The US space agency is due to retire its shuttles next year and is working on a new crew transportation system, to be introduced in about 2014-15.

BBC: Obama reviews post-shuttle plans

Before landing, the flight crew were not aware the nose wheel steering system was not working, as the hydraulic fluid level was low.

BBC: NEWS | Europe | Isle of Man | Air crew criticised for fire risk

An announcement over the ship's public address system said the crew was trying to fix the problem and was working on the generators, according to Stark.

CNN: STORY HIGHLIGHTS