People love a good military conspiracy theory, including the one that the Air Force has its very own space shuttle. It all sounds very James Bond, but the truth is that the military actually never had a secret space shuttle. Instead, it used NASA's space shuttle fleet until 2011. Then it built and flew its own mini-shuttle drone and continues to test it on long missions. However, while there may be great interest within the military for a "space force," there's just not one out there. There is a space command at the U.S. Air Force, mainly interested in working through issues of armed forces using space resources. However, there aren't phalanxes of soldiers "up there," just a lot of interest in what military use of space might eventually become.
The U.S. Military in Space
The theories about the military use of space stem largely from the fact that the U.S. Department of Defense flew secret missions on the shuttles when NASA was still using them to get to space. Interestingly, when NASA's fleet was being developed, there were plans to make additional copies exclusively for military purposes. That affected the specifications of the shuttle design, such as the length of its glide path, so that the vehicle could accommodate military and top-secret missions.
There was also a shuttle launch facility built in California, at Vandenberg Air Force Base. This complex, called SLC-6 (Slick Six), was supposed to be used to put shuttle missions into polar orbits. However, after the Challenger exploded in 1986, the complex was put into "caretaker status" and was never used for a shuttle launch. The facilities were mothballed until the military decided to retool the base for satellite launches. It was used to support Athena launches until 2006 when Delta IV rockets began to lift off from the site.
Use of the Shuttle Fleet for Military Operations
Ultimately, the military decided that having dedicated shuttlecraft for the military was unnecessary. Given the amount of technical support, staff, and facilities required to run such a program, it made more sense to use other resources to launch payloads into space. In addition, more sophisticated spy satellites were developed to accomplish reconnaissance missions.
Without its own fleet of shuttles, the military relied on NASA's vehicles to meet its needs for access to space. In fact, the space shuttle Discovery was planned to be available to the military as its exclusive shuttle, with civilian use as it was available. It was even going to be launched from the military's Vandenberg's SLC-6 launch complex. Ultimately the plan was scrapped following the Challenger disaster. In recent years, the space shuttle fleet has been retired and new spacecraft are being designed to take humans to space.
For years, the military used whatever shuttle was available at the time of need, and military payloads were launched from the usual launchpad at Kennedy Space Center. The last shuttle flight strictly for military use was carried out in 1992 (STS-53). The subsequent military cargo was taken up by shuttles as a secondary part of their missions. Today, with the increasingly reliable use of rockets via NASA and SpaceX (for example), the military has much more cost-effective access to space.
Meet the X-37B Mini-shuttle 'Drone'
While the military hasn't had a need for a conventional manned orbiting vehicle, some situations could call for a shuttle-type craft. However, these craft will be quite different from the current stable of orbiters-perhaps not in look, but definitely in function. The X-37 shuttle is a good example of where the military is going with a shuttle-type spacecraft. It was originally designed as a potential replacement for the current shuttle fleet. It had its first successful flight in 2010, launched from atop a rocket. The craft carries no crew, its missions are secret, and it is entirely robotic. This mini-shuttle has flown several long-term missions, most likely performing reconnaissance flights and specific types of experiments.
Clearly, the military is interested in the ability to place objects into orbit as well as have reusable spy craft; the expansion of projects like the X-37 thus seems entirely possible and very likely will continue into the foreseeable future. The U.S. Air Force space command, with bases and units around the globe, is the front line for space-based missions, and also focuses on cyberspace capabilities for the country, as needed.
Could There Ever Be a Space Force?
Occasionally politicians float the idea of a space force. What that force would be or how it would be trained are still very large unknowns. There are few facilities to get soldiers ready for the rigors of "fighting" in space. As well, there's been no talk by veterans of such training, and expenditures for such places would eventually show up in budgets. However, if there was to be a space force, massive changes to military structures would be needed. As mentioned, training would have to ramp up on a scale so far unknown to any military on the planet. That's not to say one couldn't be created in the future, but there isn't one now.
Edited and updated by Carolyn Collins Petersen.