Nasa's new 'megarocket' set for critical tests

Nasa's new 'megarocket' set for critical tests

Ryan McKibben, SLS Green Run test conductor at Stennis Space Center, told BBC News: "When you actually see the real deal, with the real avionics, the real tanks - the liquid hydrogen tank which holds 500,000 gallons and the liquid oxygen tank with over 200,000 gallons - it is an incredible vehicle."