Months after its scheduled re-entry into Earth's atmosphere — and a surprise cameo appearance in hit space flick Gravity — China's first space station boosted into a higher orbit. It still speeds around the planet, doing … what, exactly?

No one outside of China's popular but opaque space program seems to know.

Tiangong, or "heavenly palace," blasted off atop a Long March 2F booster in 2011. "Chinese Gen. Chang Wanquan, commander of China's manned space program, declared the launch a success from a control center in Beijing, drawing applause from assembled Chinese politicians and dignitaries,"Spaceflight Now reported.

During spaceflights Shenzhou 9 and Shenzhou 10, three-person Chinese crews lived aboard Tiangong's small habitat for as long as 15 days at a stretch.

The astronauts practiced rendezvousing and docking with the station, observed the Earth, conducted medical experiments, and tested equipment. Astronaut Wang Yaping wowed students back home with her live-cast zero-G science demos. The manned missions delivered NASA-style civil prestige and outreach.

All Chinese astronauts are members of the armed forces. Two-time astronaut Nie Haisheng received his promotion to general just prior to a Tiangong flight last year. The Chinese military provides much of the infrastructure and training for the civil manned space program. This is nothing unusual, as the histories of the American and Soviet space programs prove.

But China goes it alone in orbit in part because the country makes other spacefaring nations nervous. Beijing wasn't invited to the International Space Station partly because Washington worried the Chinese might steal American technology. And like other space powers, China actively seeks military advantage in space.

The bus-sized Tiangong consists of two modules together providing astronauts with around 15 cubic meters of pressurized space. Pretty crowded for three people for two weeks, but lots of space for gear if you're just dropping in every now and then.

Even without a crew, a small space station is a big bird with plenty of power and room. Tiangong would make a great orbital target for rendezvous-and-dock tests of China's forthcoming cargo spacecraft.

Or it could be doing other things. As with the U.S. Air Force's X-37B robot space plane, mystery opens the door to daydream.

That's no moon

Like its companion Shenzhou — "heavenly vessel" — spacecraft, Tiangongreflects its Soviet design heritage. Compare the layout of Tiangong to the Soviet space stations and the resemblance is clear.

The USSR seized the lead in space-station operations during the Cold War, and Russia maintains that advantage to this day. From the first Salyut space stations through the Mir station to the ISS, the USSR and Russia have advanced the art of long-term orbital presence.

ISS crews get to and from their space base aboard Soyuz spaceships very like their Shenzhou nephews. The station's "base block" core module is based an old Soviet space-station part.

During the 1960s, the U.S. Air Force spent several years and several billions of dollars pursuing a military space station. Had the government not cancelled the project, so-called Manned Orbiting Laboratories and their two-man crews would have shot into orbit aboard beefed-up Titan missiles for month-long surveillance missions.

After the 1969 cancellation, the Keyhole series of spy satellites adopted MOL's eyes-in-the-sky mission and its huge imaging systems. Drone space stations, if you will.

Meanwhile, as their own nation's moonshot faltered, the Soviet leadership decided to accelerate space-station efforts. Several military stations flew under cover of the civil Salyut program.

One mission — Salyut 3, in orbit from June 1974 to January 1975 — successfully hosted one crew and test-drove giant spy scopes and even a space cannon.

Like the Americans, the Soviets found greater success adapting these big man-rated modules into unmanned platforms. Between 1987 and 1992, two drone Almaz stations fitted with large side-looking radars gave the USSR a last, clear look from up high.

In the years since the Cold War, the Hubble Space Telescope and ISS have taught us the value of "man-tended" spacecraft. The power of modern IT and sensor technologies could exponentially boost the value and capabilities of a large orbiting platform, whether or not a human crew ever returns.

The Chinese really get space and its power. They're putting a lot of effort and hardware up there. Big sats and little sats and bus-sized human-habitable sats.

What are they doing up there? Only they know for sure. But it's obvious that Tiangong could be more than a scientific habitat.

From drones to AKs, high technology to low politics, War is Boring explores how and why we fight above, on, and below an angry world. Sign up for its daily email update here or subscribe to its RSS Feed here.

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