The US is about to send up its ‘secret space warplane’ atop its most powerful rocket

So there will be some innocuous civilian NASA science business going on. There will also, however, be some experimentation with “space domain awareness”. That sounds suitably anodyne, but in fact it is a military mission. It’s one half of the ability to wage war in space.

The lead authority for “space domain awareness” in the US military is an office of the US Space Force called Space Domain Awareness and Combat Power. The first half of fighting in space is knowing what’s happening – that’s the “awareness” bit. The second part is doing something about it: Combat Power. Space Domain Awareness and Combat Power is a large organisation with 1200 people, a mixture of uniformed Space Force service people, other government personnel, and contractors. It is handling over $10bn of projects and programmes.

One or more of those projects will have equipment aboard the X-37B when it lifts off next month. What could we be talking about?

Probably nothing hostile, not this time anyway, is the answer. But the robot mini-shuttle could do some quite naughty and interesting things if required – and what’s more, it could probably do them without anyone knowing about it.

The X-37B had a rather chequered development history. It was built by Boeing’s “Phantom Works” advanced-concepts shop, originally for NASA – though it had Air Force input from the beginning, drawing heavily on the USAF’s X-40 experiments. There was no Space Force back then.

NASA saw the craft as a lifeboat for the International Space Station, but that wouldn’t really call for a winged re-entry vehicle: the ISS lifeboat is in fact a regular Soyuz capsule – it doesn’t have wings, or any need for them.

NASA dropped the X-37 after some work involving release of test airframes in the atmosphere. But the spaceplane lived on, supported at times by funds from military tech bureau DARPA and some from the Phantom Works itself. Nowadays the project is run by the Rapid Capabilities Office as the X-37B.

The X-37B has now carried out six missions, the latest one lasting over two years. Unlike the Space Shuttle, the X-37B deploys a solar array once it is in orbit, permitting it to stay up for long periods. So far, it has been sent up mostly atop conventional Atlas V rocket stacks, though on one occasion it went up on a Falcon 9 from Elon Musk’s company SpaceX – a much more modern launcher, and very different from an Atlas in that its first stage is often recovered and re-used, but not hugely different in capability terms.

One of the things which makes the X-37B interesting is that it has a strong heat shield and sizeable wings, similarly shaped to those of the Space Shuttle of yesteryear. Perhaps the main reason that the shuttle had such big wings and such a tough (though as it turned out somewhat unreliable) heat shield was that the US military wanted it to.

Consider this quote from the Columbia accident investigation report:

“The Department of Defense wanted the Shuttle to carry a 40,000-pound payload in a 60-foot-long payload bay and, on some missions, launch and return to a West Coast launch site after a single polar orbit. Since the Earth’s surface – including the runway on which the Shuttle was to land – would rotate during that orbit, the Shuttle would need to maneuver 1,100 miles to the east during re-entry. This ‘cross-range’ requirement meant the Orbiter required large delta-shaped wings and a more robust thermal protection system”.

It’s often forgotten nowadays that the Shuttle was originally intended not just for NASA operations from Cape Canaveral, but also for military operations from a dedicated complex at Vandenberg Space Force Base in California. This would have launched military shuttles into polar orbits rather than generally easterly, low-angle ones as from Florida.

Polar-type orbits tend to be favoured for spy satellites, as the Earth turns beneath the circling spacecraft. This allows an orbital spyeye to pass over any given spot regularly, observing events of interest below.

The fact that the Earth turns, however, would normally mean that a spacecraft lifting off from Vandenberg and orbiting once around would then be above the Pacific, with no hope of returning to the USA until many more orbits had passed and America came round again. By that point such a spacecraft would very likely have been detected by suitably alert watchers around the world and details of its track worked out – so, perhaps, giving useful clues as to the path of anything it might have dropped off or picked up.

Not so in the case of a craft with heatproof wings and “cross range” capability, however. A shuttle would have been able to lift off from Vandenberg, orbit at a high angle from the Equator once – during which time it could deploy something or pick something up – and then re-enter, using its wings to bend its re-entry track east and so put down again in California, never having overflown any nation of concern.

The “some missions” referred to by the Columbia report were probably the so-called Baseline Reference Mission 3A and 3B flight plans which called for single-polar-orbit hops from Vandenberg, either deploying or recovering a spy satellite without any pass over the former USSR by the shuttle. Later, even more difficult missions were specified by the Air Force, in which the shuttle would both deploy and then recover a spy satellite during a single mission.

The military spy-sat requirements were blamed by many space enthusiasts for crippling the shuttle’s design. It was argued that without its large, heavy, heatshielded wings – necessary for the cross-range re-entry requirement, rather than for actually landing as such – the shuttle might have been a much more efficient machine for putting stuff into space.

In the event, by the time the shuttle began to fly its performance was seen as deficient for polar-orbit spysat missions lifting increasingly hefty spy satellites. High-angle launches forfeit the valuable speed boost gained by eastward takeoffs close to the Equator, as from Canaveral, and require more from the launcher. Plans were developed in the 1980s for lightened solid boosters, and even extra strap-on liquid rockets, to be used on missions out of the multibillion-dollar shuttle base at Vandenberg’s Space Launch Complex Six, now leased to SpaceX.