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At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

A new perspective on solar active regions

A flood of new observations of the solar corona have been made with high spatial resolution, good temporal coverage and resolution, and large linear dynamic range by the Soft X-ray Telescope (SXT) on Yohkoh. These data are changing our fundamental understanding of how solar magnetic fields emerge, interact, and dissipate. This paper reviews some of the results from Yohkoh in the context of earlier results from the Solar Maximum Mission (SMM) and in comjunction with ground-based optical and radio observations.

Strong, K. T.↗
NASA NTRS1996

Coronal Abundances and Their Variation

This contract supported the investigation of elemental abundances in the solar corona, principally through analysis of high-resolution soft X-ray spectra from the Flat Crystal Spectrometer on NASA's Solar Maximum Mission. The goals of the study were a characterization of the mean values of relative abundances of elements accessible in the FCS data, and information on the extent and circumstances of their variability. This is the Final Report, summarizing the data analysis and reporting activities which occurred during the period of performance, June 1993 - December 1996.

Saba, Julia L. R.↗
NASA NTRS1997

Magnetic Test Performance Capabilities at the Goddard Space Flight Center as Applied to the Global Geospace Science Initiative

Goddard Space Flight Center's (GSFC) Spacecraft Magnetic Test Facility (SMTF) is a historic test facility that has set the standard for all subsequent magnetic test facilities. The SMTF was constructed in the early 1960's for the purpose of simulating geomagnetic and interplanetary magnetic fields. Additionally, the facility provides the capability for measuring spacecraft generated magnetic fields as well as calibrating magnetic attitude control systems and science magnetometers. The SMTF was designed for large, spacecraft level tests and is currently the second largest spherical coil system in the world. The SMTF is a three-axis Braunbek system composed of four coils on each of three orthogonal axes. The largest coils are 12.7 meters (41.6 feet) in diameter. The three-axis Braunbek configuration provides a highly uniform cancellation of the geomagnetic field over the central 1.8 meter (6 foot) diameter primary test volume. Cancellation of the local geomagnetic field is to within +/-0.2 nanotesla with a uniformity of up to 0.001% within the 1.8 meter (6 foot) diameter primary test volume. Artificial magnetic field vectors from 0-60,000 nanotesla can be generated along any axis with a 0.1 nanotesla resolution. Oscillating or rotating field vectors can also be produced about any axis with a frequency of up to 100 radians/second. Since becoming fully operational in July of 1967, the SMTF has been the site of numerous spacecraft magnetics tests. Spacecraft tested at the SMTF include: the Solar Maximum Mission (SMM), Magsat, LANDSAT-D, the Fast Aurora] Snapshot (FAST) Explorer and the Sub-millimeter-Wave-Astronomy Satellite (SWAS) among others. This paper describes the methodology and sequencing used for the Global Geospace Science (GGS) initiative magnetic testing program in the Goddard Space Flight Center's SMTF. The GGS initiative provides an exemplary model of a strict and comprehensive magnetic control program.

Mitchell, Darryl R.↗
NASA NTRS1997

Ultraviolet Events Observed in Active Regions: An Interpretation of Flaring Arches and Associated Small Flares - 2

We analyze Hz, UV, and X-ray emissions in and around the spectacular arch system seen in the corona on 1980 March 27 during the Solar Maximum Mission. The flaring of the arch plasma is studied, and its dependence on triggering mechanisms related to the observed small limb flare in the arch footpoint is analyzed. To drive these events, we propose a mechanism in which small electric current circuits and the localized magnetic free energy are continuously generated at a magnetic null by a pressure gradient, which then compress or expand the plasma. This free energy dissipates by Joule effect and upward transport.

Fontenla, J.↗
NASA NTRS2005

Spectral Atlas of X-ray Lines Emitted During Solar Flares Based on CHIANTI

A spectral atlas of X-ray lines in the wavelength range 7.47-18.97 Angstroms is presented, based on high-resolution spectra obtained during two M-class solar flares (on 1980 August 25 and 1985 July 2) with the Flat Crystal Spectrometer on board the Solar Maximum Mission. The physical properties of the flaring plasmas are derived as a function of time using strong, isolated lines. From these properties predicted spectra using the CHIANTI database have been obtained which were then compared with wavelengths and fluxes of lines in the observed spectra to establish line identifications. identifications for nearly all the observed lines in the resulting atlas are given, with some significant corrections to previous analysis of these flare spectra.

Landi, E.↗
NASA NTRS2005

Hard X-ray Spectroscopic, Microwave and H-alpha Linear Polarization Studies with Hard X-Ray Observations from HESSI

The Principal Investigator (P.I.) has been pursuing a three year grant under NASA's Sun-Earth Connection Guest Investigator Program in support of the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). An objective of these efforts is to combine X-ray and other data on solar flares, coronal mass ejections and interplanetary particle events in order to obtain a more comprehensive recognition of signatures, and understanding of interplanetary proton events. Thus, part of these efforts are to investigate if signatures seen in hard X-rays and microwaves can lead to better predictions of interplanetary proton events that can be dangerous to astronauts and spacecraft. The original proposal was written in May, 2000 and it discusses a three-pronged approach for data comparisons with three new types of instrumentation observing at X-ray, microwave and optical wavelengths. The major impetus behind this work and the proposal is that the P.I. discovered a strong correlation between a particular type of hard X-ray signature seen in spectral evolutions and interplanetary proton events (Kiplinger, 1995). The basic signature is that hard X-ray flux peaks either exhibit spectra that soften on their decays (Le. show fewer and fewer high energy X-rays with time) or they harden during decays (i.e. high energy X-rays decay significantly slower that lower energy X-rays). This signature is called progressive hardening. Studies were conducted over an eight-year period of data from the Hard X-Ray Burst Spectrometer (HXRBS) of the Solar maximum mission. Out of the 750 well observed flares studied, 41 flares had major associated proton events. Of these, 29 events were predicted on the basis of progressive hardening for a hit rate of 71%. The 152 largest flares had a hit rate of 82%.

Kiplinger, Alan L.↗
NASA NTRS2023

Solar Energetic-Particle-Associated Coronal Mass Ejections Observed by the Mauna Loa Solar Observatory Mk3 and Mk4 Coronameters

We report on the first comprehensive study of the coronal mass ejections (CMEs) associated with ~25 MeV solar energetic-proton (SEP) events in 1980 – 2013 observed in the low/inner corona by the Mauna Loa Solar Observatory (MLSO) Mk3 and Mk4 coronameters. Where possible, these observations are combined with space-based observations from the Solar Maximum Mission C/P, P78-1 SOLWIND, or SOHO/LASCO coronagraphs. The aim of the study is to understand directly measured (rather than inferred from proxies) CME motions in the low to midcorona and their association with SEP acceleration, and hence attempt to identify early signatures that are characteristic of SEP acceleration in ground-based CME observations that may be used to warn of impending SEP events. Although we find that SEP events are associated with CMEs that are on average faster and wider than typical CMEs observed by MLSO, a major challenge turns out to be determining reliable estimates of the CME dynamics in the low corona from the 3-min cadence Mk3/4 observations since different analysis techniques can produce inconsistent results. This complicates the assessment of what early information on a possible SEP event is available from these low-coronal observations.

I. G. Richardson↗
NASA NTRS1985

Space salvage - A report on Shuttle mission STS 51-A

The success of the Space Shuttle Orbiter and Manned Maneuvering Unit (MMU) in the rendezvous and capture of the Westar and Palapa satellites was largely attributable to the availability and fidelity of numerous simulators, which facilitated real time development and verification of satellite rescue procedures and hardware. This complex Space Shuttle mission, STS 51-A, was developed and executed in only 8 months; by contrast, the Solar Maximum repair mission was developed over a period of three years. Attention is presently given to Orbiter sensors, satellite night stationkeeping, satellite stabilization tasks, MMU tasks, and preparatory simulations.

Hauck, F. H.↗
NASA NTRS1983

Space station: Policy, planning and utilization; Proceedings of the Symposium, Arlington, VA, July 18-20, 1983

The design, technology, and applications of the proposed Space Station (SS) are examined in contributions and discussions from the AIAA/NASA Symposium on the Space Station held on July 18-20, 1983. The role of man in space, the history of SS concepts, and the requirements of scientists, engineers, and commercial users are reviewed. Discussion is included on military space activities; the Solar Maximum Repair Mission; the role of the SS in earth sciences, life sciences, astronomy and astrophysics, and solar physics; pharmaceutical manufacturing on the SS, satellite and platform maintenance and repair from the SS; international utilization of the SS; SS architectures and user concerns; the SS as an element of the total space-system architecture; productivity on an evolutionary SS, SS information and communications systems; and environmental-control and life-support systems for the SS.

Gerard, M.↗
NASA NTRS1989

Returned Solar Max hardware degradation study results

The Solar Maximum Repair Mission returned with the replaced hardware that had been in low Earth orbit for over four years. The materials of this returned hardware gave the aerospace community an opportunity to study the realtime effects of atomic oxygen, solar radiation, impact particles, charged particle radiation, and molecular contamination. The results of these studies are summarized.

Triolo, Jack J.↗
NASA NTRS1987

Review of Low Earth Orbital (LEO) flight experiments

The atomic oxygen flux exposure experiments flown on Space Shuttle flights STS-5 and STS-8 are described along with the results of measurements made on hardware returned from the Solar Maximum repair mission (Space Shuttle flight 41-C). In general, these experiments have essentially provided for passive exposure of samples to oxygen fluences of approximately 1 to 3.5 x 10(20) atoms/sq cm. Atmospheric density is used to derive fluence and is dependent on solar activity, which has been on the decline side of the 11-year cycle. Thus, relatively low flight altitudes of less than 300 km were used to acquire these exposures. After exposure, the samples were analyzed using various methods ranging from mass loss to extensive scanning electron microscopy and surface analysis techniques. Results are summarized and implications for the space station are discussed.

Leger, L.↗
NASA NTRS1984

TRASYS/SSPSTA thermal modeling comparison

The Thermal Radiation Analysis System (TRASYS) and the Simplified Shuttle Payload Analyzer (SSPTA) are applied for the purpose of comparison to the Solar Maximum Repair Mission (SMRM) and Astro-1/UVT (Ultraviolet Telescope), making use also of the System Improved Numerical Differencing Analyzer (SINDA). The majority of radiation conductances obtained from the TRASYS and SSPTA computer codes are shown to be within + or - 20 percent of each other, though the interchange factors associated with some crucial components of the system are located beyond this region. A sample model is also considered, which consists of an outer and an inner boxes with emisivities of 0.32 and 0.80 respectively. It is concluded that a thorough, methodical comparison between the two codes is necessary.

Noravian, H.↗
NASA NTRS1984

The National Symposium and Workshop on Optical Platforms, Huntsville, AL, June 12-14, 1984, Proceedings

The present conference is concerned with space-based observatories (including future systems), interplanetary observation platforms, Space Station optical utilization, orbital earth viewing systems, and Spacelab's use as an observations platform. Attention is given to the pointing system for the Space Telescope, the Advanced X-ray Astrophysics Facility, the conceptual definition of the Space IR Telescope Facility's spacecraft, satellite servicing in light of the Solar Maximum Repair Mission, a large deployable reflector telescope concept, moon-based astronomical observatories, Space Station-based remote sensing of the earth, optical systems is geosynchronous orbit, multispectral linear array detector technology, Spacelab-based space plasma and materials processing investigations, and space construction technology for large space observatories. Also discussed are military optical platforms for sea, land and air stationing.

Wyman, C. L.↗
NASA NTRS1986

U.S. experience in satellite servicing and linkage to the Space Station era

A history of on-orbit servicing and repair is given with emphasis placed on the Solar Maximum Repair Mission. The experience gained thus far in on-orbit servicing and the design of the Space Station's servicing capabilities impose the following requirements on users: (1) satellites must have a standard grapple for capture and a standard berthing interface, (2) Space Station safety requirements must meet to preclude damage to the Space Station or injury to the EVA crew, (3) sensitive instruments will need to implement remotely controlled protective devices to prevent damage, and (4) satellite thermal systems must be designed to maintain survival temperatures during transfer from orbit to the Space Station servicing facility.

Browning, R. K.↗
NASA NTRS1987

In-orbit and laboratory exchange of ORUs designed/not designed for servicing

The practicality of employing a combination of automated and extravehicular activity forms of servicing in-orbit was demonstrated with the STS 41-C Solar Maximum Repair Mission. This shows that modular Orbital Replacement Units (ORUs) designed for servicing can be readily accommodated. Successful replacement of an experiment ORU, not designed for replacement, was performed following extensive preparations. In a laboratory, spacecraft ORUs were replaced using a completely preplanned automated approach. This was later done using a completely unstructured teleoperations mode including the complicated exchange of the instrument ORU. As a result of this effort and work on powered tools, an approach for combining these techniques is underway to produce a flight support system servicing aid to increase the STS astronauts' effective in-orbit servicing capability by several fold.

Davis, R.↗
NASA NTRS1991

Satellite Repair Program

NASA-Goddard's Satellite Repair Program counts among its major achievements the successful use of welding in servicing equipment employed in the Flight Support System (FSS) structures addressed by the the Solar Maximum Repair Mission of 1984. The FSS berthing and positioning ring will again be employed with the Space Shuttle for the anticipated upgrading of the Hubble Space Telescope; the Explorer Platform (EP) mission will also use the FSS during the planned on-orbit exchange of the EUV Explorer payload for an X-ray Timing Explorer payload. The EP, to which attention is presently given, is the first spacecraft designed to be entirely serviceable by intravehicular activity or EVA.

Davis, Robert E.↗