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Discovering the smallest observed near-earth objects with the space surveillance telescope

February 26, 2019
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Journal Article
Author:
Arthur Lue
…
Published in:
Icarus, Vol. 325, 2019, pp. 105-114.
Topic:
asteroids
R&D area:
R&D group:

Summary

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.
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Summary

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...

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Discovering the smallest observed near-earth objects with the space surveillance telescope

Shining light on thermophysical Near-Earth Asteroid modeling efforts

January 22, 2019
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Conference Paper
Author:
Katrina C. Magno
…
Published in:
1st NEO and Debris Detection Conf., 22-24 January 2019.
Topic:
asteroids
R&D area:
R&D group:

Summary

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.
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Summary

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...

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Shining light on thermophysical Near-Earth Asteroid modeling efforts

SST asteroid search performance 2014-2017

March 3, 2018
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Conference Paper
Author:
Jessica D. Ruprecht
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Published in:
2018 IEEE Aerospace Conf., 3-10 March 2018.
Topic:
asteroids
R&D area:
R&D group:

Summary

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.
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Summary

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...

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SST asteroid search performance 2014-2017

Spatially-resolved individual particle spectroscopy using photothermal modulation of Mie scattering

January 15, 2017
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Journal Article
Author:
Ryan M. Sullenberger
…
Published in:
Opt. Lett., Vol. 42, No. 2, 15 January 2017, pp. 203-6.
Topic:
optics
R&D area:
R&D group:

Summary

We report a photothermal modulation of Mie scattering (PMMS) method that enables concurrent spatial and spectral discrimination of individual micron-sized particles. This approach provides a direct measurement of the "fingerprint" infrared absorption spectrum with the spatial resolution of visible light. Trace quantities (tens of picograms) of material were deposited onto an infrared transparent substrate and simultaneously illuminated by a wavelength-tunable intensity-modulated quantum cascade pump laser and a continuous-wave 532 nm probe laser. Absorption of the pump laser by the particles results in direct modulation of the scatter field of the probe laser. The probe light scattered from the interrogated region is imaged onto a visible camera, enabling simultaneous probing of spatially-separated individual particles. By tuning the wavelength of the pump laser, the IR absorption spectrum is obtained. Using this approach, we measured the infrared absorption spectra of individual 3 um PMMA and silica spheres. Experimental PMMS signal amplitudes agree with modeling using an extended version of the Mie scattering theory for particles on substrates, enabling the prediction of the PMMS signal magnitude based on the material and substrate properties.
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Summary

We report a photothermal modulation of Mie scattering (PMMS) method that enables concurrent spatial and spectral discrimination of individual micron-sized particles. This approach provides a direct measurement of the "fingerprint" infrared absorption spectrum with the spatial resolution of visible light. Trace quantities (tens of picograms) of material were deposited onto...

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Spatially-resolved individual particle spectroscopy using photothermal modulation of Mie scattering

Asteroid search operations with the Space Surveillance Telescope

March 5, 2016
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Conference Paper
Author:
Gregory Ushomirsky
…
Published in:
2016 IEEE Aerospace Conf., 5-12 March 2016.
Topic:
asteroids
R&D area:
R&D group:

Summary

Over the past two years, the Lincoln Near Earth Asteroid Research (LINEAR) program, funded by the National Aeronautics and Space Administration (NASA), has transitioned to asteroid search operations using the new 3.5-meter wide-field-of-view Space Surveillance Telescope (SST) located at the Atom Site on White Sands Missile Range, N.M. The SST was developed for the Defense Advanced Research Projects Agency (DARPA) by MIT Lincoln Laboratory to help advance the nation's capabilities in space situational awareness. The goals of LINEAR using SST are to continue discovering Near-Earth objects (NEOs) especially focusing on improving knowledge of asteroids 140 meters in diameter and larger. In this paper, we will review results of the first two years of asteroid search operations, during which the SST has delivered over 9.4 million observations to the Minor Planet Center. Recent and planned system improvements will also be discussed.
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Summary

Over the past two years, the Lincoln Near Earth Asteroid Research (LINEAR) program, funded by the National Aeronautics and Space Administration (NASA), has transitioned to asteroid search operations using the new 3.5-meter wide-field-of-view Space Surveillance Telescope (SST) located at the Atom Site on White Sands Missile Range, N.M. The SST...

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Asteroid search operations with the Space Surveillance Telescope

Development and application of spherically curved charge-coupled device imagers

April 1, 2015
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Journal Article
Author:
James A. Gregory
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Published in:
Appl. Opt., Vol. 54, No. 10, 1 April 2015, pp. 3072-82.
Topic:
optics
R&D area:
R&D group:

Summary

Operation of a CCD imager on a curved focal surface offers advantages to flat focal planes, especially for lightweight, relatively simple optical systems. The first advantage is that the modulation transfer function can approach diffraction-limited performance for a spherical focal surface employed in large field-of-view or large-format imagers. The second advantage is that a curved focal surface maintains more uniform illumination as a function of radius from the field center. Examples of applications of curved imagers, described here, include a small compact imager and the large curved array used in the Space Surveillance Telescope. The operational characteristics and mechanical limits of an imager deformed to a 15 mm radius are also described.
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Summary

Operation of a CCD imager on a curved focal surface offers advantages to flat focal planes, especially for lightweight, relatively simple optical systems. The first advantage is that the modulation transfer function can approach diffraction-limited performance for a spherical focal surface employed in large field-of-view or large-format imagers. The second...

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Development and application of spherically curved charge-coupled device imagers

Detecting small asteroids with the Space Surveillance Telescope

September 1, 2014
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Journal Article
Author:
Jessica D. Ruprecht
…
Published in:
Icarus, Vol. 239, 2014, pp. 253-9.
Topic:
space
R&D area:
R&D group:

Summary

The ability of the Space Surveillance Telescope (SST) to find small (2-15 m diameter) NEAs suitable for the NASA asteroid retrieval mission is investigated. Orbits from a simulated population of targetable small asteroids were propagated and observations with the SST were simulated. Different search patterns and telescope time allocation cases were considered, as well as losses due to FOV gaps and weather. It is concluded that a full-time, dedicated survey at the SST is likely necessary to find a useful population of these NEAs within the mission launch timeframe, especially if an object must be observed on >1 night at SST to qualify as a detection. The simulations were also performed for an identical telescope in the southern hemisphere, which is found to produce results very similar to the SST in New Mexico due to significant (~80%) overlap in the population of objects detected at each site. In addition to considering the SST's ability to detect small NEAs, a parallel study was performed focusing on >100 m diameter objects. This work shows that even with limited telescope time (3 nights per month) a substantial number of these larger objects would be detected.
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Summary

The ability of the Space Surveillance Telescope (SST) to find small (2-15 m diameter) NEAs suitable for the NASA asteroid retrieval mission is investigated. Orbits from a simulated population of targetable small asteroids were propagated and observations with the SST were simulated. Different search patterns and telescope time allocation cases...

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Detecting small asteroids with the Space Surveillance Telescope

Geospatial analysis based on GIS integrated with LADAR

October 7, 2013
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Journal Article
Author:
Matthew R Fetterman
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Published in:
Opt. Express, Vol. 21, No. 20, 7 October 2013, pp. 23579-91.
Topic:
ladar
R&D area:
R&D group:

Summary

In this work, we describe multi-layered analyses of a high-resolution broad-area LADAR data set in support of expeditionary activities. High-level features are extracted from the LADAR data, such as the presence and location of buildings and cars, and then these features are used to populate a GIS (geographic information system) tool. We also apply line-of-sight (LOS) analysis to develop a path-planning module. Finally, visualization is addressed and enhanced with a gesture-based control system that allows the user to navigate through the enhanced data set in a virtual immersive experience. This work has operational applications including military, security, disaster relief, and task-based robotic path planning.
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Summary

In this work, we describe multi-layered analyses of a high-resolution broad-area LADAR data set in support of expeditionary activities. High-level features are extracted from the LADAR data, such as the presence and location of buildings and cars, and then these features are used to populate a GIS (geographic information system)...

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Geospatial analysis based on GIS integrated with LADAR

Exploring the variable sky with LINEAR. III. classification of periodic light curves

October 1, 2013
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Journal Article
Author:
Lovro Palaversa
…
Published in:
Astron. J., Vol. 146, No. 101, October 2013.
Topic:
LINEAR
R&D area:
R&D group:

Summary

We describe the construction of a highly reliable sample of ~7000 optically faint periodic variable stars with light curves obtained by the asteroid survey LINEAR across 10,000 deg^2 of the northern sky. The majority of these variables have not been cataloged yet. The sample flux limit is several magnitudes fainter than most other wide-angle surveys; the photometric errors range from ~0.03 mag at r = 15 to ~0.20 mag at r = 18. Light curves include on average 250 data points, collected over about 25 million objects, we selected ~200,000 most probable candidate variables with r
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Summary

We describe the construction of a highly reliable sample of ~7000 optically faint periodic variable stars with light curves obtained by the asteroid survey LINEAR across 10,000 deg^2 of the northern sky. The majority of these variables have not been cataloged yet. The sample flux limit is several magnitudes fainter...

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Exploring the variable sky with LINEAR. III. classification of periodic light curves

Exploring the variable sky with LINEAR. II. Halo structure and substructure traces by RR Lyrae stars to 30 kpc

August 1, 2013
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Journal Article
Author:
Branimir Sesar
…
Published in:
Astron. J., Vol. 146, No. 21, August 2013.
Topic:
LINEAR
R&D area:
R&D group:

Summary

We present a sample of ~5000 RR Lyrae stars selected from the recalibrated LINEAR data set and detected at heliocentric distances between 5 kpc and 30 kpc over ~8000 deg^2 of sky. The coordinates and light curve properties, such as period and Oosterhoff type, are made publicly available. We analyze in detail the light curve properties and Galactic distribution of the subset of ~4000 type ab RR Lyrae (RRab) stars, including a search for new halo substructures and the number density distribution as a function of Oosterhoff type. We find evidence for the Oosterhoff dichotomy among field RR Lyrae stars, with the ratio of the type II and I subsamples of about 1:4, but with a weaker separation than for globular cluster stars. The wide sky coverage and depth of this sample allow unique constraints for the number density distribution of halo RRab stars as a function of galactocentric distance: it can be described as an oblate ellipsoid with an axis ratio q = 0.63 and with either a single or a double power law with a power-law index in the range -2 to -3. Consistent with previous studies, we find that the Oosterhoff type II subsample has a steeper number density profile than the Oosterhoff type I subsample. Using the group-finding algorithm EnLink, we detected seven candidate halo groups, only one of which is statistically spurious. Three of these groups are near globular clusters (M53/NGC 5053, M3, M13), and one is near a known halo substructure (Virgo Stellar Stream); the remaining three groups do not seem to be near any known halo substructures or globular clusters and seem to have a higher ratio of Oosterhoff type II to Oosterhoff type I RRab stars than what is found in the halo. The extended morphology and the position (outside the tidal radius) of some of the groups near globular clusters are suggestive of tidal streams possibly originating from globular clusters. Spectroscopic follow-up of detected halo groups is encouraged.
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Summary

We present a sample of ~5000 RR Lyrae stars selected from the recalibrated LINEAR data set and detected at heliocentric distances between 5 kpc and 30 kpc over ~8000 deg^2 of sky. The coordinates and light curve properties, such as period and Oosterhoff type, are made publicly available. We analyze...

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Exploring the variable sky with LINEAR. II. Halo structure and substructure traces by RR Lyrae stars to 30 kpc
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