86 research outputs found
Monitoring Earth Surface Changes from Space
This report gives an overview of the activities which have been undertaken as part of the
technical follow-on to the large study āMonitoring Earth Surface Changes from Spaceā. In addition to the
support provided by the Keck Institute for Space Studies, these activities have been supported by
matching funds from the Gordon and Betty Moore Foundation, from UAE and Kuwait, and from the
MDAP NASA program.
Activities were organized under five different themes, each lead by a different PI:
1- Optical Image Time-Series (PI: Sebastien Leprince). These activities aim at developing
techniques to analyze optical images acquired by different imaging systems and at different times
to look at general landscape evolution (evolutions due to tectonic activity, glacier flow,
landslides, sand dunes migration, etc.). They also aim at building a framework for large scale
processing to look at global changes.
2- SAR Time-Series Analysis (PI: Mark Simons). These activities aim at developing techniques to
analyze radar image time series, in particular via interferrometric techniques. These activities
involve close interactions with JPL via the ARIA project (PI: Susan Owen).
3- Seismic Waves Imaging (PI: Pablo Ampuero). These activities aim at developing techniques for
seismic inversion with dense measurement in time and space, such as measurement that would be
provided by a space seismometer. These activities involve close interactions with JPL, which
received a matching R&TD funding to investigate the development of a space optical
seismometer (PI: David Redding).
4- Sub-surface Imaging (PI: Essam Heggy). These activities involve close interactions at testing the
possibility of an Earth orbiting Ground Penetrating Radar (GPR). Within the scope of this project,
only airborne applications will be sought after, with study for space applications.
5- Science Applications (PI: Mike Lamb). These activities involve taking advantage of the
techniques developed by the other groups. It also drives the technical developments and foresees
the external visitor program.
We detail below these activities. Each sub-section has software products, publications, and/or conference
posters/talks as outcome. All publications and presentations in international meetings are listed again at
the end of the report together with a few other publications produced by collaborators who have
participated in the KISS study but did not receive funding from us. Regarding the āseismic waves
imagingā project, we have explored different designs and mission concepts for a 4 m-class Seismic
Imager Geostationnary satellite system. We are currently working on estimating the cost and preparing a
draft GSI Mission Whitepaper
Concept for a Distributed, Modular, In-space Robotically Assembled, RF Communication Payload in GEO
In this paper, we discuss a concept for a Radio Frequency
(RF) Ka band communications payload that is robotically assembled and serviced in space using a servicing vehicle
such as the Robotic Servicing of Geosynchronous Satellites
(RSGS) vehicle being developed by the Defense Advance Research Projects Agency (DARPA). Our work focuses on how to
modularize a representative Ka band communications payload
into discrete modules that are hosted on a persistent platform. In our concept, each module consists of a primary aperture and the associated RF and electronics required to serve a particular coverage area or type. These modules are notionally packaged in a form factor capable of launching as a secondary payload via an EELV Secondary Payload Adapter (ESPA) ring or a Payload Orbital Delivery System (PODS) module. The overall payload consists of an earth coverage module, regional coverage modules, high gain regional coverage modules, and a host interface unit (HIU). We discuss the notional capabilities and requirements of each module. We present two different architecture concepts corresponding to two different persistent platform concepts. In one concept, the persistent platform is made up of small, independent spacecraft that are connected together with structural members with communication channels. The payload
modules are hosted on the individual spacecraft. In the second approach, the platform consists of a large central spacecraft with a structural truss that has power, communication and thermal loops. The payload modules are hosted on the truss through standard interfaces. We present aspects of the mission concept on how the payload may be modularized, launched (as secondary launch elements), acquired by the RSGS vehicle in space and assembled on to the persistent platform. We discuss the robotics aspects of assembly and servicing of the payload modules. A key aspect of this concept is the serviceability of the payload. Central to the modular and discrete payload design is an intent to refurbish the payload incrementally as technology evolves or the components fail. Existing geosynchronous
communication satellites are designed and built as monolithic spacecraft which makes any servicing beyond refueling fairly complicated. This makes it hard to take advantage of the post launch evolution in technology, particularly in the electronics elements. Our concept is aimed at modularizing the payload such that the modules, particularly the electronics elements, can be easily serviced using the RSGS vehicle. Our concept attempts to take advantage of the long service life of high reliability system components in the core satellite bus while allowing
rapid expansion and upgrading of the communications payload
through the addition and replacement of individual payload
modules
Concept for a Distributed, Modular, In-space Robotically Assembled, RF Communication Payload in GEO
In this paper, we discuss a concept for a Radio Frequency
(RF) Ka band communications payload that is robotically assembled and serviced in space using a servicing vehicle
such as the Robotic Servicing of Geosynchronous Satellites
(RSGS) vehicle being developed by the Defense Advance Research Projects Agency (DARPA). Our work focuses on how to
modularize a representative Ka band communications payload
into discrete modules that are hosted on a persistent platform. In our concept, each module consists of a primary aperture and the associated RF and electronics required to serve a particular coverage area or type. These modules are notionally packaged in a form factor capable of launching as a secondary payload via an EELV Secondary Payload Adapter (ESPA) ring or a Payload Orbital Delivery System (PODS) module. The overall payload consists of an earth coverage module, regional coverage modules, high gain regional coverage modules, and a host interface unit (HIU). We discuss the notional capabilities and requirements of each module. We present two different architecture concepts corresponding to two different persistent platform concepts. In one concept, the persistent platform is made up of small, independent spacecraft that are connected together with structural members with communication channels. The payload
modules are hosted on the individual spacecraft. In the second approach, the platform consists of a large central spacecraft with a structural truss that has power, communication and thermal loops. The payload modules are hosted on the truss through standard interfaces. We present aspects of the mission concept on how the payload may be modularized, launched (as secondary launch elements), acquired by the RSGS vehicle in space and assembled on to the persistent platform. We discuss the robotics aspects of assembly and servicing of the payload modules. A key aspect of this concept is the serviceability of the payload. Central to the modular and discrete payload design is an intent to refurbish the payload incrementally as technology evolves or the components fail. Existing geosynchronous
communication satellites are designed and built as monolithic spacecraft which makes any servicing beyond refueling fairly complicated. This makes it hard to take advantage of the post launch evolution in technology, particularly in the electronics elements. Our concept is aimed at modularizing the payload such that the modules, particularly the electronics elements, can be easily serviced using the RSGS vehicle. Our concept attempts to take advantage of the long service life of high reliability system components in the core satellite bus while allowing
rapid expansion and upgrading of the communications payload
through the addition and replacement of individual payload
modules
Workshop on advanced technologies for planetary instruments
NASA's robotic solar system exploration program requires a new generation of science instruments. Design concepts are now judged against stringent mass, power, and size constraints--yet future instruments must be highly capable, reliable, and, in some applications, they must operate for many years. The most important single constraint, however, is cost: new instruments must be developed in a tightly controlled design-to-cost environment. Technical innovation is the key to success and will enable the sophisticated measurements needed for future scientific exploration. As a fundamental benefit, the incorporation of breakthrough technologies in planetary flight hardware will contribute to U.S. industrial competitiveness and will strengthen the U.S. technology base. The Workshop on Advanced Technologies for Planetary Instruments was conceived to address these challenges, to provide an open forum in which the NASA and DoD space communities could become better acquainted at the working level, and to assess future collaborative efforts. Over 300 space scientists and engineers participated in the two-and-a-half-day meeting held April 28-30, 1993, in Fairfax, Virginia. It was jointly sponsored by NASA's Solar System Exploration Division (SSED), within the Office of Space Science (OSS); NASA's Office of Advanced Concepts and Technology (OACT); DoD's Strategic Defense Initiative Organization (SDIO), now called the Ballistic Missile Defense Organization (BMDO); and the Lunar and Planetary Institute (LPI). The meeting included invited oral and contributed poster presentations, working group sessions in four sub-disciplines, and a wrap-up panel discussion. On the first day, the planetary science community described instrumentation needed for missions that may go into development during the next 5 to 10 years. Most of the second day was set aside for the DoD community to inform their counterparts in planetary science about their interests and capabilities, and to describe the BMDO technology base, flight programs, and future directions. The working group sessions and the panel discussion synthesized technical and programmatic issues from all the presentations, with a specific goal of assessing the applicability of BMDO technologies to science instrumentation for planetary exploration
Recent Milestones in Unraveling the Full-Field Structure of Dynamic Shear Cracks and Fault Ruptures in Real-Time: From Photoelasticity to Ultrahigh-Speed Digital Image Correlation
The last few decades have seen great achievements in dynamic fracture mechanics. Yet, it was not possible to experimentally quantify the full-field behavior of dynamic fractures, until very recently. Here, we review our recent work on the full-field quantification of the temporal evolution of dynamic shear ruptures. Our newly developed approach based on digital image correlation combined with ultrahigh-speed photography has revolutionized the capabilities of measuring highly transient phenomena and enabled addressing key ques- tions of rupture dynamics. Recent milestones include the visualization of the complete displacement, particle velocity, strain, stress and strain rate fields near growing ruptures, capturing the evolution of dynamic friction during individual rupture growth, and the detailed study of rupture speed limits. For example, dynamic friction has been the big- gest unknown controlling how frictional ruptures develop but it has been impossible, until now, to measure dynamic friction during spontaneous rupture propagation and to understand its dependence on other quantities. Our recent measurements allow, by simul- taneously tracking tractions and sliding speeds on the rupturing interface, to disentangle its complex dependence on the slip, slip velocity, and on their history. In another application, we have uncovered new phenomena that could not be detected with previous methods, such as the formation of pressure shock fronts associated with āsupersonicā propagation of shear ruptures in viscoelastic materials where the wave speeds are shown to depend strongly on the strain rate
Highly-sensitive measurements with chirped- pulse phasesensitive OTDR
Distributed optical fiber sensing is currently a very predominant research field, which perceives optical fibers as the potential nervous system of the Earth. Optical fibers are understood as continuous densely-packed sensing arrays, able of retrieving physical quantities from the environment of the fiber.
Some of the most prominent distributed sensing implementations nowadays rely on performing interferometric measurements using the Rayleigh backscattered light, resorting to a technique called Phase-sensitive Optical Time-Domain Reflectometry (CP-ĻOTDR). A variant to this technique has been recently proposed in 2016, known as Chirped-Pulse Phase-Sensitive OTDR, which allowed to overcome most of the limitations of traditional ĻOTDR implementations while retaining a simple setup, yielding remarkably high sensitivities.
In this thesis, we aim to optimize the stability and performance of chirped-pulse ĻOTDR systems over long-term measurements, and develop novel paradigm changing applications benefiting from the high sensitivity provided by the technique. We reach a mK-scale long-term stability in ĻOTDR systems, and perform highly sensitive strain, temperature, and refractive index measurements, demonstrating new photonic applications such as distributed bolometry, electro-optical reflectometry, or distributed underwater seismology. We discuss how these applications might be able of increasing the efficiency in the energy field, paving the way towards the development of self-diagnosable grids (smart-grids), and also of revolutionizing next-generation seismological networks, allowing to overcome some of the greatest limitations faced in modern seismology today.Distributed optical fiber sensing is currently a very predominant research field,
which perceives optical fibers as the potential nervous system of the Earth. Optical
fibers are understood as continuous densely-packed sensing arrays, able of retrieving
physical quantities from the environment of the fiber.
Some of the most prominent distributed sensing implementations nowadays rely
on performing interferometric measurements using the Rayleigh backscattered light,
resorting to a technique called Phase-sensitive Optical Time-Domain Reflectometry
(ĻOTDR). A variant to this technique has been recently proposed in 2016, known
as Chirped-Pulse Phase-Sensitive OTDR, which allowed to overcome most of the
limitations of traditional ĻOTDR implementations while retaining a simple setup,
yielding remarkably high sensitivities.
In this thesis, we aim to optimize the stability and performance of chirped-pulse
ĻOTDR systems over long-term measurements, and develop novel paradigm changing
applications benefiting from the high sensitivity provided by the technique. We
reach a mK-scale long-term stability in ĻOTDR systems, and perform highly sensitive
strain, temperature and refractive index measurements, demonstrating new
photonic applications such as distributed bolometry, electro-optical reflectometry,
or distributed underwater seismology. We discuss how these applications might be
able of increasing the efficiency in the energy field, paving the way towards the development
of self-diagnosable grids (smart-grids), and also of revolutionizing nextgeneration
seismological networks, allowing to overcome some of the greatest limitations
faced in modern seismology today.
We finally conclude and summarize the objectives achieved in this thesis, commenting
on the potential of the novel applications shown, and proposing future lines
of research based on the results
Advanced technologies for planetary instruments
The planetary science community described instrumentation needed for missions that may go into development during the next 5 to 10 years. Then the DoD community to informed their counterparts in planetary science about their interests and capabilities, and to described the BMDO technology base, flight programs, and future directions. The working group sessions and the panel discussion synthesized technical and programmatic issues from all the presentations, with a specific goal of assessing the applicability of BMDO technologies to science instrumentation for planetary exploration.edited by J. Appleby.Clementine II: A Double Asteroid Flyby and Impactor Mission / Boain, R.J. -- The APX Spectrometer for Martian Missions / Economou, T. -- Clementine Sensor Processing System / Feldstein, A.A. -- The Ultraviolet Plume Instrument (UVPI) / Horan, D.M. -- New Technologies for UV Detectors / Joseph, C.L
Quantifying hurricane wind speed with undersea sound
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2006Hurricanes, powerful storms with wind speeds that can exceed 80 m/s, are one of the
most destructive natural disasters known to man. While current satellite technology
has made it possible to effectively detect and track hurricanes, expensive 'hurricanehunting'
aircraft are required to accurately classify their destructive power. Here
we show that passive undersea acoustic techniques may provide a promising tool for
accurately quantifying the destructive power of a hurricane and so may provide a safe
and inexpensive alternative to aircraft-based techniques.
It is well known that the crashing of wind-driven waves generates underwater
noise in the 10 Hz to 10 kHz range. Theoretical and empirical evidence are combined
to show that underwater acoustic sensing techniques may be valuable for measuring
the wind speed and determining the destructive power of a hurricane. This is done
by first developing a model for the acoustic intensity and mutual intensity in an
ocean waveguide due to a hurricane and then determining the relationship between
local wind speed and underwater acoustic intensity. Acoustic measurements of the
underwater noise generated by hurricane Gert are correlated with meteorological data
from reconnaissance aircraft and satellites to show that underwater noise intensity
between 10 and 50 Hz is approximately proportional to the cube of the local wind
speed. From this it is shown that it should be feasible to accurately measure the
local wind speed and quantify the destructive power of a hurricane if its eye wall
passes directly over a single underwater acoustic sensor. The potential advantages
and disadvantages of the proposed acoustic method are weighed against those of
currently employed techniques.
It has also long been known that hurricanes generate microseisms in the 0.1 to
0.6 Hz frequency range through the non-linear interaction of ocean surface waves.
Here we model microseisms generated by the spatially inhomogeneous waves of a
hurricane with the non-linear wave equation where a second-order acoustic field is
created by first-order ocean surface wave motion. We account for the propagation of
microseismic noise through range-dependent waveguide environments from the deep
ocean to a receiver on land. We compare estimates based on the ocean surface wave
field measured in hurricane Bonnie with seismic measurements from Florida.Finally, I am grateful to have been awarded the Office of Naval Research Graduate Traineeship Award in Ocean Acoustics. I also thank the MIT Sea Grant office for funding portions of this research
Earth Observation for Crustal Tectonics and Earthquake Hazards
In this paper, we illustrate some of the current methods for the exploitation of data from Earth Observing satellites to measure and understand earthquakes and shallow crustal tectonics. The aim of applying such methods to Earth Observation data is to improve our knowledge of the active fault sources that generate earthquake shaking hazards. We provide examples of the use of Earth Observation, including the measurement and modelling of earthquake deformation processes and the earthquake cycle using both radar and optical imagery. We also highlight the importance of combining these orbiting satellite datasets with airborne, in situ and ground-based geophysical measurements to fully characterise the spatial and timescale of temporal scales of the triggering of earthquakes from an example of surface water loading. Finally, we conclude with an outlook on the anticipated shift from the more established method of observing earthquakes to the systematic measurement of the longer-term accumulation of crustal strain
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