Spring

John Weirich
Congratulations to John R. Weirich, who in February 2011 successfully defended his Ph.D. dissertation on "Improvements to Ar-Ar Dating of Extra Terrestrial Materials." Tim Swindle was John's advisor. John will begin a post-doctoral position with Kip Hodges at Arizona State University's School of Earth and Space Exploration in August 2011.

Sarah Horst
Congratulations to Sarah M. Hörst, who successfully defended her Ph.D. dissertation titled "Post-Cassini Investigations of Titan Atmospheric Chemistry," on April 28, 2011. Sarah's advisor was Roger Yelle. Sarah has accepted a position as a NSF post-doctoral fellow with Maggie Tolbert at the Cooperative Institute for Research in Environmental Sciences(CIRES) in Boulder.

On December 14, 2010, University of Arizona Professor Emeritus Don Hunten died after a long illness. During his last days, he was tended by his wife and UA Senior Research Associate Ann Sprague.

On February 25, 2011, LPL hosted a celebration of the life of Donald M. Hunten. Steven Bougher, Darrell Strobel, Mark Sykes, and many other colleagues, friends, and family members were in attendance.

Hunten's scientific career began with the study of physics at McGill University, where he obtained a doctorate in 1950. While a faculty member at the University of Saskatchewan, his research concentrated on the study of aurorae (natural light displays in the sky caused by the collision of charged particles directed by the Earth's magnetic field).

By 1963 however, the space age was starting in earnest. At the invitation of Joe Chamberlain, Hunten moved to Kitt Peak National Observatory in Tucson to join the newly-formed space research group and his main research interest switched to the study of planetary atmospheres. Thus, he joined the first group of pioneers in the scientific exploration of the solar system and he was to be a leading figure in this community for nearly half a century.

The accomplishments of these pioneers were remarkable, including the first characterizations of the atmospheres in our solar system along with development of the basic understanding of the structure and chemistry of these atmospheres and the experimental and theoretical tools used to study them. Many of the ideas developed during that time are still with us today and Hunten's contributions were central to their development.

A signature achievement during this phase of his career was an understanding of how odd hydrogen chemistry stabilized the atmosphere of Mars against destruction by photodissociation. Hunten moved to the UA's Lunar and Planetary Laboratory in 1974, and his involvement in planetary research continued unabated. He also taught numerous students and post-doctoral associates.

Hunten retired in 2001 but remained active until recently. He received many honors during his career, including induction into the National Academy of Sciences, the Kuiper Prize of the Division of Planetary Sciences of the American Astronomical Society and a Regents' Professorship at the UA.

One of Hunten's most far-reaching achievements concerned the role of diffusion in atmospheric escape processes. "Don's Principle," as this is sometimes known, described how the escape rate was limited by diffusion of the escaping species through the background atmosphere.

Typical for him, the theory was formulated in response to an observation, the detection of molecular hydrogen in Titan's atmosphere, when it was expected to have a very low abundance because of rapid escape. The theory was developed in a series of papers between 1972 and 1974, including an application to the escape of hydrogen from the terrestrial atmosphere — one of the best examples of how studying other planets leads to a better understanding of our own.

Hunten was a major influence on the unmanned space program with involvement in the planning and execution of numerous NASA planetary missions including Pioneer Venus, Voyager, Galileo and Cassini. In fact, he was the godfather of so many missions that he was dubbed by his colleagues "The Don."

In addition to his direct involvement on the experiment teams, Hunten helped conceive these missions, argued for their funding, sat on (and often chaired) their planning committees, helped to define the scientific goals, and provided wise guidance during their execution.

Hunten was a scientist of extraordinary breadth. His expertise ranged across the planetary sciences from chemistry to remote sensing to thermal processes to studies of atmospheric evolution and he used a variety of tools including telescopic observations, spacecraft observations, and theoretical investigations. 

A talented tinkerer, Hunten could build a harpsichord in his garage, or repair a computer with the needle-nosed pliers and soldering iron that he kept in his office, all the while with gentle classical music playing in the background. He wrote nearly as many papers on electronics as he did on atmospheric evolution.

Throughout his career, Hunten went out his way to support and encourage younger scientists. As a result, he leaves behind legions of students and collaborators that he profoundly influenced. These intellectual disciples can be found in every planetary science research center on the globe.

Hunten's textbook, co-authored with Joe Chamberlain, "Theory of Planetary Atmospheres" was treasured by many of his colleagues. This pales though, in comparison to personal interactions, through which Hunten could more directly impart his common sense approach to planetary science.

Welcome to another edition of the Lunar and Planetary Laboratory (LPL) newsletter.

We had our usual quota of successes in research and love (we've got items about two marriages), but we've also had a very sad event---Professor Donald Hunten, a long-time LPL faculty member and the person who (literally) wrote the book on planetary atmospheres, died in December.

The intent of this newsletter is to help you catch up with your LPL family. So if you haven't heard from many of your fellow LPL veterans lately, they probably haven't heard from you either, so please consider dropping us a line so that we can include something about you in the next newsletter.

Enjoy, and we hope to see you back at LPL again soon.

Michael Drake
Michael J. Drake
Head and Director
Tim Swindle
Timothy D. Swindle
Assistant Department Head

New NESSF awards for 2018

  • Cassandra Lejoly, Coupled dust and gas evolution in the inner coma of comets of differing activity levels (advisor: Walt Harris)
  • Ben Sharkey, Investigating composition and origin of primitive bodies captured by giant planets (advisor: Vishnu Reddy)
  • Maria Steinrück, Implications of atmospheric circulation for cloud and haze formation on Neptune and sub-Neptune-sized exoplanets (advisor: Adam Showman)

Renewed for 2018

  • Jess Vriesema, "Anisotropic magnetohydrodynamics and resistive heating in Saturn’s ionosphere" (advisor: Roger Yelle)

The board game, Constellations: The Game of Stargazing and the Night Sky, produced by Xtronaut Enterprises, was awarded a 2018 Mensa Select seal from American Mensa. LPL Professor Dante Lauretta, chief science advisor for Xtronaut, co-created the game. The Mensa seal, awarded to only five games in 2018, recognizes games that are "original in concept, challenging and well-designed," and that "provide a high value for the price, are easy to comprehend and play, and prove highly entertaining."

 

 

Welcome to the latest edition of the LPL semesterly newsletter. For those of you with long associations with LPL, you may be finding that more and more of the names, even of the faculty, aren’t that familiar. And you’re right. I went through our faculty rolls, and it turns out that more than half our tenure-track faculty have come since the start of 2011. Similarly, more than half of our Research Scientists have joined the faculty since then. That makes us a remarkably young department in some ways.

But since spacecraft missions often take a long time to get selected or approved, and then often operate for an extended period of time, there are projects within the department that have very long histories. The HiRISE imager aboard Mars Reconnaissance Orbiter was launched in 2006. OSIRIS-REx, which will be arriving at asteroid Bennu in the coming months, was selected seven years ago, but work on the first proposal (as “OSIRIS”) began nearly a decade earlier. And the Cassini mission just ended last fall, but it was launched 20 years earlier. Meanwhile, LPL’s two asteroid surveys, SPACEWATCH® and Catalina Sky Survey, have been operating since the early 1980s and late 1990s, respectively.

Having that mix of old and new can be challenging to keep up with, but it’s fascinating. So take advantage of the newsletter to see who is coming and going, to learn the names of the graduate students who will be the leaders in the field in a decade or two, and generally to learn what’s happening here. Enjoy!

Timothy D. Swindle, Ph.D.
Department Head and Laboratory Director

NASA’s largest competed planetary science missions are those in the New Frontiers class. Those familiar with LPL know that the New Frontiers mission OSIRIS-REx, which will return a sample from the near-Earth object Bennu, is being operated out of LPL, with Professor Dante Lauretta as the Principal Investigator. But it seems that every New Frontiers mission has strong LPL ties, so when NASA announced the two finalists for the next New Frontiers mission, it was no surprise that both missions had LPLers in critical roles.

One of the two is CAESAR, a sample return mission to Comet 67/P Churyumov-Gerasimenko, the target for ESA’s recent Rosetta mission. Dante Lauretta is the Mission Sample Scientist for CAESAR, and Associate Professor Tom Zega is also a Co-Investigator.

The other is Dragonfly, a mission to explore Saturn’s moon Titan with a quadcopter. There, the PI is LPL alumna Elizabeth Turtle, the Deputy PI is alum Jason Barnes, and Co-Is include alums Sarah Hörst, Jeff Johnson, Erich Karkoschka (currently a Staff Scientist at LPL), Juan Lora, Catherine Neish, and Jani Radebaugh, as well as former LPL postdocs Ralph Lorenz and Aileen Yingst.

The mission that is ultimately selected (probably in 2019) will be the fourth New Frontiers mission, and will keep LPL’s record of significant involvement in such missions intact.

The first New Frontiers mission was New Horizons, which visited Pluto and is now en route to a New Year’s Day encounter with Kuiper Belt Object 2014 MU69. That mission’s Co-Is include LPL grads Marc Buie, Dale Cruikshank, Will Grundy and John Spencer, as well as former LPL postdocs Mihaly Horanyi and Bill McKinnon. Grundy is the Composition Theme Team Lead, and Spencer and McKinnon are Deputy Team Leads.

The second was Juno, the mission currently in orbit around Jupiter. Professor Emeritus Bill Hubbard played a key role in its development, and remains a Co-I. Other Co-Is include former LPL professor Jonathan Lunine, former LPL postdoc Tristan Guillot, and, until his death, LPL alum Toby Owen.

Subscribe to Spring