Astronauts are all smiles on spacewalk but budget cuts could end Nasa's hope of returning to the Moon



Hanging on the edge of the International Space Station 250miles above Earth , astronaut Nicole Stott does well to concentrate on her work despite the gloriously distracting view of our blue planet below.



She was snapped by fellow mission specialist Danny Olivas on the first spacewalk of their mission.



The pair successfully moved a cumbersome and thankfully empty ammonia tank, which will be returned to our planet. A new fully loaded tank, which plays a crucial role in keeping the orbiter cool, will be installed on a second spacewalk.



Both astronauts clearly enjoyed their six and a half hour celestial walkabout, waving and posing for pictures, despite losing contact with ground control for half an hour. Communications were knocked out due to a storm at a satellite relay station in Guam.

Astronaut Niclole Stott works in the Space Shuttle Discovery's payload bay with the dizzying sight of Earth in the background

Out on a limb: Astronaut Nicole Stott was outside of the space station for six hours and 35 minutes

Back on Earth a gathering political storm could mean the days of such shuttle adventures are numbered as the U.S. government decides if it can afford a new space exploration programme. Nasa is scheduled to retire their 30-year-old space shuttles next year and rely on Russia to hitch rides to the Space Station until it is decommissioned in 2015. But the replacement Constellation mission that is due to take man back to the Moon by 2020 may fall at the first hurdle due to budget cuts. Failure to launch While the Orion capsule spacecraft has just passed an early design review, there is uncertainty whether the Ares 1 rocket slated to launch it into orbit will ever fly. In August an independent committee reviewed Nasa's human space exploration plans and came up with four options for President Obama's consideration. Only one option included the Ares 1 rocket, while the others replaced it with alternatives. If Ares 1 is cancelled it would add years and huge expense to Orion's development. Just another day on the job: Danny Olivas perches on the European Space Agency's Columbus module Back inside the station, Nicole Stott and European Space Agency astronaut Frank De Winne, both Expedition 20 flight engineers, work in the Kibo laboratory of the International Space Station

Manager of NASA's Constellation program, Jeff Hanley, said: 'It's important for folks to understand that the rocket and the spacecraft fly as an integrated system.

'So whatever we do with respect to the launcher, we would have to go back and redo, to some extent, work that is already done.'

President Obama faces the difficult decision of whether or not to plough billions more dollars into the programme as the country struggles with the world-wide recession.

So far Nasa has spent £1.9billion developing Orion, which has been designed to deliver crew to the space station and the Moon. The Constellation programme has cost £4.7billion and Nasa will need at least another £21billion for the mission to succeed.

Many experts including Buzz Aldrin, the second man to walk on the Moon, have wondered what America hopes to gain from a return visit to our natural satellite.

'Why do we want to go to go back to the Moon?' he asked a British audience recently to mark the Apollo anniversary.



'There's no reason for us to go back. We can look at the effects of long-term missions in space by flying around comets, rather than setting up a base on the Moon. We're not going to launch any missions from there.'

Astronauts install a new freezer (l) and Canadian Robert Thirsk checks the storage containers



A gibbous Moon above the Earth's atmosphere as seen from the Discovery shuttle. Nasa hopes to return to the Moon with its Constellation mission

Astronaut Danny Olivas is captured in close-up during the spacewalk

Away from politics the rest of the crew on board the International Space Station unpacked their new exercise machine - the Colbert treadmill.

Nasa named it after Stephen Colbert (Combined Operational Load Bearing External Resistance Treadmill) known for his Comedy Central program 'The Colbert Report,' as a consolation prize. The comedian won an online vote earlier this year for naming rights to a new space station room but Nasa called it Tranquility instead.

Mr Colbert said:'My treadmill will... help trim down those famously fat astronauts. Lay off the Tang, Chubby!'



The treadmill is in more than 100 pieces. The bags containing all those parts will remain in a corner of the space station until September, when Nicole Stott has time to put together the running machine.



Stott, the space station's newest resident, hitched a ride up aboard Discovery. She will spend the next three months in orbit.



Meanwhile it has emerged that the International Space Station may fire its thrusters to avoid a piece of space junk that could pass within two miles of the orbiting complex.

The U.S. space agency is tracking debris from a portion of a European rocket, the Ariane 5, that was launched more than three years ago.



The debris could pass close enough to require astronauts to fire thrusters to move the station and shuttle Discovery that is docked there out of the way, NASA officials said. There are currently 13 astronauts living in space together.

Smile you're on camera! Astronaut John 'Danny' Olivas, STS-128 mission specialist during the mission's first spacewalk