Publications
The need for spectrum and the impact on weather observations
July 1, 2021
Journal Article
Published in:
Bull. Am. Meteorol. Soc., Vol. 102, No. 7, July 2021, E1402-7.
Topic:
Summary
One of the most significant challenges—and potential opportunities—for the scientific community is society's insatiable need for the radio spectrum. Wireless communication systems have profoundly impacted the world's economies and its inhabitants. Newer technological uses in telemedicine, Internet of Things, streaming services, intelligent transportation, etc., are driving the rapid development of 5G/6G (and beyond) wireless systems that demand ever-increasing bandwidth and performance. Without question, these wireless technologies provide an important benefit to society with the potential to mitigate the economic divide across the world. Fundamental science drives the development of future technologies and benefits society through an improved understanding of the world in which we live. Often, these studies require use of the radio spectrum, which can lead to an adversarial relationship between ever evolving technology commercialization and the quest for scientific understanding. Nowhere is this contention more acute than with atmospheric remote sensing and associated weather forecasts (Saltikoff et al. 2016; Witze 2019), which was the theme for the virtual Workshop on Spectrum Challenges and Opportunities for Weather Observations held in November 2020 and hosted by the University of Oklahoma. The workshop focused on spectrum challenges for remote sensing observations of the atmosphere, including active (e.g., weather radars, cloud radars) and passive (e.g., microwave imagers, radiometers) systems for both spaceborne and ground-based applications. These systems produce data that are crucial for weather forecasting—we chose to primarily limit the workshop scope to forecasts up to 14 days, although some observations (e.g., satellite) cover a broader range of temporal scales. Nearly 70 participants from the United States, Europe, South America, and Asia took part in a concentrated and intense discussion focused not only on current radio frequency interference (RFI) issues, but potential cooperative uses of the spectrum ("spectrum sharing"). Equally important to the workshop's international makeup, participants also represented different sectors of the community, including academia, industry, and government organizations. Given the importance of spectrum challenges to the future of scientific endeavor, the U.S. National Science Foundation (NSF) recently began the Spectrum Innovation Initiative (SII) program, which has a goal to synergistically grow 5G/6G technologies with crucial scientific needs for spectrum as an integral part of the design process. The SII program will accomplish this goal in part through establishing the first nationwide institute focused on 5G/6G technologies and science. The University of California, San Diego (UCSD), is leading an effort to compete for NSF SII funding to establish the National Center for Wireless Spectrum Research. As key partners in this effort, the University of Oklahoma (OU) and The Pennsylvania State University (PSU) hosted this workshop to bring together intellectual leaders with a focus on impacts of the spectrum revolution on weather observations and numerical weather prediction.
Summary
One of the most significant challenges—and potential opportunities—for the scientific community is society's insatiable need for the radio spectrum. Wireless communication systems have profoundly impacted the world's economies and its inhabitants. Newer technological uses in telemedicine, Internet of Things, streaming services, intelligent transportation, etc., are driving the rapid development of...
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What could we do with a 20-meter tower on the Lunar South Pole? Applications of the Multifunctional Expandable Lunar Lite & Tall Tower (MELLTT)
November 16, 2020
Conference Paper
Published in:
ASCEND, virtual event, 16-18 November 2020.
Summary
Lunar polar regions and permanently shadowed regions (PSRs) are a key component of NASA's exploration objectives for the lunar surface, given their potential for a high abundance of volatiles like water. The Massachusetts Institute of Technology (MIT) Big Idea Challenge Team proposed the use of deployable towers to support robotic and remote exploration of these PSRs, alleviating limitations imposed by the rugged terrain. This deployable tower technology (called MELLTT) could enable an extended ecosystem on the lunar surface. This paper seeks to build on this initial concept by showcasing the advantages of self-deploying lightweight lunar towers through the development of various payload concepts. The payloads include 5-kg packages for an initial proof-of-concept deployment, as well as 50-kg payloads and payloads across multiple towers for future exploration architectures. The primary goal of a 5-kg tower payload is to return unique scientific data from a PSR while minimizing risk to a tower technology demonstration mission. Concepts include passive imagers to provide a step-change improvement in resolution, solar reflectors capable of illuminating PSRs, communications infrastructure for human and robotic exploration, a power beaming demonstration, and a PSR impactor. These payloads demonstrate the utility of towers on the lunar surface and how incremental improvements in the capability of towers can further NASA's exploration program.
Summary
Lunar polar regions and permanently shadowed regions (PSRs) are a key component of NASA's exploration objectives for the lunar surface, given their potential for a high abundance of volatiles like water. The Massachusetts Institute of Technology (MIT) Big Idea Challenge Team proposed the use of deployable towers to support robotic...
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Data trust methodology: a blockchain-based approach to instrumenting complex systems
August 5, 2020
Technical Report
Published in:
MIT Lincoln Laboratory Report TR-1256
Summary
Increased data sharing and interoperability has created challenges in maintaining a level of trust and confidence in Department of Defense (DoD) systems. As tightly-coupled, unique, static, and rigorously validated mission processing solutions have been supplemented with newer, more dynamic, and complex counterparts, mission effectiveness has been impacted. On the one hand, newer deeper processing with more diverse data inputs can offer resilience against overconfident decisions under rapidly changing conditions. On the other hand, the multitude of diverse methods for reaching a decision may be in apparent conflict and decrease decision confidence. This has sometimes manifested itself in the presentation of simultaneous, divergent information to high-level decision makers. In some important specific instances, this has caused the operators to be less efficient in determining the best course of action. In this paper, we will describe an approach to more efficiently and effectively leverage new data sources and processing solutions, without requiring redesign of each algorithm or the system itself. We achieve this by instrumenting the processing chains with an enterprise blockchain framework. Once instrumented, we can collect, verify, and validate data processing chains by tracking data provenance using smart contracts to add dynamically calculated metadata to an immutable and distributed ledger. This noninvasive approach to verification and validation in data sharing environments has the power to improve decision confidence at larger scale than manual approaches, such as consulting individual developer subject matter experts to understand system behavior. In this paper, we will present our study of the following: 1. Types of information (i.e., knowledge) that are supplied and leveraged by decision makers and operational contextualized data processes (Figure 1) 2. Benefits to verifying data provenance, integrity, and validity within an operational processing chain 3. Our blockchain technology framework coupled with analytical techniques which leverage a verification and validation capability that could be deployed into existing DoD data-processing systems with insignificant performance and operational interference.
Summary
Increased data sharing and interoperability has created challenges in maintaining a level of trust and confidence in Department of Defense (DoD) systems. As tightly-coupled, unique, static, and rigorously validated mission processing solutions have been supplemented with newer, more dynamic, and complex counterparts, mission effectiveness has been impacted. On the one...
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Design, simulation, and fabrication of three-dimensional microsystem components using grayscale photolithography
October 1, 2019
Journal Article
Published in:
J. Micro/Nanolith., Vol. 18, No. 4, October - December 2019, 043507.
Summary
Grayscale lithography is a widely known but underutilized microfabrication technique for creating three-dimensional (3-D) microstructures in photoresist. One of the hurdles for its widespread use is that developing the grayscale photolithography masks can be time-consuming and costly since it often requires an iterative process, especially for complex geometries. We discuss the use of PROLITH, a lithography simulation tool, to predict 3-D photoresist profiles from grayscale mask designs. Several examples of optical microsystems and microelectromechanical systems where PROLITH was used to validate the mask design prior to implementation in the microfabrication process are presented. In all examples, PROLITH was able to accurately and quantitatively predict resist profiles, which reduced both design time and the number of trial photomasks, effectively reducing the cost of component fabrication.
Summary
Grayscale lithography is a widely known but underutilized microfabrication technique for creating three-dimensional (3-D) microstructures in photoresist. One of the hurdles for its widespread use is that developing the grayscale photolithography masks can be time-consuming and costly since it often requires an iterative process, especially for complex geometries. We discuss...
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Discovering the smallest observed near-earth objects with the space surveillance telescope
February 26, 2019
Journal Article
Published in:
Icarus, Vol. 325, 2019, pp. 105-114.
Topic:
R&D area:
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.
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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Shining light on thermophysical Near-Earth Asteroid modeling efforts
January 22, 2019
Conference Paper
Published in:
1st NEO and Debris Detection Conf., 22-24 January 2019.
Topic:
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.
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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Adversarial co-evolution of attack and defense in a segmented computer network environment
July 15, 2018
Conference Paper
Published in:
Proc. Genetic and Evolutionary Computation Conf. Companion, GECCO 2018, 15-19 July 2018, pp. 1648-1655.
Summary
In computer security, guidance is slim on how to prioritize or configure the many available defensive measures, when guidance is available at all. We show how a competitive co-evolutionary algorithm framework can identify defensive configurations that are effective against a range of attackers. We consider network segmentation, a widely recommended defensive strategy, deployed against the threat of serial network security attacks that delay the mission of the network's operator. We employ a simulation model to investigate the effectiveness over time of different defensive strategies against different attack strategies. For a set of four network topologies, we generate strong availability attack patterns that were not identified a priori. Then, by combining the simulation with a coevolutionary algorithm to explore the adversaries' action spaces, we identify effective configurations that minimize mission delay when facing the attacks. The novel application of co-evolutionary computation to enterprise network security represents a step toward course-of-action determination that is robust to responses by intelligent adversaries.
Summary
In computer security, guidance is slim on how to prioritize or configure the many available defensive measures, when guidance is available at all. We show how a competitive co-evolutionary algorithm framework can identify defensive configurations that are effective against a range of attackers. We consider network segmentation, a widely recommended...
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SST asteroid search performance 2014-2017
March 3, 2018
Conference Paper
Published in:
2018 IEEE Aerospace Conf., 3-10 March 2018.
Topic:
R&D area:
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.
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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Asteroid search operations with the Space Surveillance Telescope
March 5, 2016
Conference Paper
Published in:
2016 IEEE Aerospace Conf., 5-12 March 2016.
Topic:
R&D area:
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.
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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Detecting small asteroids with the Space Surveillance Telescope
September 1, 2014
Journal Article
Published in:
Icarus, Vol. 239, 2014, pp. 253-9.
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R&D area:
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.
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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