Mysterious Mars The Sky at Night

This month, a majestic sight in our night skies. Mars is the closest and brightest it's been for years.

Mars captures the imagination like no other planet

so come with us and let us take you to this amazing world.

Let's journey to Mars.

We're in Stevenage, where Airbus has built a small slice of Mars

here on Earth to test out prototypes for Europe's ExoMars Rover.

And, coming up, geologist Iain Stewart will reveal how these rocks

help unlock the secrets of Mars.

So this really is evidence that through here in the past

once flowed a mighty river.

Pete Lawrence will be showing us

the great things we can see on Mars from right here on Earth.

That's fantastic. There's so much detail there.

We'll be giving one of you the chance to capture your very own

photograph of Mars by taking control of the most powerful

camera in Martian orbit.

Away from Mars, could this be the scientific discovery of the century?

But, first, our journey to Mars begins above the Red Planet.

It's astonishing what discoveries have been made

without even landing on the surface.

Though we're used to thinking of Mars as a dry and dusty red desert,

it's actually an amazingly varied and even a dynamic place.

The HiRISE camera on NASA's Mars Reconnaissance Orbiter

allows us to see the planet in exquisite detail.

It reveals a series of extraordinary landscapes, from these vast

fields of ice sculpted into varied and wonderful forms...

To shifting seas of sand dunes, their shady sides covered in frost.

There are areas covered in polygons where ice has thawed and cracked,

creating these almost leaf-like structures.

And impact craters that help tell us

the age of the surface of the planet.

And the HiRISE camera has revealed that this dynamic world

can also change almost in front of our eyes.

This is an image of spring arriving at the polar ice caps on Mars.

Mars is tilted on its axis, just like the Earth, and so it too has seasons.

What you can see here in this sort of brain-like image is the ground

emerging through the ice as it begins to thaw.

But this is actually frozen water and frozen carbon dioxide,

otherwise known as dry ice.

Mars's atmosphere is so thin

it can't sustain liquid water on its surface in most circumstances,

but have a look at these images from near the Martian equator.

There seems to be something flowing down this slope.

This is quite controversial because there's debate as to what it is.

Some people think water, some people think it's salt water, which is

actually fluid at a much lower temperature.

Other people think it's just carbon dioxide

or maybe some dust rolling down a slope.

If not, though, this could be the first images to show liquid

moving on the Martian surface.

Now, the Martian atmosphere might be incredibly thin, but it doesn't mean

there's no weather there, as we can see in this image.

This spiral is a dust devil half a mile high,

a huge tornado in the Martian atmosphere.

Now, this is one of my favourite images.

This is a uniquely Martian scene.

This is the result of blocks of dry ice skidding down a slope,

almost as if they were skiing.

Now, we use dry ice here on Earth at room temperature

to create nice atmospheric smoky scenes

but on Mars the atmosphere's at minus 150 degrees C,

and so the dry ice stays frozen.

So what we're seeing is something that couldn't happen on Earth.

Mars is a funny planet. Sometimes it looks so Earth-like

and sometimes it does something like this that's uniquely Martian.

A little later we'll be giving you an exciting opportunity

to take control of the HiRISE camera and get your very own image of Mars.

Thanks to HiRISE and the other orbiting cameras,

we've been able to explore the Mars of today.

And what's really exciting is trying to understand the Mars of the past.

Today the Red Planet is a hostile environment for life

but it now seems, over 3½ billion years ago, it was very different.

This history has been uncovered by a succession of rovers

that have travelled to Mars as our surrogate explorers.

In 2004, two rovers, Spirit and Opportunity, arrived on the planet.

They were designed to survive for 90 days

but Opportunity is still going strong, 10 years later.

And then, in 2012, the much larger Curiosity rover arrived.

In just a single decade these missions have

transformed our understanding of Mars by allowing us

to read the secrets contained within its rocks.

Geologist Iain Stewart has been investigating how

the rocks on Mars have allowed us to search for signs of ancient water

and recreate the planet's astonishing past.

Inside here is something really precious.

That...is a slice of another planet.

This tiny rock is a bit of a meteorite

which fell in Oman in the desert in 1999.

But actually it's from Mars.

It's one of about 130 or so meteorites that came from Mars,

blasted off by asteroid impacts.

The thing is, you can tell a lot about a place and its past

from the rocks that it leaves behind.

So this, I know, is an igneous rock, it's a basalt,

which means at some point in the past

volcanoes were erupting on Mars.

This little rock tells us a great deal about how Mars formed

but it doesn't help us with the really big question -

could the planet have once harboured life?

The Mars rovers are roaming the surface of the Red Planet,

searching for rocks that reveal clues

to what the environment was like in the past.

Reading this evidence is a skill we've perfected here on earth.

This rock face is part of the Jurassic coastline in Devon.

It was formed around 240 million years ago

and it provides a detailed record of different environmental conditions.

There's a whole set of layers in this cliff, and the thing is,

if you know how to read them properly,

you can create these different environments.

So here we've got a layer of cobbles,

there's a layer of sand coming through

and here's more of these cobbles, sand, cobbles,

and then we get this, it's more of a soil.

This is an ancient land surface.

Then, above that, it's just sand blown around by the wind.

Now, these, these are really distinctive.

You can see how beautifully rounded all those pebbles are.

Look at them, incredible.

So they would have started off as just general angular rocks

but what's made them all smooth is water.

They've been churned around in a turbulent flow.

Imagine a big river of debris coming along,

knocking the edges off the clasts as they go,

just creating these beautifully smooth pebbles.

So this really is evidence that through here in the past

once flowed a mighty river.

The one key condition that most scientists agree

is needed for life to have existed on Mars is water.

So the rovers have been searching for rounded pebbles

that might be signs of riverbeds.

But just along the coast, there's a different kind of rock formation

that shows a very different kind of evidence of contact with water.

And potentially an even more favourable environment

to search for life.

What we've got in front of us here is just a wall of sand,

just layer upon layer of sand dunes piled on top of each other.

But in amongst it there's these little bands. There's another one.

And they get a little bit thicker

and they look different to the sand above.

In fact, if you look in here, how crumbly this is.

Because what we've got here is a deposit that's been laid down

by really fine sediment settling out of standing water.

Essentially this is a temporary lake among the sand.

You only get rocks with this incredibly fine-grained structure

if they were formed when water becomes really still,

as it is in lakes and ponds.

I've just taken a big dollop of sand here

and as I swirl it around you see that, as long as I keep

the swirl going, then most of the sediment is still in the water.

But watch what happens if I stop the flow.

Immediately the finer sediment, the mud and the silt, just settles out.

So that means that whenever we see a kind of thin band of really

fine sediment, we know that it must have fallen out from still water.

This kind of sediment is much more likely to preserve signs of life

because it formed in a much gentler way.

Using these geological tricks we've built up this detailed

and compelling picture of the history of water on Earth.

But what does all this mean for Mars?

NASA's Mars Curiosity rover

has been taking close-up images of rocks on Mars

and sending them back to Earth for scientists to analyse.

Sanjeev Gupta is a geologist on the Curiosity team.

So this is a photograph taken by Curiosity, is that right?

That's right, this is Curiosity in Gale Crater.

You can see these beautiful planes that Curiosity is driving over,

searching for rock layers that might contain evidence for past life.

So what kind of rocks did it encounter, then?

So here we are, we can see these beautiful rock layers here.

-If we zoom in, you can see...

-Oh, wow.

..that it's actually made up of lots and lots

of small particles, pebbles.

But what's really exciting about this rock

-is that the pebbles themselves are actually rounded.

-Mm.

So we actually interpret this rock layer to be actually

-an ancient stream bed.

-That's so cool.

That's the first time we've had that sort of evidence.

Now, rivers aren't that great for looking for ancient life.

You know, you can imagine these pebbles are being

tumbled in these flows and it's just too high energy.

And what geologists really look for, for searching,

are quiet water environments, calm environments,

where particles, sediment particles,

can settle out of suspension and trap organic matter, for example.

You know, the best environment would be an ancient lake.

Now, we never dared expect to find an ancient lake,

but this is what we saw.

So here's one of the first-ever drill holes

-on the surface of another planet.

-That's extraordinary.

-That's something we do all the time on Earth.

-That's right.

This is one of the first ones.

And you can see this drill hole is about 2½ centimetres in diameter

and you can see the rock powder

that's resulted in the drill tailings over here.

The next image is just fantastic

because this is actually an angled view into that drill hole.

Into the hole.

And you can see the grains over here, very, very fine-grained.

-This hole is about 2½cm across.

-So these are smaller than sand grains.

They're smaller than sand grains.

And these layers have basically built up through time in an ancient lake,

and this is a perfect environment to look for clues for ancient life.

Curiosity has been able to go even further,

creating the clearest picture yet of Mars over 3½ billion years ago.

Using its on-board laboratory, it's analysed these samples

to show that not only did Mars have water

but that the water would have been fresh.

It's amazing to think how much we've managed to learn

by studying the rocks on another planet

without having to actually go there ourselves.

The picture it reveals is Mars over 3½ billion years ago,

awash with fresh water

and prime with the ingredients to support life.

Not only that, but we now have a good idea about where to look

for direct signs of past life on Mars.

And that's exactly what the next rover will do.

Mars has captivated us for millennia and one of the reasons is

that as our next-door neighbour, it's an unmissable presence in our skies.

And so Pete Lawrence begins this month's Star Guide

with some tips on how to observe Mars.

Now is a great time to go and view magnificent Mars

and you can see it up there just off to the left of the moon.

The reason why this is such a good time to look for it

is that the Earth is currently located between Mars and the sun

and that means that Mars is at its closest to us.

This occurs roughly every two years or so.

When it happens, Mars appears bright in the sky

and is really easy to find with the naked eye.

The motion of Mars across the night sky is extraordinary.

It appears to wander back and forth, performing a giant loop.

Mars isn't actually moving around the solar system

in an unruly fashion.

What's happening is that we're seeing an illusion

caused by the fact that the Earth is orbiting the sun faster than Mars.

As we overtake the Red Planet,

so Mars appears to loop back on itself in the sky,

an effect known as retrograde motion.

Of course, its most obvious attribute is its colour.

The colour comes from the rocks on the surface of the planet

but it's not uniformly red, which means with a good telescope

you can still see some splendid features on its surface.

And that's exactly what the members of the Bedford Astronomical Society are doing.

Oh, this looks interesting.

Well, that's an image we captured of Mars last Friday.

I was really pleased with it, we got some nice detail showing up.

You've got that lovely V shape feature there,

which is Syrtis Major of course.

And then further to the south of Syrtis Major

-you've got that bright patch there.

-It's so bright.

It looks to me like it's a polar cap, but it's not, is it?

No, it's the Hellas Basin, this huge impact feature.

It's nine kilometres deep and it just must be

full of cloud at the moment, which is why it's so white and shiny.

But that bright patch you've got at the top there, that is a polar cap.

That's a genuine polar cap but it's decreasing all the time.

That's fantastic, so much detail.

Now, we've seen some fabulous images of Mars tonight

and if you manage to get any of your own, send them through

and we'll put up a selection on our website.

Now, Mars is an amazing object to view and observe at the moment

but there's plenty on offer around that part of the sky as well,

so here's this month's Star Guide.

Mars is currently rising in the south-east in the constellation

of Virgo as darkness falls, and throughout the month tracks west.

It begins close to the bright white star Spica

and ends the month just south of the middle bright star Porrima.

Porrima sits at the bottom of a large semicircular pattern of stars

known as the Bowl of Virgo.

If you have a telescope, select a low-power eyepiece

and sweep through the region close to the top of the Bowl.

It's known as the Realm of Galaxies.

This part of the sky is full of distant galaxies

which appear like faint smudges.

The region to the left of the bowl

currently plays host to dwarf planet Ceres and minor planet Vesta.

Vesta is currently on the verge

of naked eye visibility from a dark sky site

but both objects are well within binocular range.

Finally, let's return to Mars.

The most distinctive feature you can pick out with a telescope

is known as the Syrtis Major, a large dark V shaped pattern.

The best time to look for it throughout April

is around 11pm between the 18th and the 28th.

More from Mars in a few minutes.

But first, last month we showed you how to take

amazing images of the night sky with a smartphone,

and you've been sharing your results with us.

This image by Andrew Carter shows the Clavius crater

on the moon in fantastic detail.

Paul Newton caught Venus transiting the sun.

And you can make out the shadow of Jupiter's moon Io

in this image by Damian Weatherly.

And Michelle Reitsma managed to capture Saturn and its famous rings.

Now it's time for this month's astro news, and there's been

a lot happening in the astronomical world since we were last on air.

Certainly has. For starters, the solar system has a new member, and here it is.

-This is 2012 VP113.

-Snappy!

-It will get a better name soon.

But what we can see here is images taken over six hours

and coloured so that you can see that something's moving.

And that's actually a dwarf planet in the outer solar system.

Now this thing's in a really unusual orbit,

much further out than Pluto, 2½ times as far from the sun as Neptune is

and orbiting in a place where it's got no right to be.

The only other thing around there is something called Sedna,

which we found just over a decade ago,

but those two things are on orbits that we can't explain using

conventional solar system mechanics, so it's a very exciting time.

And another potential dwarf planet.

That's right, another dwarf planet, assuming it holds up.

We don't quite know its size yet.

But there have been other weird discoveries

-in the outer solar system as well.

-And this time much closer to home.

There was a collection of asteroid-like bodies

that lie between Saturn and Uranus. They're called the centaurs.

And one of these, the largest one,

has actually been discovered to have rings.

This is an artist's impression of it.

So that's the object, and here are the two rings around it.

Now, this was actually discovered in about 20 seconds of data.

Because the asteroid was passing in front of a star

and you get a dip in the light level, an occultation.

Usually with a large object like this, you'll just get a single dip,

but what happened here is they got five,

four little ones and one big one,

which actually was an indication of you're passing through these rings.

It's the first time that we've seen rings on a body this size

and the mystery is, why were they formed, where did they come from?

You just don't get them on things this size.

But I think we'll be looking out for them in the future.

Of course the story dominating the news at the moment

is the results from BICEP2 in the South Pole,

which, if confirmed, could lead to some Nobel Prizes.

But, more importantly, it seems to be telling us about a time

just a ten-million-billion-billion-billionth of a second after the Big Bang,

when something called cosmic inflation took place,

with the universe expanding from a tiny subatomic particle to something

much larger, setting the stage for everything that's happened since.

The idea of inflation was introduced to explain

some oddities about the universe around us.

No matter which direction you look,

on a large scale everything's the same.

You get the same number of galaxies

and the universe is at the same temperature.

It seems like a cosmic coincidence.

What you might expect is a universe that's far lumpier.

The expansion introduced by inflation

means that any lumpiness would be smoothed away.

But, until last month,

we had no direct evidence that inflation took place at all.

One of the leaders of the experiment that may have discovered

the signature of cosmic inflation is Clem Pryke.

Now, to look for the signal, you have to go, of all places,

to the South Pole. So here's your Antarctic telescope

and BICEP2 is actually in this dish here.

Yeah, in this conical-shaped shield is the BICEP 2 telescope itself.

-And why Antarctica?

-So we go to Antarctica

because the atmosphere there is fantastically dry.

-Now, this is counterintuitive...

-This is water that you're sitting on.

When you get off the plane, you're standing on two miles thick of ice,

10,000 feet of ice, and they tell you it's a hyper desert.

And what little moisture there is in the atmosphere

is in the form of ice and not liquid water.

Liquid water is a killer for these kinds of observations,

because it basically renders the atmosphere opaque.

So essentially we can look straight out into outer space without the atmosphere getting in the way.

OK, and you're looking at the cosmic microwave background,

the oldest light we can see.

Here's an image of the whole sky in microwaves and it's a picture

of the universe as it was, what, 400,000 years or so

after the Big Bang.

Right, so these blobs, these hot and cold spots,

red and blue spots, are places where there's a little more matter

and a little less matter.

And these blobs actually evolved into the galaxy clusters

and galaxies that we see in the universe today.

Now, what BICEP2 has given us, or seems to have given us,

is the first evidence, first direct evidence, for this inflation.

So what is it in this light that gives you this signal?

So inflation was already a popular theory,

but in some sense it was kind of made up to fit observational facts.

But what it also does is made an additional prediction

which was not observed, which hadn't been observed...

And this is to do with gravitational waves, ripples in space.

Essentially ripples in space-time.

So, that was an additional prediction,

so when you have a theory,

which is a very nice theory, a lot of people like it,

-you want to find some prediction that it makes that you can additionally go and check.

-Right.

And that's... So the detection of these gravitational waves

-has been called a smoking gun for inflation.

-Right.

Now what they do is they impart on the polarisation pattern

of the microwave background a small additional signature,

-a small degree of swirliness, as it were.

-OK, so let's have a look.

This is the patch of sky,

this is the BICEP2 result with that swirliness

that we were talking about,

-so these little arrows are the polarisation signal.

-Right.

But here we've subtracted out the expected part, as it were,

and we are left with the so-called B-mode,

which is the swirliness of the pattern.

Only gravitational waves, crucially, only gravitational waves,

can make the swirly part of the pattern.

And so it's the detection of this swirliness is the signature

of that inflationary moment.

It's the signature of gravity waves,

and the only plausible source for such strong,

relatively strong gravitational waves, is the inflationary theory.

The competing theories don't predict...

So that's why this is such an exciting result.

I think you were surprised by the signal, weren't you?

Not that necessarily it was there,

but it was stronger than some people thought.

Yeah, so it's perhaps about as strong as was originally

expected from the simplest inflationary theories,

the ones that were formulated back in the '80s.

Since then, more sophisticated theories

have tended to predict lower levels,

so this week's result was quite a surprise.

There must be personal satisfaction in this.

People have been talking, it's too early to talk about this,

but people have been talking about Nobel prizes

and speculating and so on.

Do you wander round the lab, late at night, thinking,

"Well, you know, maybe this is it"?

Well, it's only been a week.

But before that, we were just very focused on doing

the most careful possible job that we could in the data analysis

and just really being as sure as we possibly could be.

Very nerve-racking, actually, to be sitting on something like this.

-Yeah.

-Quite stressful.

-All right, well, we'll let you get back to it.

-Thanks a lot.

-Thank you very much.

Now back to Mars.

And a mission that's been planned to take our exploration of the planet

to a whole new level.

The European Space Agency ExoMars mission is aiming to be

the first rover to directly search for life on the Red Planet.

It will be equipped with a drill that will let it dig two metres

below the Martian surface

to a level protected from deadly solar radiation.

If all goes to plan, it will be travelling to Mars in 2018.

I'm currently standing on what appears to be

a patch of the Red Planet right here on Earth.

This is the Mars Yard, built by Airbus,

to test the ExoMars rover, and put it through its paces.

Now, that's really necessary,

because ExoMars is going to go to a very alien environment.

I've got Abbie Hutty here,

who's the structural engineer on the ExoMars project.

So what are the challenges that ExoMars

will face on the real Martian surface?

One of the first things that we've got to consider is that

Mars is really very cold, so we've got night-time temperatures

that go down to -125 degrees Celsius.

-That's brisk!

-Yeah, a little bit chilly.

Then during the day it might not even get much warmer than -85,

so you're going all the way between those two, and materials,

as we know, expand and contract

as they go through the different temperatures.

That's especially a problem where you've got structures that might

be made of more than one different type of material,

because where those two materials meet,

they actually just tear themselves apart from each other.

I guess radiation is a problem, too?

Well, yes, we've only got 1% of the atmosphere on Mars

to what we have on Earth, so down on the Martian surface,

you are receiving a lot more of that radiation dose

and that can be really damaging for your electronics

and also for optical devices,

like lenses can blacken with that radiation dose

and that can obviously have a huge impact on how far you can see

or your senses that require those optics.

So, this is a prototype called Bryan,

one of a series of prototypes

and, looking at it, the wheels are a bit freaky.

-How do these work?

-Well, we've actually had to

develop these specifically for the Mars project

because we can't take rubber tyres with us.

Rubber is an organic molecule.

Yes, and you are looking for signs of life.

Absolutely, so we've got very strict regulations in place

to make sure that we don't take anything with us

that could be in any way confused for an organic molecule.

So we have developed these wheels.

They are entirely metallic,

but you've also got to retain the flexibility of the wheel...

That you'd get from rubber.

..so we've got these very thin wafers of metal

that actually are still flexible because they are so thin.

But how do you navigate across the Martian surface?

Well, that's one of the really big developments with ExoMars

and that is one of the reasons that we've got this Mars Yard here.

Because you've got such a long-distance to Mars,

it means you've actually got a 22-minute delay

between sending your signal and it being received,

so all of our rovers are going to be able to

actually autonomously navigate around the surface.

We've got two cameras at the top of the mast so we can see in 3-D.

It can build up a map of how big the obstacles are

and where they are in front of it and then it can actually classify

the different areas into,

"This is too big a rock, I can't climb over this,"

or, "This is a safe, flat bit, this is good to climb over,"

and then it can pick its own path through that map.

Well, I can't wait until ExoMars gets to Mars

and thank you so much for sharing this with us.

-Absolutely, it's been a pleasure.

-Thank you.

Now for that special treat we mentioned earlier.

The team behind the HiRISE camera

that showed us the amazing images earlier in the programme

are giving you the opportunity to take control

and select the location for the next image of Mars.

It's a spectacular opportunity

and what we need is a scientific justification for your choice,

so it could be an unusual formation,

some strange colours, or maybe a famous place

that you would like to see for the first time with HiRISE resolution.

To take part, you can go to our website and tell us

where you think the camera should be pointed.

We will close the entries on 27th April

and we will announce the winner in next month's programme.

It's a fantastic opportunity, so please do enter.

Well, we can't leave you without showing one last image

from the Martian surface and here it is.

This is an image taken by the Curiosity rover on 31st January.

Rising high in the Martian sky is a fabulous evening star.

But that is no star, that is Earth and I find it wonderful and humbling

that we can see ourselves in the sky of an alien world.

It is a fantastic image, but that's it for this programme.

Next month, we will be coming from the Brecon Beacons AstroCamp,

where we will be looking deep into space.

And you will also have the chance to discover your very own asteroid

as part of a real scientific search for near-Earth asteroids.

-So, until then, get outside and get looking up!

-Good night.