The Sitting Ducks of Space

For most of the modern era, military satellites operated under the assumption that they were too hard to reach and too politically consequential to attack. Major powers built small numbers of large, sophisticated platforms, put them in high orbits, and treated them as effectively invulnerable.

Over the past two decades, especially in the last five years, the ability to target satellites has moved from an idea to a real possibility. China destroyed one of its own weather satellites with a direct-ascent missile in 2007, creating more than 2,700 pieces of trackable debris that will remain in orbit for decades. Russia did the same in November 2021, generating another 1,500 tracked fragments. Both countries have since operationalised these systems and actively train on them. Russia has deployed orbital ASAT prototypes that have followed US satellites in orbit. China is developing "inspection and repair" satellites that could function as weapons. Both countries are assessed to be working toward ASAT capabilities that can reach the highest orbits where major communications and surveillance satellites operate (around 36,000 kilometres above Earth), which would put almost every strategic satellite in the world within reach.

The defensive problem this creates has a few distinct layers worth separating.

The first is that modern militaries depend on satellites for almost everything. Intelligence, surveillance, reconnaissance, missile warning, precision navigation, secure communications, weather data. None of these will work without space-based infrastructure. A big conflict could very well start with the space layer being degraded or taken completely offline. The side that loses its satellites first will essentially fight blind.

The second is that the traditional architecture is badly suited to this threat. Large and expensive slow-to-replace satellites in predictable orbits are the ideal targets. They are easy to find and track, and every one you take out eliminates a meaningful fraction of your adversary's capability. Concentrating hundreds of billions of dollars of national security function on a handful of platforms made sense when nobody could shoot them down. This just doesn't hold anymore.

The third is the debris problem. Every successful ASAT strike creates thousands of fragments travelling at orbital speeds. Enough strikes in low earth orbit could trigger a cascading collision scenario, referred to as the Kessler syndrome. This would render entire orbital bands unusable for decades. Mutual vulnerability does act as a deterrent, but it hasn't stopped countries from testing these capabilities, and it wouldn't necessarily stop them from using them in a real conflict.

The response from US and allied defence planners has been a shift toward lots of smaller, cheaper satellites working together, where the logic changes from "don't attack our satellites, they're too valuable" to "it's not worth attacking our satellites, we have too many". The cost of shooting down one satellite would ideally be greater than the cost of fielding one. If a constellation has 400 satellites and you can kill 10, you haven't materially degraded the mission. You've just generated debris and escalated politically.

But simply having more satellites isn't a solution. A nuclear ASAT, which Russia is reportedly developing, could render entire orbital bands unusable in a single event. The defensive architecture must be thought about as a whole system, not just as a satellite count.

What would deterrence in space look like? On Earth, deterrence is built on decades of strategy, agreements, and a shared sense of where escalation begins. In space, none of that really exists yet. The line between a warning and an act of war is still very unclear. A satellite moving close to another can feel threatening without attacking. A laser that temporarily disrupts a sensor is very different from a missile that destroys a satellite.

For defence ministries, the strategic implication is fairly clear. The space layer has become the contested layer. Any serious military must assume that its satellites will be targeted in a future conflict, that the debris environment will get worse before it gets better, and that the entire architecture of space-based military capability needs to be redesigned around resilience rather than invulnerability.

The transition from a satellite being assumed safe to space now being actively contested has happened faster than most national security establishments have managed to adapt. The next decade will be about who rebuilds their architecture for that reality first.