With his upright posture and shiny gold helmet, this space robot looks more suited to the set of Star Wars than the International Space Station.

But the C3PO lookalike, the first humanoid robot in space, has spent almost two years orbiting the Earth while learning to perform tasks which are more suited to machines than human crew members.

Robonaut 2 - nicknamed R2 in a nod to the Star Wars trilogy - was launched in February 2011 on the last flight of NASA's Discovery space shuttle.

It began work last March, practicing some of the duller or more dangerous jobs which astronauts hope it will carry out on their behalf, and was pictured on Wednesday during another round of testing.

An Earth-based team of programmers remotely controlled the robot as it operated valves on a task board in the space station's Destiny laboratory.

One of the roles R2 was designed to fulfil was monitoring air flow in front of vents on board the ISS - a crucial check to make sure that none of the ventilation apparatus becomes blocked or clogged up.

The task requires a very steady hand and samples can be spoiled by other sources of air flow, such as human breath, making a robot the perfect candidate for the job.