Kites

In space combat, Kites are the go-to human armament. They were first developed by necessity in preparation for the Contact War out of a need to compete with advanced spacys within the limits of available human technology. While humanity has advanced since then, no other option within our reach has proven more practical than the Kite.   The Logic of Space Weapons   There are a lot of factors important to consider in space combat, but for weapons few things are more important than enemy reaction time. The longer they have to take action between becoming aware of your attack and that attack actually hitting them, the less likely your attack matters. Across solar distances, even a tiny change of course can turn the best aimed shot into a miss effortlessly, or be shot down by point defenses.   For this reason, the faster your attack can close the distance (and thus reduce the window of enemy reaction time) the better. This is harder than it sounds when engaging the enemy across a distance measured in millions of kilometers.   Lasers have excellent reaction time limits, being speed of light weapons, but they are also very easy to defend against and cannot be relied upon to be deadly weapons.   Particle beams are extremely energy hungry, are shorter range if you want to maintain effect, and are generally outside of human capability at our current tech level.   Railgun impactors or other pure projectile weapons are woefully impractical for anything other than orbital strikes, because they cannot course-correct AND they need to impart all of their velocity explosively at the start. Any railgun capable of launching a projectile fast enough not to be avoided is either in knife-fighting distances or has cracked the ship it is mounted on in half through the recoil and then melted.   Missiles sound like the best idea, being self-propelled and capable of course correction, but in practice they are almost worthless due to the limits of rocketry. If you want an engine that can catch up to a starship, you need an engine as powerful as that of the starship. And any missile with an engine powerful enough to matter loses that engine in the course of its intended purpose, making good missiles both massive in size and extremely expensive. Missiles can catch up to aircraft in an atmosphere because air resistance and the limits of how fast a plane can go give the missile an advantage. No such advantage exists in space. Rockets do serve a function in space combat, but largely are only effective against immobile or otherwise defenseless targets or against enemies that are already closing the distance with you (and, thus, cannot outrun your missiles).   So what does this leave you with?   The Kite Solution   The answer is Kites. Kites are a 2-stage Laser Accelerated Projectile, sometimes a 3-stage one.   The first stage is that you use a railgun to impart the Kite's initial velocity. This is not enough to make the Kite a viable long distance weapon, but it does get the ball rolling and carries the Kite far enough away from its parent ship to deploy. The Kite will then unfold itself and reveal its true form: a payload with ablative, reflective sails. The parent ship then uses onboard lasers (many are designed with the laser built into the same railgun platform that launched the kite) to push the Kite from behind by aiming for the sails. This externalizes the motive power to the ship, rather than onboard the payload, thus eliminating the need to carry propellant or a heavy engine. The payload is capable of a vastly smaller minimum mass, and thus is easier to accelerate. Thus laser-propelled, the Kite can maintain a constant acceleration, building up velocity over time and thus being at its fastest right before it hits the target - which is to say limiting the window of point defenses to activate. Modern Kites achieve a dual purpose, the sail designed to sublimate into gas when heated and shaped to utilize that ejected material as propellant for even faster acceleration. Kite payload can be variable. Some are just metal slugs, others are nuclear warheads. Many Kites are designed to split apart on final approach, creating a cone of death or releasing short range missiles at the final stage to course-correct for a moving target with the advantage of the velocity built up by the kite. Kites do have limitations, especially when facing targets that are maneuvering around the parent ship. Kites have only some ability to course-correct, as if the Kite is not between the parent ship and its target it can no longer receive the pushing laser.   While an inelegant solution, Kites have proven effective weapons. The Frogs were impressed enough with the crude ingenuity of the design that they have since adapted the model for use on their own disposable ships, which is high praise from a civilization that is otherwise much more advanced than we are.