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SMC's Next Big Thing is Small

LOS ANGELES AIR FORCE BASE, Calif. -- There's a display case that welcomes visitors with miniature models of rockets and satellites from the Space and Missile Systems Center's proud heritage of space exploration. The replicas of the Delta IV rocket and GPS Block 1 satellite are among the many miniatures that, in reality, weigh several tons, and tower over many buildings at Los Angeles Air Force Base, Calif.

However, one day, there is likely to be a satellite nestled into the glass display case that while it may be a replica, is not a miniature, but a 1:1 scale model. Meet the nanosatellite.

The SMC's Development Planning Directorate is leading the Space Environmental NanoSatellites Experiment. It will test the suitability of three-unit CubeSat technology for operational space missions. It is powered by one bi-fold and one tri-fold solar array along with body-mounted array that provide the vehicle with 10 watts of power. Communications is handled by a unified S-band transceiver with a miniaturized encryption module that enables 256-bit Type II encryption. Four reaction wheels and three torque coils will control attitude and position using star cameras, inertial measurement units, magnetometers and GPS. What is unusual about the 3U CubeSat bus is that it is no larger than a shoebox with a mass of about four kilograms.

Capt. George Sondecker, SENSE program manager, who has worked on the program since July 2011, joined the program just three months after the contract was awarded to build the satellites.

"Because SENSE was a twenty-month rapid acquisition, my colleagues and I have had the unique opportunity to lead the program from concept to launch," said Sondecker.
"I believe this arrangement has been a huge advantage for both the SENSE program and the officers supporting it. The program benefited from personnel continuity, and the officers were able observe the entire satellite acquisition process in a single assignment."

The CubeSat specifications were originally developed in 1999 by faculty at California Polytechnic Institute San Luis Obispo and Stanford University to assist graduate students in building and operating affordable spacecraft. The first launch occurred in 2003. CubeSat specifications have since emerged as the international standard for nanosatellites. So far, more than 75 CubeSats have been launched as rideshare payloads or deployed from the International Space Station. Many of the components to build the satellite are off-the-shelf items.

"Nations, universities, private companies and even curious high school students around the world are building and launching nanosatellites," said Sondecker.

"Thanks in large part to the CubeSat Standard established by the California Polytechnic State University, there are loads of commercial off-the-shelf parts and open source software available to nanosatellite developers. While these small satellites do not possess nearly the complexity of the SENSE nanosatellites, the threshold has been dramatically lowered so that anyone with a basic technical background and a few thousand dollars can build and fly a simple satellite."

The modular design comes in a 10-cubic centimeter basic size and is often called a "1U" CubeSat meaning one unit. The design is scalable along a single axis by 1U increments. A single handheld 1U CubeSat is about the size of an oversized Rubik's Cube. Now in use for nearly a decade by NASA, university researchers and private companies, the CubeSat Design Specification offers the Department of Defense an opportunity to rapidly procure and deploy satellite systems that use commercial off-the-shelf technology slashing both development costs and the duration of the acquisition cycle.

While SENSE is a pathfinder mission to determine the suitability of 3U CubeSat technology for SMC, SENSE has a vital science mission. Each vehicle will carry a suite of thee Space Environmental Monitoring payloads. The vehicles are identical except for their playloads. The SENSE architecture is comprised of two 3U CubeSats (Space Vehicle 1 and Space Vehicle 2) and a supporting global ground system of several antennae. The difference is SV-1 will carry the CubeSat Tiny Ionospheric Photometer, and SV-2 will carry the Winds-Ion-Neutral Composition Suite. Developed by the Navy, WINCS will acquire densities, velocities and temperatures of ions and neutral particles. CTIP, developed by the Stanford Research Institute, will measure electron density profiles, total electron content and identify features of the E and F2 regions of the Earth's atmosphere.

The data collected by SENSE will support the Utah State University Global Assimilative Ionospheric Model with near real-time measurements of Earth's ionosphere. Using The Aerospace Corporation's Compact Total Electron Content Sensor, the SENSE mission will also characterize the GPS signals as they travel through Earth's ionosphere.

The Research and Development, Test and Evaluation Support Complex at Kirtland Air Force Base, N.M., will control the satellites using Common Ground Architecture. Developed by the Naval Research Laboratory, CGA allows operators to manage simultaneous space vehicle passes and schedule operations without an operator being present. Throughout the SENSE mission, CGA's autonomy combined with its user-friendly interface will provide substantial cost savings to the Air Force.

As with any mission, multiple organizations across SMC and the Air Force Research Laboratory were involved in the acquisition and supporting SENSE. The Weather Directorate is the primary sponsor, while the Development Planning Directorate led the acquisitions effort. The Space Development and Test Directorate is owner-operator of the SENSE ground system, which was funded in part by SMC's Infrared Space Systems Directorate to support future missions after SENSE. Additionally, the Space Vehicles Directorate at AFRL is responsible for data processing, analysis and distribution.

"The SENSE program's contributions toward sensor miniaturization are truly remarkable," said Sondecker. "Thanks to advances in microelectronics and the scientific talent of our instrument developers, the SENSE satellites offer the potential to satisfy military weather requirements that previously required much larger and more costly satellites to accomplish."

There is much anticipation in the Air Force Space community surrounding the upcoming launch of the SENSE CubeSats into orbit aboard the Minotaur I Enabler mission from NASA's Wallops Flight Facility, Va. While the two nanosatellites may be small in size, the SENSE mission is one giant step towards future affordable and resilient space systems for Air Force Space Command.