Standard Interfaces Could Help Unlock Potential of Small Sats

WASHINGTON -The U.S. Defense Department’s interest in small satellites has given rise to efforts to develop platforms and components with standard interfaces that would allow planners to mix and match hardware to perform a variety of missions at an economical cost.

In one such effort, the Pentagon expects to award a contract in late 2005 for development of the Standard Interface Vehicle, a common satellite platform that could host a variety of payloads.

The Standard Interface Vehicle could lead to cost savings that enable the military to fly more of the experimental payloads that get built but then languish on the ground because funds are not available to launch them, according to a Defense Department Space Test Program statement-of-objectives document for the program dated June 13.

The Space Test Program finds rides to space for military experiments that have been ranked in priority by a Defense Department-wide group called the Space Experiments Review Board. The program finds rides at no charge to the experimenter for ranked projects, but provides launches for unranked payloads on a reimbursable basis.

The Standard Interface Vehicle should be compatible with a variety of rockets, according to the document, which was posted on a Pentagon Web site. Among these rockets are Boeing’s Delta 4 and Lockheed Martin’s Atlas 5, which were developed under the U.S. Air Force’s Evolved Expendable Launch Vehicle (EELV) program and which launch the majority of U.S. military payloads. Therefore the platform must be compatible with the EELV Secondary Payload Adapter, a ring-shaped device that enables both vehicles to accommodate multiple secondary payloads, the document said.

The Space Test Program hopes to launch the first Standard Interface Vehicle in late 2008, according to Air Force Lt. Col. Dan Griffith, acting director of the Space Test Program.

Pentagon leaders have expressed increasing interest in recent years in using small satellites, not just for experiments but also to support military operations. One set of Pentagon programs, generally referred to under the heading of responsive space, aims to develop a new breed of satellites and rockets that can be launched on short notice to meet military contingencies as they arise.

Congress has been largely supportive of the effort. For example, some of the committees that oversee Pentagon spending have proposed increasing the military’s 2006 budget request for responsive space activities.

The Standard Interface Vehicle is by no means the only effort of its type. The Pentagon’s Office of Force Transformation in Arlington, Va., is developing a common spacecraft platform that could debut later this decade as part of its TacSat program, which aims to develop small satellites that can be tasked and controlled by forces in the field. The proposed mission, dubbed TacSat-3, would fly an experimental hyperspectral imaging payload, according to Pentagon officials.

Meanwhile, the Naval Research Laboratory in Washington, and the Johns Hopkins Applied Physics Laboratory in Laurel, Md., are leading an industry and academic consortium developing a more advanced version of the platform intended for use on TacSat-3.

Pat Patterson, manager of the Technology Development branch at the Utah State University’s Space Dynamics Laboratory in Logan, said the adoption of standard interfaces for small satellite hardware could lead to capabilities that cannot even be imagined today.

To illustrate that point, Patterson drew an analogy with the personal computer industry, where the use of common ports for Internet connections and accessories enable easy integration of systems. This has led to the development of new devices such as flash memory cards that can be carried on a keychain and plugged into most computers, he said.

Another advantage of standardized satellite platforms with common component and instrument interfaces is that they would be less costly than custom-built hardware because they could be produced in relatively large quantities, Patterson said.

Despite these advantages, not everyone is sold on the benefits of standardization, and industry has made few strides in that direction, said Patterson, who is chairman of the 19th Annual American Institute of Aeronautics and Astronautics/Utah State University Conference on Small Satellites in Logan Aug. 8-11. The conference will feature a variety of presentations on the pros and cons of standardization.

One of the downsides of standardization is that it can require compromises in capability, said Quinn Young, a senior mechanical engineer at the Space Dynamics Laboratory. Standardization also can drive up the weight of a satellite because the platform is designed to accommodate a large number of applications, he said.

The potential market for satellite platforms, components and instruments with standard interfaces is not clear at this point, Young said. While the Pentagon has several standardization initiatives under way, neither the military nor NASA is buying small satellites in large quantities, he said.

This leaves some companies uncertain as to whether it is worth investing significant internal research and development dollars on standard hardware that may be used on only a few satellites, Young said.