0:00:02 > 0:00:04We are Dr Chris and Dr Xand van Tulleken
0:00:04 > 0:00:07- and we're tracking down the most awesome...- Incredible...
0:00:07 > 0:00:11..and epic things in the universe!
0:00:21 > 0:00:25Come with us and discover unbelievable things...
0:00:25 > 0:00:26that will blow your mind!
0:00:27 > 0:00:31Blow Your Mind will be bringing you loads of top experts
0:00:31 > 0:00:35and scientists to help you find out more about some amazing stuff.
0:00:35 > 0:00:38From the Arctic to elephants, spaceships to sharks,
0:00:38 > 0:00:43and this week, it's all about ice. Yes, frozen water.
0:00:43 > 0:00:46- So hold on to your brains. - Here's what's coming up.
0:00:47 > 0:00:50Today we explore an incredible
0:00:50 > 0:00:53and dangerous underground world of caves and tunnels...
0:00:54 > 0:00:57..play pooh sticks in a glacial river...
0:00:58 > 0:01:00..and get up close to a cute little arctic fox.
0:01:03 > 0:01:04Now, icebergs are incredible.
0:01:04 > 0:01:07They're born - or carved - from glaciers,
0:01:07 > 0:01:10but one of the amazing things for me is their massive size,
0:01:10 > 0:01:12the sheer quantities of ice involved.
0:01:12 > 0:01:14That's right, millions of tonnes of ice,
0:01:14 > 0:01:18mile upon mile of the stuff, just making its way to the sea.
0:01:18 > 0:01:20Now, massive icebergs are actually called mega-bergs
0:01:20 > 0:01:22and I joined a bunch of scientists
0:01:22 > 0:01:26and lived on a glacier for three weeks in Greenland to find out more.
0:01:26 > 0:01:30- Now, Xand, do you have any idea what a moulin is?- Why yes, I think I do.
0:01:30 > 0:01:33A moulin is basically the French word for a windmill.
0:01:33 > 0:01:36Erm, well, yes.
0:01:36 > 0:01:37A windmill can be a moulin,
0:01:37 > 0:01:40but the exact translation is a grinder.
0:01:40 > 0:01:44In the world of glaciers, a moulin is a gigantic hole in the ice
0:01:44 > 0:01:47which has been ground out over time by water.
0:01:47 > 0:01:50Like most things to do with glaciers and icebergs,
0:01:50 > 0:01:51they can be absolutely massive.
0:01:51 > 0:01:54Gosh, Chris, well, you must have been very brave
0:01:54 > 0:01:56to go in one of those on the expedition.
0:01:56 > 0:01:59Oh, well, I am brave, yes, but I didn't actually go down it.
0:01:59 > 0:02:01I left it to the experts,
0:02:01 > 0:02:03because they had a good scientific reason to go in there.
0:02:03 > 0:02:05Take a look at this.
0:02:08 > 0:02:12There were over 20 scientists and experts on the expedition
0:02:12 > 0:02:14but these are the main people you'll meet today.
0:02:16 > 0:02:19Chris Packham, wildlife and nature expert.
0:02:21 > 0:02:24Expedition doctor and all-round brave guy, me.
0:02:26 > 0:02:29Helen Czerski, physicist and oceanographer.
0:02:30 > 0:02:34Andy Torbet, extreme explorer and glacial diver.
0:02:35 > 0:02:39Michelle Koppes, glaciologist and ice expert.
0:02:40 > 0:02:45Mark Neal, computer scientist and electronics expert.
0:02:47 > 0:02:50The team headed to the middle of the glacier.
0:02:50 > 0:02:53They had already carried out experiments on the huge blue lakes,
0:02:53 > 0:02:57here, but still had some unanswered questions.
0:02:57 > 0:03:00I'm a little bit sceptical that all the water can get
0:03:00 > 0:03:04all of the way from the surface, all the way down to the bottom.
0:03:04 > 0:03:08They were going to explore one of the many super-sized holes,
0:03:08 > 0:03:11or moulins, that form on the glacier.
0:03:11 > 0:03:14These were once plugholes for massive blue lakes that have
0:03:14 > 0:03:16now cracked and drained.
0:03:17 > 0:03:21So these are like big drainpipes going down
0:03:21 > 0:03:24- and the question is - how far down they go?- Exactly.
0:03:24 > 0:03:27Expert ice climber, Andy Torbet,
0:03:27 > 0:03:31intended abseiling down into this gigantic hole.
0:03:31 > 0:03:34He'd be the first person to ever descend into this moulin.
0:03:37 > 0:03:41This was an incredibly dangerous task, Andy had safety ropes attached
0:03:41 > 0:03:46in case he fell, but the ice was so unpredictable, bits often broke off.
0:03:48 > 0:03:51DISTANT RUMBLE
0:03:51 > 0:03:55Big rumble, just then. All the walls are pretty unstable.
0:03:55 > 0:03:58There's all these big icicles and big, like, snowflakes,
0:03:58 > 0:04:00so the quicker we get down and out, the better.
0:04:00 > 0:04:04The biggest risk for Andy was from those colossal pieces
0:04:04 > 0:04:06of over-hanging ice that could detach
0:04:06 > 0:04:08and smash into him on the way down.
0:04:09 > 0:04:12I get so tense watching this, it's so exciting and scary!
0:04:12 > 0:04:14I was very tense there on the day.
0:04:14 > 0:04:16People said that Andy was brave,
0:04:16 > 0:04:18but I'm not sure he wasn't a bit foolish.
0:04:18 > 0:04:21It was incredibly dangerous.
0:04:21 > 0:04:24Andy always seems to be the guy that does the dangerous things.
0:04:24 > 0:04:27Well, that is what he's trained to do, but he is a careful guy,
0:04:27 > 0:04:29so let's see what happened.
0:04:30 > 0:04:33As team medic, I was very nervous.
0:04:35 > 0:04:37I feel fairly redundant because, of all the things that can
0:04:37 > 0:04:40happen to him, there are very few I'm going to be able to fix.
0:04:44 > 0:04:46But Andy was making good progress
0:04:46 > 0:04:50deep down in the moulin - but he was being very, very cautious.
0:04:53 > 0:04:55I can see the floor beneath me.
0:04:56 > 0:04:59Some of these huge blocks of ice...
0:04:59 > 0:05:03Things as big as cars are lying down there.
0:05:03 > 0:05:06And they weigh tonnes, and they've all peeled off from up above me.
0:05:06 > 0:05:09So if that was to happen while I was hanging here, that would be it.
0:05:10 > 0:05:13As Andy abseiled deeper down, suddenly,
0:05:13 > 0:05:16he discovered something unexpected.
0:05:16 > 0:05:17Whoa!
0:05:18 > 0:05:21There's a massive, absolutely enormous
0:05:21 > 0:05:23side passage.
0:05:25 > 0:05:29You could drive a double-decker bus with another double-decker bus
0:05:29 > 0:05:32on top of it and it would still fit through there, quite easily.
0:05:34 > 0:05:37This tunnel was a crucial finding
0:05:37 > 0:05:41because it would have drained the lake not downwards, but sideways.
0:05:41 > 0:05:43This important discovery was only found
0:05:43 > 0:05:46because Andy risked his life abseiling into the moulin.
0:05:46 > 0:05:48And there's been no-one down here before us
0:05:48 > 0:05:51and the chances are there will never be anyone down here again.
0:05:51 > 0:05:55This is proper exploration. This is all completely virgin territory.
0:05:55 > 0:05:57And this... This is the crowning glory.
0:05:58 > 0:06:02This immense, cathedral-like tunnel.
0:06:02 > 0:06:04Chris, I keep using the word amazing,
0:06:04 > 0:06:08but that is truly, truly amazing!
0:06:08 > 0:06:10I mean, the size of that hole is mind-blowing.
0:06:10 > 0:06:13I don't know about mega-bergs, but that is certainly a mega hole.
0:06:13 > 0:06:17It must have been awesome for Andy going down into it, knowing that
0:06:17 > 0:06:20he was the first person ever to go there and almost certainly the last.
0:06:20 > 0:06:24It's unbelievable to think you could get two double-decker buses
0:06:24 > 0:06:26stacked on top of each other into that tunnel -
0:06:26 > 0:06:29that's actually higher than the Channel Tunnel.
0:06:29 > 0:06:31I know, but it was incredibly dangerous in there, too.
0:06:31 > 0:06:34You heard Andy say that these pieces of ice at the bottom were
0:06:34 > 0:06:37the size of cars, so if one of those broke off and fell
0:06:37 > 0:06:38while he was in there...
0:06:38 > 0:06:41Yeah, I don't think you'd catch me going down in there.
0:06:41 > 0:06:45I can't wait to see more, though, it's nail-bitingly exciting.
0:06:45 > 0:06:47Well, you might not want to go down there,
0:06:47 > 0:06:50but we had to get the camera crew down so they could film it.
0:06:50 > 0:06:52But just as they got to the tunnel,
0:06:52 > 0:06:56they were reminded how much danger they were in.
0:06:56 > 0:06:58LOUD BANG
0:06:58 > 0:07:00BANG AND SOUND OF FALLING DEBRIS
0:07:00 > 0:07:04- I think we should get out. - Yeah. OK, got your gear.
0:07:04 > 0:07:06That stuff up the top is not good.
0:07:08 > 0:07:10The roof of the tunnel started to crack.
0:07:12 > 0:07:14If it collapsed, it would have
0:07:14 > 0:07:17buried the camera crew under thousands of tonnes of ice.
0:07:19 > 0:07:20It was a tense race to get out.
0:07:28 > 0:07:29But eventually they made it.
0:07:33 > 0:07:36- I'm glad to be out of there. - It was huge.- Absolutely massive.
0:07:36 > 0:07:39- And we got out, which is even better. - Which is always nice.
0:07:39 > 0:07:40That was terrifying!
0:07:40 > 0:07:43- These guys are brave, aren't they?- Yes, we are.
0:07:43 > 0:07:45But that is the nature of exploration
0:07:45 > 0:07:48and this is true exploration, in every sense of the word.
0:07:48 > 0:07:50All right, Chris. Now, did they learn much
0:07:50 > 0:07:51from what they saw down there?
0:07:51 > 0:07:54Yes, they brought back vital information
0:07:54 > 0:07:57about the side tunnels and how they take meltwater away.
0:07:57 > 0:07:59But the team still wanted to find out more.
0:08:00 > 0:08:04The team already knew that melted ice water forms blue lakes
0:08:04 > 0:08:08which drain to the bottom of the glacier, helping it move.
0:08:08 > 0:08:12But now they'd discovered that water doesn't always drain
0:08:12 > 0:08:15straight downwards - sometimes it takes other routes.
0:08:16 > 0:08:21The glacier has an immense hidden water system, a huge network
0:08:21 > 0:08:24of tunnels that carry vast amounts of meltwater
0:08:24 > 0:08:26through the ice sideways.
0:08:26 > 0:08:28Now that we've seen this moulin,
0:08:28 > 0:08:31we've seen that it's not a simple picture.
0:08:31 > 0:08:34It's not straight down the plughole to the bottom,
0:08:34 > 0:08:36it's much more complex.
0:08:36 > 0:08:38Water goes down a little way, then maybe it goes sideways,
0:08:38 > 0:08:40then maybe it falls down a bit more,
0:08:40 > 0:08:43eventually all going towards the sea
0:08:43 > 0:08:46but getting there by a huge variety of different routes.
0:08:47 > 0:08:50Helen, Alan and Michelle wondered
0:08:50 > 0:08:54if these side tunnels play a part in the creation of mega-bergs,
0:08:57 > 0:09:00so they decided to try and trace the route of the meltwater
0:09:00 > 0:09:03through the tunnels out to the front of the glacier.
0:09:05 > 0:09:09We found a moulin that's about 8km up from the ice front
0:09:09 > 0:09:14and it looks like the water that's flowing down into this moulin
0:09:14 > 0:09:19is making a direct connection down to the north side of the ice front.
0:09:21 > 0:09:25To track the route, they decided to chuck 30 plastic balls called
0:09:25 > 0:09:28cryospheres into a moulin.
0:09:28 > 0:09:31Even though these balls look a bit home-made, they're actually packed
0:09:31 > 0:09:35with electronics which will measure their speed and the water pressure.
0:09:35 > 0:09:39It looks reasonably likely that the water that's flowing past us
0:09:39 > 0:09:41here will, at some point, flow out of the glacier front that
0:09:41 > 0:09:44- we've been watching for the past week or so.- Exactly.
0:09:44 > 0:09:46So if we can find these at the other end,
0:09:46 > 0:09:49lots of useful information is going to come out of them.
0:09:57 > 0:10:01Unfortunately, even though the balls were packed with electronics,
0:10:01 > 0:10:04they didn't have GPS, so we'd all have to search for them
0:10:04 > 0:10:06- at the other end.- Off it goes.
0:10:10 > 0:10:12Whoo-hoo!
0:10:13 > 0:10:17Far be it from me to criticise these very clever scientists,
0:10:17 > 0:10:19but isn't this just a rather thinly-disguised
0:10:19 > 0:10:20game of pooh sticks?
0:10:20 > 0:10:22Well, I suppose that's like what they're doing,
0:10:22 > 0:10:23but it's really useful
0:10:23 > 0:10:26because it helps them to find out the route that the water takes.
0:10:26 > 0:10:28Hmm, and they can have a really good game of pooh sticks
0:10:28 > 0:10:31- while they're at it. - I don't think they're thinking
0:10:31 > 0:10:32about playing games, this is
0:10:32 > 0:10:36serious stuff that could help prove or disprove their theories.
0:10:36 > 0:10:39Dr Mark Neal designed the cryospheres and,
0:10:39 > 0:10:41after they'd all been chucked into the moulin,
0:10:41 > 0:10:44he joined the search to try and find them.
0:10:44 > 0:10:48The problem was that the glacier's ice front was 8km wide
0:10:48 > 0:10:50and the balls could come out anywhere.
0:10:52 > 0:10:54So Mark took to the sky to try and track them down...
0:10:57 > 0:10:59..whilst Chris Packham took to the sea.
0:11:05 > 0:11:08- Hello.- Just having a look at the ice field.- Well, good luck.
0:11:08 > 0:11:10My eyes are bleeding down here.
0:11:12 > 0:11:14But no-one was having any luck.
0:11:14 > 0:11:16No sign of any orange things.
0:11:16 > 0:11:18If they've come out, or if they're going to come out -
0:11:18 > 0:11:20they probably have come out by now...
0:11:20 > 0:11:23I'm not going to tell you how many hours we've been out here now,
0:11:23 > 0:11:26looking for these tiny orange ping-pong balls
0:11:26 > 0:11:31which are packed full of this scientific paraphernalia,
0:11:31 > 0:11:33but we haven't found them.
0:11:33 > 0:11:37It became obvious this experiment had been less than successful.
0:11:39 > 0:11:44So, Chris, erm, are the words "less than successful" a scientific term?
0:11:44 > 0:11:46What do you mean, a scientific term?
0:11:46 > 0:11:48I mean, the scientific term for a failure,
0:11:48 > 0:11:51like, the failure of the orange ping-pong balls.
0:11:51 > 0:11:52It sounds a bit like a movie,
0:11:52 > 0:11:55The Failure Of The Orange Ping-Pong Balls,
0:11:55 > 0:11:57coming soon to a glacier near you.
0:11:57 > 0:11:59Very funny, but you're wrong, it wasn't a complete failure,
0:11:59 > 0:12:01but it was a little bit less than successful.
0:12:01 > 0:12:04Less Than Successful, coming soon to a...
0:12:04 > 0:12:06Look, there was a lot of interesting stuff
0:12:06 > 0:12:09that came out of that experiment and that's the way it goes in science,
0:12:09 > 0:12:11sometimes you think one thing will happen
0:12:11 > 0:12:12and then something different happens.
0:12:12 > 0:12:14All right, I take your point.
0:12:14 > 0:12:17Now, when we all got back from a hard day throwing ping-pong balls,
0:12:17 > 0:12:18we were all famished,
0:12:18 > 0:12:20but Chris Packham decided to do something else instead.
0:12:22 > 0:12:25We'd just started tucking in to a hearty meal
0:12:25 > 0:12:27when we observed a little visitor.
0:12:27 > 0:12:29Chris Packham couldn't help himself
0:12:29 > 0:12:32and decided to share his dinner with one of the locals.
0:12:33 > 0:12:37This little arctic fox has been coming into our camp
0:12:37 > 0:12:40almost every day, on the scrounge for food, of course.
0:12:40 > 0:12:44But then, things aren't easy up here, there's not a lot of food about.
0:12:44 > 0:12:48They feed on young birds they find in the nest, ptarmigan, hare,
0:12:48 > 0:12:51that would be a pretty special day.
0:12:51 > 0:12:54I have to say, a lot of people haven't taken a shine to the fox,
0:12:54 > 0:12:58they come up with these stories about them breaking into the tents
0:12:58 > 0:13:01and chewing all the cables, I can't see it, myself.
0:13:02 > 0:13:06In the winter, it'd be bright white and they have an amazing winter coat.
0:13:06 > 0:13:09Of course, they are a bit different than our foxes,
0:13:09 > 0:13:10much smaller, of course,
0:13:10 > 0:13:14blunter nose, smaller ears, shorter legs.
0:13:14 > 0:13:18That's all about conserving heat when it's cold, here.
0:13:20 > 0:13:22Hey.
0:13:22 > 0:13:24Come on, you're going to get me into trouble.
0:13:24 > 0:13:28I'm going to get told off for encouraging you into the camp.
0:13:28 > 0:13:31I don't care, though. I'd rather have the fox than the food.
0:13:31 > 0:13:33That's typical Chris Packham, isn't it?
0:13:33 > 0:13:35He'd rather play with the animals than have dinner.
0:13:35 > 0:13:37To be fair, that was a cute little thing.
0:13:37 > 0:13:39It was, but you had to keep an eye on it so it didn't
0:13:39 > 0:13:41chew through anything really important.
0:13:41 > 0:13:44You greedy guts could have given him more food and then
0:13:44 > 0:13:46he wouldn't have had to chew through your cables.
0:13:46 > 0:13:49- Anyway, it's time to go. - What, already?
0:13:49 > 0:13:53So join us next time so we can blow your mind.