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Dr. Joseph Razzell Hollis
Postdoctoral Fellow At NASA’s JPL

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.

Born and raised in London, United Kingdom, Joseph wanted to be an astronaut when he was young. He pursued an undergraduate Masters degree in chemistry at the University of Sussex, specializing in theoretical chemistry. He then went on to do a Masters degree in Research and a PhD in Physics at Imperial College where he studied plastic electronics. He investigated new semiconducting organic  polymers that were being used to make the next generation solar cells. This is where his knowledge of Raman spectroscopy really took off. He was fascinated by how light interacts with matter to give such valuable information about the molecules within a sample. Read more below.

Dr. Joseph Razzell-Hollis and mockup of Perseverance



Video Script

Interview with Dr. Joseph Razzell Hollis, Postdoctoral Scholar, NASA Jet Propulsion Laboratory

Interviewer: Dr. Adam Hopkins

Dr. Adam Hopkins: So, right off the bat, let me just ask you to briefly describe your involvement with the Perseverance Rover project.

Dr. Joseph Razzell Hollis: Okay, yes, so I am a postdoctoral scientist at the Jet Propulsion Laboratory. I’m specifically working on SHERLOC, which is one of the spectrometers on board the rover.

I’ve been at JPL for just over three years now, so I’ve had the opportunity to be involved in the project kind of, sort of at the finalization stage, right. So, it was when they were sort of putting together the last parts of the rover, assembling the whole thing, shipping it off to the launch site, and then, of course, launching it and landing it.

And now my job primarily focuses on getting ready to interpret the data that we’re going to be getting back very shortly.

London, United Kingdom

photophysical chemistry

WHAT DID YOU WANT TO BE (when you were young)?:

Undergraduate Masters degree in Chemistry (University of Sussex), Masters degree in Research (Imperial College), PhD in Physics (Imperial College)

Postdoctoral Scholar

NASA Jet Propulsion Laboratory

Raman spectroscopy

Science is not a fixed path you commit to when you choose your first major, I have found that changing disciplines during my career actually provided me with a broader, more unique perspective that has made me a better scientist overall.

I am still in the above role, but as of 02/01/2022 I will be a Marie Skłodowska-Curie Postdoctoral Fellow at the Natural History Museum in London where I will be studying the impact of microplastic pollution on seabirds.

“The Player of Games” by Iain M. Banks

“Galaxy Quest”

rogan josh with saffron rice

Before I became a scientist I worked in the film industry as a visual effects artist, and my first film credit was on a rather gory cult B movie named “Mutant Chronicles”

Member of the SHERLOC science team, routinely supporting instrument operations as payload uplink lead

WOULD YOU GO TO MARS (if it were possible)?:
Absolutely, as long as it wasn’t a one-way trip and we were confident that there would be no risk of endangering the potential biosphere of Mars by sending humans there.


After completing his PhD Dr. Razzell Hollis, who was still interested in space and the possibility of life elsewhere, contacted Dr. Luther Beegle at NASA’s JPL, the principal investigator of SHERLOC. He wanted to see if he could apply his knowledge of quantitative Raman spectroscopy of organic solar cells to the interpretation of deep UV Raman spectra obtained from Mars. He submitted a proposal and received funding for a NASA postdoctoral fellowship, a significant achievement in its own right.

Dr. Razzell Hollis is responsible for streamlining the data analysis process. When data is acquired and returned to Earth, he must determine how to extract information from the spectra and images as efficiently as possible. Due to a custom instrument that generates custom data formatting, Dr. Razzell Hollis had to learn Python. Although he does not think it to be a critical skill, he highly recommends that any aspiring spectroscopist learn to code. “You can incorporate your own functions that are not available elsewhere.” He performs a lot of custom coding to minimize human intervention from baselining spectra to extracting peak positions from fittings. Concurrently, him and his team collect a library of UV Raman spectra of different organic compounds and minerals relevant to the Mars environment, so that when the spectra from the unknown samples return, they immediately have something for comparison.

An integral part of the Perseverance’s goal is to collect samples that will be picked up by a future Mars mission. If a sample of interest is found, the arm of the rover must extract some of that material, put it in a tube and seal it before it drives off to another location. He explains, “We’re looking at raw data and making interpretations because it informs the decisions being made for what the rover’s going to do next.” As practice, a bunch of his colleagues went out in the field with cameras and portable Raman instruments so Dr. Razzell Hollis and his team could compile a list of commands for the rover. By the next day the data would return and they would have to analyze the spectra and images under restricted circumstances and strict time constraints. “Going through this process is very exciting, which is not like any spectroscopy I have ever done before,” he says with a smile.

Dr. Razzell Hollis conducts his research by doing what any productive scientist does: ask questions. He asks himself how light is introduced to a sample by the instrument, how it interacts with the molecules in the sample and how the scattered light returns to the spectrometer to produce the observed spectrum. In one study, he came up with an optical model to describe how light from the laser interacted with the sample. He used an unconventional laser beam, not a cylindrical one but an annular one, in which the majority of light intensity was quite far from the centre, resulting in a very different volume to analyze.1 “I was able to determine exactly how that light interacted with that volume and how that image projected through the instrument onto the detector influenced the signal and the width of the peaks,” he says. “It was an attempt to learn how far into the sample the laser penetrates.” By the time he completed his final equation to describe the propagation of the laser intensity through the sample volume, it spanned two to three lines of text.

In his role at NASA’s JPL, Dr. Razzell Hollis is an astrobiologist, but interestingly enough, he never formally studied astronomy or biology. This shows that passion and strong work ethic can take you a long way. In his next career move, he plans on pursuing a Marie Curie postdoctoral fellowship at the National Museum in London where he will be investigating the impact of microplastic pollution on seabirds. He believes science is not a fixed path and changing disciplines has given him a unique perspective that makes him a better scientist. With his diligence, intelligence and dedication to the field of science and applied spectroscopy, it will be exciting to see all that he accomplishes.


1) An Optical Model for Quantitative Raman Microspectroscopy; J. Razzell Hollis, D. Rheingold, R. Bhartia, L.W. Beegle, Appl. Spectrosc. 2020, 74, 684-700.


Dr. Shiv Sharma

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.

Dr. S. Michael Angel

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).

Dr. Roger Wiens

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.

Dr. Vivian Z. Sun

Dr. Sun helps put together the rover’s daily plans and acts as a liaison between the engineering team at JPL and science teams from around the world.

Dr. Sanford Asher

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.



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