The cost of launching a satellite into space is relatively high. For example, the cost of inserting a single communications satellite into orbit using an expendable launch vehicle can exceed $100 million. The cost to launch a spacecraft can be significantly reduced by launching two or more spacecraft on a single launch vehicle. One method of launching multiple spacecraft with a single launch vehicle is by positioning one of the spacecraft above the other spacecraft within the launch vehicle in a dual-manifest arrangement.
One drawback for such an arrangement is the relatively high bending loads on the lower spacecraft structure due to the distance between the upper spacecraft and the launch vehicle interface relative to the shorter distance from the lower spacecraft to the launch vehicle interface. Such high bending loads may be induced as a result of aerodynamic turbulence acting on the launch vehicle at high altitudes. In a dual-manifest arrangement, the structure supporting the upper spacecraft must be capable of transmitting the loads from the upper spacecraft into the launch vehicle. In addition, the structure must possess the required stiffness characteristics while supporting the upper spacecraft.
Unfortunately, the structure supporting the upper spacecraft may require a different configuration than the structure supporting the lower spacecraft. The different structural configurations of the upper and lower spacecraft may negatively impact cost and schedule due to the unique design, analysis, manufacturing, and testing requirements of the upper spacecraft structure and the lower spacecraft structure. For example, the different structural configurations of the upper and lower spacecraft may necessitate different tooling and assembly fixtures, different planning and build instructions, and different ground support equipment, all of which increases the overall cost and schedule for launching the spacecraft into orbit.
As can be seen, there exists a need in the art for a structural arrangement for an upper and lower spacecraft of dual-manifest launch which can be provided at reduced cost.