The U.S. military's mysterious X-37B space plane is just 10 days away from launching on its next mission.
The X-37B is scheduled to lift off atop a United Launch Alliance Atlas V rocket from Florida's Cape Canaveral Air Force Station on May 16, kicking off the sixth mission for the robotic vehicle, Space Force and Air Force officials announced Wednesday (May 6).
"This important mission will host more experiments than any prior X-37B flight, including two NASA experiments," Secretary of the Air Force Barbara Barrett said Wednesday during a webinar hosted by the nonprofit Space Foundation.
One of those NASA payloads will examine the effects of space radiation on seeds, and the other will assess the performance of various materials in the space environment, Barrett explained.
Another experiment, designed by the U.S. Naval Research Laboratory, "transforms solar power into radio-frequency microwave energy, then studies transmitting that energy to Earth," she said.
The upcoming mission, known as OTV-6 (short for "Orbital Test Vehicle-6") and Space Force-7, will also deploy FalconSat-8, a small satellite developed by the U.S. Air Force Academy that itself carries five separate experiments.
To accommodate these and other payloads, the space plane has been outfitted with a service module for OTV-6 — a first for the X-37B program, Air Force officials said in a statement Wednesday.
The Air Force has two X-37B vehicles that we know of, both of which were built by Boeing. The vehicles look like NASA's old space shuttle orbiters, only much smaller. Each X-37B is 29 feet (8.8 meters) long by 9.5 feet (2.9 m) tall, with a wingspan of about 15 feet (4.6 m) and a payload bay the size of a pickup truck bed.
For comparison, each space shuttle was 122 feet (37 m) long with a wingspan of 78 feet (24 m).
The X-37B allows the U.S. military to test a variety of new tech in the space environment and return the gear to the ground for analysis. Many of the payloads that go up are classified, and military officials tend not to disclose many details of the vehicles' activities in orbit.
"The X-37B team continues to exemplify the kind of lean, agile and forward-leaning technology development we need as a nation in the space domain," Gen. Jay Raymond, the U.S. Space Force Chief of Space Operations, said in Wednesday's statement. (The newly formed Space Force, which is part of the Department of the Air Force, is responsible for X-37B launches, orbital operations and landings.)
"Each launch represents a significant milestone and advancement in terms of how we build, test and deploy space capabilities in a rapid and responsive manner," Raymond added.
It's unclear how long OTV-6 will last, but precedent suggests that the mission will be a sustained one. Each OTV flight has broken duration records for the program, and OTV-5, which landed in October 2019, circled Earth for 780 days.
The five previous X-37B missions racked up a combined 2,865 days in orbit, Barrett said. That's about 7 years and 10 months of off-Earth technology testing.
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Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.