Earlier this year Iran's defense minister put the world on notice: His nation had developed the ability to "easily" watch spacewalking astronauts from the ground. The announcement was largely ignored, in part because it made the minister sound like a James Bond villain. The boast was also a bit anticlimactic, given that even amateur astronomers are already recording in detail what happens in low Earth orbit. Both the technology involved and the techniques used to observe satellites and even the occasional astronaut perched outside the International Space Station (ISS) are improving, much to the presumed chagrin of governments looking to keep certain on orbital activity confidential.

In a development harkening back to the earliest days of desktop computing, highly skilled stargazers are hacking together optics, electronics and software to create sophisticated observatories of their own. In fact, one French astrophotographer, Emmanuel Rietsch, has begun selling software and hardware that make it possible for backyard astronomers to track and record satellites.

High-end consumer telescopes resting on motorized, programmable mounts that match Earth's rotational speed to keep the scope pointed at stars and planets as they cross the sky have long been standard equipment. Rietsch's innovation, developed at the request of Thierry Legault, a friend and fellow French astrophotographer, is hardware and software that pushes the mount to operate many times faster in order to keep up with comparatively speedy satellites. Legault and Rietsch use Prism and Adobe Premiere to improve the clarity of the images they capture and VirtualDub to convert the images for use online.

With the hacked-together system, Legault produced "the first useful images I have seen" of last year's doomed Russian Mars probe Phobos–Grunt as well as spy satellites, veteran backyard astronomer Ted Molczan says. Together, Reitsch and Legault "have advanced the amateur state of the art by combining high-quality optics and cameras with an automated tracking system built by Rietsch," adds Molczan, himself well-known for observing man-made satellites in orbit and posting information about them to the Web. This includes the American military satellite USA 193, which malfunctioned after little more than a year and was shot down by a U.S. warship in 2008.

In fact, amateur astronomers were the first to report publicly, late last year, that as Russia's Phobos–Grunt sat helplessly inert in Earth orbit—the spacecraft initially was in a fixed orientation relative to the sun. The news gave some space science boosters (short-lived) hope that the mission could be salvaged. It wasn't the first time stargazers had successfully tracked objects in space, but it was the first time they were able to report in such detail.

And the number of objects being cataloged is increasing: A backyard spotter in Ontario, Kevin Fetter, won notoriety for sighting among other things an errant NASA tool bag and, last fall, China's Tiangong 1 space station test vehicle. Fetter captured the spacecraft on video with a static, comparatively low-powered telescope, yielding little more detail than could be seen with the unaided eye.

Other experienced backyard trackers have also gained notoriety for spotting spy satellites, in particular the National Reconnaissance Agency's (NRO) highly secret Lacrosse 5. Soon after the craft was launched in 2005, amateur astronomers reported its "disappearance trick." Apparently alone among all of the U.S.'s space spy fleet, the Lacrosse 5 periodically disappears from view for seconds before reappearing. It is the opposite of a flare, in which a satellite reflects a brief glint of sunlight. A much-discussed murky video shows a glowing, distinctly oblong object, said to be Lacrosse 5, quickly dimming before brightening again. The discovery was a sensation in satellite-hunting circles, inspiring some of the conspiratorially minded peepers to wonder if the U.S. could actually hide orbiting equipment from them.

There may be implications for national security. Spy satellites are the original battlefield reconnaissance drones, and they remain unparalleled treasures for any nation capable of getting one into orbit. The NRO builds and launches spy satellites, and would prefer people know as little about them as possible. When contacted in March, the NRO refused to comment on whether sophisticated hobbyists are compromising security when they catalogue spy satellite passes, much less publish and puzzle over Lacrosse 5's disappearance trick.

It is unlikely that scores of enthusiasts will buy or build systems to spy on the spies, though. No astronomical component–makers sell complete, soup-to-nuts systems enabling amateur astrophotographers to peer into and capture detailed images as distant as low Earth orbit, defined by NASA as ranging from 80 to 2,000 kilometers in altitude. The hardware and software needed to record the wallflower Lacrosse 5 costs between $20,000 and $30,000, and it demands a lot of skill using telescopes, of course, but also mounts, custom software, mathematics and cameras.

The following list of parts is by no means complete. Precision, motorized mounts, which swing the telescope tube about, can run about $13,000. A 20-centimeter telescope costs about $2,600. A fast monochrome digital video camera runs from $600 to $1,200. Software needed to track and record objects runs on any standard PC laptop (no Macs), but the computer has to have enough memory to be able to digest 100 images per second or more without choking.

In addition to the growing cost and complexity of equipment, there is always the question of whether amateur astrophotographers like Legault and Rietsch might someday attract too much attention for their work, earning them a visit from certain three-initial government agencies. Legault, who is also known for having captured the image of astronaut Steve Bowen outside the ISS, laughs off the prospect. Rietsch also makes light of such a possibility: "I am not working right now," he says. "If an agency comes to my door, I'm happy! I'll make electronics for anybody."