The goal of this project is to identify high-density plasma formed in the lower ionosphere due to lightning in order to understand the effects on ground-to-satellite RF communication. In particular, we are deploying co-located lightning and ionospheric arrays in New Mexico in order to understand the mechanism for generating sporadic-E during thunderstorm activity. Our array consists of a suite of lightning ground-based RF receivers at VLF and VHF, and 4 HF transceivers covering 1-30 MHz that allow 6 oblique cuts through the ionosphere. These data are then incorporated into 4-D inversion algorithms that allow for sub-km resolution of the lower ionosphere.
Prof. Close's research involves space weather detection and modeling for improved spacecraft designs, and advanced signal processing and electromagnetic wave interactions with plasma for ground-to-satellite communication systems. These topics fall under the Space Situational Awareness (SSA) umbrella that include environmental remote sensing using satellite systems and ground-based radar. Her current efforts are the MEDUSSA (Meteoroid, Energetics, and Debris Understanding for Space Situational Awareness) program, TALIS (Tomographic Array for Lightning and Ionospheric Studies) using ground-based and space-based RF sensors, and using ground-based radar data to characterize the meteoroid population and its threat to spacecraft. Future work includes using CubeSats for asteroid detection and characterization.
Last modified Mon, 14 Jan, 2013 at 23:06
|Investigating the Crumbs of Creation||01-2012|
|Measurements of freely-expanding plasma from hypervelocity impacts||N. Lee; S. Close; D. Lauben; I. Linscott; A. Goel; T. Johnson; J. Yee; A. Fletcher; R. Srama; S. Bugiel; A. Mocker; P. Colestock; S. Green||International Journal of Impact Engineering||01-2012|
|Meteoroid head echo polarization features studied by numerical electromagnetics modeling||L. E. Vertatschitsch; J. D. Sahr; P. Colestock; S. Close||Radio Science||12-2011|
|Polarization and scattering of a long-duration meteor trail||Close et al.||JGR||12-2011|
|Electrical effects of hypervelocity impacts||Ashish Goel, Nicolas Lee, Sigrid Close||10-2011|
|A medium-scale traveling ionospheric disturbance observed from the ground and from space||Dymond; K. F.; C. Watts; C. Coker; S. A. Budzien; P. A. Bernhardt; N. Kassim; T. J. Lazio; K. Weiler; P. C. Crane; P. S. Ray; A. Cohen; T. Clarke; L. J. Rickard; G. B. Taylor; F. Schinzel; Y. Pihlstro||Radio Science||09-2011|
|A compressed sensing approach to observing distributed radar targets||Ryan Volz and Sigrid Close||08-2011|
|Study of Hypervelocity Impact Plasma Expansion||Nicolas Lee; Sigrid Close; David Lauben; Ivan Linscott; Ashish Goel; Theresa Johnson; Ralf Srama; Sebastian Bugiel; Anna Mocker||06-2011|
|RF Signatures of Hypervelocity Impacts on Spacecraft||Sigrid Close; Michael C. Kelley; Alex Fletcher; Nicolas Lee; Patrick Colestock||06-2011|
|Diffusion of Plasmas from Ablating Meteoroids in the Ionosphere||Jonathan Yee; Sigrid Close||06-2011|
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NSF CAREER award (2011-2016)
Elected Vice Chair Commission G (URSI)
Arecibo Science Advisory Panel
National Research Council Aeronautics and Space Engineering Board Micrometeoroid and Orbital Debris Panel Member
Hellman Faculty Scholar 2010
Meteoroids 2010 Scientific Organizing Committee
National Research Council Aeronautics and Space Engineering Board Review of Near-Earth Object Surveys and Hazard Mitigation Strategies Mitigation Panel Member
Planetary Decadal Survey Interplanetary Dust
Cover of IEEE Spectrum 2008
1st Place Student Paper Competition International Union of Radio Science
Exceptional Efforts in Meteoroid Impact Study
Joe D. Marshall Award presented by AFTAC for Outstanding Technical Briefing
MIT Lincoln Scholar
Prof. Close is leading the American effort for the QB50 project run by the von Karman Institute for Fluid Dynamics. These 50 CubeSats will be used to measure lower thermospheric properties.
The focus of this program is to detect and model meteoroid impacts on spacecraft in order to understand the properties of hypervelocity particles and their damage mechanism through both mechanical and electrical effects. The data include both ground-based hypervelocity impact tests, and in situ impacts of hypervelocity impacts and a modeling component that encompasses electromagnetic emission from dense plasmas. We are currently designing the MEDUSSA spacecraft, which is a CubeSat containing RF, optical and silicon detectors aimed at characterizing the electromagnetic pulse formed upon meteoroid impact. We are also conducting experiments at the Max Planck Institute for Nuclear Physics in Germany in order to characterize the plasma and RF from a hypervelocity impact on a satellite.
We are investigating the origins and impacts of interplanetary dust in order to drive the science and engineering missions for the next decade. Primarily we use high-power, large-aperture radars around the world to detect and characterize the plasma formed when a meteoroid enters into Earth's atmosphere. Our students are working with radars in southern Argentina, the Kwajalein Atoll in the Pacific Ocean, the Jicamarca radar in Peru, the MIT Millstone Radar in Massachusetts, and the Arecibo Radar in Puerto Rico. These projects also include modeling and simulation using the latest Particle-in-Cell (PIC) techniques.