Kinetic Physical/Hard-Kill

Also known as simply ‘kinetic’, or ‘kinetic impactors’, these technologies can be used to strike a space system component directly or to detonate a warhead near it. Although most deem kinetic and hard-kill to be synonyms, there are some that consider the former to refer solely to those capabilities dependent on the destructive power generated by their motion and interception trajectory, instead of an explosive. Hardkill, on the other hand, is a broader term that comprises kinetic physical capabilities, but also includes the aforementioned explosive payloads. Kinetic physical capabilities are sometimes referred to as hit-to-kill. It should be noted that official United Nations nomenclature does not use the terms ‘kinetic physical’ or ‘hardkill’.*

A kinetic physical or hard-kill hostile act can be carried out in different manners:

• Direct-ascent ASATs are launched from the Earth (ground, sea, or air) to place a kinetic kill vehicle on a ballistic trajectory through space. Once the kinetic kill vehicle has separated from the launch vehicle, it tracks the targeted space object to strike it in a hypervelocity collision.
• Co-orbital ASATs place an interceptor into orbit, which is then manoeuvred using a rendezvous and proximity operation (RPO) to situate it close to its target. This manoeuvre does not necessarily take place immediately after the object is put in orbit and the co-orbital ASAT can remain dormant for some time. Satellites used as weapons by causing them to collide with another satellite, or the employment of projectiles by satellites, are also considered co-orbital ASATs, even if they are repurposed for this function despite having been designed for a benign and non-weapons-related application that is in line with the peaceful purposes principle. A kinetic co-orbital ASAT can damage or destroy its target through a direct collision, detonation in close proximity to the target to create shrapnel, the release of fragments that would collide with the target, or the use of a robotic arm to damage or disable the target. Certain concepts for co-orbital ASATs may employ various means or methods including, but not limited to, explosive fragmentation, harpoons, nets, chemical sprayers or adhesives.
• Ground station hostile actions consist of the targeting of sites located on Earth which are responsible for the command and control of a satellite, or the relay of satellite data.

The use of kinetic counterspace technologies is likely to cause irreversible damage to the target in a manner that is relatively easy to attribute. If the target is located in orbit, the use of these technologies produces space debris, which can be dangerous to other space objects as well, and can remain in orbit for weeks, months, or even years, depending on the altitude of the strike and the mass of the target.

*For other terms used to refer to these capabilities, see Report of the Secretary-General A/76/77, on Reducing space threats through norms, rules and principles of responsible behaviours (13 Jul. 2021), https://undocs.org/en/A/76/77.