Image: X-37B plane
USAF/Vandenberg Air Force Base
An Air Force photographer snapped this profile view of the X-37B shortly after its landing on Dec. 3, 2010, which marked the end of the secret vehicle's maiden space mission.
By
updated 1/6/2012 7:30:14 PM ET 2012-01-07T00:30:14

Contrary to rampant speculation, the United States military's secretive X-37B space plane is most likely not spying on a prototype Chinese space module, experts say.

According to a recent report by the BBC, a new article in Spaceflight Magazine suggests that the robotic X-37B space plane might be surveilling China's recently launched space laboratory Tiangong 1. As evidence, the article notes apparently striking similarities in the orbits of the two spacecraft. But in reality, these orbits are quite different, other analysts contend, making it extremely unlikely that the X-37B is keeping an eye on Tiangong 1.

"I would go as far as to say, 'no chance,' " said Brian Weeden, a technical adviser with the Secure World Foundation and a former orbital analyst with the U.S. Air Force. "It's not practical."

Differences in the orbits
The Air Force launched the experimental X-37B on a classified mission in March 2011, putting the vehicle into space for just the second time ever. The spacecraft is known as the Orbital Test Vehicle 2, or OTV-2. [ Photos: Air Force's 2nd Secret X-37B Mission ]

China's space agency launched its unmanned Tiangong 1 space lab in September and is using the vessel to carry out orbital docking tests, which are considered key to the nation's goal of building a manned space station by 2020.

The Air Force doesn't make details of the X-37B's orbit or mission public, but amateur astronomers have been keeping a close eye on the space plane's movements.

These and other observations have shown that the X-37B and Tiangong 1 have broadly similar orbits. Both are currently about 180 miles above our planet, with an inclination of roughly 43 degrees with respect to the equator (meaning their orbits range from 43 degrees south latitude to 43 degrees north latitude).

However, the orbits of the X-37B and Tiangong 1 differ greatly — by about 100 degrees — in a parameter called right ascension, which describes where a craft crosses the equator, Weeden said. So the two satellites actually take disparate paths around the globe, with their orbits intersecting just twice per circuit.

That means that the X-37B and Tiangong 1 could theoretically approach each other a maximum of two times per orbit, if the timing works out perfectly. And even then, they'd scream past each other at very high speeds — not exactly optimum conditions for a spy mission.

  1. Space news from NBCNews.com
    1. KARE
      Teen's space mission fueled by social media

      Science editor Alan Boyle's blog: "Astronaut Abby" is at the controls of a social-media machine that is launching the 15-year-old from Minnesota to Kazakhstan this month for the liftoff of the International Space Station's next crew.

    2. Buzz Aldrin's vision for journey to Mars
    3. Giant black hole may be cooking up meals
    4. Watch a 'ring of fire' solar eclipse online

Weeden compared the satellites' motions to two cars on separate roads that intersect at two different points.

"And there's no stoplight," he told Space.com. "You're just blowing through the intersection at 7 kilometers a second."

Another analyst contacted by Space.com echoed Weeden's reasoning, saying the two vehicles' orbits do not support the assertion that the X-37B is spying on Tiangong 1.

While the United States may well be interested in Tiangong 1, the government has better information-gathering tools at its disposal than the X-37B for the job, Weeden added.

"The U.S. has this whole network of ground-based telescopes and radars, several of which can do imaging — either radar or optical imaging of space objects — that are better suited for this," he said.

What's the X-37B doing up there?
So if the X-37B isn't keeping tabs on Tiangong 1, what is it up to? The Air Force has said repeatedly that the space plane's primary mission is to test out new technologies. Weeden, who published a report in 2010 that investigated the X-37B and its likely missions, thinks this rather vague description is probably accurate.

He reckons the X-37B is likely trying out some new spy gear, perhaps instruments optimized to observe in wavelengths outside of the visible-light spectrum.

The space plane's orbit also offers some possible clues about its activities. Rather than looping around the Earth in a polar orbit, which enables a good look at every spot on the globe, the X-37B is flying repeatedly over the stretch from 43 degrees north latitude to 43 degrees south.

"It's probably using that new technology to observe the Middle East and Afghanistan — those are the places," Weeden said.

The Air Force has said the X-37B was designed for space missions lasting a maximum of 270 days. The first X-37B flight launched in April 2010 and landed that December, coming in under the nine-month limit. However, the current mission has been aloft for more than 10 months, so the military may be putting the vehicle through something of an endurance test.

"I think that they are looking to push the second one," Weeden said. "Because it is an experimental vehicle, they kind of want to see what its limits are."

The X-37B looks a bit like NASA's recently retired space shuttle, but it's far smaller. The X-37B is about 29 feet long and 15 feet wide, with a payload bay about the size of a pickup truck bed. Two X-37B vehicles could fit inside the payload bay of a space shuttle.

The spacecraft's orbital longevity is enabled by its solar array, which generates power after deploying from its payload bay.

You can follow Space.com senior writer Mike Wall on Twitter:@michaeldwall. Follow Space.com for the latest in space science and exploration news on Twitter@Spacedotcomand on Facebook.

© 2013 Space.com. All rights reserved. More from Space.com.

Photos: Month in Space: January 2014

loading photos...
  1. Southern stargazing

    Stars, galaxies and nebulas dot the skies over the European Southern Observatory's La Silla Paranal Observatory in Chile, in a picture released on Jan. 7. This image also shows three of the four movable units that feed light into the Very Large Telescope Interferometer, the world's most advanced optical instrument. Combining to form one larger telescope, they are greater than the sum of their parts: They reveal details that would otherwise be visible only through a telescope as large as the distance between them. (Y. Beletsky / ESO) Back to slideshow navigation
  2. A balloon's view

    Cameras captured the Grandville High School RoboDawgs' balloon floating through Earth's upper atmosphere during its ascent on Dec. 28, 2013. The Grandville RoboDawgs’ first winter balloon launch reached an estimated altitude of 130,000 feet, or about 25 miles, according to coaches Mike Evele and Doug Hepfer. It skyrocketed past the team’s previous 100,000-feet record set in June. The RoboDawgs started with just one robotics team in 1998, but they've grown to support more than 30 teams at public schools in Grandville, Mich. (Kyle Moroney / AP) Back to slideshow navigation
  3. Spacemen at work

    Russian cosmonauts Oleg Kotov, right, and Sergey Ryazanskiy perform maintenance on the International Space Station on Jan. 27. During the six-hour, eight-minute spacewalk, Kotov and Ryazanskiy completed the installation of a pair of high-fidelity cameras that experienced connectivity issues during a Dec. 27 spacewalk. The cosmonauts also retrieved scientific gear outside the station's Russian segment. (NASA) Back to slideshow navigation
  4. Special delivery

    The International Space Station's Canadian-built robotic arm moves toward Orbital Sciences Corp.'s Cygnus autonomous cargo craft as it approaches the station for a Jan. 12 delivery. The mountains below are the southwestern Alps. (NASA) Back to slideshow navigation
  5. Accidental art

    A piece of art? A time-lapse photo? A flickering light show? At first glance, this image looks nothing like the images we're used to seeing from the Hubble Space Telescope. But it's a genuine Hubble frame that was released on Jan. 27. Hubble's team suspects that the telescope's Fine Guidance System locked onto a bad guide star, potentially a double star or binary. This caused an error in the tracking system, resulting in a remarkable picture of brightly colored stellar streaks. The prominent red streaks are from stars in the globular cluster NGC 288. (NASA / ESA) Back to slideshow navigation
  6. Supersonic test flight

    A camera looking back over Virgin Galactic's SpaceShipTwo's fuselage shows the rocket burn with a Mojave Desert vista in the background during a test flight of the rocket plane on Jan. 10. Cameras were mounted on the exterior of SpaceShipTwo as well as its carrier airplane, WhiteKnightTwo, to monitor the rocket engine's performance. The test was aimed at setting the stage for honest-to-goodness flights into outer space later this year, and eventual commercial space tours.

    More about SpaceShipTwo on PhotoBlog (Virgin Galactic) Back to slideshow navigation
  7. Red lagoon

    The VLT Survey Telescope at the European Southern Observatory's Paranal Observatory in Chile captured this richly detailed new image of the Lagoon Nebula, released on Jan. 22. This giant cloud of gas and dust is creating intensely bright young stars, and is home to young stellar clusters. This image is a tiny part of just one of 11 public surveys of the sky now in progress using ESO telescopes. (ESO/VPHAS team) Back to slideshow navigation
  8. Fire on the mountain

    This image provided by NASA shows a satellite view of smoke from the Colby Fire, taken by the Multi-angle Imaging SpectroRadiometer aboard NASA's Terra spacecraft as it passed over Southern California on Jan. 16. The fire burned more than 1,863 acres and forced the evacuation of 3,700 people. (NASA via AP) Back to slideshow navigation
  9. Where stars are born

    An image captured by NASA's Spitzer Space Telescope shows the Orion Nebula, an immense stellar nursery some 1,500 light-years away. This false-color infrared view, released on Jan. 15, spans about 40 light-years across the region. The brightest portion of the nebula is centered on Orion's young, massive, hot stars, known as the Trapezium Cluster. But Spitzer also can detect stars still in the process of formation, seen here in red hues. (NASA / JPL-Caltech) Back to slideshow navigation
  10. Cygnus takes flight

    Orbital Sciences Corp.'s Antares rocket rises from NASA's Wallops Flight Facility on Wallops Island, Va, on Jan. 9. The rocket sent Orbital's Cygnus cargo capsule on its first official resupply mission to the International Space Station. (Chris Perry / NASA) Back to slideshow navigation
  11. A long, long time ago...

    This long-exposure picture from the Hubble Space Telescope, released Jan. 8, is the deepest image ever made of any cluster of galaxies. The cluster known as Abell 2744 appears in the foreground. It contains several hundred galaxies as they looked 3.5 billion years ago. Abell 2744 acts as a gravitational lens to warp space, brightening and magnifying images of nearly 3,000 distant background galaxies. The more distant galaxies appear as they did more than 12 billion years ago, not long after the Big Bang. (NASA / NASA via AFP - Getty Images) Back to slideshow navigation
  12. Frosty halo

    Sun dogs are bright spots that appear in the sky around the sun when light is refracted through ice crystals in the atmosphere. These sun dogs appeared on Jan. 5 amid brutally cold temperatures along Highway 83, north of Bismarck, N.D. The temperature was about 22 degrees below zero Fahrenheit, with a 50-below-zero wind chill.

    Slideshow: The Year in Space (Brian Peterson / The Bismarck Tribune via AP) Back to slideshow navigation
  1. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  2. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  3. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  4. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

Discuss:

Discussion comments

,

Most active discussions

  1. votes comments
  2. votes comments
  3. votes comments
  4. votes comments