A precise measurement of the Cosmic X-Ray Background (CXB) is crucial for constraining models of the evolution and composition of the universe. While many large, expensive satellites have measured the CXB as a secondary mission, there is still disagreement about normalization of its spectrum. The Cosmic X-Ray Background NanoSat (CXBN) is a small, low-cost satellite whose primary goal is to measure the CXB over its two-year lifetime. Benefiting from a low instrument-induced background due to its small mass and size, CXBN will use a novel, pixelated Cadmium Zinc Telluride (CZT) detector with energy resolution < 1 keV over the range 1-60 keV to measure the CXBN with unprecedented accuracy. This paper describes CXBN and its science payload, including the GEANT4 model that has been used to predict overall performance and the backgrounds from secondary particles in Low Earth Orbit. It also addresses the strategy for scanning the sky and calibrating the data, and presents the expected results over the two-year mission lifetime.

(MSU), Morehead, KY (USA) engages undergraduate students in the development and operation of nano-and microsatellite systems to provide real-world engineering opportunities and training experiences. The Space Science Center operates several ground stations, including low-bandwidth VHF/UHF systems and a 21-meter diameter, full motion, parabolic dish antenna system, to support these and other university-based small satellite missions. The MSU 21-m Space Tracking Antenna is capable of providing telemetry, tracking, and command (TT&C) services for a wide variety of space missions. The 21-m has the capacity to track satellites in low earth orbit (LEO) with extremely low transmission power, as well as satellites at geostationary, lunar, and Earth-Sun Lagrangian orbits. The system currently operates at L-, S-, C-, X-and Ku-bands. The instrument is primarily operated by undergraduate students who work in the associated laboratories to gain hands-on training in RF systems and techniques. The 21-m is also used as a test bed for advanced RF systems developed by faculty and collaborators, and has been employed in a growing portfolio of satellite missions including serving as the primary ground station for KySat-1, a secondary ground station for EduSat, and as the primary high-bandwidth ground stations for Radio Auroral Explorer 2 (RAX2) and the Cosmic X-Ray Background NanoSatellite (CXBN) missions. The system has also been employed in the testing and calibration of the NASA Lunar Reconnaissance Orbiter synthetic aperture radar (mini-SAR) at X-and S-bands. The team is in the process of upgrading the system to incorporate automated operations and to become Space Link Extension (SLE) compliant. This paper describes the current nanosatellite missions managed by the Space Science Center and the ground operations components of these missions (including the challenges and constraints imposed by the university-based non-commercial structure), all of which are

MSU), Morehead, KY (USA) operates a 21 meter diameter, full motion, research quality, parabolic dish antenna system, built under contract for MSU by Vertex-RSI, one of the premier fabrication corporations for high gain antennas. This system, referred to as the MSU 21 m Space Tracking Antenna, is engaged in ongoing research programs in radio astronomy and is also capable of operation in a satellite ground station mode, providing telemetry, tracking, and command (TT&C) services for a wide variety of satellite systems. The 21 m is used as a test bed for advanced RF systems developed by the faculty, students, and collaborators. This system has the capability of tracking fast moving, low transmitting power small satellites in low Earth orbit (LEO), as well as satellites at geostationary, lunar, and potentially Earth-Sun Lagrangian orbits. Currently configured for operation at L-,band and Ku-band, with feeds being implemented at S-band and near term plans for the development of a C-band system, with others planned. The instrument also serves as an active laboratory for students engaged in research and training in space science, electrical and mechanical engineering, telecommunications electronics, astrophysics, and space systems operation. The instrument is largely operated by undergraduate students who work in the associated laboratories to achieve hands-on training in RF systems and techniques. The instrument serves as the primary Earth station facility for the Kentucky Space Program which develops and operates small satellites (cubesats and other picosats) for education and workforce development. Cubesat (1 kg pico-class satellites) programs offer outstanding education and training experience at low cost. They have evolved into a highly flexible and useful platform, having been flown by numerous universities, NASA, and a number of aerospace companies. The 21 m supports the small satellite community and in particular cubesat programs. In addition to providing ground operations support for small satellite programs, the 21 m is currently engaged in a rigorous scientific program in fundamental research (radio observations of micro-variability in active galactic nuclei (AGNs) and observations of transient events, (i.e. radio afterglow of Gamma Ray Bursts) and applied research (RF systems development). Current ongoing missions supported by the 21 m include the Kentucky Space program orbiting satellite (KySat-1), scheduled for launch in November 2010 as secondary payload on NASA's Glory mission, and suborbital missions typically flown on sounding rockets from NASA's Wallops Flight Facility (Wallops Island, VA). Additional missions include supporting ongoing testing and calibration of the NASA Lunar Reconnaissance Orbiter (LRO) Mini-RF instrument, a multi-function payload that includes capabilities as a spacebased synthetic aperture radar and communication system, among others.

Preface A major research effort, the Global Tropospheric Experiment (GTE), has been initiated by the National Aeronautics and Space Administration (NASA) to study the chemistry of the global troposphere and its interaction with the stratosphere, land, and oceans. The first phase of GTE is aimed at developing and validating measurement techniques for trace species in tropospheric chemical cycles. It is designed to lead toward development and implementation of a cooperative research program involving NASA, scientists sponsored by the National Science Foundation, other government agencies, and research institutions abroad. The goal of the GTE is to understand the chemical cycles that control the composition of the global troposphere and its changes. The first major field program conducted as part of the GTE was denoted as Chemical Instrumentation Test and Evaluation (CITE 1). The principal thrusts of CITE 1 were aimed at evaluating advanced technologies for measurement of carbon monoxide (CO), nitric oxide (NO), and the hydroxyl radical (OH). An ad hoc scientific steering committee, established in 1982, recommended a three-step test and evaluation program involving a ground-based inter-comparison; an airborne intercomparison in the tropical troposphere, with particular attention to the boundary layer; and an airborne ]ntercomparison in the upper troposphere. This strategy was adopted in order to expose the measurement systems under evaluation to conditions expected to be encountered during future GTE field experiments. Island, Virginia, in July 1983. The airborne portions of CITE 1 were conducted onboard the NASA CV-990 aircraft platform. The first airborne mission focused on intercomparison in a tropical troposphere and was conducted in October 1983. The second airborne mission focused on the upper troposphere and was conducted in April 1984. The GTE/CITE 1 papers in this issue are devoted to a description of the activities and results from the ground-based intercomparison. Results from the airborne missions will be reported in a subsequent special issue of this journal.

No abstract