This paper will describe the scientific goals of our sounding rocket program, the Solar Ultraviolet Magnetograph
Investigation (SUMI). This paper will present a brief description of the optics that were developed to meet SUMI's
scientific goals, discuss the spectral, spatial and polarization characteristics of SUMI's optics, describe SUMI's flight
which was launched 7/30/2010, and discuss what we have learned from that flight.
This paper will describe the Marshall Space Flight Center's Solar Ultraviolet Magnetograph (SUMI) sounding rocket
program, with emphasis on the polarization characteristics of the VUV optics and their spectral, spatial and polarization
resolution. SUMI's first flight (7/30/2010) met all of its mission success criteria and this paper will describe the data
that was acquired with emphasis on the MgII linear polarization measurements.
KEYWORDS: Ultraviolet radiation, Spectral calibration, Solar processes, Aerospace engineering, Current controlled current source, Rockets, UV optics, Polarization, Magnetism, Sun
This paper describes the scientific goals of a sounding rocket program called the Solar Ultraviolet Magnetograph Investigation (SUMI), presents a brief description of the optics that were developed to meet those goals and discusses the spectral, spatial and polarization characteristics of SUMI's Toroidal Variable-Line-Space (TVLS) gratings, which are critical to SUMI's measurements of the magnetic field in the Sun's transition region.
Toroidal variable-line-space (VLS) gratings are very important in the design of an efficient VUV solar telescope that will measure the CIV (155nm) and MgII (280nm) emissions lines in the Sun's transition region. In 1983 Kita and Harada described spherical VLS gratings but the technology to commercially fabricate these devices is a recent development, especially for toroidal surfaces. This paper will describe why this technology is important in the development of the Solar Ultraviolet Magnetograph Investigation (SUMI) sounding rocket program (the good), the delays due to the conversion between the TVLS grating design and the optical fabrication (the bad), and finally the optical testing, alignment and tolerancing of the gratings (the ugly).
KEYWORDS: Magnetism, Polarization, Vacuum ultraviolet, Solar processes, Coronagraphy, Interferometers, Doppler effect, 3D modeling, Remote sensing, Current controlled current source
Marshall Space Flight Center's (MSFC) is developing a Vacuum Ultraviolet (VUV) Fabry-Pérot Interferometer that will be launched on a sounding rocket for high throughput, high-cadence, extended field of view CIV (155nm) measurements. These measurements will provide (i) Dopplergrams for studies of waves, oscillations, explosive events, and mass motions through the transition region, and, (ii), polarization measurements to study the magnetic field in the transition region. This paper will describe the scientific goals of the instrument, a brief description of the optics and the polarization characteristics of the VUV Fabry Pérot.
This paper will describe the objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph
Investigation (SUMI) and the unique optical components that have been developed to meet those objectives. A sounding
rocket payload has been developed to test the feasibility of magnetic field measurements in the Sun's transition region.
The optics have been optimized for simultaneous measurements of two magnetic sensitive lines formed in the transition
region (CIV at 1550 Å and MgII at 2800 Å). This paper will concentrate on the polarization properties SUMI's toroidal
varied-line-space (TVLS) gratings and its system level testing as we prepare to launch in the Summer of 2008.
We present measurements of toroidal variable-line-space (TVLS) gratings for the Solar Ultraviolet Magnetograph
Investigation (SUMI), currently being developed at the National Space Science and Technology Center (NSSTC).
SUMI is a spectro-polarimeter designed to measure magnetic fields in the solar chromosphere by observing two UV
emission lines sensitive to magnetic fields, the CIV line at 155nm and the MgII line at 280nm. The instrument uses a
pair of TVLS gratings, to observe both linear polarizations simultaneously. Efficiency measurements were done on
bare aluminum gratings and aluminum/MgF2 coated gratings, at both linear polarizations.
KEYWORDS: Magnetism, Mirrors, Polarization, Space telescopes, Solar processes, Telescopes, Spatial resolution, Sun, Optical coatings, Signal to noise ratio
The Magnetic Transition Region Probe is a space telescope designed to measure the magnetic field at several heights and temperatures in the solar atmosphere, providing observations spanning the chromospheric region where the field is expected to become force free. The primary goal is to provide an early warning system (hours to days) for solar energetic particle events that pose a serious hazard to astronauts in deep space and to understand the source regions of these particles. The required magnetic field data consist of simultaneous circular and linear polarization measurements in several spectral lines over the wavelength range from 150 to 855 nm. Because the observations are photon limited an optical telescope with a large (>18m2) collecting area is required. To keep the heat dissipation problem manageable we have chosen to implement MTRAP with six separate Gregorian telescopes, each with ~ 3 m2 collecting area, that are brought to a common focus. The necessary large field of view (5 × 5 arcmin2) and high angular resolution (0.025 arcsec pixels) require large detector arrays and, because of the requirements on signal to noise (103), pixels with large full well depths to reduce the readout time and improve the temporal resolution. The optical and engineering considerations that have gone into the development of a concept that meets MTRAP's requirements are described.
This paper will describe the objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph Investigation (SUMI) and the optical components that have been developed to meet those objectives. A sounding rocket payload is being developed to test the feasibility of magnetic field measurements in the Sun's transition region. The optics have been optimized for simultaneous measurements of two magnetic lines formed in the transition region (CIV at 1550Å and MgII at 2800Å). Finally, this paper will concentrate on the polarization properties of the SUMI polarimeter and toroidal variable-line-space gratings.
This paper will describe the objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph Investigation (SUMI) and the optical components that have been developed to meet those objectives. In order to test the scientific feasibility of measuring magnetic fields in the UV, a sounding rocket payload is being developed. This paper will discuss: (1) the scientific measurements that will be made by the SUMI sounding rocket program, (2) how the optics have been optimized for simultaneous measurements of two magnetic lines CIV (1550Å) and MgII (2800Å), and (3) the optical, reflectance, transmission and polarization measurements that have been made on the SUMI telescope mirrors and polarimeter.
The polarizing optics that are being developed for the Solar UV Magnetograph Investigation (SUMI) are described. This polarimeter is being designed for a sounding rocket payload which will make simultaneous measurements of two magnetically sensitive lines CIV and MgII. With a limited observing program, the polarizing optics will be optimized for circular and linear polarization measurements in active regions. The Q polarization will represent exploratory measurements of the transverse field in strong sunspots. This paper will give a brief overview of the SUMI instrument and its scientific goals, will describe the polarimeter that will be used in the sounding rocket program, and will present some of the measurements that have been made on the SUMI polarization optics.
This paper will describe the scientific objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph Investigation (SUMI) and the optical components that have been developed to meet those objectives. In order to test the scientific feasibility of measuring magnetic fields in the UV, a sounding rocket payload is being developed. This paper will discuss: (1) the scientific measurements that will be made by the SUMI sounding rocket program, (2) how the optics have been optimized for simultaneous measurements of two magnetic lines CIV (1550 Angstroms) and MgII (2800 Angstroms), and (3) the optical, reflectance, transmission and polarization measurements that have been made on the SUMI telescope mirrors and polarimeter.
Traditional magnetographs measure the solar magnetic field at the visible 'surface' of the Sun, the photosphere. The Solar Ultraviolet Magnetograph Investigation (SUMI) is a hardware development study for an instrument to measure the solar magnetic field higher in the atmosphere, in the upper chromosphere and in the transition region at the base of the corona. The magnetic pressure at these levels is much stronger than the gas pressure (in contrast to the situation at the photosphere), so the field controls the structure and dynamics of the atmosphere. Rapid changes in the magnetic structure of the atmosphere become possible at this height, with the release of energy. Measurements of the vector magnetic field in this region will significantly improve our understanding of the physical processes heating the Sun's upper atmosphere and driving transient phenomena such as flares and coronal mass ejections. The instrument will incorporate new technologies to achieve the polarization efficiencies required to measure the magnetic splitting of lines in the VUV an UV (CIV at 1550 angstrom and MgII at 2800 angstrom). We describe the scientific goals, the optical components that are being developed for a sounding rocket program, and the SUMI baseline design.
Studies of the 3D structure and dynamics of the solar corona have been severely limited by the constraint of single viewpoint observations. The Stereo X-Ray Coronal Imager (SXCI) mission will send a single instrument, an X-ray telescope, into deep space expressly to record stereoscopic images of the solar corona. The SXCI spacecraft will be inserted into an approximately 1 ZAU heliocentric orbit leading Earth by approximately 25 degrees at the end of nine months. The SXCI x-ray telescope forms one element of a stereo pair, the second element being an identical x-ray telescope in Earth orbit placed there as part of the NOAA GOES program. X-ray emission is a powerful diagnostic of the corona and its magnetic fields, and 3D information on the coronal magnetic structure would be obtained by combining the data from the two x-ray telescopes. This information can be used to address the major solar physics questions of (1) what causes explosive coronal events such as coronal mass ejections, eruptive flares and prominence eruptions and (2) what causes the transient heating of coronal loops. Stereoscopic views of the optically thin corona will resolve some ambiguities inherent in single line-of-sight observations. Triangulation gives 3D solar coordinates of features which can be seen in the simultaneous images form both telescopes. As part of this study, tools were developed for determining the 3D geometry of coronal features using triangulation. Advanced technologies for visualization and analysis of stereo images were tested. Results of mission and spacecraft studies are also reported.
Filters fabricated from metalized polyimide have been specified for a number of x-ray astronomy missions, including the Advanced X-ray Astrophysics Facility (AXAF), the x-ray spectrometer (XRS) on Astro-E, the Advanced Composition Explorer (ACE), and the Geostationary Operational Environmental Satellite (GOES). Polyimide offers greater strength, improved temperature stability, and effectiveness in blocking unwanted ultraviolet radiation compared to polymeric films previously employed. This paper reviews the various x- ray astronomy missions and the particular challenges that were met with polyimide filters. The paper also reviews the development of free standing thin foils of polyimide with mechanical properties optimized for x-ray astronomy and other applications, such as synchrotron research.
Dennis Socker, S. Antiochos, Guenter Brueckner, John Cook, Kenneth Dere, Russell Howard, Judith Karpen, James Klimchuk, Clarence Korendyke, Donald Michels, J. Daniel Moses, Dianne Prinz, N. Sheely, Shi Wu, Andrew Buffington, Bernard Jackson, Barry Labonte, Philippe Lamy, H. Rosenbauer, Rainer Schwenn, L. Burlaga, Joseph Davila, John Davis, Barry Goldstein, Henry Harris, Paulett Liewer, Marcia Neugebauer, E. Hildner, Victor Pizzo, Norman Moulton, J. Linker, Z. Mikic
A STEREO mission concept requiring only a single new spacecraft has been proposed. The mission would place the new spacecraft in a heliocentric orbit and well off the Sun- Earth line, where it can simultaneously view both the solar source of heliospheric disturbances and their propagation through the heliosphere all the way to the earth. Joint observations, utilizing the new spacecraft and existing solar spacecraft in earth orbit or L1 orbit would provide a stereographic data set. The new and unique aspect of this mission lies in the vantage point of the new spacecraft, which is far enough from Sun-Earth line to allow an entirely new way of studying the structure of the solar corona, the heliosphere and solar-terrestrial interactions. The mission science objectives have been selected to take maximum advantage of this new vantage point. They fall into two classes: those possible with the new spacecraft alone and those possible with joint measurements using the new and existing spacecraft. The instrument complement on the new spacecraft supporting the mission science objectives includes a soft x-ray imager, a coronagraph and a sun-earth imager. Telemetry rate appears to be the main performance determinant. The spacecraft could be launched with the new Med-Lite system.
The sun emits hard X-rays (above 10 keV) during solar flares. Imaging hard X-ray sources on the sun with spatial resolutions on the order of 1-5 arcsec and integration times of 1 sec will provide greater insight into the energy release processes during a solar flare. In these events, tremendous amounts of energy stored in the solar magnetic field are rapidly released leading to emission across the electromagnetic spectrum. Two Fourier telescope designs, a spatial modulation collimator and a rotating modulation collimator, were developed to image the full sun in hard X-rays (10-100 keV) in an end-to-end simulation. Emission profiles were derived for two hard X-ray solar flare models taken from the current solar theoretical literature and used as brightness distributions for the telescope simulations. Both our telescope models, tailored to image solar sources, were found to perform equally well, thus offering the designer significant flexibility in developing systems for space-based platforms. Given sufficient sensitive areas, Fourier telescopes are promising concepts for imaging solar hard X-rays.
Several approaches to imaging hard X-rays emitted from solar flares have been proposed or are planned for the nineties including the spatial modulation collimator (SMC) and the rotating modulation collimator (RMC). A survey of current solar flare theoretical literature indicates the desirability of spatial resolutions down to 1 arcsecond, field of views greater than the full solar disk (i.e., 32 arcminutes), and temporal resolutions down to 1 second. Although the sun typically provides relatively high flux levels, the requirement for 1 second temporal resolution raises the question as to the viability of Fourier telescopes subject to the aforementioned constraints. A basic photon counting, Monte Carlo 'end-to-end' model telescope was employed using the Astronomical Image Processing System (AIPS) for image reconstruction. The resulting solar flare hard X-ray images compared against typical observations indicated that both telescopes show promise for the future.
Several approaches to imaging hard x-rays emitted from solar flares have been
proposed for the nineties. These include the fixed modulation collimator, the
rotating modulation collimator (RMC), the spiral fresnel zone pattern, and the
redundantly coded aperture. These techniques are under consideration for use in the
Solar Maximum '91 balloon program, the Japanese Solar-A satellite, the Controls,
Astrophysics, and Structures Experiment in Space (CASES), and the Pinhole/Occulter
Facility (P/OF) and are outlined and discussed in the context of preliminary results
from numerical modeling done at MSFC and the requirements derived from current ideas
as to the expected hard x-ray structures in the impulsive phase of solar flares.
Preliminary indications are that all of the approaches are promising, but each has
its own unique set of limitations.
A single high-energy instrument based on rotating modulation collimators with germanium semiconductor
spectrometers as the detectors can provide high angular resolution (< 1 arc sec), high time resolution
(< 1 s), and high spectral resolution (about one keV), all in one package. Such rotating modulation-
collimator optics provide excellent spatial (u,v)-plane coverage for high-contrast images in the hard X-ray
domain, where there will be a large signal-to-noise ratio during even modest flares. The use of thick
modulation plates will make it possible to image gamma rays with < 5 arc sec angular resolution to
energies in excess of 10 MeV during the more energetic flares without compromising the ability of the
germanium detectors to resolve the gamma-ray lines. Energetic neutrons will also be imaged for the first
time with < 20 arc sec angular resolution. This combination of imaging and spectroscopy at high resolution
will be a powerful tool for helping to answer central questions of solar flare physics, especially if such an
instrument were supported by observations at longer wavelengths. The timing of solar activity dictates a
launch of such a High-Energy Solar Physics (HESP) mission by 1998.
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