The National Radio Astronomy Observatory (NRAO) builds, operates, and maintains a suite of premier radio antennas, including the 100m aperture Green Bank Telescope, the largest fully-steerable antenna in the world. For more than five decades the NRAO has focused on astrophysics, providing researchers with the most advanced instruments possible: large apertures, extremely low-noise receivers, and signal processors with high frequency and time resolution. These instruments are adaptable to Space Situational Awareness (SSA) tasks such as radar detection of objects in near-Earth and cis-Lunar space, high accuracy orbit determination, object surveillance with passive methods, and uplink and downlink communications. We present the capabilities of antennas and infrastructure at the NRAO Green Bank Observatory in the context of SSA tasks, and discuss what additions and modifications would be necessary to achieve SSA goals while preserving existing radio astronomy performance. We also discuss how the Green Bank Observatory’s surrounding topography and location within the National Radio Quiet Zone will enhance SSA endeavors.
We present the design, commissioning, and initial results of the Green Bank Earth Station (GBES), a RadioAstron data downlink station located at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia. The GBES uses the modernized and refurbished NRAO 140ft telescope. Antenna optics were refurbished with new motors and drives fitted to the secondary mirror positioning system, and the deformable subreflector was refurbished with a new digital controller and new actuators. A new monitor and control system was developed for the 140ft and is based on that of the Green Bank Telescope (GBT), allowing satellite tracking via a simple scheduling block. Tools were developed to automate antenna pointing during tracking. Data from the antenna control systems and logs are retained and delivered with the science and telemetry data for processing at the Astro Space Center (ASC) of the Lebedev Physical Institute (LPI) of the Russian Academy of Sciences and the mission control centre, Lavochkin Association.
With a 100-meter aperture, and recent improvements to its surface accuracy and servo system upgrades, the Robert C.
Byrd Green Bank Telescope is the most sensitive telescope operating at 90 GHz. A dual-feed heterodyne receiver is
developed for observations at the lower frequency end of the 3-4mm atmospheric window (67 to 93 GHz). The science
goals are primarily molecular spectroscopic studies of star formation and astrochemistry both internal and external to the
Milky Way galaxy. Studies of the structural and physical properties of star-forming, cold-cloud cores will be
revolutionized with molecular spectroscopy of the deuterium and other important species within the band. Essential for
spectroscopy is the ability to remove slow gain and atmospheric variations. An optical table external to the cooled
components rotates into the path of either beam an ambient temperature load, an offset mirror for viewing an internal
cold load, or a quarter-wave plate that produces circular polarization for VLBI observations. A composite waveguide
window comprised of HDPE, Zitex, and z-cut quartz provides a high-strength, low-loss medium for transmission of the
signal to the cooled corrugated feed horn. An orthomode transducer separates the polarization components which are
amplified by low noise HEMT amplifiers. Warm W-band MMIC amplifiers are required to compensate a negative gain
slope and to reduce noise contributions from the down conversion to the GBT IF frequencies. Initial science results and
receiver performance during commissioning observations will be presented along with details of the component design.