The STEREO Observatory

The Solar Terrestrial Relations Observatory (STEREO) is the third mission in NASA’s Solar Terrestrial Probes program. The mission is managed by the Goddard Space Flight Center (GSFC) and implemented by The Johns Hopkins University Applied Physics Laboratory (JHU/APL). This two-year mission provides a unique and revolutionary view of the Sun–Earth system. Consisting of two nearly identical observatories, one ahead of Earth in its orbit around the Sun and the other trailing behind the Earth, the spacecraft trace the flow of energy and matter from the Sun to Earth and reveal the three-dimensional structure of coronal mass ejections (CMEs) to help explain their genesis and propagation. From its unique side-viewing vantage point, STEREO also provides alerts for Earth-directed solar ejections. These alerts are broadcast at all times and received either by NASA’s Deep Space Network (DSN) or by various space-weather partners.     

SOHO: The Solar and Heliospheric Observatory

The Solar and Heliospheric Observatory (SOHO), together with the Cluster mission, constitutes ESA's Solar Terrestrial Science Programme (STSP), the first Cornerstone of the Agency's long-term programme Space Science — Horizon 2000. STSP, which is being developed in a strong collaborative effort with NASA, will allow comprehensive studies to be made of the both the Sun's interior and its outer atmosphere, the acceleration and propagation of the solar wind and its interaction with the Earth. This paper gives a brief overview of one part of STSP, the SOHO mission.     

The IMAGE High-Resolution Data Set

The entire IMAGE mission high resolution (level 0.5) data set is being archived in Universal Data Format (UDF). This data format is self-documenting, does not alter the incoming telemetry values, allows for easy access through a small number of generic software routines, and returns data in any physical unit for which an algorithm has been constructed. This paper discusses the UDF in general, the UDF as applied to IMAGE, the UDF interface software, and UDF-based display software.     

The comptel experiment on the NASA Gamma-Ray Observatory

The imaging Compton telescope COMPTEL will be flown on the NASA Gamma-Ray Observatory at the beginning of the next decade. The instrument with its wide field of view and improved angular resolution will provide the first sky survey at MeV energies, as well as deep studies of galactic and extragalactic gamma-ray point sources and diffuse emission. The hardware preparations are close to completion, with calibrations to be done in 1987 prior to integration of the instrument onto the observatory carrying 3 other gamma ray detectors.     

The IMAGE science and mission operations center

The Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) will produce forefront science by quantifying the response of the magnetosphere to the time variable solar wind. It will acquire, for the first time, a variety of three-dimensional images of magnetospheric boundaries and plasma distributions extending from the magnetopause to the inner plasmasphere. The images will be produced on time scales needed to answer important questions about the interactions of the solar wind and the magnetosphere. The IMAGE team will provide open access to all IMAGE data. Thus there will be no proprietary rights or periods. All IMAGE data products will be archived and available to the scientific research community. The IMAGE mission will operate with a near 100% duty cycle with all instruments in their baseline operational modes. A Science and Mission Operations Control Center or SMOC has been developed at the NASA Goddard Space Flight Center (GSFC) to be the main data and command processing system for IMAGE. The IMAGE Level-0 data will be processed into Level 0.5 and Level-1 data and browse products within 24 hours after their receipt of raw data in the SMOC. These data products will be transferred to the NSSDC, for long-term archiving, and posted immediately on the world-wide-web for use by the international scientific community and the public.     

The low-energy neutral atom imager for IMAGE

The `Imager for Magnetosphere-to-Aurora Global Exploration (IMAGE) will be launched early in the year 2000. It will be the first mission dedicated to imaging, with the capability to determine how the magnetosphere changes globally in response to solar storm effects in the solar wind, on time scales as short as a few minutes. The low energy neutral atom (LENA) imager uses a new atom-to-negative ion surface conversion technology to image the neutral atom flux and measure its composition (H and O) and energy distribution (10 to 750 eV). LENA uses electrostatic optics techniques for energy (per charge) discrimination and carbon foil time-of-flight techniques for mass discrimination. It has a 90°×° field-of-view in 12 pixels, each nominally 8°×°. Spacecraft spin provides a total field-of-view of 90°×360°, comprised of 12×45 pixels. LENA is designed to image fast neutral atom fluxes in its energy range, emitted by auroral ionospheres or the sun, or penetrating from the interstellar medium. It will thereby determine how superthermal plasma heating is distributed in space, how and why it varies on short time scales, and how this heating is driven by solar activity as reflected in solar wind conditions.     

The near infrared high resolution imaging camera program of Beijing Observatory

This paper introduces the program of an adaptive optics system using an infrared camera for the near infrared observations based on the 2.16 m telescope of Beijing Observatory. This system consists of 3 parts: (1), the 2.16 m telescope; (2), the adaptive optics system that will be mounted at the coudé focus on an optical table. It will be used to remove the effect of atmospheric turbulence on the imaging observations; (3), the infrared camera with a 512×512 PtSi IR detector array.     

THEMIS Ground Based Observatory System Design

The comprehensive THEMIS approach to solving the substorm problem calls for monitoring the nightside auroral oval with low-cost, robust white-light imagers and magnetometers that can deliver high time resolution data (0.33 and 2 Hz, respectively). A network of 20 Ground-Based Observatories (GBOs) are deployed across Canada and Alaska to support the collection of data from these instruments. Here we describe the system design of the observatory, with emphasis on how the design meets the environmental and data-collection requirements. We also review the design of the All Sky Imager (ASI), discuss how it was built to survive Arctic deployments, and summarize the optical characterizations performed to qualify the design to meet THEMIS mission requirements.     

Timekeeping at the US Naval Observatory

No one can stop time, but time can stop a system. Users need to be aware of the different flavors of time, depending upon their needs. Most systems require that all their components be on common time (synchrony), but they cannot keep them on time unless they are also on a common frequency (syntony). Other systems simply require syntony. The US Naval Observatory (USNO) is the timing reference for GPS. Its master clock (MC) is based upon 72 HP5071 cesium and 17 hydrogen maser frequency standards in three buildings at two sites, and their data are used to generate UTC (USNO). The USNO disseminates and distributes the time not only via GPS, but also with Loran, network time protocol (NTP), and two-way-satellite time transfer (TWSTT). Our emphasis is on robustness through repeated calibration and multiplicity of systems, and we recommend this for our users as well. Further details and explanations of our services can be found on: http://tycho.usno.navy.mil, or by contacting the author directly.     

IMAGE mission overview

The Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) mission is the first mission in NASA's MIDEX (Mid-size Explorer) program. It is the first satellite mission that is dedicated to imaging the Earth's magnetosphere. IMAGE will utilize the techniques of ultraviolet imaging, neutral atom imaging, and radio plasma imaging to map out global distributions of the electron and proton aurora; the helium ions of the plasmasphere; the ionospheric ion outflow; the medium-energy ions of the near-Earth plasma sheet, ring current, and polar cusp; the high-energy ions of the ring current and trapped radiation belts; and the total plasma density from the ionosphere out to the magnetopause. The imaging perspective is from an elliptical polar orbit with apogee at latitudes from 40° to 90° in the northern hemisphere. For ultraviolet and neutral atom imaging, the time resolution is set by the two-minute spin period of the IMAGE spacecraft, which will be sufficient to track the development of magnetospheric substorms. An important feature of the IMAGE mission is its completely open data set with no proprietary data or intervals. All data, along with software needed for plotting and analysis, will be available within 24 hours of acquisition.     

The scientific payload of the space-based Solar and Heliospheric Observatory (SOHO)

The space-based Solar and Heliospheric Observatory (SOHO) is a joint venture of ESA and NASA within the frame of the Solar Terrestrial Science Programme (STSP), the first Cornerstone of ESA's long-term programme Space Science — Horizon 2000. The principal scientific objectives of the SOHO mission are: a) a better understanding of the structure and dynamics of the solar interior using techniques of helioseismology, and b) a better insight into the physical processes that form and heat the Sun's corona, maintain it and give rise to its acceleration into the solar wind. To achieve these goals, SOHO carries a payload consisting of 12 sets of complementary instruments which are briefly described here.     

VLBI Space Observatory Programme (VSOP) satellite

The Institute of Space and Astronautical Science (ISAS), Japan, is developing a satellite, named MUSES-B, for VLBI (very long baseline interferometry) observations from space. The science observation program using MUSES-B is called the VLBI Space Observatory Programme (VSOP). The satellite is formed as an orbiting radiotelescope with a parabolic antenna of 8 meters diameter. Fine-resolution and high-quality imaging of active galactic nuclei and quasars, and observations of maser sources, are the main science objectives. The satellite will be launched in summer 1996. The satellite operation and science observations will be performed in collaboration with NASA and ground radio observatories around the world     

不完整投影数据情况下的图像重建

给出了代数重建收敛准则和图像重建算法,重构出7幅图像,并对代数重建算法存在的问题进行了讨论和改进.     

The Solar Terrestrial Relations Observatory (STEREO) Education and Outreach (E/PO) Program

The STEREO mission’s Education and Outreach (E/PO) program began early enough its team benefited from many lessons learned as NASA’s E/PO profession matured. Originally made up of discrete programs, by launch the STEREO E/PO program had developed into a quality suite containing all the program elements now considered standard: education workshops, teacher/student guides, national and international collaboration, etc. The benefit of bringing so many unique programs together is the resulting diverse portfolio, with scientists, E/PO professionals, and their education partners all of whom can focus on excellent smaller programs. The drawback is a less cohesive program nearly impossible to evaluate in its entirety with the given funding. When individual components were evaluated, we found our programs mostly made positive impact. In this paper, we elaborate on the programs, hoping that others will effectively use or improve upon them. When possible, we indicate the programs’ effects on their target audiences.     

APPLICATION OF MVP IN REAL TIME IMAGE PROCESSING

Inthe field of communication,radar and im-age processing,real- time analysis demands somuch data that the traditional method can't bear,and therefore,the focus is transitioned to parallelprocessing.MVP( made by Texas Instrument)can integrate severalfunctions into one board to re-alize the image or voice processing system whichhas been made with several boards and severalchips before.MVP has five programmable digitalsignal processors in it,and is of MIMD structure.The crossbar connects five…     

Global imaging of O+ from IMAGE/HENA

The magnetospheric O⁺ population in the 52–180 keV range during storms is investigated through the analysis of energetic neutral atom (ENA) images. The images are obtained from the high energy neutral atom (HENA) imager onboard the IMAGE satellite. At each substorm onset following the commencement of a geomagnetic storm the oxygen ENA display ～30 min intense bursts. Only very weak corresponding features in the 60–119 keV hydrogen ENA can be occasionally seen. The dominating fraction of the oxygen ENA emissions are produced when O⁺ ions mirror/precipitate at low altitudes, where the number density of the neutral atmosphere is high. During the storm we observed several bursts of oxygen ENA, but it is still not clear how much the O⁺ content of the ring current increases during the storm main phase. Our observations suggest that the responsible injection mechanism is mass-dependent and scatters the pitch angles. This leads us to favor a non-adiabatic mechanism proposed by (Delcourt, 2002).     

Summary of quantitative interpretation of IMAGE far ultraviolet auroral data

Direct imaging of the magnetosphere by instruments on the IMAGE spacecraft is supplemented by simultaneous observations of the global aurora in three far ultraviolet (FUV) wavelength bands. The purpose of the multi-wavelength imaging is to study the global auroral particle and energy input from the magnetosphere into the atmosphere. This paper describes the method for quantitative interpretation of FUV measurements. The Wide-Band Imaging Camera (WIC) provides broad band ultraviolet images of the aurora with maximum spatial resolution by imaging the nitrogen lines and bands between 140 and 180 nm wavelength. The Spectrographic Imager (SI), a dual wavelength monochromatic instrument, images both Doppler-shifted Lyman-α emissions produced by precipitating protons, in the SI-12 channel and OI 135.6 nm emissions in the SI-13 channel. From the SI-12 Doppler shifted Lyman-α images it is possible to obtain the precipitating proton flux provided assumptions are made regarding the mean energy of the protons. Knowledge of the proton (flux and energy) component allows the calculation of the contribution produced by protons in the WIC and SI-13 instruments. Comparison of the corrected WIC and SI-13 signals provides a measure of the electron mean energy, which can then be used to determine the electron energy flux. To accomplish this, reliable emission modeling and instrument calibrations are required. In-flight calibration using early-type stars was used to validate the pre-flight laboratory calibrations and determine long-term trends in sensitivity. In general, very reasonable agreement is found between in-situ measurements and remote quantitative determinations.