A Career in Thin Air

This is a description of my 60‐year career in space science. I was lucky that my career started pretty much with the beginning of the space science era, when most measurements presented something new, exciting, and unexpected. It was also a time when there were plenty of opportunities and finding support was relatively easy.Key PointBiography of authorPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152475/1/jgra55224.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152475/2/jgra55224_am.pd

Comment on “Ionospheric evidence of hot oxygen in the upper atmosphere of Venus”

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95022/1/grl6627.pd

Hot oxygen atoms in the upper atmospheres of Venus and Mars

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94642/1/grl3908.pd

Ion escape fluxes from Mars

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95499/1/grl22882.pd

Photochemistry of planetary ionospheres

The basic photochemical processes in the upper atmospheres and ionospheres of the various bodies in our solar system (planets, moons and comets) are similar. However, there are many different factors (e.g. gas composition, energy input, gravity) which control/change the relative importance of these controlling processes. The photo-chemistry of the inner planets is reasonably well understood at this time, thus there is good agreement between model calculations and most of the observational data base. The extremely limited information that we have available on the ionospheres of the outer planets leads to significant uncertainties about some of the controlling processes. Some important questions (e.g. Is the charge exchange process H+ + H2(v>=4) --> H2+ + H important? Is water vapor influx from the rings important?) remain unanswered at this time. In cometary atmospheres the freshly evaporated parent molecules are rapidly photodissociated and photoionized, therefore most of the chemical kinetics of cometary ionospheres involve these rapidly moving and highly reactive ions and radicals.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26878/1/0000444.pd

Three‐dimensional, multifluid, high spatial resolution MHD model studies of the solar wind interaction with Mars

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95318/1/jgra21138.pd

Impact of space shuttle orbiter reentry on mesospheric NOx.

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76223/1/AIAA-1973-525-785.pd

All Ionospheres are not Alike: Reports from other Planets

Our understanding of planetary ionospheres made some progress during the last four years. Most of this progress was due to new and/or improved theoretical models, although some new data were also obtained by direct and remote sensing observations. The very basic processes such as ionization, chemical transformations and diffusive as well as convective transports are analogous in all ionospheres; the major differences are the result of factors such as different neutral atmospheres, intrinsic magnetic field strength, distance from the Sun, etc. Improving our understanding of any of the ionospheres in our solar system helps in elucidating the controlling physical and chemical processes in all of them. New measurements are needed to provide new impetus, as well as guidance, in advancing our understanding and we look forward to such information in the years ahead

Time-dependent polar wind modeling

In the presence of a strong magnetic field (such as the geomagnetic field) the plasma tends to flow along the magnetic field lines, therefore in most ionospheric flow calculations the use of the gyrotropic approximation is justified. In the first part of this paper it is shown that the gyrotropic twenty moment approximation is equivalent to the gyrotropic sixteen moment approximation. The second part of the paper is devoted to the study of return current generated polar wind transients. Ionospheric return currents generate significant downward heavy ion flows in the topside ionosphere with peak values well exceeding 108 cm-2s-1. When the return current ceases the polar ionosphere rapidly returns to its previous equilibrium state. During the recovery phase of the return current event an upward propagating heavy ion transient is formed, which is mainly characterized by a relatively short O+ upwelling event. The H+ escape flux remains relatively constant (within 10-20%) during field-aligned current events.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27460/1/0000501.pd

Recent advances in model calculations of the Venus ionosphere

Our understanding of the physical and chemical processes which control the behavior of the Venus ionosphere has advanced significantly during the last few years. These advances are the result of a still growing data base and a variety of evolving theoretical models. This review summarizes some of these recent studies, especially those concerning the dynamics of the ionosphere, the maintenance of the nightside ionosphere, the energetics of the nightside ionosphere, and the time evolution of magnetic fields in the dayside ionosphere.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25850/1/0000413.pd