INVOLVED WITH THE DEVELOPMENT OF THE RAMAN SPECTROMETER AND ULTRAVIOLET LASER IN SHERLOC
Dr. Sanford Asher
Distinguished Professor of Chemistry
Sanford Asher, a Distinguished Professor in the Department of Chemistry at the University of Pittsburgh, is involved with the development of the Raman spectrometer and the ultraviolet laser in SHERLOC.1,2
Dr. Asher’s fascination with the stars and space began when he was a teenager and saw a telescope on television. He worked odd jobs to save enough money to purchase his own telescope and his space exploration began. He studied hard and earned a doctorate degree in Chemistry from the University of California, Berkeley and carried out a research fellowship at Harvard University before becoming a Professor of Chemistry at the University of Pittsburgh. Read more below.
DR. SANFORD ASHER
Interview with Dr. Sanford Asher, Distinguished Professor of the University of Pittsburgh
Interviewer: Emily Seo
Dr. Sanford Asher: Mars is a pretty hostile place right now. And there doesn’t seem to be presently any evidence of life on Mars.
Emily Seo: Right.
Dr. Sanford Asher: But at some point, billions of years ago the conditions on Mars were not so different than the conditions on Earth at that same time. And what’s known from the Earth’s history is life developed in hundreds of millions of years. And so, it’s possible that life originally developed there, and that there might be some evidence for that, if you look carefully at Mars itself.
Pittsburgh, Pennsylvania, USA
Science, chemistry and little green men and women
WHAT DID YOU WANT TO BE (when you were young):
A scientist or engineer
B.A., Chemistry, University of Missouri, St. Louis, January 1971
Ph.D., Chemistry, University of California, Berkeley, June 1977
Distinguished Professor of Chemistry
University of Pittsburgh, Department of Chemistry
Physical chemistry, biophysical chemistry, colloids, optical devices, spectroscopy, laser development
TEACHING COURSES: Undergraduate Quantum Mechanics, Instrumental Analysis, Graduate level Spectroscopy, Physical Chemistry and Analytical Chemistry
ADVICE FOR FUTURE SCIENTISTS: Be curious and stay confused
Paul Krugman’s “Arguing with Zombies: Economics, Politics, and the Fight for a Better Future”
I have many but my favorite is “The Never Ending Story”
All food, particularly French food
If I tell you, it won’t be unknown.
MARS MISSION 2020 ROLE:
Scientist working on SHERLOC. Helped design and develop deep UV laser source. Studies composition of rock and soil on Mars. Looks for material that could have derived from life.
WOULD YOU GO TO MARS (if it were possible)?:
MORE IN DEPTH WITH DR. ASHER
Early in his career, Dr. Asher pioneered the development of UV Raman spectroscopy. At that time, the instrumentation still needed to be advanced in order to make the measurements work and that included developing a new laser source. He teamed up with laser companies and funding agencies to advance the technology in this field. Around the same time William F Hug was building a novel laser made from a silver hollow cathode. Dr. Asher believes he was the first to purchase this laser which he used in his Raman spectrometer.3 He continued to collaborate with Hug from Photon Systems, who ultimately built the first robust deep UV laser source in SHERLOC, and their work together led to the publication of several papers which discussed the opportunities that exist for UV laser systems.
Later in his group, Dr. Asher had a postdoctoral fellow who was interested in studying materials from space and together with his own interest in space, they began UV Raman measurements of meteorites. The data provided a lot of information and consequently, proof of concept was demonstrated. When discussions of attaching a Raman spectrometer on a Mars rover grew, Dr. Asher was asked to be a part of the SHERLOC team. He worked on developing UV Raman spectroscopy applications for the SHERLOC instrument going to Mars.
Lasers are notorious for being difficult to align even in stable laboratories on Earth. Alignment is even more difficult to accomplish on Mars where the conditions such as temperature, pressure and gravity are very different from those on Earth. “Basically, what you need is a UV Raman laser that can cycle down to liquid nitrogen temperatures and up to room temperature, and stay aligned,” says Dr. Asher. The major advantage of the UV laser source in SHERLOC is that it has the ruggedness to survive not only the shocks and vibrations involved in space travel and landing but also to withstand the temperature and pressure changes on Mars so that its alignment is maintained.
Dr. Asher points out that due to the solar wind which has been bombarding Mars for billions of years, the planet is covered by a significant amount of degraded matter, posing another challenge for analyzing the chemistry on Mars. SHERLOC has been equipped with a tool to drill holes so the laser can pass through and access more geologically relevant material. He emphasizes that a lot of care has been exercised in the design and implementation of the drill that is used to measure rocks buried under the surface.
When Dr. Asher was still school aged, he thought about the differences between molecules that are associated with life with those that are not, and although he says that this may have been naïve, this is exactly the type of fundamental question that drives genuine learning and lifelong interest about a topic. Perhaps during those days, he never imagined he would be part of a team that works on an instrument that travels to MARS in order to determine just that: are the molecules derived from life? When asked about life on Mars, he jokes, “There’s not a lot of bars open with little green ladies and men having drinks.”
Professor Asher is a humble scientist and believes he only played a small part in the development of the SHERLOC; nevertheless, it is a vital role and a valuable contribution to the field of applied sciences. His advice for future scientists: be curious and stay confused. “If you are not confused, you are not thinking hard enough,” he adds.
1) Calibration of the SHERLOC Deep Ultraviolet Fluorescence-Raman Spectrometer on the Perseverance Rover; Uckert, K., Bhartia, R., Beegle, L.W., Monacelli, B., Asher, S.A., Burton, A.S., Bykov, S.V., Davis, K., Fries, M.D., Jakubek, R.S., Razzell Hollis, J., Roppel, R.D., Wu, Y.H., Appl. Spectrosc. 2021, 75(7), 763-773.
2) Perseverance’s Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) Investigation; Bhartia. R. et al., Space Science Reviews 2021, 217(4), No. 58.
3) A New 224 nm Hollow Cathode UV Laser-Raman Spectrometer; M.C. Sparrow, J.F. Jackovitz, C.H. Munro, W.F. Hug, and S.A. Asher, Appl. Spectrosc. 2001, 55(1), 66-70.
MEET THE OTHER SCIENTISTS
Dr. Joseph Razzell Hollis is a postdoctoral fellow at NASA’s Jet Propulsion Laboratory (JPL) in California where he works on the SHERLOC team and plays a key role in optimizing the data analysis pipeline.
Dr. Shiv Sharma is a Tenured Research Professor at the Hawaii Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology (SOEST) at the University of Hawaii at Manoa. He is one of the Co-Principal Investigators for SuperCam on the Perseverance rover.
Professor Stanley Michael Angel is a Carolina Trustee Professor and Fred M. Weissman Palmetto Chair in Chemical Ecology, Department of Chemistry and Biochemistry at the University of South Carolina. He currently works on the SuperCam team as a Scientific Research Collaborator and Scientific Payload Download Leader (sPDL).
Roger Wiens is the Principal Investigator of SuperCam and one of the co-investigators of SHERLOC. In 2016, the government of France knighted Wiens for his contribution in forging strong bonds between the French and American scientific communities.
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