A United Launch Alliance (ULA) Atlas V rocket successfully launched the U.S. Air Force X-37B space plane on May 20, 2015.
Credit: ULA

The hush-hush mission by the U.S. Air Force’s X-37B space plane has sailed past a previous program record for time in orbit.

Launched atop an Atlas booster on May 20, 2015, the OTV-4 (Orbital Test Vehicle-4) has winged past 674 days – a long-duration flight milestone for the program reached back in October 2014.

The first X-37B Orbital Test Vehicle waits in the encapsulation cell of the Evolved Expendable Launch vehicle on April 5, 2010 at the Astrotech facility in Titusville, Fla. Half of the Atlas V five-meter fairing is visible in the background.
Credit: U.S. Air Force

The robotic mini-space plane now in orbit is one of two reusable X-37B vehicles that constitute the space plane “fleet.” Also, this current OTV-4 space trek is the second flight of the second X-37B vehicle built for the Air Force by Boeing.

Space drone

Appearing like a miniature version of NASA’s now-retired space shuttle orbiter, the reusable military space plane is 29 feet (8.8 meters) long and 9.6 feet (2.9 meters) tall, and has a wingspan of nearly 15 feet (4.6 meters).

The space drone has a payload bay about the size of a pickup truck bed that can be outfitted with a robotic arm. It has a launch weight of 11,000 pounds (4,990 kilograms) and is powered on orbit gallium arsenide solar cells with lithium-ion batteries.

A third mission of the Boeing-built X-37B Orbital Test Vehicle was completed on Oct. 17, 2014, when it landed and was recovered at Vandenberg Air Force Base in California following a successful 674-day space mission. The upcoming space plane flight – on the program’s fourth mission — may land at the Kennedy Space Center in Florida.
Credit: Boeing

Track record

What this “winged warrior” is doing high above Earth is an on-going, tight-lipped affair.

Some payloads onboard the OTV-4 craft have been previously identified.

For example, Aerojet Rocketdyne has said that its XR-5A Hall Thruster had completed initial on-orbit validation testing onboard the X-37B space plane. Also onboard is a NASA advanced materials investigation.

The first OTV mission began April 22, 2010, and concluded on Dec. 3, 2010, after 224 days in orbit.

The second OTV mission began March 5, 2011, and concluded on June 16, 2012, after 468 days on orbit.

An OTV-3 mission chalked up nearly 675 days in orbit when it landed Oct. 17, 2014.

Recovery crew members process the X-37B Orbital Test Vehicle at Vandenberg Air Force Base after the program’s third mission complete.
Credit: Boeing

Land ho?

There’s no telling how long the now-orbiting space plane will continue to fly. All the OTV craft to date have guided their way on auto-pilot to a Vandenberg Air Force Base, California tarmac-touchdown.

But that could change with the OTV-4 mission.

What is known is that progress has been made on consolidating X-37B space plane operations, including use of NASA’s Kennedy Space Center (KSC) in Florida as a landing site for the robotic space plane.

A former KSC space-shuttle facility known as Orbiter Processing Facility (OPF-1) was converted into a structure that will enable the Air Force “to efficiently land, recover, refurbish and relaunch the X-37B Orbital Test Vehicle (OTV),” according to Boeing.

Former shuttle processing area at the Kennedy Space Center has been overhauled by Boeing to prep the military’s secretive X-37B space plane.
Credit: Malcolm Glenn

Rapid capabilities

The X-37B vehicle development falls under the Boeing Space and Intelligence Systems in El Segundo, California, the firm’s center for all space and experimental systems and government and commercial satellites.

The Air Force Rapid Capabilities Office is leading the Department of Defense’s OTV initiative, by direction of the Under Secretary of Defense for Acquisition, Technology and Logistics and the Secretary of the Air Force.

What’s up?

“The Air Force continues to push the envelope of what the X37B can do, likely toward determining operational mission capabilities in the future,” explains Joan Johnson-Freese, Professor in the Department of National Security Affairs at the Naval War College. “It remains unclear what capabilities the spacecraft will add to those already available, other than duration in orbit,” she told Inside Outer Space.

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