Satellite observations of upper atmosphere O3 and HNO3 from the Limb Infrared Monitor of the Stratosphere (LIMS) experiment on Nimbus 7

The Limb Infrared Monitor of the Stratosphere (LIMS) experiment is a limb scanning infrared sounder designed to measure vertical temperature profiles and the concentrations of key chemical compounds which are important in the stratospheric ozone-nitrogen photochemistry. This paper describes results from the O₃ and HNO₃ channels with emphasis on validation of the data. Similar discussions of results from the other channels are presented in two companion papers published in these proceedings.     

FIGARO: An experiment for pulsar and variable source studies in the MeV range

We present a large area, balloon borne, NaI(Tl) detector for low-energy gamma rays with temporal signature : FIGARO.The main detector is a mosaic of 12 NaI(Tl) tiles 22.5 × 15 × 5 cm, for a total geometric area of 4050 cm².In the energy band 140 keV - 6 MeV, the expected background counting rate at float altitude is in the range of two to three thousands counts per second.For pulsar analysis the expected 3δ sensitivity for 5 hours exposition time is 2.5 10^?4 ph/cm².s.MeV (150–500 keV) 1.5 10^?4 ph/cm².s.MeV (1–6 MeV). This performance, together with the large effective area and the relatively short duration of a balloon flight, make FIGARO particularly suitable for the identification of sources by means of temporal analysis.For objectives in the Northern sky, including the Crab pulsar, a transmediterranean flight is planned for the summer of 1982 ; a Southern mission is scheduled in Brazil for the fall of 1983 (Vela, PSR 1822-09).     

Initial results from COMPTEL onboard GRO

COMPTEL is the first imaging telescope to explore the MeV gamma-ray range (0.7 to 30 MeV). At present, it is performing a complete sky survey. In later phases of the mission selected celestial objects will be studied in more detail. The data from the first year of the mission have demonstrated that COMPTEL performs very well. First sky maps of the inner part of the Galaxy clearly identify the plane as a bright MeV-source (probably due to discrete sources as well as diffuse radiation). The Crab and Vela pulsar lightcurves have been measured with unprecedented accuracy. The quasars 3C273 and 3C279 have been seen for the first time at MeV energies. Both quasars show a break in their energy spectra in the COMPTEL energy range. The 1.8 MeV line from radioactive ²⁶A1 has been detected from the central region of the Galaxy and a first sky map of the inner part of the Galaxy has been obtained in the light of this line. Upper limits to gamma-ray line emission at 847 keV and 1.238 MeV from SN 1991T have been derived. Upper limits to the interstellar gamma-ray emissivity have been determined at MeV-energies. Several cosmic gamma-ray bursts within the field-of-view have been located with an accuracy of about 1°. On 1991 June 9, 11 and 15, COMPTEL observed gamma-ray emission (continuum and line) from three solar flares. Also neutrons were detected from the June 9 and June 15 flares.     

Expression of cloned genes of transgenic microorganisms introduced into man-made ecosystems.

Modeling of transgenic microorganism introduction into small man-made ecosystems can help forecast changes in expression of cloned genes under different conditions of existence. Introduction of the E. coli Z905/pPHL7 strain containing a plasmid with luminescent system genes of luminous bacteria led to changes in cell and colony morphology, reduction in metabolic activity of cells, and, as a result, a lower level of expression of cloned gene. A low concentration of nutrients has been shown to favor greatly the phenotypic change of cells of the recombinant strain. Expression of cloned genes changed due to: a lower concentration of plasmid DNA, a change in regulation of cloned genes, and a change in cells of biosynthesis of substrates needed for expression of luminescent genes. The conducted investigations can provide a basis for the use of marker transgenic microorganisms in closed ecosystems of different types. Grant numbers: 99-04-96017, 00-07-9011.     

Transformation of a delta: Converting estuaries to lakes

In this century large-scale transformations have been carried out in the delta of the Rhine, Meuse and Scheldt in The Netherlands. The following principal consequences are considered: the loss of estuarine ecosystems, the change in the process of sedimentation and erosion, and the development of new aquatic and terrestrial ecosystems. The ecological consequences of the transformation of the Grevelingen estuary into a salt-water lake and some surprising developments are described briefly. The need for a limited restoration of the water exchange between the lake and the North Sea is indicated, as well as the major impacts of the exchange. The necessity for the maintenance or restoration of estuaries, the ecological development and the possibilities of the new lakes, and the management of these lakes by engineering structures are discussed. Careful land-use planning and ecosystem management, backed by research, are needed to make the fullest possible use of the potential offered by new lakes. It is also concluded that salt lakes have interesting perspectives.     

Bodies in flowing plasmas: Laboratory studies

A brief review of early laboratory investigations of bodies in flowing, rarefied plasmas is given together with a discussion of more recent parametric studies carried out at NASA/Marshall Space Flight Center (MSFC), which include the effects of the ion acoustic Mach number and the normalized test body potential. Good agreement is found between the experimental results and theoretical calculations which omit ion thermal motion. The relation between laboratory investigations and the results of satellite-borne measurements is addressed. This relationship has led to an appreciation for the benefits of applying the methods and techniques of laboratory plasma physics to investigations in space, where several limitations inherent to the laboratory can be circumvented. These types of investigations, conducted in Earth orbit, can enhance our understanding of space plasma physics and have direct application to certain types of solar system phenomena.     

Climate studies from satellite observations: Special problems in the verification of earth radiation balance,cloud climatology,and related climate experiments

A body of techniques that have been developed and planned for use during the Earth Radiation Budget Experiment (ERBE), the International Satellite Cloud Climatology Project (ISCCP), and related climate experiments of the 1980's are reviewed. Validation and verification methods must apply for $\text{systems}$ of satellites. They include: (1) use of a normalization or intercalibration satellite, (2) special intensive observation areas located over ground-truth sites, and (3) monitoring of sun and earth by several satellites and/or several instruments at the same time. Since each climate application area has a hierarchy of user communities, validation techniques vary from very detailed methods to those that simply assure high relative accuracy in detecting space and time variations for climate studies. It is shown that climate experiments generally require more emphasis on long-term stability and internal consistency of satellite data sets than high absolute accuracy.     

Problems in the analysis of gamma-ray burst spectra

Spectral measurements by the Solar Maximum Mission have been used to confirm the cyclotron lines in gamma-ray bursts reported from the Konus experiment. We present ISEE-3 data for the same burst (GB800419) during the same period of time which show no line. We discuss various problems in the analysis of scintillator spectra and point out that unfolded spectra are not necessarily unique and that the position of a data point in a deconvolved spectrum may vary depending on the assumed overall shape of the spectrum. As a result, if the analysis assumes a soft spectrum (such as optically thin thermal bremsstrahlung) an absorption feature might appear, whereas a harder spectrum (such as a Comptonized blackbody) would not require the feature. Since the continuum shape probably changes during the duration of a typical burst, the nonuniqueness of the spectral unfolding, combined with the assumption that the continuum is optically thin thermal bremsstrahlung, could give rise to spurious “absorption” features which vary on a time scale of seconds. Despite these problems, there is still some evidence for $\text{narrow}$ spectral lines in the range 45 to 65 keV but not for the broad lines reported from the Konus experiment. Unfortunately, the range 45 to 65 keV is the most difficult spectral region to unfold.     

On the generation of satellite position (and velocity) by a mixed analytical-numerical procedure

The generation of accurate Earth-satellite ephemerides by numerical integration, over a period of perhaps weeks, can consume an inordinate amount of computer time. No satisfactory purely analytical procedure exists, but if short-period components of the standard elliptic elements are removed analytically, the resulting mean elements can be integrated with a step time that is longer than the satellite's orbital period.The definition of the mean elements depends on the particular perturbations included in the orbit generator and regarded as non-resonant. It is best if short-period perturbations are not applied to the orbital elements themselves but to the satellite's position (and velocity if required), expressed in a system of cylindrical polar coordinates, and the paper shows how mean elements can be recovered from position and velocity.A computer program has been written to test the proposed procedure for generating ephemerides, using a truncated potential field. Some results from this program are presented.