HOW DID WE GET HERE

 

William B. Hanson

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Berkner

 

A Short History

In 1961 Lloyd Berkner was named President of the Graduate Research Center of the Southwest (GRCSW) which was housed on the SMU campus.

 

In 1962 Erik Jonsson, chairman of the board of the Center, and of Texas Instruments, announced the formation ofSouthwest Center for Advanced Studies (SCAS) to be administered by GRCSW and housed on a new campus in Richardson.

The land and funds for the buildings were raised from private donations.

Green, McDermott and Jonsson

Three families, Cecil and Ida Green, Eugene and Margaret McDermott and Erik and Margaret Jonsson were in large part the benefactors of the Center and the drive towards its outstanding future.

 

 

The Graduate Research Center would have two components; Southwest Center for Advanced Studies and the Institute for Graduate Education and Research. The idea was to interface with universities to provide graduate education and research opportunities that would encourage the accumulation of intellectual and scientific talent in the Texas area.

By fall 1964 the Southwest Center for Advanced Studies was located in a new home in Richardson and was headed by Professor Lloyd Berkner. There were to be laboratories specializing in Earth and Planetary Science, Materials Science, Molecular Sciences, Electronics, and Computer Sciences. The Center would be home for permanent faculty, visiting professors and post doctoral research associates.

Founders Building

 

The Earth and Planetary Sciences Laboratory comprising divisions in Atmospheric and Space Sciences, Geosciences, and Mathematics, was the first to be built in the Founders Building.

 

 

 

 

Johnson

 

In 1965 Professor Francis S. Johnson headed the Earth and Planetary Sciences Laboratory.

 

Following a heart attack in 1965 Professor Lloyd Berkner resigned his post as President of GRCSW to spend more time pursuing his interests in atmospheric sciences and to oversee the activities at SCAS. Gifford Johnson became the second President of the GRSCW. Sadly Lloyd Berkner died at age 62 in 1967. As part of the development of the Space Sciences Division Frank Johnson recruited Professor William B. Hanson in 1962 to begin pioneering research activities at GRCSW.

In 1969, the continued success of SCAS, coupled with increasing need to expand the research and educational activities, led to the transfer of the activities, the buildings and the land to the University of Texas system.

Johnson

 

The University of Texas at Dallas was formed as a graduate school at that time, and Professor Francis S. Johnson became the first acting president of UTD.

 

 

 

In 1969 Professor William B. Hanson became Director of the Division of Atmospheric and Space Sciences which later became the Center for Space Sciences in the Physics Program at UTD. He remained the director, until his death in 1994. In recognition of his efforts to build a Center of international excellence it has been named The William B. Hanson Center for Space Sciences.

Hanson

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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William B. Hanson 

William B. Hanson 1923 - 1994: A Retrospective

R.A. Heelis

William B. Hanson Center for Space Sciences

Universityof Texas at Dallas

Richardson, TX 75080

Bill Hanson has said that he was fortunate to have his career span the periodmarking the beginning of the space age and in some respects the dawn of thecomputer age. However, as he did with every aspect of his life, he recognizedthe opportunities offered by these circumstances and capitalized upon them tothe fullest extent possible. His work is noted for its breadth and depth, butperhaps most notably for the thoroughness in his examination of a chosenproblem.

After his graduate training in experimental low temperature physics he movedto Lockheed Space and Missiles Corporation in 1956 and pursued the developmentof techniques to measure ionospheric parameters. His drive to understand thebehavior of the ionosphere beyond the descriptions provided by measurementalone, would also result in contributions to advances in numerical modeling andbasic, but fundamental, mathematical and physical evaluations designed to exposethe most important processes at work.

Hanson moved to the newly formed Southwest Center for Advanced Studies in1962. There he played a leading role in the formation of the Center for SpaceSciences which became part of the University of Texas at Dallas in 1969. Hecontinued in his role as the Center director and as a professor of physics untilhis death in 1994. Throughout his career Bill Hanson continued to keep abreastof the advances being made in the field and was driven by an intense curiosityabout the underlying physics of the ionosphere. His early work illustrates therather unique combination of contributions to the interpretation of observationsand to the development of both observational and computational tools to furtherthe investigation of the terrestrial upper atmosphere. A long-standingcollaboration with scientists from the United Kingdom allowed ideas concerningthe distribution of neutral and ionized species in the topside ionosphere to bedeveloped. Inspired initially by whistler measurements [Storey, 1953], aninvestigation of the diurnal variation of the ion concentration in theprotonosphere, led to a detailed understanding of the coupling between theionosphere and the protonosphere and the development of mathematical models thatcould describe the coupling processes [Hanson and Patterson, 1964]. Thiswork highlighted the importance of plasma transport perpendicular to themagnetic field as well as the diffusion of plasma along the magnetic field andappropriate chemical reactions. A combination of physical interpretation ofavailable observations, mathematical manipulation of the relevant diffusionequations, and refinement of numerical techniques for solving differentialequations eventually produced a rather robust model of the ionospheric plasma [Sterlinget al., 1969], and provided the foundation upon which many of the mostsophisticated models now rest.

The power and utility of such a model in handling the transport and chemistry ofthe ionospheric plasma was demonstrated in a description of the ionosphericfountain effect [Hanson and Moffett, 1966] giving rise to the Appletonanomaly. Figure 1, showing the plasma motion resulting from ExB drift anddiffusion of ions near the dip equator, has been used by scientists andeducators alike to aid in interpretation and understanding of the equatorialionosphere. In addition to being observed from the ground, the Appleton peakswere also observed in some of the first airglow measurements from space. Withhis interest in the anomaly sparked by recent modeling efforts, Hanson[1969] showed that airglow enhancements might be expected in these regions ofenhanced concentration due to the radiative recombination of O+, a fact that isnow well established and used with great success to provide a powerful remotesensing of the region.

During this same period Hanson began the evaluation of measurements fromrocket and satellite borne ion traps. [Hanson and McKibbin, 1961, Hansonet al., 1964]. These rather simple devices, were the forerunners of what isnow the planar retarding potential analyzer (RPA) that has been flownsuccessfully on the OGO-6 satellite, the Atmosphere Explorer (AE) satellites,the Dynamics Explorer (DE) satellite, the San Marco-D satellite, and the DefenseMeteorological Satellite Program (DMSP). Following the first measurements fromthe RPA on OGO 6 we see the fondness for a combination of observed phenomena,physical interpretation, and confirmation modeling, being revealed in the workof Bill Hanson. The discovery of Fe+ at high altitudes on OGO 6 and thesuggestion that they are transported to such altitudes by ExB drifts [Hansonand Sanatani 1970], was followed by modeling efforts to reinforce thishypothesis [Hanson et al., 1972]. Measurements of unusually low iontemperatures near the dip equator were thought to be due to adiabatic expansionof the plasma as it moved along the magnetic field lines [Hanson et al.,1973]. This hypothesis was subsequently reinforced by calculations of the effectthat showed the measurements to be consistent with expected interhemispherictransport velocities [Bailey et al., 1973]. It is particularlyinteresting to note that the OGO 6 RPA provided some of the first in-situmeasurements of equatorial plasma irregularities termed spread-F plasma [Hansonand Sanatani, 1973], and later to be termed "plasma bubbles".These observations sparked an interest in Bill Hanson that continued throughouthis career. Indeed, some of his most recent work concerned the properties of thebubble plasma at altitudes near 800 km [Hanson and Urquhart, 1994].

The initial observations and studies, stimulated by the wealth of data fromOGO 6, led to Hanson's intimate involvement in the development of the AtmosphereExplorer project. A relatively small group of scientists at universities, NASAfield centers, and NASA Headquarters, spear-headed this effort that was toprovide a wealth of data that is still being examined by scientists around theworld. For this project it became clear that a measurement of the plasma motionwas essential to the resolution of many of the problems being posed. With thismotivation Hanson used his considerable experimental skills to design an iondrift meter (IDM) to be flown on AE-C, AE-D, and AE-E. Further refinements tothe drift meter have been made since that time, but the simple yet elegantdesign remains at the core of this sensor that has provided key measurements forthe subsequent DE mission and DMSP. Figure 2 shows measurements of the total ionconcentration and the horizontal (Y), and vertical (P), ion drift velocitiesobtained from the IDM on the Atmosphere Explorer satellite. Data like this,taken at low and high latitudes, have been used by a large number of scientiststo increase our understanding of plasma structure throughout the F-regionionosphere.

In addition to the recurring research problems attached to interhemisphericplasma transport, spread-F, and meteoric ions, the AE mission opened new avenuesof research into ionospheric chemistry and electrodynamics that also peaked theinterest and imagination of Hanson. The development of more capable massspectrometers led to accurate observations of most of the ionospheric statevariables, leaving only the chemical reaction rates to be evaluated [Torr etal., 1977]. Measurement of the ionospheric drift velocity vector provided anopportunity to more fully understand the ionospheric plasma circulation at highlatitudes and the coupling between the ionosphere and the magnetosphere [Heeliset al., 1976]. These new missions also saw the development of computersystems designed to disseminate the data to a broader science community. It isevident that Hanson understood that it was not only necessary to disseminate thedata, but also to share the intimate knowledge of its advantages and itsshortcomings. All who have worked with Bill Hanson have benefited greatly fromthe enthusiasm with which he shared the findings from the data, and his ideasabout the measured behavior of the ionosphere.

Along with his interest in the terrestrial ionosphere, Hanson shared asimilar curiosity about the ionospheres and atmospheres of the other planets. In1969 he began working with the entry science team of the Viking mission to Mars.The implementation phase was extraordinarily long, at that time, but new andexciting data was provided by the RPA, designed by Hanson, when the spacecraftarrived at Mars in the summer of 1976 [Hanson et al., 1977]. In fact thisdata set has provided continued challenges to our understanding of theinteraction of the planet with the interplanetary medium, resulting inpublications as recent as 1992 [Johnson and Hanson, 1992].

The breadth of Hanson's work is accompanied by an underlying and constantinterest in the ubiquitous nature of irregularities in the ionospheric plasma.From the first observations of backscatter plumes and satellite measurements inthe late 60's and early 70's it is clear that Hanson has advanced ourunderstanding of this phenomena, with detailed descriptions of the phenomenologyinvolved, and insights into the physical principles that must be adhered to. Hedescribed a special class of irregularities with a discrete spatial scale sizeon the bottomside of the F-region [Valladares et al., 1982]. He examinedthe relationships between plasma motion parallel and perpendicular to themagnetic field inside plasma bubbles [Hanson and Bamgboye, 1984] and mostrecently noted that bottomside ionospheric irregularities may be observed ashigh as 800 km in the equatorial region [Hanson and Urquhart, 1994].

At all times Bill Hanson's propensity to study the data at all locations andall conditions shows through. Continued study of the AE data allowed details ofion sputtering from spacecraft surfaces to be revealed [Hanson et al.,1981], which may be useful to future low altitude missions. In the F-region, thegeometry of the DE satellite and its orientation to the magnetic field producesan interesting plasma interaction with the surface, [Cragin et al., 1993]leading to density structure that is an artifact rather than a geophysicalsignature. In addition, Hanson was constantly alert to the need for new, or moreefficient, measurement techniques and, just prior to his death, had developed asatellite borne transverse neutral wind detector as part of a collaboration withscientists and engineers in Italy [Hanson et al., 1992]. Most recentlythe confidence levels with which interpretation of electric fields and iondrifts may be made has been well documented for future reference [Hanson etal., 1994]. Hanson's long and tireless hours spent pouring over the data,coupled with a broad knowledge of the physical principles involved in itsinterpretation, produced a world renowned "gastric computer" and oneof the best human "expert systems" to be used by most scientists inthe field. Figure 3 shows just two entries in the many notations made on eachdata segment display from the Atmosphere Explorer mission. The remarks show theinterest and enthusiasm with which Bill studied the data and that he continuallystrived to improve the performance of the analysis and interpretation proceduresthat were used.

Beyond the work of Bill Hanson, reflected in the published record, is areputation for inspiring excellence and thoroughness in others. His ability tounderstand the basic physical principles involved in most scientific endeavorsmade him an ideal and frequently used "sounding board". His opinionsand insights were highly respected and he served valuably on many advisorypanels to national and international institutions. He also served as presidentof the Solar Terrestrial Physics Section of the American Geophysical union from1978 to 1980.

I once asked Bill Hanson what part of ionospheric science he found mostinteresting. He replied "I'm a beachcomber. I really enjoy just looking atthe data, any data really. I can always find some repetitive little signaturethat gets my attention and then I try to understand it well enough to figure outwhere it comes from." The work of Bill Hanson attests to his outstandingability to identify important signatures and perhaps, equally important are thenumerous interactions that continue to inspire the work of his colleagues andstudents and attest to his desire to share this fascination for the"beach" with everyone.

It is quite straightforward to reflect on the many scientific achievements ofBill Hanson and to recognize the talent and dedication that accompanies thiswork. However, it is particularly hard to document the features of Bill Hanson'scareer that I believe will be also warmly remembered. These involve the way heapproached personal and professional challenges, and the way he interacted withthe many colleagues who became his friends around the world. In 1985 he wasawarded the John Adam Fleming Medal by the AGU in recognition of unselfishcontributions to the study of ionospheric physics and aeronomy. Bill Hanson alsocared about people and the environment in which they live. His solutions to someof the environmental and social issues of the day, were sometimes controversial,but his goal was always to maximize the quality of life for all. As one who wasprivileged to be close to this man I can say that few things gave him greaterpleasure than the sharing of his knowledge and his ideas with the friends thatsurrounded him.

REFERENCES

Bailey, G. J., R. J. Moffett, W. B. Hanson, and S. Sanatani,Effects of Interhemisphere Transport on Plasma Temperatures at Low Latitudes, J.Geophys. Res., 78, 5597, 1973

Cragin, B. L., and W. B. Hanson, Equatorial spacecraft-plasmainteraction phenomon observed by DE 2, J. Geophys. Res., 98, 19,141,1993.

Hanson, W. B., Radiative Recombination of Atomic Oxygen Ionsin the Nighttime F Region, J. Geophys. Res., 74, 3720, 1969

Hanson, W. B. and D. K. Bamgboye, The Measured Motions InsideEquatorial Plasma Bubbles, J. Geophys. Res., 89, 8997, 1984

Hanson, W. B. and R. J. Moffett, Ionization Transport Effectsin the Equatorial F Region, J. Geophys. Res., 71, 5559, 1966

Hanson, W. B. and D. D. McKibbin, An Ion-Trap Measurement ofthe Ion Concentration Profile Above the F2 Peak, J. Geophys. Res., 66,1667, 1961

Hanson, W. B., D. D. McKibbin, and G. W. Sharp, SomeIonospheric Measurements with Satellite-Borne Ion Traps, J. Geophys. Res., 69,2747, 1964

Hanson, W. B., A. F. Nagy, and R. J. Moffett, OGO 6Measurements of Supercooled Plasma in the Equatorial Exosphere, J. Geophys.Res., 78, 751, 1973

Hanson, W. B. and T. N. L. Patterson, The Maintenance of theNight-Time F Layer, Planet. Space Sci,, 12, 979, 1964

Hanson, W. B. and S. Sanatani, Meteric Ions above the F2 peak,J. Geophys. Res., 75 5483, 1970

Hanson, W. B. and S. Sanatani, Large Ni Gradients Belowthe Equatorial F Peak, J. Geophys. Res., 78, 1167, 1973

Hanson, W. B., S. Sanatani, and D. R. Zuccaro, The MartianIonosphere as Observed by the Viking Retarding Potential Analyzers, SpecialViking Issue, J. Geophys. Res., 82, 4351, 1977

Hanson, W. B., D. L. Sterling, and R. F. Woodman, Source andIdentification of Heavy Ions in the Equatorial F Layer, J. Geophys.Res., 77, 5530, 1972

Hanson, W. B., S. Sanatani, and J. H. Hoffman, Ion Sputteringfrom Satellite Surfaces, J. Geophys. Res., 86, 11,350, 1981

Hanson, W. B., U. Ponzi, C Arduini, and M. Di Ruscio, Asatellite anemometer, J. Astronaut. Sci., 3, 429, 1992.

Hanson, W. B., W. R. Coley, R. A. Heelis, N. C. Maynard, andT. Aggson, A comparison of in situ meaurements of E and -VxB from DynamicsExplorer-2, J. Geophys. Res., 98, 21,501, 1994.

Hanson, W. B. and A. L. Urquhart, High Altitude BottomsideBubbles?, Geophys. Res. Lett., 21, 2051, 1994

Heelis, R. A., W. B. Hanson, and J. L. Burch, Ion ConvectionVelocity Reversals in the Dayside Cleft, J. Geophys. Res., 81, 3803, 1976

Johnson, F. S. and W. B. Hanson, Viking 2 ElectronObservations at Mars, J. Geophys Res., 97, 6523, 1992

Sterling, D. L., W. B. Hanson, R. J. Moffett, and R. G.Baxter, Influence of Electromagnetic Drifts and Neutral Air Winds on SomeFeatures of the F2 Region," Radio Science, 4, 1005, 1969

Storey, L. R. O., An Investigation of Whistling Atmospherics, Phil.Trans. Roy. Soc., A, 246, 113, 1953

Torr, D. G., N. Orsini, M. R. Torr, W. B. Hanson, J. H.Hoffman, and J. C. G. Walker, Determination of the Rate Coefficient for the N2++ O Reaction in the Ionosphere, J. Geophys. Res., 82, 1631, 1977

Valladares, C. E., W. B. Hanson, J. P. McClure, and B. L.Cragin, Bottomside Sinusoidal Irregularities in the Equatorial F Region, J.Geophys. Res., 88, 8025, 1983

FIGURE CAPTIONS

Figure 1. Plot of the ionospheric electron fluxes associated with the ExBdrift motion and diffusion leading to the Appleton anomaly. [after Hanson andMoffett, 1966]

Figure 2. The horizotal (following Y) and vertical (following P) ion driftsassociated with large equatorial plasma depletions called bubbles. [after Hansonand Bamgboye, 1984].

Figure 3. Annotations added to the data displays produced during theAtmosphere Explorer program. Shown here are an interest in determining wherelarge Joule heating events occur, but also how to improve the analysisprocedures during such times.

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