Operating the Hubble space telescope : Goddard Space Flight Center : a closer look : Space Telescope Project--Goddard /

Shipping list no.: 85-926-P.

Proceedings of a conference held at Goddard Space Flight Center, Greenbelt, Maryland, June 15-16, 1970.

Includes bibliographical references.

Models of Venus atmosphere (1972) [Prepared for NASA under the cognizance of the NASA Goddard Space Flight Center.

Cover title.

Goddard '66; a year in review at Goddard Space Flight Center, National Aeronautics and Space Administration.

Cover title.

The proceedings of a symposium held by Goddard Space Flight Center at New Carrollton, Maryland on March 5-9, 1973.

Vol. 2, edited by S. C. Freden, E. P. Mercanti, and D. E. Witten, published by Goddard Space Flight Center, Greenbelt, Md.; v. 3, edited by S. C. Freden and E. P. Mercanti, also published by Goddard.

Goddard Space Flight Center.

Cover title.

Flight Mechanics/Estimation Theory Symposium 1992 : proceedings of a symposium sponsored by NASA Goddard Space Flight Center and held at Goddard Space Flight Center, Greenbelt, Maryland, May 5-7, 1992 /

Includes bibliographical references.

Marshall Space Flight Center.

Cover title.

NASA Marshall Space Flight Center.

Mode of access: Internet.

Space missions to comets : a conference /

Includes bibliographies.

Robert H. Goddard : American rocket pioneer.

Shipping list no.: 89-654-P.

Telescopes and space exploration /

Mode of access: Internet.

Study of the solar cycle from space : proceedings of a symposium /

Includes bibliographical references.

Magnetic helicity as a constraint on coronal dissipation

The Taylor hypothesis has provided a model for the relaxed magnetic configurations of not only laboratory plasmas, but also of astrophysical plasmas. However, energy dissipation is possible only for systems which depart from a strict Taylor state, and hence a parameter describing that departure must be introduced, when the Taylor hypothesis is used to estimate the dissipation. An application of the Taylor hypothesis to the problem of coronal heating provides an insight into this difficult problem. When particular sorts of footpoint motions put energy and helicity in the corona, the conservation of helicity puts a constraint on how much of the energy can be dissipated. However, on considering a random distribution of footpoint motions, this constraint gets washed away, and the Taylor hypothesis is probably not going to play any significant role in the actual calculation of relevant physical quantities in the coronal heating problem.

Modeling of Surface UV Radiation Using Satellite Data

Solar UV radiation is harmful for life on planet Earth, but fortunately the atmospheric oxygen and ozone absorb almost entirely the most energetic UVC radiation photons. However, part of the UVB radiation and much of the UVA radiation reaches the surface of the Earth, and affect human health, environment, materials and drive atmospheric and aquatic photochemical processes. In order to quantify these effects and processes there is a need for ground-based UV measurements and radiative transfer modeling to estimate the amounts of UV radiation reaching the biosphere. Satellite measurements with their near-global spatial coverage and long-term data conti-nuity offer an attractive option for estimation of the surface UV radiation. This work focuses on radiative transfer theory based methods used for estimation of the UV radiation reaching the surface of the Earth. The objectives of the thesis were to implement the surface UV algorithm originally developed at NASA Goddard Space Flight Center for estimation of the surface UV irradiance from the meas-urements of the Dutch-Finnish built Ozone Monitoring Instrument (OMI), to improve the original surface UV algorithm especially in relation with snow cover, to validate the OMI-derived daily surface UV doses against ground-based measurements, and to demonstrate how the satellite-derived surface UV data can be used to study the effects of the UV radiation. The thesis consists of seven original papers and a summary. The summary includes an introduction of the OMI instrument, a review of the methods used for modeling of the surface UV using satellite data as well as the con-clusions of the main results of the original papers. The first two papers describe the algorithm used for estimation of the surface UV amounts from the OMI measurements as well as the unique Very Fast Delivery processing system developed for processing of the OMI data received at the Sodankylä satellite data centre. The third and the fourth papers present algorithm improvements related to the surface UV albedo of the snow-covered land. Fifth paper presents the results of the comparison of the OMI-derived daily erythemal doses with those calculated from the ground-based measurement data. It gives an estimate of the expected accuracy of the OMI-derived sur-face UV doses for various atmospheric and other conditions, and discusses the causes of the differences between the satellite-derived and ground-based data. The last two papers demonstrate the use of the satellite-derived sur-face UV data. Sixth paper presents an assessment of the photochemical decomposition rates in aquatic environment. Seventh paper presents use of satellite-derived daily surface UV doses for planning of the outdoor material weathering tests.