Remote Ultra-Low Light Imaging detectors are photon limited detectors developed at Los Alamos National
Laboratories. RULLI detectors provide a very high degree of temporal resolution for the arrival times of detected photoevents,
but saturate at a photo-detection rate of about 106 photo-events per second. Rather than recording a conventional
image, such as output by a charged coupled device (CCD) camera, the RULLI detector outputs a data stream consisting
of the two-dimensional location, and time of arrival of each detected photo-electron. Hence, there is no need to select a
specific exposure time to accumulate photo-events prior to the data collection with a RULLI detector - this quantity can
be optimized in post processing. RULLI detectors have lower peak quantum efficiency (from as low as 5% to perhaps as
much as 40% with modern photocathode technology) than back-illuminated CCD's (80% or higher). As a result of these
factors, and the associated analyses of signal and noise, we have found that RULLI detectors can play two key new roles
in SSA: passive imaging of exceedingly dim objects, and three-dimensional imaging of objects illuminated with an
appropriate pulsed laser. In this paper we describe the RULLI detection model, compare it to a conventional CCD
detection model, and present analytic and simulation results to show the limits of performance of RULLI detectors used
for SSA applications at AMOS field site.
The number of objects orbiting the Earth has been increasing dramatically since the launch of Sputnik in the late 1950's. Thousands of orbiting objects, active satellites or debris, need to be tracked to ensure the accuracy of their orbital elements. To meet the growing needs for space surveillance and orbital debris tracking, the Air Force Maui Optical and Supercomputing Site (AMOS) on Maui, Hawaii is bringing back one of the original Baker-Nunn cameras as the Phoenix Telescope to contribute to these efforts. The Phoenix Telescope retains the wide-field attribute of the original system, while the addition of enhanced optics allows the use of a 4k × 4k pixels back-illuminated CCD array as the imaging camera to provide a field-of-view of 6.8 degrees square (9.6 degrees diagonal). An integrated software suite automates the majority of the operational functions, and allows the system to process in-frame multiple-object acquisitions. The wide-field capability of the Phoenix Telescope is not only an effective tool in the space surveillance effort, but it also has a very high potential value for efforts in searching for and tracking Near-Earth objects (NEO). The large sky coverage provided by the Phoenix Telescope also has the potential to be used in searching for supernova and other astronomical phenomena. An overview of the Phoenix system and results obtained since first-light are presented.
The AMOS 1.2-m telescope is being used 18 nights per month to search for Near-Earth Asteroids (NEA). Since telescope time is a very valuable resource, our goal is to use the telescope as efficiently as possible. This includes striving to maximize the utility of each observation. Since the NEAT searches are within the ecliptic, the same part of the sky as geosynchronous satellites, these search fields contain satellite tracks as well as asteroids. We present the results of simulations of the number of satellites that should be found within the field of view based upon the field centers and times for several nights. We have also examined the NEAT images for geosynchronous objects and present these results. During the remaining nights each month, we use the NEAT camera to obtain observations of deep-space satellites. This data will also be presented. We also present the results of simulations for optimizing search strategies for deep-space objects using NEAT and other AMOS sensors.
The purpose of this research is to improve the knowledge of the physical properties of orbital debris, specifically the material type. Combining the use of the fast-tracking United States Air Force Research Laboratory (AFRL) telescopes with a common astronomical technique, spectroscopy, and NASA resources was a natural step toward determining the material type of orbiting objects remotely. Currently operating at the AFRL Maui Optical Site (AMOS) is a 1.6-meter telescope designed to track fast moving objects like those found in lower Earth orbit (LEO). Using the spectral range of 0.4 - 0.9 microns (4000 - 9000 angstroms), researchers can separate materials into classification ranges. Within the above range, aluminum, paints, plastics, and other metals have different absorption features as well as slopes in their respective spectra. The spectrograph used on this telescope yields a three-angstrom resolution; large enough to see smaller features mentioned and thus determine the material type of the object. The results of the NASA AMOS Spectral Study (NASS) are presented herein.
The Spica and Kala spectrographs located at the rear blanchard of the 1.6 m telescope and the trunnion port of the AEOS 3.67 m telescope, respectively, have been utilized by several DoD and NASA agencies requiring relatively high resolution spectroscopic observations. The sensors are located at the Air Force Maui Optical Station (AMOS), Haleakala, Maui. Three R&D programs utilizing these instruments will be described. The AFRL propulsion directorate's demonstration called the electric propulsion space experiment (ESEX) utilized Spica to evaluate high powered arc-jet thruster firings from the ARGOS satellite. AFRL Det. 15 and Air Force Battlelab sponsored a project called SILC to explore the advantages of applying spectroscopic analysis to help reduce satellite cross- tagging and augment Satellite Object Identification (SOI). Thirdly, the NASA Johnson Space Center Space Debris Program obtained spectroscopic data on Low Earth Orbit (LEO) targets to help determine albedo and material composition of space debris.
The Raven optical sensor is a commercial system being developed and tested by the Air Force Research Laboratory. It allows for a low cost method for obtaining high accuracy angular observations of space objects (manmade and celestial) with a standard deviation of approximately one arcsecond or less. Presented here is an overview of the past and present successes and future projects utilizing Raven. This system has evolved into a very viable and cost effective solution for obtaining low-cost observations for satellite and asteroid catalog and follow-up maintenance. Collaborative efforts between AFRL and several space agencies (JPL, NASA, Space Battlelab, Canadian Defense Ministry, etc) have successfully demonstrated and utilized the Raven system for their missions, including improved satellite orbit determination accuracy, NEO follow-ups, and remote autonomous collecting and reporting of metric data on deep space objects.