A Mysterious Space Plane Will Launch This Week

Though much of the X-37B’s mission is top secret, details are emerging about experiments that will go into orbit with the unmanned craft

The Atlas V rocket launches the X-37B on a 2012 mission. The craft will launch again Wednesday from Cape Canaveral, Florida. DoD/Corbis

On Wednesday, the United States Air Force will launch the X-37B space plane on an enigmatic mission. And though much remains secret about the classified cargo of the mini space shuttle, for the first time the public is being told at least part of what’s inside: NASA test materials, a CubeSat satellite, and a futuristic ion engine.

Space.com’s Mike Wall reports that the Orbital Test Vehicle 4 (OTV-4) mission will be the unmanned X-37 program’s fourth. The specific vessel launching this week is one of two space plans in the program, hence the additional B in its name. It will travel to space carrying a number of NASA experiments, including what the agency has dubbed the Materials Exposure and Technology Innovation in Space (METIS) investigation. Nearly 100 materials will make their way to space for tests over the course of 200 days, building on data already collected on the International Space Station in other experiments.

The craft will also test LightSail, a solar sailing satellite from the CubeSat program that the Planetary Society characterizes as “about the size of a loaf of bread.” The project was crowd-funded to advance solar sail technology, in which a small satellite uses pressure generated by solar radiation to accelerate and move. Though the craft’s developers have been struggling with tech bugs, they hope to obtain images from outer space and understand how the satellite could behave when it begins its flagship mission in 2016.

Though the Air Force has traditionally been tight-lipped about the X-37 missions, it is speaking up about another test occurring on board: an experiment with a new ion engine that may eventually power military satellites. In a release, the Air Force says that the xenon-powered engine is fuel-efficient and capable of supporting better maneuvers and carrying larger payloads than traditional rocket engines.

What other payloads will the miniature, unmanned space shuttle take to space? That’s where things get murkier. Wall reports that “most of the X-37B’s payloads and specific activities are classified,” and that the military’s refusal to reveal details has spurred speculation that they’re developing “some kind of space weapon.”

Though theories as to the craft’s real purpose continue to proliferate, the Air Force insists it’s flying the craft for a more benign reason: “risk reduction, experimentation, and concept of operations development for reusable space vehicle technologies.” The launch has been declared a go for Wednesday morning in Cape Canaveral, Florida.

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