NASA's deep space launch test

The SLS five-segment Solid Rocket Motor undergoes a static test fire at the Orbital ATK facility in Promontory, Utah, March 11, 2015. The beefed-up space shuttle solid rocket motor passed a two-minute test firing on Wednesday, a key milestone toward the debut flight of NASA's deep-space launcher in 2018. REUTERS/Jim Urquhart

The SLS five-segment Solid Rocket Motor undergoes a static test fire at the Orbital ATK facility in Promontory, Utah, March 11, 2015. REUTERS/Orbital ATK/NASA

Members of the media gather around the SLS five-segment Solid Rocket Motor before it undergoes a static test fire at the Orbital ATK facility in Promontory, Utah, March 11, 2015. REUTERS/Jim Urquhart

The SLS five-segment Solid Rocket Motor undergoes a static test fire at the Orbital ATK facility in Promontory, Utah, March 11, 2015. REUTERS/Jim Urquhart

People take pictures as the SLS five-segment Solid Rocket Motor undergoes a static test fire at the Orbital ATK facility in Promontory, Utah, March 11, 2015. REUTERS/Jim Urquhart

Engineers ready the SLS five-segment Solid Rocket Motor for a static test fire at the Orbital ATK facility in Promontory, Utah, March 11, 2015. REUTERS/Jim Urquhart

People take pictures as the SLS five-segment Solid Rocket Motor undergoes a static test fire at the Orbital ATK facility in Promontory, Utah March 11, 2015. REUTERS/Jim Urquhart

Members of the media gather around the SLS five-segment Solid Rocket Motor before it undergoes a static test fire at the Orbital ATK facility in Promontory, Utah, March 11, 2015. REUTERS/Jim Urquhart

People take pictures as the SLS five-segment Solid Rocket Motor undergoes a static test fire at the Orbital ATK facility in Promontory, Utah, March 11, 2015. REUTERS/Jim Urquhart