Air Force's Mystery X-37B Space Plane Fuels Speculation

The U.S. Air Force is on the verge of showcasing a new and long-sought after spaceflight capacity with its X-37B space plane, but it will do so on a space mission that?s cloaked in secrecy.

What the X-37B mission truly portends is in the eye of the beholder, from a game-changing tool to hone military hardware to a provocative harbinger of things-to-come in terms of space warfare.

Now ready for an Atlas boost into Earth orbit from Florida on April 20, the reusable robotic X-37B Orbital Test Vehicle (OTV) is a small space shuttle-like craft. The craft will wing its way into Earth orbit, remain aloft for an unspecified time, then high-tail its way back down to terra-firma ? auto-piloting down to a landing at Vandenberg Air Force Base in California, or at neighboring Edwards Air Force Base as back-up [more photos of the X-37B space plane].

The X37-B craft was built by Boeing?s Phantom Works with the mission run under the wing of the Air Force Rapid Capabilities Office. The reusable and diminutive OTV space plane is the first vehicle since the space shuttle orbiter able to return experiments to Earth for further inspection and analysis.

Its stats are modest: The vehicle tips the scales at 11,000 pounds (4,989 kg) and is just over 29 feet (8.8 meters) in length and stands slightly more than 9 1/2 feet (2.9 meters) in height. It sports a wingspan of a little over 14 feet (4.2 meters).

The designed maximum on-orbit duration for the X-37B is 270 days, said Angie Blair, an Air Force spokeswoman for the project, but that flight time will be driven more by success in achieving demonstration objectives.

?The X-37B is a risk reduction vehicle for space experimentation and to explore concepts of operation for a long duration, reusable space vehicle. The first flight will focus on vehicle checkout and test of subsystems such as thermal management, power control and distribution, and attitude control,? Blair said.

Glass half-full, half-empty

Joan Johnson-Freese, Professor of National Security Studies at the Naval War College in Newport, Rhode Island sees the upcoming flight as a glass half-full, half-empty enterprise.

If the glass is half-full, Johnson-Freese observed that the X-37B could be to spaceflight what Global Positioning System (GPS) satellites ? which had no specific mission originally when developed by the military either -- has become to navigation. ?It could push the hypersonic envelope and advance spaceflight in ways not seen since the 1960?s, she said.

If the glass is half-empty, Johnson-Freese added, then the X-37B could be a project taken this far because the Air Force has always wanted a crewed space plane, and this was the closest they could get, and supporting it as innovative has helped the careers of those who have apparently pushed it through the halls of the Pentagon.

?In any case, it is likely that other countries will see it as another capability intended to assure the United States will be able to dominate access to and the use of space,? Johnson-Freese concluded.

Three vital characteristics

A reusable space plane can offer a range of capabilities, said William Scott, coauthor of the acclaimed techno-novel, Counterspace: The Next Hours of World War III, and former Rocky Mountain Bureau Chief for Aviation Week & Space Technology magazine.

Scott observes that an X-37B-type, reusable space plane would be invaluable for reconstitution of limited on-orbit capabilities, such as signal intelligence, imaging, or missile warning. ?It could deliver small satellites having specific, limited roles to bridge critical capabilities gaps,? he said.

There are three vital characteristics of a reusable space plane, Scott said, whether it?s piloted or unpiloted:

• Launch-on-demand: Ideally, a small fleet of these space planes would be available for immediate launch, backed by a supply of specialized small satellites that could be pulled off the shelf and loaded into the space plane to perform critical missions. The ultimate would be having these vehicles in an ?alert? status, similar to how fighters and bombers sat alert, during the Cold War, ready to deploy at-will.

• Surprise factor: On the first orbit, a space plane could capture data, before the ?target? knew it was coming. Not as predictable as a satellite?s orbit - at least on the first pass.

• Flexibility: A space plane could be launched into any orbit, at any inclination, providing prompt ?eyes-on? of virtually any area of the world. Altitude could be varied, as well. A space plane might also be used in a sub-orbital ?arc? flight profile, perform its duties, then be recovered at a remote air field half-way around the globe.

?Ultimately, weapons could be delivered from a space plane in low Earth orbit,? Scott said, citing a ?Rods from God? scenario. That idea is akin to a lawn-dart weapon idea that uses tungsten rods lobbed from space to hit a cross-haired target on the ground.

?I did a story about the rods concept in 1994 or 1995, based on concepts being discussed in the U.S. Air Force at the time,? Scott said. ?Fifteen years later, maybe they?re ready for testing.?

Tactical advantage

Viewing the X-37B as a fascinating project, and one that fuels speculation is Everett Dolman, Professor of Comparative Military Studies at the School of Advanced Air and Space Studies at the Maxwell-Gunter Air Force Base in Montgomery, Alabama.

?It is not possible to tell yet whether the program is an example of the output of bureaucratic inertia or the beginning of something much bigger, Dolman advised.

The value of a true space plane to military thinkers and planners has long been evident, Dolman suggested, from thoughts in the early 1900s to the original grand visions for the space shuttle. Fast forward to today, in the case of the X-37B, while none of the planned missions for the space plane are public as of yet, he continued, a few of the potential missions are easy to conjure up.

?Regardless of its original intent, the most obvious and formidable is in service as a space fighter - a remotely piloted craft capable of disabling multiple satellites in orbit on a single mission and staying on orbit for months to engage newly orbited platforms,? Dolman said. That capability ?would be a tremendous tactical advantage.?

Furthermore, the small size of the X-37B, coupled with maneuverability on orbit would make it almost impossible for non U.S. space watchers to keep an eye on its whereabouts, Dolman said.

Test platform for what?

Even if it were not used to engage and disable satellites, Dolman said, it could be maneuvered up close and personal to inspect orbiting satellites at a level of detail currently unimaginable. ?With the anticipated increase in networked-microsatellites in the next few years, such a platform might be the best ? and only ? means of collecting technical intelligence in space.?

Dolman also sees another use for the automated X-37B. It could be pressed into service, he said, not only as a resupply vehicle for routine resupply or maintenance of space platforms, even for the International Space Station as a publicly visible mission.

?If a reasonably-priced, reliable transport for supply and maintenance becomes operational, a whole new set of on-orbit possibilities opens up,? Dolman noted. ?What the U.S. Air Force has not had is a dedicated, secure platform for weapons research and, potentially, testing.?

Laser and directed energy testing ? to include relaying beams ? could be done on civilian platforms in small strengths for communications or power-generating applications. Still, the results needed for weapons research would be unsatisfactory and potentially compromised, Dolman said. ?All of the information leaked about the X-37B suggests its primary function will be as a test platform, but a test platform for what??

While there will be some who suggest the X-37B is a program that just limped along, ?it seems there are at least a few U.S. Air Force planners who are looking to the future, as well as a few civilian supporters who see the value in a reusable space plane, Dolman observed. ?The X-37B is a viable and important project whose time is past due.?

Technology-fed arms race

Mark Gubrud is a physicist in the Laboratory for Physical Sciences at the University of Maryland in College Park, and a proponent of space arms control. As a robot shuttle, he senses that the X-37B would finally give the U.S. military flexible two-way access to space, as well as some in-plane maneuver capability in orbit.

The X-37B is a product, in part, of the maturing of robotics, space robotics, military robotics and the military's confidence in robotics, Gubrud suggested.

?We are seeing a partly technology-fed arms race. But the technology for space weapons is still quite exquisite and needs extensive development and testing,? Gubrud said. ?I don?t see the X-37 itself as a space weapon, because it is probably too expensive to use it that way,? he said, compared with the kind of alternatives ? smaller, more specialized space weapons ? that the X-37B could be utilized to test and develop.

Gubrud pointed out there is a realistic way to limit the threat posed by the X-37 or similar vehicles produced by any country. That is, to account for their numbers and demand that they be kept either in verifiable storage or in use for declared non-weapons purposes, and that the numbers be commensurate with their declared purposes. 

To that end, ?basic information about the payload mass and volume, burnout velocity, orbital maneuver capability and remotely observable characteristics, as well as the numbers of such vehicles, should be required to be reported,? Gubrud suggested.

• Gallery - Photos of the X-37B Space Plane
• Top 10 Weapons in History
• Images - X Planes, Part 2, Part 3

Leonard David has been reporting on the space industry for more than five decades. He is past editor-in-chief of the National Space Society's Ad Astra and Space World magazines and has written for SPACE.com since 1999.