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The current Department of Defense (DoD) satellite communications (SATCOM) network consists of large, exquisite, and expensive constellations providing service across the radio frequency spectrum. However, the current SATCOM architecture is vulnerable to adversary actions including interference, jamming, directed energy, and antisatellite weapons. Despite the rise in adversary threats, the DoD continues to grow more reliant on SATCOM services in execution of all seven joint warfighting functions. The Marine Corps Operating Concept acknowledges that traditional beyond line-of-sight (BLOS) communications capabilities will be severely degraded or non-existent in the future fight. This research demonstrates a near-term solution that increases resiliency in BLOS communications consisting of a rocket-delivered expeditionary narrowband radio relay with an applicable use case. The payload of the relay consists of a software-defined radio controlled by a single-board computer and demonstrates resiliency by cross-banding signals between very high frequency and ultra high frequency transmit and receive frequencies, respectively. After a rigorous design and test process, this research culminated with an actual demonstration over the air and an attempted delivery by an actual rocket to a target altitude of 30,000 feet. http://archive.org/details/fillingthegaproc1094562697 Major, United States Marine Corps Approved for public release; distribution is unlimited.

With traditional radio frequency (RF) bands becoming congested and the Department of Defense (DoD) expanding its efforts in the field of small satellites, the need for an on-orbit software-defined radio (SDR) has emerged. SDRs are a compact, off-the-shelf, low-cost, low-risk options for small satellite communication and can provide the flexibility of on-orbit configurability. This study includes the research toward the development of an on-orbit SDR CubeSat payload that can transmit on X-band spectrum (8–12 GHz). This band of interest can provide higher data rates and more bandwidth. Work in CubeSat transmitters and receivers supports development of national capabilities in space of benefit to warfighters. The payload designed, built, and tested for this research is called Com-Cube. Com-Cube utilizes hardware components and software considered for incorporation into a future CubeSat payload. Com-Cube was tested on a low altitude balloon (LAB) flight and demonstrated the transmission of images taken in-flight to a ground station via an amateur radio C-band frequency (5.75 GHz). This work directly supports a transmitter and receiver needed for future telemetry, tracking, and command (TT&C) and payload applications in the field of small satellites. This type of payload provides a test platform for further NPS research in the Mobile CubeSat Command and Control (MC3) ground station network operations and broadcast and receive experiments at frequencies of interest. http://archive.org/details/softwaredefinedr1094561218 Outstanding Thesis Lieutenant, United States Navy Approved for public release; distribution is unlimited.

Space situational awareness is extremely important in order to maintain the safety and usability of earth-orbiting satellites, as well as protecting astronauts living and working in space. Traditional space situational awareness is achieved using ground-based radar and optical sensors. This thesis explores the feasibility of space-based space situational awareness using a 3U CubeSat with an optical imager to augment the Space Surveillance Network by capturing conjunctions in space, from which ephemeris data of earth orbiting objects can be updated to more accurately predict future orbital positions. Work completed includes preliminary work towards building, testing, and using a Colony II Bus emulator and interface mechanism, allowing smooth payload and bus integration. Analysis of orbital trajectories for a reference orbit and potential crossing satellites provides insight into the capabilities of the SSA CubeSat. Future work is discussed. http://archive.org/details/enhancingspacesi109455001 US Navy (USN) author Approved for public release; distribution is unlimited.