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Oral Histories in Meteoritics and Planetary Sciencexvi: Grenville Turner Meteoritics & Planetary Science 47, Nr 3, 434–448 (2012) doi: 10.1111/j.1945-5100.2012.01335.x Report Oral Histories in Meteoritics and Planetary Science––XVI: Grenville Turner Derek W. G. SEARS NASA Ames Research Center, Mountain View, California 94035, USA. E-mail: [email protected] (Received 03 January 2012; revision accepted 17 January 2012) Abstract–In this interview, Grenville Turner (Fig. 1) recounts how he became interested in meteorites during postdoctoral research with John Reynolds at the University of California, Berkeley, after completing a DPhil with Ken Mayne at the University of Oxford. At Berkeley, he worked on xenon isotopes with fellow students Bob Pepin and Craig Merrihue, but Reynolds’ insistence that they analyze all the inert gases in their samples meant that they also made important contributions to Ne isotope studies and potassium-argon dating leading to the Ar-Ar technique. In 1964, Grenville obtained a teaching position at the University of Sheffield where he developed his own laboratory for inert gas isotope measurements. After the return of samples from the Moon by the Apollo program, he became involved in determining the chronology of volcanism and major impacts on the Moon. In 1988, Grenville and his team moved to the University of Manchester as part of a national reorganization of earth science departments. During the post Apollo years, Grenville’s interest turned to the development of new instrumentation (resonance ionization mass spectrometry and the ion microprobe), and to problems in terrestrial isotope geochemistry, particularly the source of inert gases in fluid inclusions. He received the Leonard Medal of the Meteoritical Society in 1999, and he has also received awards from the Royal Society, the European Association of Geochemistry, and the Royal Astronomical Society. DS: Grenville, thank you for doing this. Let me start that the neutron source at Oxford was not going to the way Ursula Marvin always started, how did you produce much 3He, so I decided unilaterally to go to become interested in meteorites? Harwell and use their cyclotron and study proton-induced GT: I was doing my DPhil degree in Oxford with Ken reactions. Ken Mayne made a critically important Mayne, who will be known to meteoriticists by the paper contribution to my career by suggesting that I apply for a with Paneth and Reasbeck (Paneth et al. 1952). Paneth job in John Reynolds’s laboratory at Berkeley and at and Reasbeck extracted helium from iron meteorites and Oliver Schaeffer’s lab at Brookhaven. Well, John was the Mayne measured the 3He ⁄ 4He ratios. This demonstrated first to reply, offering me a post as an acting assistant that the helium was cosmogenic in origin and not from professor at what seemed, considering my minuscule uranium decay, which was previously assumed. When you student grant, an astronomical salary. assumed that the helium was radiogenic you got ages of DS: So you went for the money! 6 Gyr or so. I was there doing a nuclear physics degree GT: That was incidental and I suppose it would have with the job of building a very early ultrahigh vacuum been the same or more at Brookhaven, but the prospect mass spectrometer. At that time, there was no link with of going to Berkeley and California was particularly meteorites. The idea was to measure 3He and 4He from exciting. Also the prospect of getting experience teaching 14 MeV neutron capture reactions on various elements. I undergraduates was an added advantage. As it realized, after struggling with UHV systems for 2 years happened, I taught a different course in each of my four Ó The Meteoritical Society, 2012. 434 The Oral History of Grenville Turner 435 first ultra high vacuum static mass spectrometer, capable of analyzing noble gases with unprecedented sensitivity. In Oxford, I had just built one out of stainless steel based on the same principles. TODMORDEN, CAMBRIDGE, AND OXFORD DS: Now let’s take you back to how you started in life. GT: I was born in Todmorden, which was a semirural cotton town on the Lancashire ⁄ Yorkshire border. The cotton has now completely gone. I don’t know what people do for a living there now. I think many may commute into Manchester, the nearest big city. My mother was a weaver and my father was a tackler, which is the name for the person who keeps the looms running. The official title was a loom over-looker. I went to Todmorden Grammar school, an architecturally imposing building built in 1912, which sadly closed in 1978 when a new, unimposing, Comprehensive School Fig. 1. Grenville Turner. on another site replaced it. In its 66-year history, it produced two Nobel Prize winners; one was John semesters in Berkeley. In those days, it was quite Cockcroft who, with Ernest Walton, developed the common after a doctorate to spend time in the United Cockcroft Walton high-voltage generator, and used it to States, known as a BTA degree, Been To America. accelerate protons onto a lithium target, ‘‘splitting the DS: So when did you handle your first meteorite? atom’’ artificially for the first time. The other was GT: At Berkeley. Reynolds had suggested a project Geoffrey Wilkinson, a chemist awarded the prize for his based on work of Kurt Fredriksson and Paul DeCarli. work on organometallic compounds. I went from there to They had shocked Bjurbole, and had implanted St. John’s College in Cambridge on an exhibition, more terrestrial argon into it. Bob Pepin had measured the or less survived the culture shock, and after I got my amount of argon implanted and found high degree there, went to Oxford to do my DPhil with Ken concentrations. I was given the job of working on a Mayne. chondrule that had not been shocked for comparison DS: What do you mean by ‘‘exhibition.’’ and to determine the diffusion properties of the argon. GT: It’s a scholarship. ‘‘Exhibition,’’ £40 per year; The paper, my first, was published, with a companion ‘‘Minor Scholarship,’’ £60 per year; and ‘‘Major one by Fredriksson and DeCarli on April 1st Scholarship,’’ £100 per year. Coming from my school, that (Fredriksson and deCarli 1964; Pepin et al. 1964)! It was was fine. Incidentally, the government clawed back the £40 particularly interesting from Bob Pepin’s point of view from my State Scholarship. because 20 years later, he was looking at the DS: What time are we talking about now? concentrations of Martian atmospheric gases in GT: This was 1955. EETA79001, which was critical in establishing the DS: So you did your first degree in physics? Martian origin of SNC meteorites, having previously GT: Well, the last year was all physics. In the other made the very measurement that demonstrated the years I did some mathematics, geology, and chemistry as effectiveness of shock implantation. well. DS: So would it be fair to say that you became DS: So you enjoyed your undergraduate career? interested in meteorites because of the unique nuclear GT: Yes, it was an idyllic time. In the Physics chemistry possibilities? Society, I remember hearing Fred Hoyle describe his new GT: I was interested because I was working in theory for the origin of the elements, and Martin Ryle Reynolds’s lab where he had just made the ground- argue against the Bondi, Gold, and Hoyle steady state breaking discovery of excess 129Xe in the Richardton universe. Then I moved to Oxford for the DPhil and I meteorite caused by the presence in the early solar had to build this dratted machine. It was early days for system of now extinct 129I. I also went there because not ultra high vacuum technology and leaks were a perpetual only had he just discovered the first extinct nuclide, but problem. Gaskets were a major source of leaks and using in 1956, he had designed and built, in glass, the world’s the correct grade of high purity copper, or gold wire, was 436 D. W. G. Sears key to success. Nowadays, everything is off the shelf and doing. He seemed to be frequently on the phone arguing works first time. A major curse which lots of people in with the university administration. In my second that era experienced was the need to fill liquid nitrogen semester, he stoically attended Portuguese classes 3 days traps at unsociable hours. The nitrogen in mine lasted a week at 8 am prior to coming into the lab. This was in only 12 hours so every evening was interrupted by the preparation for him setting up a new dating lab at the journey to the labs to ‘‘fill the traps.’’ I was married in University of Sau Paulo in Brazil in his forthcoming my last year and my wife Kate frequently accompanied Sabbatical year. It was a good place. There were also his me on my motor bike. In the end, it took 4 years to get students, Bob Pepin and Craig Merrihue. Pepin seemed the thing working and get some data. Using the to spend his time in his windowless office with a cup of cyclotron at Harwell made it a lot quicker to get results cold coffee trying to work out the various noble gas in my final year once the mass spectrometer problems components that might be present in meteorites. were overcome. Fortunately, I had easy access to the Essentially, it was what he is doing now, working on Harwell cyclotron and lots of help from the staff there. theoretical explanations of noble gas abundances and DS: Is there anything interesting you remember isotopes. What Pepin said became gospel. Craig was a about your graduate school, any interesting colleagues? healthy looking individual, tanned, a mountain climber.
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