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Three challenges down, and by now the team are starting to look a little worse for wear - and to be honest, they’re not smelling great either. So this time their challenge is to get themselves - and their clothes - clean. Jonathan has to build a washing machine from scratch. It’s a task that stretches his ingenuity to the limit. His solution is a toploader made from a bucket, a bicycle wheel, some tennis balls and an old power drill. That turns out to be the easy bit - it's the electronic valves and the control system that really tax his brain cells. Will he have to head off for a launderette after all? Ellen helps him out by going in search of a plant that will provide the washing soap. She finds what she's looking for, yucca, but will the strange looking liquid she gets out of the plant really make clothes cleaner? The rest of the team attempt different ways to reduce body odour. Hermione makes a deodorant out of rocks. Things don't entirely go to plan when she has a nasty surprise with a supposedly heat-proof beaker. Mike sets his sights on stopping sweat by creating the same chemical that's used in most commercial antiperspirants. Using aluminium foil and household bleach he sets to work. But all he seems to succeed in doing is creating some very nasty smells. Lastly, Ellen makes a triple action botanical roll-on using a variety of local plants. The three deodorants are put to the test in an armpit sniff trial with Kate as the sniffer dog. For Kate this could be a particularly rough episode of Rough Science.

The Rough Science base this year sits on the slopes of a magnificent mountain: Mount Kendall. And for this week’s challenge the team will have the task of getting to know this peak very well, working out how high it is and how much it weighs. Not just the part we can see sticking up above the Mill, but the root of the mountain, too, right down to the bottom of the Earth's crust. There’s a lot of maths to combine with some canny field geology to pull this one off and Hermione and Ellen pull together a unique blend of botany and geology to try and crack the dimensions Whilst the girls get to grips with the mountain, the boys are tasked with producing a pair of sun glasses to protect Kate from the glare of the Sun. At the altitudes they are working, the Sun is particularly glaring. Mike thinks he can make glass out of sand, but it’ll need Jonathan to build a furnace that can produce temperatures of over 1200oC for hours at a time. It’s not something Jonathan feels confident about, and it takes the whole of the first day to come up with a design for an oven that can get anywhere near those conditions. Even when Mike find a possible source of sand nearby, the prospect of making glass, let alone making sun-glasses still seems remote... Back on the mountain, in a combination of tree line mapping, clay model building, good old geological mapping and weighing their rock samples the girls are close to an answer for the mass of the entire mountain – roots and all. But with all their assumptions, estimates and the general inaccuracies of a flat-out three day attempt to survey an entire mountain how close will they get to the real figure?

For this programme the team are tackling two environmental hazards: fire and pollution. Fire is a major hazard in the dry Colorado environment and Mike and Jonathan’s challenge is to build a carbon dioxide fire extinguisher. The basis of the extinguisher is a simple reaction of baking soda plus acid, which fizzes up to create the gas they want. But to make the acid they need Mike has to go out and find fool's gold and then work out how to transform it. Jonathan's task is to make the extinguisher itself. He needs to find a way to keep the components separate until needed. It's a tricky problem, but Jonathan works out a clever and elegant solution. Unfortunately, the first test goes badly wrong leaving him with less than an hour to fix it in time for the final test when they have to extinguish a blazing fire. Will the pair pull it together, or will their challenge go up in smoke? Meanwhile, Hermione and Ellen have an even tougher task. They have to find a way to clean up the polluted water flowing out of an old mine. The mine water is acidic and contains high levels of toxic metals and this mine run-off flows into streams and rivers killing off aquatic life. Hermione's plan is to use a rock - limestone - to neutralise the acidity. She manages to find a local source of limestone - and even proves that it works in a small scale test. But making a full size system that can cope with a continuous flow of polluted water is another matter... Ellen's task is to deal with the toxic metals in the water, and she harnesses the power of bacteria from a surprising source - horse manure. She builds a bioreactor hoping that once the bacteria start working they'll take the metals out of the water. But getting the system up and running in 3 days proves a very tough challenge. Waiting for them at the end of the test is a highly sensitive panel of judges - a group of water fleas will determine if they've made the water pure enough...

Kicking off the new series of Rough Science, at their high altitude base in the Rocky Mountains, the team attempt to make the old mill a little more hospitable - they’ve got to supply the rickety old building with gas and electricity. In just three days they have to use natural resources to generate their own power and produce their own gas. With no time to waste Hermione hits the road in search of coal deposits and Mike works on a gas production system to try and extract coal gas from any coal she can bring back. Her prospecting takes her out of the mountains and in to the flatter plains to the south where, by reading the landscape, she stumbles across a natural gas seep. Methane is bubbling out of a stream bed - suggesting that coal isn’t far below the surface. Hermione eventually tracks it down late in the day in trees near-by and spends a long evening digging with Kate! Ellen and Jonathan try to crack the electricity problem - finding a nearby fast flowing stream to harness. By piping water down from higher up the stream they can produce enough pressure to hopefully drive a water wheel and a generator. Ellen sets to work building a dam 50 metres above where the water wheel will be - drawing her inspiration from the local beaver population. Jonathan cannibalises a bicycle wheel and using some kitchen utensils comes up with an improvised Pelton water wheel. By the end of day two the team have some gas, but it’s not burning very brightly and they’ve got a fast spinning water wheel but no power. With so much to still accomplish on the last day it'll be a real rush to complete the challenge before the time runs out...

In Programme One the Rough Scientists had to make a Mars Rover which could explore strange new worlds. This week Kathy and Jonathan have to go one better and design an aerial surveyor that can explore much greater areas by floating above land. Just like the rover challenge, they've been given a tiny camera which will record whatever the aerial surveyor sees. Back on Earth, Mike has a very different challenge. Back in 1970 the crew of Apollo XIII faced certain death when an accident damaged their oxygen tanks. To survive they had to build a carbon dioxide filter - and Mike has to do the same. In 1872 California experienced one of the biggest earthquakes ever recorded in the United States. Ellen and Iain have to work out where the epicentre of the quake was, and its magnitude. Kathy and Jonathan decide to make a solar balloon - heated by the power of the sun. Made by sticking black bin bags together, the idea is to hang the camera below it. (An idea, incidentally, that NASA are actively exploring for Mars.) Unfortunately the Rough Science version encounters a series of unexpected setbacks, and on Day Three it is touch and go whether it will get off the ground. For Mike to make his carbon dioxide filter he needs to make limewater. To do that he needs to find limestone, heat it up to make quicklime, and then dissolve it in water. However, making quicklime proves to be more difficult than anticipated, and on Day Three he faces a classic Rough Science test to see if he has succeeded in making a working carbon dioxide filter. Ellen and Iain take to the air to try and find the site of the 1872 earthquake. Their first task is to find the fault line which marks the location of the earthquake. They then set out to measure the amount of movement that occurred along the fault, to work out where the maximum displacement was. This should give them the epicentre of the earthquake, and also provide the information they need to calculate its magnitude. Should - but will it?

Ellen's task this week is to devise a way of waterproofing a tent that Mike B and Mike L will take on an expedition to seek out gold. Meanwhile Kathy and Jonathan build a seismograph using parts from an old alarm clock.

Fresh and spiffing after last week's cleaning challenges, our Rough Scientists are about to get all messy again. This week's challenge is to find a way to detect radioactive rocks and flammable gases. But that's not all. On day three they must explore a wet dark mine using the gas detector and a reliable light source. Hermione decides to make a cloud chamber using a jam jar. She hopes to see the trail of destruction caused by radioactive particles. First, though, she'll need to make some frozen carbon dioxide which involves a bit of help from Mike. But not all goes to plan... Mike and Ellen work on a safety lamp to detect flammable gases, which surprisingly needs a flame. Ellen sets off to make a beeswax candle using a local hive. Meanwhile Mike finds an ingenious way to use the candle flame as a gas detector using kitchen implements. Will two artfully put together sieves and some homemade beeswax candles really detect flammable gas? Meanwhile Jonathan sets to work on making a generator to power his rugged torch. With hundreds of coils of wire and some strong magnets, Jonathan can light a dim bulb by turning the magnets constantly. But when Jonathan tries to store energy in his torch, he runs into problems. What seemed simple becomes more and more tricky as the deadline approaches. Will Jonathan be able to get his lamp to illuminate the mine? And when they get there, what will the team find?

The five scientists are taken to a mystery location in the Mediterranean. Their first challenge is to determine their latitude and longitude and thus pinpoint exactly where they are. They are also asked to create insect repellent and a radio.

The entire team are taken on a journey to the Franz Josef glacier and must pool their knowledge to work out both how fast the glacier is moving, and how fast it is melting. They must also create heat to keep themselves warm - but without lighting a fire.

With the team's time in New Zealand running out, Kate offers the team some extra gold to help them make their jewelery. But it's buried somewhere on a nearby mountainside - so the scientists will need cunning to work out exactly where. Meanwhile Kathy searches for gold on a beach, and the two Mikes work out how to extract the gold from rocks collected earlier in the series.

This week's programme is all about meteorites and asteroids. Not too far from the Rough Science base on the edge of Death Valley is Meteor Crater. Iain, Kathy and Mike have to work out how big the meteor that caused this huge crater must have been. But it's not just the Earth that gets hit by objects from outer space - the moon is also a target, as evidenced by its heavily cratered surface. So Jonathan and Ellen have to pick a crater on the moon - any crater will do - and measure how big it is. And because they'll be doing their measurements at night, Ellen has to come up with some lights. The Meteor Crater team decide they have to split their work. Kathy and Iain head off to the crater itself to try and measure its diameter. This is the first essential step if they are to work out how big the meteor was that caused the crater. At the same time, they are hoping to find out more about the meteor in the hope this will give them clues about its size. Meanwhile Mike stays behind to try and make his own crater. He performs a series of impact experiments, dropping heavy objects into sand in an effort to work out the relationship between the size of an object and the size of crater it forms. Jonathan and Ellen have been given a high quality optical mirror, and so to find and measure a crater on the moon, they build a reflecting telescope. Their plan is to time how long it takes the whole moon to travel across a fixed point in their eyepiece, and then time how long it takes their chosen crater to travel across that same fixed point. Because they know that the moon is 3500 kilometres across, they can use this as a starting point to calculate the diameter of the crater. For her lights Ellen heads to the hills and collects pine sap. She melts it to remove some of the most volatile compounds, and then uses bark fibres as wicks, to make highly effective Rough Science candles.

The waters around Zanzibar are teeming with life and they are surprisingly noisy. The team’s challenge this week is to eavesdrop on the underwater sounds of the reef to discover what is making all the noise. Jonathan and Mike will work together to construct a hydrophone – an underwater listening device. Kathy has to build a contraption that will allow them to see under the water. Meanwhile, Ellen has to fend off some of the island’s less desirable wildlife – mosquitoes.

In the first set of gold-mining challenges in New Zealand's Westland National Park, Ellen, Mike B and Mike L attempt to pan gold from a river while Jonathan builds a metal detector and Kathy devises a balance scale capable of weighing tiny amounts of gold to the nearest millionth of a gram.

Although everyone thinks of space as very cold, in fact, if you stood on the sunny side of the moon, the temperature would be hot enough to boil the blood in your body. Spacesuits are designed to protect astronauts from these extremes of temperature. So for this week's challenge the Rough Scientists have to collectively design a cooling system for their very own spacesuit. And to test it out, at the end of day three, they're going to have to go to Death Valley and do a mock moon walk in their spacesuit - hopefully staying deliciously cool. They decide that they need to make a portable Rough Science fridge. Ellen creates a copper pipe system that will go from the fridge to the spacesuit, carrying cool water from the fridge to the astronaut. Jonathan devises a pump to keep the water moving through the system. Kathy suggests that the fridge should use the principle of evaporation - the same principle that cools us when we sweat. She needs to get water evaporating inside the fridge. And the best way to do that is to lower the pressure; this speeds up evaporation and therefore cooling. But there's a problem - all that evaporating water is trapped inside the fridge, and unless they can get it out then it will destroy the vacuum. Fortunately there's a magic mineral called zeolite that has a special property - it absorbs water vapour. So if they can find zeolite and put it in the fridge it will suck up the water vapour, preserving the vacuum. Mike attempts to extract zeolite from washing powder, whilst Iain tries to find naturally occurring zeolite in the rocks around the mine. So at the end of day three the Rough Scientists decamp to Death Valley where Ellen is dressed in their spacesuit for a spacewalk which will reveal whether their cooling system really can keep someone cool in one of the hottest places on Earth.