Dr. Sanford Asher
Distinguished Professor of Chemistry

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.

Back to Professor Sanford Asher’s profile.

References:

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.