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NASA NTRS2002

Automation of Coordinated Planning Between Observatories: The Visual Observation Layout Tool (VOLT)

Fulfilling the promise of the era of great observatories, NASA now has more than three space-based astronomical telescopes operating in different wavebands. This situation provides astronomers with the unique opportunity of simultaneously observing a target in multiple wavebands with these observatories. Currently scheduling multiple observatories simultaneously, for coordinated observations, is highly inefficient. Coordinated observations require painstaking manual collaboration among the observatory staff at each observatory. Because they are time-consuming and expensive to schedule, observatories often limit the number of coordinated observations that can be conducted. In order to exploit new paradigms for observatory operation, the Advanced Architectures and Automation Branch of NASA's Goddard Space Flight Center has developed a tool called the Visual Observation Layout Tool (VOLT). The main objective of VOLT is to provide a visual tool to automate the planning of coordinated observations by multiple astronomical observatories. Four of NASA's space-based astronomical observatories - the Hubble Space Telescope (HST), Far Ultraviolet Spectroscopic Explorer (FUSE), Rossi X-ray Timing Explorer (RXTE) and Chandra - are enthusiastically pursuing the use of VOLT. This paper will focus on the purpose for developing VOLT, as well as the lessons learned during the infusion of VOLT into the planning and scheduling operations of these observatories.

Maks, Lori↗

NASA NTRS2003

The Swift Project Contamination Control Program: A Case study of Balancing Cost, Schedule and Risk

The Swift Observatory will be launched in early 2004 to examine the dynamic process of gamma ray burst (GRB) events. The multi-wavelength Observatory will study the GRB afterglow characteristics, which will help to answer fundamental questions about both the structure and the evolution of the universe. The Swift Observatory Contamination Control Program has been developed to aid in ensuring the success of the on-orbit performance of two of the primary instruments: the Ultraviolet and Optical Telescope (UVOT) and the X-Ray Telescope (XRT). During the design phase of the Observatory, the contamination control program evolved and trade studies were performed to assess the risk of contaminating the sensitive UVOT and XRT optics during both pre-launch testing and on-orbit operations, within the constraints of the overall program cost and schedule.

Hansen, Patricia A.↗

NASA NTRS2004

External and Internal Reconnection in Two Filament-Carrying Magnetic-Cavity Solar Eruptions

We observe two near-limb solar filament eruptions, one of 2000 February 26 and the other of 2002 January 4. For both we use 195 Angstroms Fe XII images from the Extreme-Ultraviolet (EUV) Imaging Telescope (EIT) and magnetograms from the Michelson Doppler Imager (MDI), both on the Solar and Heliospheric Observatory (SOHO) satellite. For the earlier event we also use soft X-ray telescope (SXT), hard X-ray telescope (HXT), and Bragg Crystal Spectrometer (BCS) data from the Yohkoh satellite, and hard X-ray data from the BATSE experiment on the Compton Gamma Ray Observatory (CGRO). Both events occur in quadrupolar magnetic regions, and both have coronal features that we infer belong to the same magnetic-cavity structures as the filaments. In both cases the cavity and filament first rise slowly at approximately 10 kilometers per second prior to eruption, and then accelerate to approximately 100 kilometers per second during the eruption, although the slow-rise movement for the higher-altitude cavity elements is clearer in the later event. We estimate both filaments and both cavities to contain masses of approximately 10(exp 14-15) g and approximately 10(exp 15-16) g respectively. We consider whether two specific magnetic-reconnection-based models for eruption onset, the tether cutting and the breakout models, are consistent with our observations. In the earlier event soft X-rays from SXT show an intensity increase during the 12-minute interval over whch fast eruption begins, which is consistent with tether-cutting-model predictions. Substantial hard X-rays, however, do not occur until after fast eruption is underway, and so this is a constraint the tether-cutting model must satisfy. During the same 12-minute interval over which fast eruption begins, there are brightenings and topological changes in the corona indicative of high-altitude reconnection early in the eruption, and this is consistent with breakout predictions. In both eruptions, however, the onset of the filament fast-rise phase occurs while overlying cavity-related coronal loops are still evolving from a "closed" state to an "open" state, and our observations of the time evolution of these loops compared to the eruption state in both events are constraints the breakout model must meet. Therefore our findings are consistent with runaway-tether-cutting-type reconnection and fast breakout-type reconnection both occurring early in the fast phase of the February eruption and with both types of reconnection being important in unleashing the explosion, but we are not able to say which, if either, type of reconnection actually triggered the fast phase. We have also found specific constraints that either model, or any other model, must satisfy if correct.

Sterling, Alphonse C.↗

NASA NTRS2004

The Swift Project Contamination Control Program: A Case Study of Balancing Cost, Schedule and Risk

Hansen, Patricia A.↗

NASA NTRS2006

Rapid Identification of GRB Afterglows with Swift/UVOT

As part of the automated response to a new gamma-ray burst (GRB), the Ultraviolet and Optical Telescope (UVOT) instrument on Swift starts a 200-second exposure with the V filter within approximately 100 seconds of the BAT burst trigger. The instrument searches for sources in a 8' x 8' region, and sends the list of sources and a 160" x 160" sub-image centered on the burst position to the ground via Tracking and Data Relay Satellite System (TDRSS). These raw products and additional products calculated on the ground are then distributed through the GCN within a few minutes of the trigger. We describe the sensitivity of these data for detecting afterglows, summarize current results, and outline plans for rapidly distributing future detections.

Marshall, F. E.↗

NASA NTRS2007

UVOT Detection of GRB Afterglows

The automated response of the UltraViolet and Optical Telescope (UVOT) on Swift to new GRBs has remained stable since March 15,2006. From then through August 10, 2007, UVOT observed 122 of the 129 GRBs detected with Swift's Burst Alert Telescope (BAT). UVOT typically takes an initial 100-s exposure with the White filter (160-650 nm) starting 60 - 180 s after the trigger followed by exposures with the other 6 filters. UVOT detected 37% of the 79 long GRBs (T90 > 2.0 s) that had modest reddening in the Milky Way (E(B-V) < 0.5) and were observed within 180 seconds of the trigger. Magnitudes ranged from 12.8 to the sensitivity limit of approx.21. Only 1 of 8 short GRBs were detected, and its magnitude was near the sensitivity limit. We also report correlations of afterglow magnitudes with other GRB properties.

Marshall, Frank↗

NASA NTRS2010

Strong Rotation of an Erupting Quiescent Polar Crown Prominence

On 5-6 June 2007, a large quiescent polar crown prominence was observed to erupt by the two Solar Terrestrial Relations Observatory (STEREO) spacecraft. This eruption was particularly visible in the 304 A channel of the Extreme Ultraviolet Imager (EUVI) telescopes. A detailed analysis of the fine structures in the images allows the three-dimensional structure of the erupting prominence to be derived. The prominence is seen to undergo substantial rotation of at least 90 along the radial axis as it rises, with indications that additional rotation occurred before the prominence rose into the STEREO fields of view. Two temporary structures ("spurs") are seen to form at an angle to the main spine of the prominence, and are interpreted as signs of reconnection. These reconnection events contribute to the overall rotation of the prominence. A significant fraction of the prominence material is drained through new field lines caused by one of the reconnection events, resulting in only a weak coronal mass ejection event observed by the STEREO and SOHO coronagraphs. The eruption is interpreted as being initiated by the helical kink instability, with subsequent modification by the reconnection events.

Source record↗

NASA NTRS2016

NASA's Physics of the Cosmos and Cosmic Origins Technology Development Programs

The strategic astrophysics missions of the coming decades will help answer the questions "How did our universe begin and evolve?" and "How did galaxies, stars, and planets come to be?" Enabling these missions requires advances in key technologies far beyond the current state of the art. NASA's Physics of the Cosmos (PCOS) and Cosmic Origins (COR) Program Offices manage technology maturation projects funded through the Strategic Astrophysics Technology (SAT) program to accomplish such advances. The PCOS and COR Program Offices, residing at the NASA Goddard Space Flight Center (GSFC), were established in 2011, and serve as the implementation arm for the Astrophysics Division at NASA Headquarters. We present an overview of the Programs' technology development activities and the current technology investment portfolio of 23 technology advancements. We discuss the process for addressing community-provided technology gaps and Technology Management Board (TMB)-vetted prioritization and investment recommendations that inform the SAT program. The process improves the transparency and relevance of our technology investments, provides the community a voice in the process, and promotes targeted external technology investments by defining needs and identifying customers. The Programs' priorities are driven by strategic direction from the Astrophysics Division, which is informed by the National Research Council's (NRC) "New Worlds, New Horizons in Astronomy and Astrophysics" (NWNH) 2010 Decadal Survey report [1], the Astrophysics Implementation Plan (AIP) [2] as updated, and the Astrophysics Roadmap "Enduring Quests, Daring Visions" [3]. These priorities include technology development for missions to study dark energy, gravitational waves, X-ray and inflation probe science, and large far-infrared (IR) and ultraviolet (UV)/optical/IR telescopes to conduct imaging and spectroscopy studies. The SAT program is the Astrophysics Division's main investment method to mature technologies that will be identified by study teams set up to inform the 2020 Decadal Survey process on several large astrophysics mission concepts.

SPIE paper↗

NASA NTRS2016

Identifying Planetary Biosignature Impostors: Spectral Features of CO and O4 Resulting from Abiotic O2/O3 Production

O2 and O3 have been long considered the most robust individual biosignature gases in a planetary atmosphere, yet multiple mechanisms that may produce them in the absence of life have been described. However, these abiotic planetary mechanisms modify the environment in potentially identifiable ways. Here we briefly discuss two of the most detectable spectral discriminants for abiotic O2/O3: CO and O4. We produce the first explicit self-consistent simulations of these spectral discriminants as they may be seen by James Webb Space Telescope (JWST). If JWST-NIRISS (Near InfraRed Imager and Slitless Spectrograph) and/or NIRSpec (Near InfraRed Spectograph) observe CO (2.35, 4.6 micrometers) in conjunction with CO2 (1.6, 2.0, 4.3 micrometers) in the transmission spectrum of a terrestrial planet it could indicate robust CO2 photolysis and suggest that a future detection of O2 or O3 might not be biogenic. Strong O4 bands seen in transmission at 1.06 and 1.27 micrometers could be diagnostic of a post-runaway O2-dominated atmosphere from massive H-escape. We find that for these false positive scenarios, CO at 2.35 micrometers, CO2 at 2.0 and 4.3 micrometers, and O4 at 1.27 micrometers are all stronger features in transmission than O2/O3 and could be detected with sigal to noise ratios greater than or approximately 3 for an Earth-size planet orbiting a nearby M dwarf star with as few as 10 transits, assuming photon-limited noise. O4 bands could also be sought in UV/VIS/NIR reflected light (at 0.345, 0.36, 0.38, 0.445, 0.475, 0.53, 0.57, 0.63, 1.06, and 1.27 micrometers) by a next generation direct imaging telescope such as LUVOIR (Large Ultraviolet Visible Infrared)/HDST (High-Definition Space Telescope) or HabEx (Habitable-Exoplanet Imaging Mission) and would indicate an oxygen atmosphere too massive to be biologically produced.

planetary atmosphere↗

NASA NTRS1967

Stellar photometry from a satellite vehicle.

Far UV radiation flux measurement by satellite- borne telescopic stellar spectrophotometer

STELLAR SPECTROPHOTOMETRY↗

NASA NTRS1994

Ultraviolet interstellar polarization observed with the Hubble Space Telescope

We have used the Faint Object Spectrograph of the Hubble Space Telescope to observe interstellar linear polarization from 1300 to 3300 A in two stars with well-studied interstellar polarization at visible wavelenths. The wavelength dependence of linear polarization declines smoothly with decreasing wavelength and is devoid of structure associated with the prominent 2175 A absorption bump in the interstellar extinction curve. The data for one star (HD 161056) are consistent with an extrapolation based on the Serkowski formula of a fit to the ground-based polariztion; the other star (HD 7252) shows excess (super-Serkowski) polarization relative to the extrapolation. Out of a total of 10 stars now studied by means of spectropolarimetry in the satellite ultraviolet, including eight obseved with the Wisconsin Ultraviolet Photopolarimeter, five (those of longest lambda (sub max)) show Serkowski behavior, and four others show super-Serkowski behavior; only one (HD 197770) shows evidence for polarization associated with the 2175 A bump. These results place important constraints on the nature of the bump feature.

Somerville, W. B.↗

NASA NTRS1983

A survey of ultraviolet interstellar absorption lines

A telescope-spectrometer on the Copernicus spacecraft made possible the measurement of many ultraviolet absorption lines produced by the interstellar gas. The present survey provides data on ultraviolet absorption lines in the spectra of 88 early-type stars. The stars observed are divided into four classes, including reddened stars, unreddened bright stars, moderately reddened bright stars, and unreddened and moderately reddened faint stars. Data are presented for equivalent width, W, radial velocity V, and rms line width, D, taking into account some 10 to 20 lines of N I, O I, Si II, P II, S II, Cl I, Cl II, Mn II, Fe II, Ni II, Cu II, and H2. The data are based on multiple scans for each line. Attention is given to details of observations, the data reduction procedure, and the computation of equivalent width, mean velocity, and velocity dispersion.

Bohlin, R. C.↗

NASA NTRS1992

Near-ultraviolet imaging of Jupiter's satellite Io with the Hubble Space Telescope

The surface of Jupiter's Galilean satellite Io has been resolved for the first time in the near ultraviolet at 2850 A by the Faint Object Camera (FOC) on the Hubble Space Telescope (HST). The restored images reveal significant surface structure down to the resolution limit of the optical system corresponding to approximately 250 km at the sub-earth point.

Paresce, F.↗

NASA NTRS1979

Wolter-Schwarzschild optics for the extreme-ultraviolet - The Berkeley stellar spectrometer and the EUV Explorer

The design, fabrication and performance of two Wolter-Schwarzschild grazing incidence optics are described. Both telescopes have been figured by single point diamond turning and have achieved better than 15-arcsec on-axis imaging. The telescope for the stellar spectrometer is an f/10 Type II system with an effective area of 225 sq cm at 250 A and 300 cm2 at 500 A. The primary has a maximum diameter of 38 cm and was fabricated in three elements. The copper-plated aluminum substrate was diamond turned; following nickel plating, the surface was polished and coated with evaporated gold. The performance during a sounding rocket flight is discussed. The prototype telescope for the Extreme Ultraviolet Explorer is an f/1.24 Type I system with an effective field of view of 5.0-deg diameter. The telescope has a maximum diameter of 40 cm and was fabricated as a single element. The aluminum substrate is to be diamond turned; the nickel plated surface will be polished and electroplated with gold. The design choice and defocusing optimization aimed at maximizing the field of view and number of image pixels is examined.

Malina, R. F.↗

NASA NTRS1994

Solar coronal temperature diagnostics using emission line from multiple stages of ionization of iron

We obtained spatially resolved extreme-ultraviolet (EUV) spectra of AR 6615 on 1991 May 7 with NASA/ Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph (SERTS). Included are emission lines from four different stages of ionization of iron: Fe(+15) lambda 335 A, Fe(+14) lambda 327 A, Fe(+13) lambda 334 A, and Fe(+12) lambda 348 A. Using intensity ratios from among these lines, we have calculated the active region coronal temperature along the Solar Extreme Ultraviolet Telescope and Spectrograph (SERTS) slit. Temperatures derived from line ratios which incorporate adjacent stages of ionization are most sensitive to measurement uncertainties and yield the largest scatter. Temperatures derived from line ratios which incorporate nonadjacent stages of ionization are less sensitive to measurement uncertainties and yield little scatter. The active region temperature derived from these latter ratios has an average value of 2.54 x 10(exp 6) K, with a standard deviation approximately 0.12 x 10(exp 6) K, and shows no significant variation with position along the slit.

Brosius, Jeffrey W.↗

NASA NTRS1999

STS-93: Crew Interview - Steve Hawley

Live footage of a preflight interview with Mission Specialist Steven A. Hawley is presented. The interview addresses many different questions including why Hawley wanted to be an astronaut, his career path, and how this historic flight (first female Commander of a mission) draws attention from the media. Other interesting information that this one-on-one interview discusses is the deployment of the Chandra satellite, why people care about x ray energy, whether or not Chandra will compliment the other X Ray Observatories currently in operation, and his responsibilities during the major events of this mission. Hawley mentions the Inertial Upper Stage (IUS) rocket that will deployed the Chandra Telescope, and the design configuration of Chandra to gather and transfer information. The Southwest Research Ultraviolet Imaging System (SWUIS) Telescope on board Columbia, the Plant Growth Investigation in Microgravity (PGIM) and Gelation of Sols: Applied Microgravity Research (GOSAMR) experiments, and the two observatories presently in orbit (Gamma Ray Observatory, and Hubble Space Telescope) are also discussed.

Source record↗

NASA NTRS1994

Cooling of the white dwarf in U Geminorum between outbursts

We have obtained far-ultraviolet (1150-1610 A) spectra of U Gem with the Faint Object Spectrograph on the Hubble Space Telescope approximately 13 and 70 days after the end of a normal dwarf nova outburst of the system. Both spectra appear dominated by the White Dwarf (WD) in U Gem. At 1400 A, the flux from U Gem declined approximately 28% between the two observations. Detailed comparison of the spectra with solar abundance WD models suggest that average surface temperature of the WD surface cooled from approximately 39,400 K to approximately 32,100 K between the two observations. The main features which are not fitted well by WD models are absorption due to N V lambda lambda-1239, 1243 and emission at Lyman-alpha. These observations provide unambiguous confirmation that the WD in U Gem cools during quiescence, as was suggested by analyses of far-ultraviolet spectra obtained with International Ultraviolet Explorer (IUE) and Hopkins Ultraviolet Telescope (HUT).

Long, Knox S.↗

NASA NTRS2017

Hinode: A Decade of Success in Capturing Solar Activity

As the present solar cycle passes into its minimum phase, the Hinode mission marks its tenth year of investigating solar activity. Hinode's decade of successful observations have provided us with immeasurable insight into the solar processes that invoke space weather and thereby affect the interplanetary environment in which we reside. The mission's complementary suite of instruments allows us to probe transient, high energy events alongside long-term, cycle-dependent phenomena from magnetic fields at the Sun's surface out to highly thermalized coronal plasma enveloping active regions (ARs). These rich data sets have already changed the face of solar physics and will continue to provoke exciting research as new observational paradigms are pursued. Hinode was launched as part of the Science Mission Directorate's (SMD) Solar Terrestrial Probes Program in 2006. It is a sophisticated spacecraft equipped with a Solar Optical Telescope (SOT), an Extreme-ultraviolet Imaging Spectrometer (EIS), and an X-Ray Telescope (XRT) (see x 4). With high resolution and sensitivity, Hinode serves as a microscope for the Sun, providing us with unique capabilities for observing magnetic fields near the smallest scales achievable, while also rendering full-Sun coronal context in the highest thermal regimes. The 2014 NASA SMD strategic goals objective to "Understand the Sun and its interactions with the Earth and the solar system, including space weather" forms the basis of three underlying Heliophysics Science Goals. While Hinode relates to all three, the observatory primarily addresses: Explore the physical processes in the space environment from the Sun to the Earth and through the solar system. Within the NASA National Research Council (NRC) Decadal Survey Priorities, Hinode targets: (a) Determine the origins of the Sun's activity and predict the variations of the space environment and (d) Discover and characterize fundamental processes that occur both within the heliosphere and throughout the universe. In response to the 2012 NRC Decadal Survey Science Challenges and 2014 Heliophysics Roadmap Research Focus Areas, the Hinode mission has set forth four Prioritized Science Goals (PSGs): (a) Study the sources and evolution of highly energetic dynamic events; (b) Characterize cross-scale magnetic field topology and stability; (c) Trace mass and energy flow from the photosphere to the corona; and (d) Continue long term synoptic support to quantify cycle variability.

review↗