Roman Ulrich Sexl
University of Georgia
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Roman Ulrich Sexl.
Earth Moon and Planets | 1971
Roman Ulrich Sexl; Hannelore Sexl; Hanns Stremnitzer; Donald G. Burkhard
A theory of the directional characteristics of the lunar infrared radiation measured by Saari and Shorthill has been derived. This theory is in excellent agreement with experiment at all angles of observation and at all phase angles. The radiation law used to describe the angular dependence of the infrared radiation emitted by a flat element of the lunar surface is 0.85 cosθ + 0.22 cos2θ, where θ is the angle between the surface normal and the direction of observation. This radiation law is subsequently modified by taking into account lunar surface roughness. We assume a surface covered in part with spherical craters of various depth to diameter ratios as a model for the lunar soil. Re-radiation within the craters has been accounted for. Extensive use is made of group theoretical and invariant tensor methods which enable us to show that most of the details of the radiation pattern do not depend on the detailed nature of the surface features assumed, but only on the average surface slope. A best fit to the Saari-Shorthill data has been obtained by assuming 50% of the lunar surface to be covered with craters with a depth to diameter ratio of 1:3, while the remainder of the surface is essentially flat. The mean deviation between theory and experiment is 4K.
Thermal Design Principles of Spacecraft and Entry Bodies | 1969
Roman Ulrich Sexl; Donald G. Burkhard
Received October 7, 1968 (not preprinted). Work supported by NASA Contract NAS8-20746, Marshall Space Flight Center, Huntsville, Ala., through PEC Associates, Inc., Louisville, Colo.
Archive | 1979
Roman Ulrich Sexl; Hannelore Sexl
Archive | 1975
Roman Ulrich Sexl; Hannelore Sexl
Space Science Reviews | 1981
Roman Ulrich Sexl; Hannelore Sexl; Franco Pacini
Archive | 1981
Roman Ulrich Sexl; Hannelore Sexl
American Journal of Physics | 1981
Roman Ulrich Sexl; Hannelore Sexl; Alan Spero
Archive | 1980
Roman Ulrich Sexl; Hannelore Sexl
Archive | 1980
Roman Ulrich Sexl; Hannelore Sexl; R. N. Henriksen
Nature | 1980
Roman Ulrich Sexl; Hannelore Sexl; John D. Barrow