Wilmore taking a selfie of himself during his spacewalk on 21 February (Nasa) / Nasa

SpaceX have said that they plan on sending their first manned commercial  flights to the ISS in 2017

Nasa has released fascinating footage showing the second of three spacewalks being carried out on the International Space Station, in preparation for a new docking system that will be able to receive commercial aircraft in 2017.

The video which was released today, captures Nasa astronauts Barry 'Butch' Wilmore and Terry Virts conducting crucial lube and cable work to ensure that the two new International Docking Adapters that are set to arrive later this year are ready and functioning.

The walk, which took place at 11:00GMT, was broadcast live on Nasa TV and saw the two men hanging off the side of the ISS carrying out the intricate work. It is hoped that the two new Docking Adapters will be ready to receive commercial aircraft by 2017, with Boeing and SpaceX having already secured contracts to develop, test and fly capsules to the ISS.

SpaceX plan to send their first manned flight to the ISS in 2017, while Boeing are hoping to send an unmanned flight to the station in April 2017.

This is the second of three maintenance space walks that are to be carried out by Virts and Wilmore.

On 21 February, the two astronauts spent six hours and 41 minutes working on on the craft’s robotic arm.

The third walk is scheduled for 1 March.