By Dr David Whitehouse BBC News Online science editor

Engineers from Russia's spacesuit manufacturer, Zvezda, have been advising the British explorers who intend to ride a balloon to the fringes of space.

The environment that Andy and Colin will encounter will be similar in terms of atmosphere, temperature and pressure to the surface of Mars

Dr Richard Crowther, QinetiQ

The UK duo, Colin Prescot and Andy Elson, will attempt to set a new world balloon altitude record in July.

They hope to get to a height of 40,000 metres (132,000 feet) in the largest helium balloon ever constructed.

The Russian spacesuits are tailored for the mission's diverse requirements of sun and shade, dramatic changes in temperature and the need for flexibility.

Zvezda has made all spacesuits for the Russian space programme since the 1950s, as well as the spacesuits currently worn on the International Space Station.

Open flight platform

The QinetiQ 1 balloon will be 400 times the size of a typical hot-air balloon and as tall as the Empire State Building; or seven times the height of Nelson's Column. The weather window for the launch has been set between July and September this year.

The pilots will be making their ascent on an open flight deck - their hi-tech suits will have to protect them from the elements. The whole trip is expected to last 12 hours.

They hope to get to a height of 40,000 metres

The spacesuits make the mission possible, by supplying pure oxygen to breathe and maintaining a pressurised environment.

The open flight platform will carry the pilots from the moment of launch, right through to a splash down in the Atlantic Ocean. The duo will remain seated all the time.

The base of the platform includes crumple zones to absorb the impact of a normal or emergency landing, with Andy and Colin protected above.

Life support

Go above about 12,200 m (40,000 ft) and a pressurized suit is essential - without it, breathing 100% oxygen is no longer sufficient to support human life, because the partial pressure in the lungs is so low that the body cannot absorb enough of the gas to maintain its functions.

An individual would quickly suffer from hypoxia and ultimately die.

Prescot and Elson will sit on an open deck

At about 19,200 m (63,000 ft), the ambient air pressure is so low that theoretically blood will boil - and remember that Prescot and Elson want to go to 40,000 metres.

Dr Richard Crowther, of QinetiQ, told BBC News Online: "The environment that Andy and Colin will encounter will be similar in terms of atmosphere, temperature and pressure to the surface of Mars."

The suits are being tailor-made for the QinetiQ 1 mission, as is their life support system.

"The clever part of this system is the way that it recycles the air through a special 'scrubbing mechanism' back to the pilots to breathe again," Dr Richard Crowther said.

"This helps to cut down the weight that the balloon needs to carry. The work we're doing now is a good test of this life support system for this and for future flights."