Launches of satellites for the Department of Defense (DoD) or other government agencies often cost hundreds of millions of dollars each and require scheduling years in advance for one of the handful of available slots at the nation's limited number of launch locations. This slow, expensive process is causing a bottleneck in placing essential space assets in orbit, especially in geosynchronous Earth orbit (GEO) approximately 22,000 miles (36,000 kilometers) above the Earth.

Launches of commercial communications satellites, on the other hand, are relatively frequent and inexpensive. Commercial launch vehicles also often have unused carrying capacity that their operators can offer to other satellite owners through "hosted payload" services. Unfortunately, no technology currently exists to enable government and military satellites to share rides and separate themselves from commercial communications satellites headed to GEO.

To help foster the creation of such a capability, DARPA's Phoenix program has shared its Hosted POD Assembly Interface Control Document. The document provides specifications for Phoenix's Payload Orbital Delivery (POD) system, a standardized mechanism currently in development that is intended to safely carry a wide variety of payloads to GEO aboard commercial communications satellites.

PODs are designed to help take advantage of the frequency of commercial satellite launches and associated hosted payload service opportunities to enable faster and lower-cost delivery of payloads to GEO. DARPA is also pursuing a possible risk-reduction flight to validate the POD technology, which could eventually provide "FedEx to GEO" capabilities to make space deliveries to high-altitude orbits much easier and faster.

Each POD would have dimensions of roughly 1.3 feet (0.4 meter) by 1.6 feet (0.5 meter) by 3.3 feet (1 meter) and could carry a payload ranging from approximately 150 pounds (68 kg) to 220 pounds (100 kg), depending on the configuration selected. A standardized interface would attach the POD to the host satellite and then release the POD at the desired orbit.

The POD system is one of three main technology research areas for Phoenix, which seeks to enable robotics servicing and asset life extension in GEO while developing new satellite assembly architectures to reduce the cost of space-based systems. Last month, DARPA released a Request for Information (RFI) seeking insights regarding a potential flight demonstration to introduce DARPA-developed space robotics capabilities in GEO within the next five years.

The RFI also seeks input into potentially establishing a public-private partnership that would make cooperative robotic servicing available to both military and commercial GEO satellite owners on a fee-for-service basis.