SIPROC 4: Spy Satellite Shields

Modern spy satellites, such as the NROL-15 payload, may include an inflatable shield designed to hide the satellite from would be trackers. Image credit: USPTO.

Spy satellites seemingly hold the ultimate high ground, keeping a watchful eye on their targets from the vacuum of space. But this high ground comes at a cost: there aren’t nice rocks or trees to hide behind in space so satellites are easy to spot and plan for. The United States, China, Russia, and even Iran are very skilled at spotting satellites and getting their most cherished secret projects under cover before the prying eyes of a satellite pass overhead. Techniques for tracking aircraft via radar and direct sightings have been adapted, enabling spy satellite tracking via radar, optical telescopes, and orbit tracking and prediction software.

In order to combat these tracking techniques, satellite designers have adapted stealth plane technologies to modern spy satellites in order to provide these satellites with partial cover in the barren emptiness of space.

Two weeks ago, an uprated Delta IV Heavy rocket launched the classified NROL-15 payload into orbit. Allegedly, the NROL-15 payload was an ultra-classified National Reconnaissance Office spy satellite in the vein of the KH-11, Misty, and Hubble Space Telescopes (Hubble being a spy satellite derivative pointed in the “wrong” direction). It is likely that the NROL-15 payload included modern stealth satellite technologies, some of which we know about because of issued patents!

No rocks to hide behind in space

Clandestine service people like the Navy SEALs and James Bond often take advantage of the land in order to sneak up on their targets. They hide under or behind trees and boulders. In space, though, there aren’t convenient rocks to duck behind. So how does a spy satellite hide? It brings its own boulder!

Since as early as 1963, stealth satellite R&D has been performed. According to, the fruits of these labors have created modern spy satellites, which look “somewhat like a stubby Hubble space telescope stuffed in a giant F-117 stealth fighter with diverse angles to reflect radar signals in directions other than back to receivers on the ground.” The moderns spy satellite “is also covered in deep black materials designed to absorb so much light that it cannot be tracked optically from the ground.” Many believe that the NROL-15 payload was a spy satellite, such as a KH-11, fitting this description.

The patented, inflatable space cover

Analyst’s theories on the shape of modern spy satellites, such as the classified NROL-15 payload, are supported in part by a patent issued to Teledyne Industries, now Teledyne Brown Engineering, Inc. Teledyne helped develop the KH-9 HEXAGON spy satellite.  Today, they’re still in the imaging business. Teledyne recently announced a deal with NASA to develop MUSES, a series of Earth observation instruments which will be deployed on the International Space Station. Time on MUSES instruments will be commercially available.

In 1994, Teledyne was issued US Patent No. 5345238, entitled “Satellite Signature Suppression Shield.” The patent discloses a satellite shield comprising a cone shaped inflatable bladder made of a light weight material, such as Mylar. This shield is pointed toward the Earth and connected to one end of a satellite, such as an optical spy satellite.

Some shields may consist of a Mylar bladder coated with a layer of radiation reflecting material, such as a thin coating of gold. The gold layer and the oblique angle of the bladder are designed to reflect radar, laser, and infrared tracking signals. This shield may be up to 40 feet in diameter and is designed to be inflated after the satellite reaches orbit. The patent depicts fairly smooth, conical bladders. As pointed out, it is likely that moderns spy satellites have a more irregular shape in order to confound radar systems. The Teledyne patent is not limited to the conical bladders shown in its figures. In fact, modern satellite signature suppression shields may look more like children’s bounce houses in order to better avoid detection.

One aspect of note: this shield is likely movable. That is, the shield operates like a camera lens cover. It covers the aperture of the spy satellite when the satellite is not imaging a target, but is rotated out of the way when the satellite is in use.

One piece of the puzzle

Signature suppression shields, such as those disclosed in the Teledyne patent are just one piece of the satellite hiding puzzle: it is rumored that the NROL-15 Delta IV Heavy launch flew a trajectory designed to confuse and confound satellite trackers, enabling the Heavy’s payload to be placed in a secret orbit. Maintaining secrecy of the orbital insertion is a critical step in hobbling the efforts of the new satellite’s would be trackers. Knowing general information about where a satellite achieved orbit reduces where trackers have to look, otherwise they might have to search much broader swaths of the sky. Such a search would likely be orders of magnitude more difficult because, to quote Billy Bob Thornton in Armageddonit’s a big-ass sky.

Happy Creating!

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