The X-37B vehicle and its cargo bay packed with a classified payload is set to make the third mission of the program. Also called Orbital Test Vehicle-3, or OTV-3, the unpiloted craft is slated to be hurled into Earth orbit by an Atlas 5 rocket from Florida’s Cape Canaveral Air Force Station (CCAFS) at 1:03 p.m. EST (1803 GMT).
There’s an interesting angle to the upcoming mission. This third flight will use the same X-37B spacecraft that flew the first test flight, the OTV-1 mission, back in 2010.
That maiden voyage of the miniature space plane lasted a little over 224 days, orbiting Earth from April 22, 2010 to Dec. 3 of that year, and finally landing on autopilot at a specially prepared runway at Vandenberg Air Force Base in California. [Photos: U.S. Military’s X-37B Space Plane]
A different X-37B vehicle made a similar Vandenberg touchdown this past June 16, after staying in orbit 469 days on its OTV-2 mission.
The OTV-3 flight had been delayed for several months due to an accident investigation board looking into why a Delta 4 rocket’s RL-10B-2 upper stage engine did not perform as expected on Oct. 4 during a launch that successfully orbited a Global Positioning System 2F-3 satellite.
The Atlas 5 that will hurl the OTV-3 into Earth orbit utilizes a different model of the Pratt & Whitney Rocketdyne RL-10 engine. However, per standard processes, the Air Force reviews all flight data to determine readiness to press forward with the next liftoff.
According to launch service provider United Launch Alliance (ULA), which makes the Atlas 5 and Delta 4, a thorough flight clearance process was executed and all “credible crossover implications” from the Delta anomaly to the OTV-3 Atlas vehicle and engine system have been thoroughly addressed and mitigated. That work culminated in the flight clearance decision for the OTV-3 launch. The investigation into the Delta rocket flight data anomaly continues.
( via space.com )