WASHINGTON — The United States is right to be worried about competitors catching up in the race for space supremacy, Vice Chairman of the Joint Chiefs of Staff Air Force Gen. Paul Selva said Tuesday.

Defending space is hard because U.S. secrets are out in the open, Selva said during a breakfast meeting with reporters.“We’ve yielded an awful lot of ground to the Russians and the Chinese in space security.”

Space and cyber warfare experts like Gen. John Hyten, commander of U.S. Strategic Command, have warned that China and Russia are developing “counter space capabilities” such as electronic jammers and advanced signal scramblers specifically to target U.S. military satellites.

Selva said he agrees with Hyten about the seriousness of these threats. But even more alarming, he said, is the idea that U.S. space capabilities are becoming easier to track and attack if someone were determined to do it.

“Space is really an open architecture,” he said. “If you have enough hobbyists with telescopes, you can detect all the satellites in low-Earth orbit. If you know where all those hobbyists are and you can precisely map their GPS coordinates — and you can map the time they saw the object you’re actually interested in — you can develop a reasonable detection and targeting system.”

This means the nation’s space assets can be detected even without “elegant radar and telescopes,” said Selva. “Russia and China possess both elegant radar systems and elegant space detection systems and they are able to subscribe to all of those other capabilities that already exist.”

Anyone with a late-model iPad can download the Spacewalk open source “upstream community” app and watch what happens in space, Selva noted. “Go out to your back yard the next time the International Space Station flies over, hold your iPad up to the station, and see how close the track is,” he said. “It’s nearly perfect.”

Spacewalk also catalogs all of the known satellites in low-Earth orbit. “You can watch them fly by with the naked eye, sometimes with binoculars,” Selva said. “The basic existence of that data gives potential competitors knowledge of the space enterprise that all they have to do is add more high-fidelity sensors to it and they get a really good picture of what’s up there.”

Can the Pentagon do more to protect sensitive space capabilities? Yes it can, Selva said. But the genie is out of the bottle.

“We have to be very disciplined about what we say regarding space,” Selva said. “There are things we should never talk about.”

But big-data apps and other technologies make it all that much harder to protect sensitive information. The space problem is not unlike the fitness tracker issue that the Pentagon recently discovered when it was revealed that the Strava big-data firm published an interactive map showing the movements of military subscribers to its fitness service. Although the Pentagon says this information did not expose any classified secrets, it has launched a review of the use of personal fitness trackers and wearable electronics.

“What are you going to do when the enemy knows everything about you simply because they can exploit big data?” Selva asked. The Strava app simply did a big data analysis of all the GPS gadgets people carry when they do physical activity. “Their motive wasn’t evil,” he said. Strava, like other software firms, just takes advantage of very accurate GPS location and metadata that exists on personal devices. “If you can map the global universe of that data, some really interesting things come out,” Selva said.

With regard to space technology, the Pentagon should not underestimate enemies’ resolve to counter U.S. advantages, Selva insisted. Even the military’s most sophisticated surveillance satellites are becoming less effective. The North Koreans, for instance, have figured out how to hide ballistic missiles so they are not seen by space sensors.

Military satellites with powerful heat sensors can detect the infrared signature of a missile launch, identify its location and characterize what kind of rocket it is. Over time, North Korea has gotten “very good at predicting when those satellite will come across the top of North Korea,” said Selva. “They watch” and make sure missiles are concealed when they suspect satellites are overhead.

Sandra Erwin writes about military space programs, policy, technology and the industry that supports this sector. She has covered the military, the Pentagon, Congress and the defense industry for nearly two decades as editor of NDIA’s National Defense...