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.

Then came the Challenger disaster of 1986, which imposed years more delay and still more expense. By the time the shuttle had weathered that storm, the military had mostly turned its back on the troubled spaceplane. No shuttles ever flew from Vandenberg on polar missions, and the ambitious military plans to recover and re-use colossally expensive spy sats – perhaps modifying and upgrading them, or repairing them after faults, as one might a normal aeroplane – came to nothing.

It seems, to be fair, that the military was probably just as disappointed in the shuttle as civil space enthusiasts were. Unlike the civil space programme, however, the US Space Force is carrying on with the spaceplane idea. And it does seem that it is mostly doing so with the idea of testing out new kit in space without having to build it into its own satellite every time.

Test capability alone might justify the Space Force continuing with X-37B. However the design of the robot spaceplane does suggest that sneaky, low profile cross-range re-entries may also be a card the US military yet aspires to have up its sleeve.

If you want to get out into the wilder speculative realms you could postulate a mission lifting off to retrieve, not a US satellite, but someone else’s. The initial launch would be explained as delivery of a normal secret payload, but in fact the spaceplane would lift empty, scoop up its target on one pass and return to land on a “Mission 3B” style profile without ever flying above a hostile telescope or radar station. The owners of the sat-napped spacecraft, out of sight on the other side of the world, would never know what had happened to their kit.

Less aggressively, missions of this sort might instead make a close pass by opposition spacecraft without anyone knowing about it – maybe just to get a good visual or electronic look at them, or perhaps to interfere with them in some suitably deniable way. This sort of thing would perhaps be practical with the existing X-37B; there’d be no need for a larger craft.

The US itself is known to be quite paranoid about this sort of thing being done to its own satellites: it is spending a lot of money on kit which would let a satellite’s operators know what was happening to it in such an event (normally it would simply go mysteriously offline) and on dedicated guardian sats intended to watch over other US spacecraft even when they’re above other people’s airspace.

The US probably has good reason to be paranoid. A Russian satellite designated Kosmos-2558 has been making close passes by a US military secret satellite known as USA-326 since last year, and Kosmos-2558 is not the first such Russian “inspector” satellite. China for its part operates a mini-shuttle not unlike the X-37B.

In this context the Space Force mention of “new orbital regimes” for the X-37B on this mission is significant, especially given the fact that this time the little spaceplane is going up on a Falcon Heavy.

The Falcon Heavy, from Elon Musk’s famous firm SpaceX, is the most powerful launch rocket operating today. In theory NASA’s much delayed Space Launch System rocket – intended one day to carry astronauts beyond low orbit for the first time since the Moon landings – is even more powerful, but it has flown only once so far and it’s not available for taskings other than exploration. The Falcon Heavy uses three Falcon 9 first stages fixed together side by side: and just one Falcon 9 has previously put the X-37B into space without trouble.

It’s clear that the upcoming mission will have power and to spare, and is plainly intended for some very high-energy orbit. That could be geostationary, up high above the Equator where the world’s TV and communications satellites are found, or a very high-angle, polar spy satellite type of orbit. One of the jobs the Falcon Heavy was built for is the putting of big, heavy spy satellites into high-angle orbits: it’s a lucrative business, as America’s “black” space programme is generally though to have a considerably larger budget than NASA.

Nobody outside the secret apparatus of the US space military knows for sure what the X-37B will be doing on its new mission. It will, probably, not be anything too aggressive.

But the combination of X-37B and Falcon Heavy could be used to do all kinds of things. It’s a new piece on the game board, and a warning if nothing else to America’s rivals that the USA intends to maintain dominance – and achieve “combat power” – in space.