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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRSDate not supplied

TARDIS: Acelerating TVAC Transitions

"Large spacecraft components, including instruments, require long durations to transition between temperature plateaus during TVAC (Thermal Vacuum) testing. This is especially true for cryogenic instruments whose operating temperatures are extremely low. Due to the T4 relation, using radiative heat transfer alone for temperature transitions to cryogenic temperatures is extremely time consuming. The Wide Field Instrument (WFI) on the upcoming Roman Space Telescope (RST) is one such cryogenic instrument. The TARDIS (Thermal Acceleration Rate Device for Integrated Systems) is a heat switch device which will be used during the WFI TVAC test campaign in order to decrease WFI transition times. Over the course of the planned ___ week WFI instrument-level TVAC testing, TARDIS is being estimated to save ___ days of test time. By reducing the total TVAC duration, TARDIS is providing significant cost and schedule savings to the RST WFI project. Based on the successful design of the LUCY L’Ralph AZQ Heat Switch, TARDIS can provide both high conductivity for temperature transitions and low conductivity Zero-Q for thermal balances. This is achieved by use of a mechanical clamp heat switch and actively controlled cold plate. Using this method, TARDIS is estimated to be able to change its conductance from approximately 0.20 W/K to ¬¬0.002 W/K, for a turndown ratio of 100. This paper details the design, analysis, and testing of TARDIS. It also previews the operation of TARDIS in the upcoming WFI TVAC test campaign. "

TVAC, Heat Switch↗
NASA NTRS2009

First Year Results from the Fermi Gamma-Ray Space Telescope

After one year of survey observations and more than 70 billion triggers, Fermi is revealing an unprecedented view of the high energy gamma-ray sky. The observatory .carries two instruments, the Gamma-ray Burst Monitor (GB, 8 keV - 40 MeV) and the Large Area Telescope (LAT, 20 MeV greater than or equal to 300 GeV), which in combination cover over 7 orders of magnitude in energy for transient phenomena. The LAT provides substantially more sensitivity than previous instruments in this waveband and has opened up the energy window from 10-100 GeV. The first year has produced many important results, from detections of extremely energetic and distant gamma-ray bursts, to monitoring daily variations in emission caused by massive black holes at the cores of galaxies, to identifying a new population of gamma-ray bright pulsars, to measuring the spectrum of diffuse emission from our own. Galaxy and the spectrum of the local cosmic electrons. I'll review highlights from the first year and discuss how the data are answering questions from the past and raising new ones for the future.

Hays, Elizabeth↗
NASA NTRS2011

Fermi-LAT Gamma-ray Bursts and Insight from Swift

A new revolution in GRB observation and theory has begun over the last 3 years since the launch of the Fermi gamma-ray space telescope. The new window into high energy gamma-rays opened by the Fermi-LAT is providing insight into prompt emission mechanisms and possibly also afterglow physics. The LAT detected GRBs appear to be a new unique subset of extremely energetic and bright bursts. In this talk I will discuss the context and recent discoveries from these LAT GRBs and the large database of broadband observations collected by Swift over the last 7 years and how through comparisons between the Swift, GBM, and LAT GRB samples, we can learn about the unique characteristics and relationships between each population.

Racusin, Judith L.↗
NASA NTRS1988

Design of the Extreme Ultraviolet Explorer long-wavelength grazing incidence telescope optics

Designing optics for photometry in the long-wavelength portion of the EUV spectrum (400-900) A) poses different problems from those arising for optics, operating shortward of 400 A. The available filter materials which transmit radiation longward of 400 A are also highly transparent at wavelengths shortward of 100 A. Conventional EUV optics, with grazing engles of less than about 10 deg, have very high throughput in the EUV, which persists to wavelengths shortward of 100 A. Use of such optics with the longer-wavelength EUV filters thus results in an unacceptably large soft X-ray leak. This problem is overcome by developing a mirror design with larger graze angles of not less than 20 deg, which has high throughput at wavelengths longer than 400 A but at the same time very little throughput shortward of 100 A.

Finley, David S.↗
NASA NTRS2000

The Solar-B Mission

The Solar-B mission is a joint enterprise between Japan, the United States of America and the United Kingdom. The collaboration is led by ISAS, the Japanese Institute for Space and Astronautical Science (ISAS), NASA and PPARC (Particle Physics and Astrophysics Research Council) play supporting roles in the development of the scientific objectives and provision of the scientific instruments. The mission's primary objective is to conduct a systems study of the solar atmosphere through the acquisition of coordinated measurements of the photosphere, the transition region/low corona and the upper corona using three instruments: an optical telescope, an extreme ultraviolet imaging spectrometer and a soft x-ray telescope. Drs. Saku Tsuneta (NAOJ) and Alan Title (LMSAL) lead the optical imaging team. The optical telescope is a 50-cm aperture, diffraction limited, Gregorian. The focal plane package will record high resolution images, Dopplergrams, and vector magnetic fields on spatial scales dominated by elemental photospheric flux tubes, and over a field of view large enough to contain small active regions. Drs. Tetsuya Watanabe, Len Culhane (MSSL) and George Doschek (NRL) led the EUV imaging and spectroscopy team. The EUV telescope has a 15-cm primary mirror feeding a toroidal grating. The optics have multiplayer coatings which select two wavebands between 180-204 A and 250-290 A. Drs. Kiyoto Shibasaki (NAOJ) and Leon Golub (SAO) lead the X-ray imaging team. The x-ray telescope will provide full disk, soft x-ray images with twice the spatial resolution of the Yohkoh SXT and enhanced sensitivity to longer (>40 A) wavelengths. The launch of Solar-B, into a sun-synchronous orbit, is scheduled for August 2004. Solar-B is the second mission in the Sun-Earth Connection, Solar-Terrestrial Probe Program which is managed by the Goddard Space Flight Center. The Science Directorate of the Marshall Space Flight Center manages the Solar-B Project for the ST Probe Project Office. This paper discusses the objectives, specifications, and design of the scientific instruments as presented at the Preliminary Design Review held at MSFC in May 2000.

Davis, John M.↗
NASA NTRS1994

A Remarkable Auroral Event on Jupiter Observed in the Ultraviolet with the Hubble Space Telescope

Two sets of ultraviolet images of the Jovian north aurora were obtained with the Faint Object Camera on board the Hubble Space Telescope. The first series shows an intense discrete arc in near corotation with the planet. The maximum apparent molecular hydrogen emission rate corresponds to an electron precipitation of approximately 1 watt per square meter, which is about 30,000 times larger than the solar heating by extreme ultraviolet radiation. Such a particle heating rate of the auroral upper atmosphere of Jupiter should cause a large transient temperature increase and generate strong thermospheric winds. Twenty hours after initial observations, the discrete arc had decreased in brightness by more than one order of magnitude. The time scale and magnitude of the change in the ultraviolet aurora leads us to suggest that the discrete Jovian auroral precipitation is related to large-scale variations in the current system as is the case of for Earth's discrete aurorae.

Gerard, J. C.↗
NASA NTRS2017

Synergies of Subaru and CGI

Given the limited observing time and demanding scenarios of the WFIRST coronagraph instrument (CGI), it is critical to consider how Subaru observations can benefit its observing program. Subaru telescope has a suite of instruments with their adaptive optics (AO) and extreme adaptive optics modules (SCExAO). With SCExAO, the Subaru telescope is capable of detection and spectral characterization of binaries and bright (greater than 5(exp -6) contrast) companions in the near-infrared. This will enable the vetting of targets, disk detection and characterization, and potentially some additional science should CGI identify interesting targets during its technology demonstration and potential guest observer program. Additionally, large companions that are within the inner working angle of the coronagraph can be identified using the VAMPIRES aperture masking interferometer. With highly complementary target brightness and significantly overlapping fields of view, there is a great deal of potential for combined observations with Subaru and CGI. This will represent the first time single observations spanning the visible to near-infrared will be possible for high contrast imaging. We will discuss the overlap of instrumentation over time, the implication of instrument evolution as TMT comes online, and how this can be used to improve both science and technology demonstrations for CGI.

adaptive optics (AO↗
NASA NTRS2019

Optical Design of the Extreme Coronagraph for Living Planetary Systems Instrument for the LUVOIR Mission Study

The large UV/optical/IR surveyor (LUVOIR) is a concept for a highly capable, multiwavelength space observatory with ambitious science goals. Finding and characterizing a wide range of exoplanets, including those that might be habitable, is a major goal of the study. The ambitious science goals drive the challenges of optical design. This paper will present how the optical design meets the unique challenges for coronagraphs on large telescopes to achieve high contrast for a wide wavelength range from 200 to 2000 nm. Some of these unique challenges include the position and size of occulter masks, deformable mirror placement and separation, tight tolerances on the optical system and each element, and finally, packaging all instruments in a limited space. Three types of modules are designed after the coronagraph to explore the exoplanets and analyze the spectrum of detected exoplanet signals: two imaging cameras, two integral field spectrographs, and one high-resolution spectrometer. All of them work together to provide information to meet scientific challenges in searching for habitable planets. The optical designs, unique challenges, and the solutions for all coronagraph and spectral modules are presented. Their specifications derived from science goals are also presented.

Qian Gong↗
NASA NTRS2019

Optical design of the Extreme Coronagraph for Living Planetary Systems instrument for the LUVOIR mission study

The large UV/optical/IR surveyor (LUVOIR) is a concept for a highly capable, multiwavelength space observatory with ambitious science goals. Finding and characterizing a wide range of exoplanets, including those that might be habitable, is a major goal of the study. The ambitious science goals drive the challenges of optical design. This paper will present how the optical design meets the unique challenges for coronagraphs on large telescopes to achieve high contrast for a wide wavelength range from 200 to 2000 nm. Some of these unique challenges include the position and size of occulter masks, deformable mirror placement and separation, tight tolerances on the optical system and each element, and finally, packaging all instruments in a limited space. Three types of modules are designed after the coronagraph to explore the exoplanets and analyze the spectrum of detected exoplanet signals: two imaging cameras, two integral field spectrographs, and one high-resolution spectrometer. All of them work together to provide information to meet scientific challenges in searching for habitable planets. The optical designs, unique challenges, and the solutions for all coronagraph and spectral modules are presented. Their specifications derived from science goals are also presented.

Qian Gong↗
NASA NTRS2013

NuSTAR Detection of the Blazar B2 1023+25 at Redshift 5.3

B2 1023+25 is an extremely radio-loud quasar at zeta = 5.3 that was first identified as a likely high-redshift blazar candidate in the SDSS+FIRST quasar catalog. Here, we use the Nuclear Spectroscopic Telescope Array (NuSTAR) to investigate its non-thermal jet emission, whose high-energy component we detected in the hard X-ray energy band. The X-ray flux is approximately 5.5 × 10 (exp −14) erg cm(exp −2) s(exp −1) (5-10 keV) and the photon spectral index is Gamma(x) approx. =1.3-1.6. Modeling the full spectral energy distribution, we find that the jet is oriented close to the line of sight, with a viewing angle of approximately 3deg, and has significant Doppler boosting, with a large bulk Lorentz factor approximately 13, which confirms the identification of B2 1023+25 as a blazar. B2 1023+25 is the first object at redshift larger than 5 detected by NuSTAR, demonstrating the ability of NuSTAR to investigate the early X-ray universe and to study extremely active supermassive black holes located at very high redshift.

X-rays: general↗
NASA NTRS1989

A space qualified thermal imaging system using a Pt Si detector array

EDO Corporation, Barnes Engineering Division designed and constructed a high resolution thermal imaging system on contract to Lockheed for use in the SDI Star Lab. This employs a Pt Si CCD array which is sensitive in the spectral range of 3 to 5 microns. Star Lab will be flown in the Shuttle bay and consists basically of a large, reflecting, tracking telescope with associated sensors and electronics. The thermal imaging system is designed to operate in the focal plane of this telescope. The configuration of the system is illustrated. The telescope provides a collimated beam output which is focussed onto the detector array by a silicon objective lens. The detector array subtends a field of view of 1.6 degrees x 1.22 degrees. A beam switching mirror permits bypassing the large telescope to give a field of 4 degrees x 3 degrees. Two 8 position filter wheels are provided, and background radiation is minimized by Narcissus mirrors. The detector is cooled with a Joule-Thompson cryostat fed from a high pressure supply tank. This was selected instead of a more convenient closed-cycle system because of concern with vibration. The latter may couple into the extremely critical Starlab tracking telescope. The electronics produce a digitized video signal for recording. Offset and responsivity correction factors are stored for all pixels and these corrections are made to the digitized output in real time.

Astheimer, Robert W.↗
NASA NTRS1975

A large cooled infrared telescope facility for Spacelab

An optimized cooled IR telescope of 1 m aperture diameter will offer sensitivities over the 1 micron to 1 mm spectrum at least 1000 times greater than can be achieved from the ground in the atmospheric windows, and comparable sensitivities at wavelengths that are outside the windows. A study has shown that a cryogenically-cooled telescope of up to 1.6 m aperture diameter for Spacelab is feasible without new technology, although some development of detectors and scientific instruments to take advantage of the extreme sensitivity is indicated.-

Mccarthy, S. G.↗
NASA NTRS1981

Management of optics

American Science and Engineering, Inc., designed the large X-ray optic for the HEAO-2 X-ray Telescope. The key element in this project was the High Resolution Mirror Assembly (HRMA), subcontracting the fabrication of the optical surfaces and their assembly and alignment. The roles and organization of the key participants in the creation of HRMA are defined, and the degree of interaction between the groups is described. Management of this effort was extremely complex because of the intricate weaving of responsibilities, and AS&E, as HEAO-2 Program managers, needed to be well versed in the scientific objectives, the technical requirements, the program requirements, and the subcontract management. Understanding these factors was essential for implementing both technical and management controls, such as schedule and budget constraints, in-process control, residence requirements, and scientist review and feedback. Despite unforeseen technical problems and interaction differences, the HEAO-2 was built on schedule and to specification.

Kirchner, T. E.↗
NASA NTRS1994

The luminosity function at the end of the main sequence: Results of a deep, large-area, CCD survey for cool dwarfs

The luminosity function at the end of the main sequence is determined from V, R, and I data taken by the charge coupled devices (CCD)/Transit Instrument, a dedicated telescope surveying an 8.25 min wide strip of sky centered at delta = +28 deg, thus sampling Galactic latitudes of +90 deg down to -35 deg. A selection of 133 objects chosen via R - I and V - I colors has been observed spectroscopically at the 4.5 m Multiple Mirror Telescope to assess contributions by giants and subdwarfs and to verify that the reddest targets are objects of extremely late spectral class. Eighteen dwarfs of type M6 or later have been discovered, with the latest being of type M8.5. Data used for the determination of the luminosity function cover 27.3 sq. deg down to a completeness limit of R = 19.0. This luminosity function, computed at V, I, and bolometric magnitudes, shows an increase at the lowest luminosities, corresponding to spectral types later than M6- an effect suggested in earlier work by Reid & Gilmore and Legget & Hawkins. When the luminosity function is segregated into north Galactic and south Galactic portions, it is found that the upturn at faint magnitudes exists only in the southern sample. In fact, no dwarfs with M(sub I) is greater than or equal to 12.0 are found within the limiting volume of the 19.4 sq deg northern sample, in stark contrast to the smaller 7.9 sq deg area at southerly latitudes where seven such dwarfs are found. This fact, combined with the fact that the Sun is located approximately 10-40 pc north of the midplane, suggests that the latest dwarfs are part of a young population with a scale height much smaller than the 350 pc value generally adopted for other M dwarfs. These objects comprise a young population either because the lower metallicities prevelant at earlier epochs inhibited the formation of late M dwarfs or because the older counterparts of this population have cooled beyond current detection limits. The latter scenario would hold if these late-type M dwarfs are substellar. The luminosity function data together with an empirical derivation of the mass-luminosity relation (from Henry & McCarthy) are used to compute a mass function independent of theory. This mass function increases toward the end of the main sequence, but the observed density of M dwarfs is still insufficient to account for the missing mass. If the increases seen in the luminosity and mass functions are indicative of a large, unseen, substellar population, brown dwarfs may yet add significantly to the mass of the Galaxy.

Kirkpatrick, J. Davy↗
NASA NTRS2006

Future Gamma-Ray Observations of Pulsars and their Environments

Pulsars and pulsar wind nebulae seen at gamma-ray energies offer insight into particle acceleration to very high energies under extreme conditions. Pulsed emission provides information about the geometry and interaction processes in the magnetospheres of these rotating neutron stars, while the pulsar wind nebulae yield information about high-energy particles interacting with their surroundings. During the next decade, a number of new and expanded gamma-ray facilities will become available for pulsar studies, including Astro-rivelatore Gamma a Immagini LEggero (AGILE) and Gamma-ray Large Area Space Telescope (GLAST) in space and a number of higher-energy ground-based systems. This review describes the capabilities of such observatories to answer some of the open questions about the highest-energy processes involving neutron stars.

Thompson, David J.↗
NASA NTRS1988

Scientific investigations at a lunar base

Scientific investigations to be carried out at a lunar base can have significant impact on the location, extent, and complexity of lunar surface facilities. Among the potential research activities to be carried out are: (1) Lunar Science: Studies of the origin and history of the Moon and early solar system, based on lunar field investigations, operation of networks of seismic and other instruments, and collection and analysis of materials; (2) Space Plasma Physics: Studies of the time variation of the charged particles of the solar wind, solar flares and cosmic rays that impact the Moon as it moves in and out of the magnetotail of the Earth; (3) Astronomy: Utilizing the lunar environment and stability of the surface to emplace arrays of astronomical instruments across the electromagnetic spectrum to improve spectral and spatial resolution by several orders of magnitude beyond the Hubble Space Telescope and other space observatories; (4) Fundamental physics and chemistry: Research that takes advantage of the lunar environment, such as high vacuum, low magnetic field, and thermal properties to carry out new investigations in chemistry and physics. This includes material sciences and applications; (5) Life Sciences: Experiments, such as those that require extreme isolation, highly sterile conditions, or very low natural background of organic materials may be possible; and (6) Lunar environmental science: Because many of the experiments proposed for the lunar surface depend on the special environment of the Moon, it will be necessary to understand the mechanisms that are active and which determine the major aspects of that environment, particularly the maintenance of high-vacuum conditions. From a large range of experiments, investigations and facilities that have been suggested, three specific classes of investigations are described in greater detail to show how site selection and base complexity may be affected: (1) Extended geological investigation of a complex region up to 250 kilometers from the base requires long range mobility, with transportable life support systems and laboratory facilities for the analysis of rocks and soil. Selection of an optimum base site would depend heavily on an evaluation of the degree to which science objectives could be met. These objectives could include lunar cratering, volcanism, resource surveys or other investigations; (2) An astronomical observatory initially instrumented with a VLF radio telescope, but later expanding to include other instruments, requires site preparation capability, "line shack" life support systems, instrument maintenance and storage facilities, and sortie mode transportation. A site perpetually shielded from Earth is optimum for the advanced stages of a lunar observatory; (3) an experimental physics laboratory conducting studies requiring high vacuum facilities and heavily instrumented experiments, is not highly dependent on lunar location, but will require much more flexibility in experiment operation and EVA capability, and more sophisticated instrument maintenance and fabrication facilities.

Extraterrestrial Environment↗
NASA NTRS1979

Optical infrared sky survey instrumentation

An unusual, highly modified, Baker reflector-corrector class telescope has been adapted for wide field survey photography in the near infrared. This optical system uses a full field corrector plate and a field flattening lens to provide a flat field subtending about 4.5 deg on the sky. The small aperture telescope (20 inch primary) has been modified for use in the Newtonian focus configuration while preserving the optical elements of the Prime focus configuration. The telescope has been further modified to accept a very large format (146mm diameter photocathode) image intensifier camera to serve as a detector. The camera output is recorded photographically on film rather than glass plates. This unique instrument system is used in a program of sky survey photography in the optical infrared (8000-9000A bandpass) supplemented by visual bandpass photography. The photographs obtained with this system are of value not only for the extreme redness of the band but also because of their high resolution and their freedom from hydrogen emission.

Craine, E. R.↗
NASA NTRS1999

Coronal Magnetography of Solar Active Regions Using Coordinated SOHO/CDS and VLA Observations

The purpose of this project is to apply the coronal magnetographic technique to SOHO (Solar Heliospheric Observatory) /CDS (Coronal Diagnostic Spectrometer) EUV (Extreme Ultraviolet Radiation) and coordinated VLA microwave observations of solar active regions to derive the strength and structure of the coronal magnetic field. A CDS observing plan was developed for obtaining spectra needed to derive active region differential emission measures (DEMs) required for coronal magnetography. VLA observations were proposed and obtained. SOHO JOP 100 was developed, tested, approved, and implemented to obtain coordinated CDS (Coronal Diagnostic Spectrometer)/EIT (Ultraviolet Imaging Telescope)/ VLA (Very Large Array)/ TRACE (Transition Region and Coronal Explorer)/ SXT (Solar X Ray Telescope) observations of active regions on April 12, May 9, May 13, and May 23. Analysis of all four data sets began, with heaviest concentration on COS data. It is found that 200-pixel (14 A in NIS1) wavelength windows are appropriate for extracting broadened Gaussian line profile fit parameters for lines including Fe XIV at 334.2, Fe XVI at 335.4, Fe XVI at 360.8, and Mg IX at 368.1 over the 4 arcmin by 4 arcmin CDS field of view. Extensive efforts were focused on learning and applying were focused on learning and applying CDS software, and including it in new IDL procedures to carry out calculations relating to coronal magnetography. An important step is to extract Gaussian profile fits to all the lines needed to derive the DEM in each spatial pixel of any given active region. The standard CDS absolute intensity calibration software was applied to derived intensity images, revealing that ratios between density-insensitive lines like Fe XVI 360.8/335.4 yield good agreement with theory. However, the resulting absolute intensities of those lines are very high, indicating that revisions to the CDS absolute intensity calibrations remain to be included in the CDS software, an essential step to deriving reliable coronal magnetograms. With lessons learned and high quality data obtained during the past year, coronal magnetography will be successfully pursued under my new SOHO GI program.

Brosius, Jeffrey W.↗