an unruly fashion.
0:13:43 > 0:13:45What's happening is that we're seeing an illusion
0:13:45 > 0:13:50caused by the fact that the Earth is orbiting the sun faster than Mars.
0:13:50 > 0:13:52As we overtake the Red Planet,
0:13:52 > 0:13:55so Mars appears to loop back on itself in the sky,
0:13:55 > 0:13:58an effect known as retrograde motion.
0:13:59 > 0:14:03Of course, its most obvious attribute is its colour.
0:14:03 > 0:14:06The colour comes from the rocks on the surface of the planet
0:14:06 > 0:14:10but it's not uniformly red, which means with a good telescope
0:14:10 > 0:14:13you can still see some splendid features on its surface.
0:14:14 > 0:14:20And that's exactly what the members of the Bedford Astronomical Society are doing.
0:14:20 > 0:14:21Oh, this looks interesting.
0:14:21 > 0:14:23Well, that's an image we captured of Mars last Friday.
0:14:23 > 0:14:26I was really pleased with it, we got some nice detail showing up.
0:14:26 > 0:14:29You've got that lovely V shape feature there,
0:14:29 > 0:14:31which is Syrtis Major of course.
0:14:31 > 0:14:35And then further to the south of Syrtis Major
0:14:35 > 0:14:38- you've got that bright patch there. - It's so bright.
0:14:38 > 0:14:41It looks to me like it's a polar cap, but it's not, is it?
0:14:41 > 0:14:44No, it's the Hellas Basin, this huge impact feature.
0:14:44 > 0:14:47It's nine kilometres deep and it just must be
0:14:47 > 0:14:51full of cloud at the moment, which is why it's so white and shiny.
0:14:51 > 0:14:54But that bright patch you've got at the top there, that is a polar cap.
0:14:54 > 0:14:57That's a genuine polar cap but it's decreasing all the time.
0:14:57 > 0:14:59That's fantastic, so much detail.
0:15:01 > 0:15:04Now, we've seen some fabulous images of Mars tonight
0:15:04 > 0:15:07and if you manage to get any of your own, send them through
0:15:07 > 0:15:09and we'll put up a selection on our website.
0:15:11 > 0:15:15Now, Mars is an amazing object to view and observe at the moment
0:15:15 > 0:15:18but there's plenty on offer around that part of the sky as well,
0:15:18 > 0:15:20so here's this month's Star Guide.
0:15:20 > 0:15:24Mars is currently rising in the south-east in the constellation
0:15:24 > 0:15:29of Virgo as darkness falls, and throughout the month tracks west.
0:15:29 > 0:15:32It begins close to the bright white star Spica
0:15:32 > 0:15:36and ends the month just south of the middle bright star Porrima.
0:15:36 > 0:15:40Porrima sits at the bottom of a large semicircular pattern of stars
0:15:40 > 0:15:43known as the Bowl of Virgo.
0:15:43 > 0:15:47If you have a telescope, select a low-power eyepiece
0:15:47 > 0:15:49and sweep through the region close to the top of the Bowl.
0:15:49 > 0:15:53It's known as the Realm of Galaxies.
0:15:53 > 0:15:55This part of the sky is full of distant galaxies
0:15:55 > 0:15:58which appear like faint smudges.
0:15:59 > 0:16:01The region to the left of the bowl
0:16:01 > 0:16:05currently plays host to dwarf planet Ceres and minor planet Vesta.
0:16:07 > 0:16:09Vesta is currently on the verge
0:16:09 > 0:16:12of naked eye visibility from a dark sky site
0:16:12 > 0:16:15but both objects are well within binocular range.
0:16:16 > 0:16:19Finally, let's return to Mars.
0:16:19 > 0:16:22The most distinctive feature you can pick out with a telescope
0:16:22 > 0:16:27is known as the Syrtis Major, a large dark V shaped pattern.
0:16:27 > 0:16:30The best time to look for it throughout April
0:16:30 > 0:16:33is around 11pm between the 18th and the 28th.
0:16:39 > 0:16:41More from Mars in a few minutes.
0:16:41 > 0:16:44But first, last month we showed you how to take
0:16:44 > 0:16:47amazing images of the night sky with a smartphone,
0:16:47 > 0:16:51and you've been sharing your results with us.
0:16:51 > 0:16:54This image by Andrew Carter shows the Clavius crater
0:16:54 > 0:16:56on the moon in fantastic detail.
0:16:58 > 0:17:01Paul Newton caught Venus transiting the sun.
0:17:04 > 0:17:08And you can make out the shadow of Jupiter's moon Io
0:17:08 > 0:17:11in this image by Damian Weatherly.
0:17:11 > 0:17:15And Michelle Reitsma managed to capture Saturn and its famous rings.
0:17:19 > 0:17:22Now it's time for this month's astro news, and there's been
0:17:22 > 0:17:25a lot happening in the astronomical world since we were last on air.
0:17:25 > 0:17:30Certainly has. For starters, the solar system has a new member, and here it is.
0:17:30 > 0:17:33- This is 2012 VP113.- Snappy! - It will get a better name soon.
0:17:33 > 0:17:36But what we can see here is images taken over six hours
0:17:36 > 0:17:39and coloured so that you can see that something's moving.
0:17:39 > 0:17:43And that's actually a dwarf planet in the outer solar system.
0:17:43 > 0:17:46Now this thing's in a really unusual orbit,
0:17:46 > 0:17:50much further out than Pluto, 2½ times as far from the sun as Neptune is
0:17:50 > 0:17:53and orbiting in a place where it's got no right to be.
0:17:53 > 0:17:56The only other thing around there is something called Sedna,
0:17:56 > 0:17:58which we found just over a decade ago,
0:17:58 > 0:18:02but those two things are on orbits that we can't explain using
0:18:02 > 0:18:05conventional solar system mechanics, so it's a very exciting time.
0:18:05 > 0:18:07And another potential dwarf planet.
0:18:07 > 0:18:10That's right, another dwarf planet, assuming it holds up.
0:18:10 > 0:18:11We don't quite know its size yet.
0:18:11 > 0:18:13But there have been other weird discoveries
0:18:13 > 0:18:16- in the outer solar system as well. - And this time much closer to home.
0:18:16 > 0:18:18There was a collection of asteroid-like bodies
0:18:18 > 0:18:22that lie between Saturn and Uranus. They're called the centaurs.
0:18:22 > 0:18:23And one of these, the largest one,
0:18:23 > 0:18:25has actually been discovered to have rings.
0:18:25 > 0:18:28This is an artist's impression of it.
0:18:28 > 0:18:31So that's the object, and here are the two rings around it.
0:18:31 > 0:18:34Now, this was actually discovered in about 20 seconds of data.
0:18:34 > 0:18:36Because the asteroid was passing in front of a star
0:18:36 > 0:18:39and you get a dip in the light level, an occultation.
0:18:39 > 0:18:42Usually with a large object like this, you'll just get a single dip,
0:18:42 > 0:18:44but what happened here is they got five,
0:18:44 > 0:18:46four little ones and one big one,
0:18:46 > 0:18:49which actually was an indication of you're passing through these rings.
0:18:49 > 0:18:52It's the first time that we've seen rings on a body this size
0:18:52 > 0:18:56and the mystery is, why were they formed, where did they come from?
0:18:56 > 0:18:58You just don't get them on things this size.
0:18:58 > 0:19:00But I think we'll be looking out for them in the future.
0:19:00 > 0:19:02Of course the story dominating the news at the moment
0:19:02 > 0:19:05is the results from BICEP2 in the South Pole,
0:19:05 > 0:19:08which, if confirmed, could lead to some Nobel Prizes.
0:19:08 > 0:19:11But, more importantly, it seems to be telling us about a time
0:19:11 > 0:19:15just a ten-million-billion-billion-billionth of a second after the Big Bang,
0:19:15 > 0:19:18when something called cosmic inflation took place,
0:19:18 > 0:19:22with the universe expanding from a tiny subatomic particle to something
0:19:22 > 0:19:26much larger, setting the stage for everything that's happened since.
0:19:28 > 0:19:31The idea of inflation was introduced to explain
0:19:31 > 0:19:35some oddities about the universe around us.
0:19:35 > 0:19:36No matter which direction you look,
0:19:36 > 0:19:39on a large scale everything's the same.
0:19:39 > 0:19:41You get the same number of galaxies
0:19:41 > 0:19:44and the universe is at the same temperature.
0:19:44 > 0:19:46It seems like a cosmic coincidence.
0:19:46 > 0:19:50What you might expect is a universe that's far lumpier.
0:19:52 > 0:19:55The expansion introduced by inflation
0:19:55 > 0:19:58means that any lumpiness would be smoothed away.
0:19:59 > 0:20:01But, until last month,
0:20:01 > 0:20:04we had no direct evidence that inflation took place at all.
0:20:10 > 0:20:13One of the leaders of the experiment that may have discovered
0:20:13 > 0:20:15the signature of cosmic inflation is Clem Pryke.
0:20:17 > 0:20:20Now, to look for the signal, you have to go, of all places,
0:20:20 > 0:20:23to the South Pole. So here's your Antarctic telescope
0:20:23 > 0:20:26and BICEP2 is actually in this dish here.
0:20:26 > 0:20:29Yeah, in this conical-shaped shield is the BICEP 2 telescope itself.
0:20:29 > 0:20:32- And why Antarctica? - So we go to Antarctica
0:20:32 > 0:20:35because the atmosphere there is fantastically dry.
0:20:35 > 0:20:38- Now, this is counterintuitive... - This is water that you're sitting on.
0:20:38 > 0:20:41When you get off the plane, you're standing on two miles thick of ice,
0:20:41 > 0:20:4410,000 feet of ice, and they tell you it's a hyper desert.
0:20:44 > 0:20:46And what little moisture there is in the atmosphere
0:20:46 > 0:20:48is in the form of ice and not liquid water.
0:20:48 > 0:20:51Liquid water is a killer for these kinds of observations,
0:20:51 > 0:20:53because it basically renders the atmosphere opaque.
0:20:53 > 0:20:57So essentially we can look straight out into outer space without the atmosphere getting in the way.
0:20:57 > 0:21:00OK, and you're looking at the cosmic microwave background,
0:21:00 > 0:21:02the oldest light we can see.
0:21:02 > 0:21:06Here's an image of the whole sky in microwaves and it's a picture
0:21:06 > 0:21:09of the universe as it was, what, 400,000 years or so
0:21:09 > 0:21:10after the Big Bang.
0:21:10 > 0:21:12Right, so these blobs, these hot and cold spots,
0:21:12 > 0:21:16red and blue spots, are places where there's a little more matter
0:21:16 > 0:21:18and a little less matter.
0:21:18 > 0:21:21And these blobs actually evolved into the galaxy clusters
0:21:21 > 0:21:24and galaxies that we see in the universe today.
0:21:24 > 0:21:27Now, what BICEP2 has given us, or seems to have given us,
0:21:27 > 0:21:31is the first evidence, first direct evidence, for this inflation.
0:21:31 > 0:21:34So what is it in this light that gives you this signal?
0:21:34 > 0:21:38So inflation was already a popular theory,
0:21:38 > 0:21:42but in some sense it was kind of made up to fit observational facts.
0:21:42 > 0:21:44But what it also does is made an additional prediction
0:21:44 > 0:21:47which was not observed, which hadn't been observed...
0:21:47 > 0:21:50And this is to do with gravitational waves, ripples in space.
0:21:50 > 0:21:52Essentially ripples in space-time.
0:21:52 > 0:21:54So, that was an additional prediction,
0:21:54 > 0:21:55so when you have a theory,
0:21:55 > 0:21:58which is a very nice theory, a lot of people like it,
0:21:58 > 0:22:01- you want to find some prediction that it makes that you can additionally go and check.- Right.
0:22:01 > 0:22:04And that's... So the detection of these gravitational waves
0:22:04 > 0:22:07- has been called a smoking gun for inflation.- Right.
0:22:07 > 0:22:10Now what they do is they impart on the polarisation pattern
0:22:10 > 0:22:14of the microwave background a small additional signature,
0:22:14 > 0:22:17- a small degree of swirliness, as it were.- OK, so let's have a look.
0:22:17 > 0:22:19This is the patch of sky,
0:22:19 > 0:22:22this is the BICEP2 result with that swirliness
0:22:22 > 0:22:23that we were talking about,
0:22:23 > 0:22:27- so these little arrows are the polarisation signal.- Right.
0:22:27 > 0:22:30But here we've subtracted out the expected part, as it were,
0:22:30 > 0:22:32and we are left with the so-called B-mode,
0:22:32 > 0:22:34which is the swirliness of the pattern.
0:22:34 > 0:22:37Only gravitational waves, crucially, only gravitational waves,
0:22:37 > 0:22:39can make the swirly part of the pattern.
0:22:39 > 0:22:42And so it's the detection of this swirliness is the signature
0:22:42 > 0:22:44of that inflationary moment.
0:22:44 > 0:22:46It's the signature of gravity waves,
0:22:46 > 0:22:48and the only plausible source for such strong,
0:22:48 > 0:22:52relatively strong gravitational waves, is the inflationary theory.
0:22:52 > 0:22:54The competing theories don't predict...
0:22:54 > 0:22:57So that's why this is such an exciting result.
0:22:57 > 0:22:59I think you were surprised by the signal, weren't you?
0:22:59 > 0:23:01Not that necessarily it was there,
0:23:01 > 0:23:03but it was stronger than some people thought.
0:23:03 > 0:23:07Yeah, so it's perhaps about as strong as was originally
0:23:07 > 0:23:09expected from the simplest inflationary theories,
0:23:09 > 0:23:12the ones that were formulated back in the '80s.
0:23:12 > 0:23:14Since then, more sophisticated theories
0:23:14 > 0:23:16have tended to predict lower levels,
0:23:16 > 0:23:18so this week's result was quite a surprise.
0:23:18 > 0:23:20There must be personal satisfaction in this.
0:23:20 > 0:23:23People have been talking, it's too early to talk about this,
0:23:23 > 0:23:25but people have been talking about Nobel prizes
0:23:25 > 0:23:26and speculating and so on.
0:23:26 > 0:23:28Do you wander round the lab, late at night, thinking,
0:23:28 > 0:23:31"Well, you know, maybe this is it"?
0:23:31 > 0:23:33Well, it's only been a week.
0:23:33 > 0:23:36But before that, we were just very focused on doing
0:23:36 > 0:23:40the most careful possible job that we could in the data analysis
0:23:40 > 0:23:42and just really being as sure as we possibly could be.
0:23:42 > 0:23:45Very nerve-racking, actually, to be sitting on something like this.
0:23:45 > 0:23:49- Yeah.- Quite stressful.- All right, well, we'll let you get back to it.
0:23:49 > 0:23:50- Thanks a lot.- Thank you very much.
0:23:56 > 0:23:58Now back to Mars.
0:23:58 > 0:24:01And a mission that's been planned to take our exploration of the planet
0:24:01 > 0:24:03to a whole new level.
0:24:03 > 0:24:07The European Space Agency ExoMars mission is aiming to be
0:24:07 > 0:24:11the first rover to directly search for life on the Red Planet.
0:24:13 > 0:24:16It will be equipped with a drill that will let it dig two metres
0:24:16 > 0:24:18below the Martian surface
0:24:18 > 0:24:21to a level protected from deadly solar radiation.
0:24:23 > 0:24:27If all goes to plan, it will be travelling to Mars in 2018.
0:24:28 > 0:24:31I'm currently standing on what appears to be
0:24:31 > 0:24:34a patch of the Red Planet right here on Earth.
0:24:34 > 0:24:37This is the Mars Yard, built by Airbus,
0:24:37 > 0:24:40to test the ExoMars rover, and put it through its paces.
0:24:40 > 0:24:42Now, that's really necessary,
0:24:42 > 0:24:45because ExoMars is going to go to a very alien environment.
0:24:45 > 0:24:47I've got Abbie Hutty here,
0:24:47 > 0:24:50who's the structural engineer on the ExoMars project.
0:24:50 > 0:24:52So what are the challenges that ExoMars
0:24:52 > 0:24:54will face on the real Martian surface?
0:24:54 > 0:24:57One of the first things that we've got to consider is that
0:24:57 > 0:25:00Mars is really very cold, so we've got night-time temperatures
0:25:00 > 0:25:03that go down to -125 degrees Celsius.
0:25:03 > 0:25:05- That's brisk! - Yeah, a little bit chilly.
0:25:05 > 0:25:09Then during the day it might not even get much warmer than -85,
0:25:09 > 0:25:13so you're going all the way between those two, and materials,
0:25:13 > 0:25:15as we know, expand and contract
0:25:15 > 0:25:18as they go through the different temperatures.
0:25:18 > 0:25:21That's especially a problem where you've got structures that might
0:25:21 > 0:25:23be made of more than one different type of material,
0:25:23 > 0:25:25because where those two materials meet,
0:25:25 > 0:25:28they actually just tear themselves apart from each other.
0:25:28 > 0:25:30I guess radiation is a problem, too?
0:25:30 > 0:25:34Well, yes, we've only got 1% of the atmosphere on Mars
0:25:34 > 0:25:37to what we have on Earth, so down on the Martian surface,
0:25:37 > 0:25:40you are receiving a lot more of that radiation dose
0:25:40 > 0:25:42and that can be really damaging for your electronics
0:25:42 > 0:25:44and also for optical devices,
0:25:44 > 0:25:48like lenses can blacken with that radiation dose
0:25:48 > 0:25:52and that can obviously have a huge impact on how far you can see
0:25:52 > 0:25:55or your senses that require those optics.
0:25:55 > 0:25:58So, this is a prototype called Bryan,
0:25:58 > 0:25:59one of a series of prototypes
0:25:59 > 0:26:02and, looking at it, the wheels are a bit freaky.
0:26:02 > 0:26:05- How do these work? - Well, we've actually had to
0:26:05 > 0:26:07develop these specifically for the Mars project
0:26:07 > 0:26:10because we can't take rubber tyres with us.
0:26:10 > 0:26:12Rubber is an organic molecule.
0:26:12 > 0:26:14Yes, and you are looking for signs of life.
0:26:14 > 0:26:17Absolutely, so we've got very strict regulations in place
0:26:17 > 0:26:19to make sure that we don't take anything with us
0:26:19 > 0:26:22that could be in any way confused for an organic molecule.
0:26:22 > 0:26:24So we have developed these wheels.
0:26:24 > 0:26:26They are entirely metallic,
0:26:26 > 0:26:28but you've also got to retain the flexibility of the wheel...
0:26:28 > 0:26:30That you'd get from rubber.
0:26:30 > 0:26:33..so we've got these very thin wafers of metal
0:26:33 > 0:26:37that actually are still flexible because they are so thin.
0:26:37 > 0:26:39But how do you navigate across the Martian surface?
0:26:39 > 0:26:42Well, that's one of the really big developments with ExoMars
0:26:42 > 0:26:45and that is one of the reasons that we've got this Mars Yard here.
0:26:45 > 0:26:48Because you've got such a long-distance to Mars,
0:26:48 > 0:26:51it means you've actually got a 22-minute delay
0:26:51 > 0:26:53between sending your signal and it being received,
0:26:53 > 0:26:56so all of our rovers are going to be able to
0:26:56 > 0:26:59actually autonomously navigate around the surface.
0:26:59 > 0:27:02We've got two cameras at the top of the mast so we can see in 3-D.
0:27:02 > 0:27:07It can build up a map of how big the obstacles are
0:27:07 > 0:27:10and where they are in front of it and then it can actually classify
0:27:10 > 0:27:12the different areas into,
0:27:12 > 0:27:14"This is too big a rock, I can't climb over this,"
0:27:14 > 0:27:16or, "This is a safe, flat bit, this is good to climb over,"
0:27:16 > 0:27:20and then it can pick its own path through that map.
0:27:20 > 0:27:22Well, I can't wait until ExoMars gets to Mars
0:27:22 > 0:27:24and thank you so much for sharing this with us.
0:27:24 > 0:27:27- Absolutely, it's been a pleasure. - Thank you.
0:27:33 > 0:27:35Now for that special treat we mentioned earlier.
0:27:35 > 0:27:37The team behind the HiRISE camera
0:27:37 > 0:27:40that showed us the amazing images earlier in the programme
0:27:40 > 0:27:42are giving you the opportunity to take control
0:27:42 > 0:27:45and select the location for the next image of Mars.
0:27:45 > 0:27:47It's a spectacular opportunity
0:27:47 > 0:27:50and what we need is a scientific justification for your choice,
0:27:50 > 0:27:52so it could be an unusual formation,
0:27:52 > 0:27:55some strange colours, or maybe a famous place
0:27:55 > 0:27:58that you would like to see for the first time with HiRISE resolution.
0:27:58 > 0:28:01To take part, you can go to our website and tell us
0:28:01 > 0:28:03where you think the camera should be pointed.
0:28:03 > 0:28:06We will close the entries on 27th April
0:28:06 > 0:28:09and we will announce the winner in next month's programme.
0:28:09 > 0:28:13It's a fantastic opportunity, so please do enter.
0:28:13 > 0:28:15Well, we can't leave you without showing one last image
0:28:15 > 0:28:19from the Martian surface and here it is.
0:28:19 > 0:28:23This is an image taken by the Curiosity rover on 31st January.
0:28:23 > 0:28:28Rising high in the Martian sky is a fabulous evening star.
0:28:28 > 0:28:32But that is no star, that is Earth and I find it wonderful and humbling
0:28:32 > 0:28:36that we can see ourselves in the sky of an alien world.
0:28:36 > 0:28:39It is a fantastic image, but that's it for this programme.
0:28:39 > 0:28:42Next month, we will be coming from the Brecon Beacons AstroCamp,
0:28:42 > 0:28:44where we will be looking deep into space.
0:28:44 > 0:28:47And you will also have the chance to discover your very own asteroid
0:28:47 > 0:28:51as part of a real scientific search for near-Earth asteroids.
0:28:51 > 0:28:56- So, until then, get outside and get looking up!- Good night.