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SPECIAL LPOD: B. RAY HAWKE

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Photo of B. Ray Hawke superposed on Consolidated Lunar Atlas full Moon image.

The Moon lost one of its best friends on Jan. 24, 2015, with the death of Dr. B. Ray Hawke of the University of Hawaii. He was a lunar geoscientist respected around the world.

B. Ray Hawke was born and raised in Kentucky, and received a bachelor's degree in geology from the University of Kentucky. After returning from service an Airborne Ranger in Vietnam, he enrolled as a master's student at the University of Kentucky, working on chemical analysis of lunar samples. From there he moved to Brown University for doctoral work with Dr. Jim Head. At Brown he conducted geological studies using images returned by the Lunar Orbiter missions and by Apollo. One of his most-cited papers from this time dealt with impact melts on lunar crater rims.

After obtaining his Ph.D., B. Ray moved to the University of Hawaii at Manoa, joining the research group in what is now the Hawaii Institute of Geophysics and Planetology (HIGP). Some of his early work in Hawaii involved analysis and interpretation of elemental chemistry maps derived from measurements by the Apollo orbital X-ray and gamma-ray spectrometers.

Hawaii hosts one of the best astronomical observing sites on Earth: Mauna Kea. Hawaii Island is also a place where one of the most fundamental geological processes, volcanism, can be viewed in real time at Kilauea. The success of the HIGP group's research came from combining the tools of the astronomer (telescope instruments like spectrometers) with the perspective of the geologist in attempting to understand the nature and evolution of the Moon and other solid solar system bodies. B. Ray began to observe the Moon with the 24- and 88-inch telescopes on Mauna Kea, collecting reflectance spectra with spectrometers that had been specifically developed for planetary observing by Dr. Tom McCord and his colleagues. The real workhorse was the "infrared circular-variable-filter" spectrometer. This instrument precisely measured the intensity of light reflected from a spot on the lunar surface. By analyzing the reflectance variations in the tens to hundreds of wavelength channels contained in a spectrum, it is possible to determine type and abundance of key rock-forming minerals like olivine, pyroxene, and plagioclase. To collect this type of data, the telescope had to be guided by hand, with the observer using a joystick-like controller to keep the spectrometer's aperture on target while the instrument ran through the several-minute sequence to record a spectrum. The target, viewed as a flickering image on a low-resolution monitor, was a specific geological feature 5 or 10 kilometers in diameter – 385,000 km away on the lunar surface. B. Ray's detailed knowledge of lunar geography, aided by a trusty copy of the Rectified Lunar Atlas, helped to get the telescope's narrow field of view pointed at the right location. The Moon's motion and wind shaking the telescope meant that an observer needed a deft touch and great concentration to insure that useful data was collected. B. Ray was a master.

B. Ray led a number of such observing runs from the late 1970s to the early 1990s, collecting data designed to attack a variety of problems in lunar geology. Topics included the nature of material exposed by major impact basins and the implications for the layering of the lunar crust, the discovery and importance of deposits of pure anorthosite, hidden deposits of mare basalt (later termed "cryptomaria") revealed by the presence of small impact craters with dark halos, the nature of crater rays, and the varieties of lunar explosive volcanic deposits (pyroclastics) and their importance for understanding the lunar interior and their potential utility as a lunar resource. In working with colleagues and graduate students at HIGP and collaborators at other institutions, B. Ray sought ways to integrate the telescopic spectra with other remote sensing datasets like Earth-based radar images and the Apollo orbital geochemistry maps, informed by his knowledge of the findings of lunar sample analysts.

The 1990s brought a renaissance in lunar studies. This began as the Galileo spacecraft, on its way to Jupiter, flew past the Moon in 1990 and 1992 and returned the first modern digital multispectral images obtained from space that could be employed for compositional studies of the surface (including parts of the farside, not accessible to ground-based telescopes). Clementine conducted global mapping of the Moon in 1994, providing images in visible and near-infrared light, as well as topography measured by a laser altimeter. And in 1998-99, Lunar Prospector collected global data on the Moon's elemental composition with a neutron spectrometer and a gamma-ray spectrometer, as well as data on lunar magnetism and the charged particle environment. This bounty of data permitted a range of new studies, and new ways to extend previous work. B. Ray's work in this period focused on anorthosite, geochemical anomalies and cryptomaria.

A new flood of lunar data began to arrive in 2007, with the launch of the Japanese SELENE (Kaguya) spacecraft. This was followed by China's Chang'e-1, India's Chandrayaan, Lunar Reconnaissance Orbiter, LCROSS, Chang'e-2, GRAIL, LADEE, and Chang'e-3. Selection as an LRO Participating Scientist gave B. Ray the opportunity to collaborate with an even greater number of lunar researchers. A whole new generation of younger scientists came to know the legendary B. Ray Hawke, and benefit from his knowledge and guidance.

B. Ray was a southern gentleman who tried to be kind and polite to everyone. He always remembered colleagues and students with birthday and Christmas cards and gifts. He was extremely generous with his time - mentoring students, engaging in lengthy discussions at conference poster sessions, providing extensive constructive criticism on draft papers written by colleagues, and reviewing articles for science journals. He was famous for his impressive collection of NASA t-shirts, and for the blue denim jacket he would wear with a dress shirt and tie at science conferences. He loved southern home-style cooking, barbeque, Mexican food, and margaritas. Above all, B. Ray Hawke loved the study of the Moon. Some of us had the good fortune to study the Moon with him – and we all loved B. Ray.

-- David T. Blewett, Johns Hopkins University Applied Physics Laboratory

Further tributes to Dr. Hawke can be found at the website of the University of Hawaii's Pacific Regional Planetary Data Center and in a piece written by B. Ray's longtime friend and research collaborator Paul Spudis.

CAW Note: B. Ray and I were grad students together in the late 1970s. Dave Blewett was a student and colleague of B. Ray's. We all enjoyed learning from him.


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