Analyzing the plasmas upstream and downstream of interplanetary shocks: turbulence and compressed structure science goals and methodolgy the overarching science goal of this HGI is: to determine the…

This federal contract award from the National Aeronautics and Space Administration (NASA) Shared Services Center was granted to the Space Science Institute (SSI), a nonprofit research organization based in Boulder, Colorado. The $400,000.00 grant is for the project "Analyzing the Plasmas Upstream and Downstream of Interplanetary Shocks: Turbulence and Compressed Structure Science Goals and Methodology." The project aims to study the properties and origins of plasma fluctuations around interplanetary shocks and how shocks interact with pre-existing solar wind structures. It will use data from the WIND, ACE, and STEREO spacecraft missions. This work is relevant to the Heliophysics Decadal Survey goal of discovering and characterizing fundamental processes in the heliosphere and throughout the universe. The contract does not have a set-aside designation, and SSI frequently serves as a prime contractor and grant recipient for NASA, the National Science Foundation, and the Department of Energy, leveraging its expertise in space and Earth sciences.

Analyzing the plasmas upstream and downstream of interplanetary shocks: turbulence and compressed structure science goals and methodolgy the overarching science goal of this HGI is: to determine the properties and origins of the fluctuations upstream and downstream of interplanetary shocks and to determine how interplanetary shocks and pre-existing solar-wind structure interact. Specific objectives are: objective a: to determine the statistical properties of the upstream and downstream fluctuations of shocks as a function of the type of solar-wind plasma that the shock propagates through. Objective b: to determine the degree to which the downstream fluctuations are controlled by the upstream plasma structure. Objective c: to measure the eddy turnover time downstream of interplanetary shocks. Objective d: to determine whether shock compression causes thinning of pre-existing solar-wind current sheets (directional discontinuities) and to examine the temporal recovery of that thinning with distance downstream mission data to be used this investigation will use plasma and magnetic-field measurements from wind, ACE, and stereo a+b. Data-analysis methodology statistical analysis of about 500 interplanetary shock crossings will be performed. Magnetic-field and velocity measurements in the upstream and downstream plasmas from each shock will be fourier analyzed, plasma and magnetic structure in the upstream and downstream plasmas will be characterized using cross-product methods, and current-sheet thicknesses will be measured using hightime- resolution magnetic-field measurements. Besides the unprecedented number of shocks analyzed, two unique aspects of the dataanalysis project are (1) ensembles of shock data will be sorted and analyzed according to the type of solar-wind plasma through which each shock is propagating and (2) shock sorting according to shock-normal angle will be determined from directions of the mean-fields upstream and downstream (rather than from the angle seen precisely at the spacecraft crossing of the shock). Relevance of the problem this heliophysics guest investigation will analyze data from the operating heliophysics missions wind, ACE, and stereo helping to maximize the science from those missions. This investigation is relevant to the decadal survey key science goal 4 discover and characterize fundamental processes that occur both within the heliosphere and throughout the universe: the decadal survey calls out collisionless shocks as an example of a universal process. This investigation supports the NASA heliophysics science goal explore the physical processes in the space environment from the sun to the earth and throughout the solar system. A better knowledge of the origin and properties of the turbulence upstream and downstream of shocks will improve parameters for investigating the physics of particle acceleration at shocks. This investigation will provide information about how shocks modify the structure of the solar wind and will provide information about the evolution of the solar wind and the evolution of other astrophysical plasmas that are shocked.