Publications

The Space Surveillance Telescope (SST) is an advanced optical sensor designed and tested by MIT Lincoln Laboratory for the Defense Advanced Research Projects Agency (DARPA), which is currently in the process of being integrated into the Space Surveillance Network. By operating the telescope in a manner normally intended for the discovery of small, artificial space objects, SST is serendipitously sensitive to the detection of very small asteroids as they traverse close to the Earth, passing rapidly through SST's search volume. This mode of operation stands in contrast to the standard approach for the search and discovery of asteroids and near-Earth objects (NEOs), in which longer revisit times restrict survey sensitivities to objects moving no faster than about 20 degrees/day. From data collected during SST's observation runs in New Mexico, we detail the discovery of 92 new candidate objects in heliocentric orbit whose absolute magnitudes range from H=26.4 to 35.9 (approximately 18-m to 25-cm in size). Some of these discoveries represent the smallest natural objects ever observed in orbit. We compare the candidate objects with bolide observations.

Comprehensive thermophysical analyses of Near-Earth Asteroids (NEAs) provide important information about their physical properties, including visible albedo, diameter, composition, and thermal inertia. These details are integral to defining asteroid taxonomy and understanding how these objects interact with the solar system. Since infrared (IR) asteroid observations are not widely available, thermophysical modeling techniques have become valuable in simulating properties of different asteroid types. Several basic models that assume a spherical asteroid shape have been used extensively within the research community. As part of a program focused on developing a simulation of space-based IR sensors for asteroid search, the Near-Earth Asteroid Model (NEATM) developed by Harris, A. in 1998, was selected. This review provides a full derivation of the formulae behind NEATM, including the spectral flux density equation, consideration of the solar phase angle, and the geometry of the asteroid, Earth, and Sun system. It describes how to implement the model in software and explores the use of an ellipsoidal asteroid shape. It also applies the model to several asteroids observed by NASA's Near-Earth Object Wide-field Survey Explorer (NEOWISE) and compares the performance of the model to the observations.

From 2014 to 2017, the Lincoln Near-Earth Asteroid Research (LINEAR) program performed wide-area asteroid search using the 3.5-m Space Surveillance Telescope (SST) located on Atom Peak at White Sands Missile Range, N.M. The SST was developed by MIT Lincoln Laboratory (MIT/LL) for the Defense Advanced Research Projects Agency (DARPA) to advance the nation's capabilities in space situational awareness. LINEAR asteroid search using SST was funded by the National Aeronautics and Space Administration (NASA). During three years of asteroid search operations, the SST had more than 14 million observations accepted by the Minor Planet Center (MPC) and contributed to the discovery of 142 previously unknown near-Earth objects (NEOs). This paper provides a summary of SST asteroid search performance during the three years of operation at Atom Peak, and describes performance improvements achieved through processing software upgrades, refinements in search strategy, and hardware upgrades such as the successful installation of Wide-Field Camera 2 (WFC-2) in summer 2016.

The Lincoln Near-Earth Asteroid Research (LINEAR) program has applied electro-optical technology developed for Air Force Space Surveillance applications to the problem of discovering near-Earth asteroids (NEAs) and comets. This application is natural due to the commonality between the surveillance of the sky for man-made satellites and the search for near-Earth objects (NEOs). Both require the efficient search of broad swaths of sky to detect faint, moving objects. Currently, the Air Force Ground-based Electro-Optic Deep Space Surveillance (GEODSS) systems, which operate as part of the worldwide U.S. space surveillance network, are being upgraded to state-of-the-art charge-coupled device (CCD) detectors. These detectors are based on recent advances made by MIT Lincoln Laboratory in the fabrication of large format, highly sensitive CCDs. In addition, state-of-the-art data processing algorithms have been developed to employ the new detectors for search operations. In order to address stressing space surveillance requirements, the Lincoln CCDs have a unique combination of features, including large format, high quantum efficiency, frame transfer, high readout rate, and low noise, not found on any commercially available CCD. Systems development for the GEODSS upgrades has been accomplished at the Lincoln Laboratory Experimental Test Site (ETS) located near Socorro, New Mexico, over the past several years. Starting in 1996, the Air Force funded a small effort to demonstrate the effectiveness of the CCD and broad area search technology when applied to the problem of finding asteroids and comets. This program evolved into the current LINEAR program, which is jointly funded by the Air Force Office of Scientific Research and NASA. LINEAR, which started full operations in March of 1998, has discovered through September of 1999, 257 NEAs (of 797 known to date), 11 unusual objects (of 44 known), and 32 comets. Currently, LINEAR is contributing ~70% of the worldwide NEA discovery rate and has single-handedly increased the observations submitted to the Minor Planet Center by a factor of 10. This paper covers the technology used by the program, the operations, and the detailed results of the search efforts.

Lincoln Laboratory has been developing electro-optical space-surveillance technology to detect, characterize, and catalog satellites for more than forty years. Recent advances in highly sensitive, large-format charge-coupled devices (CCDs) allow this technology to be applied to detecting and cataloging asteroids, including near-Earth objects (NEOs). When equipped with a new Lincoln Laboratory focal-plane camera and signal processing technology, the 1-m U.S. Air Force ground-based electro-optical deep-space surveillance (GEODSS) telescopes can conduct sensitive large-coverage searches for Earth-crossing and main-belt asteroids. Field measurements indicate that these enhanced telescopes can achieve a limiting magnitude of 22 over a 2-deg2 field of view with less than 100 sec of integration. This sensitivity rivals that of much larger telescopes equipped with commercial cameras. Working two years under U.S. Air Force sponsorship, we have developed technology for asteroid search operations at the Lincoln Laboratory Experimental Test Site near Socorro, New Mexico. By using a new large-format 2560 X 1960-pixel frame-transfer CCD camera, we have discovered over 10,000 asteroids, including 53 NEOs and 4 comets as designated by the Minor Planet Center (MPC). In March 1998, the Lincoln Near-Earth Asteroid Research (LINEAR) program provided over 150,000 observations of asteroids--nearly 90% of the world's asteroid observations that month--to the MPC, which resulted in the discovery of 13 NEOs and 1 comet. The MPC indicates that the LINEAR program outperforms all asteroid search programs operated to date.

Over the past several years, the Air Force has been developing new devices and technology for the detection and tracking of earth orbiting satellites. This technology has been targeted to provide an upgraded capability for an operational space surveillance system called GEODSS. Currently, a number of GEODSS systems are deployed around the world as part of the world-wide space surveillance system operated by the US Air Force. Each GEODSS site is currently equipped with 1-meter class telescopes and EBSICON detector systems which represent 1970's technology. The Air Force is now in the process of upgrading the GEODSS system to achieve the performance offered by state of the art detector systems. Under Air Force sponsorship, Lincoln Laboratory has developed a new generation of sensitive, large format, frame transfer CCD focal planes for GEODSS. These focal planes have been installed in a new generation of cameras and are currently undergoing testing at the Lincoln Laboratory Experimental Test Site (ETS). When equipped with the new focal plane and camera technology, the modest sized GEODSS telescopes have considerable capability to conduct large coverage, sensitive searches for earth crossing asteroids. Theoretical analysis has indicated that the CCD equipped GEODSS telescope will be capable of achieving a limiting magnitude of 22, over a 2 sq/deg field of view, with about 100 seconds of integration. This is comparable to the sensitivity of considerably larger telescopes equipped with current cameras. In addition to the high sensitivity, the CCD is configured for frame transfer operations which are well suited to asteroid search operations. This paper will present the results of the initial system tests conducted at the ETS and will discuss how this technology fits into a concept of operations for a planetary defense system based on the Air Force developed technology.