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Curiosity rover on mars

Gellert Group

Planetary Surface Exploration

The University of Guelph is playing an important role in the exploration of Mars. One of NASA’s current missions on Mars, the Mars Science Laboratory (MSL), involves the rover known as Curiosity, which features a scientific instrument developed by Physics Professor Ralf Gellert.

NameRole
Ralf GellertFaculty
Nick BoydResearch Associate
Michael McCraigPostdoctoral Scholar
Adam DesousaMSc Student
Annika VetterPhD Student
The APXS instrument on the robotic arm of Curiosity Mars Rover

The instrument is called the Alpha Particle X-Ray Spectrometer (APXS) and is one of 11 scientific instruments onboard the Curiosity rover. Ralf Gellert is the Principal Investigator for APXS and leads a team of scientists from the University of Guelph, NASA’s Jet Propulsion Laboratory, and other institutions.

Professor Gellert’s involvement with APXS precedes the MSL Mission, dating back to 2001 and his work on the earlier version of the instrument. At the Max-Planck Institute for Chemistry in Mainz, Germany, he worked as the lead engineer for APXS, which was selected for deployment on the Mars Exploration Rovers (MER), named Spirit and Opportunity. Gellert and a small team built the device and developed the calibration and analysis software. Gellert led the MER APXS operations and data analysis from 2005 until Opportunity, the longer standing of the two MER, stopped working in 2017. He also led a successful proposal to NASA for a new APXS for the MSL. In 2005, after the department that Gellert worked in closed, he came to the University of Guelph where he continued his work with the ongoing MER missions and built a lab to develop and test the new version of APXS for Curiosity.

Curiosity launched in November 2011, equipped with the new APXS model, and successfully landed on the surface of Mars in August 2012. Since Curiosity’s landing, the Guelph APXS team has been responsible for the daily operation of the device, collaborating with the scientists operating the other 10 instruments onboard Curiosity to determine what to do next. Gellert explains, “Each day, we are discussing with the whole science team and the rover planners, what to do next. This involves ‘That rock looks interesting, let’s drive over there’, then there is a discussion of ‘ok, is it worth the resources or could we drive somewhere else?’”. Once a decision is reached, measurements are taken and data are collected, which are then used to inform future decisions. 

The APXS is used to measure the chemical composition of Martian rocks and soils. It is located on the robotic arm of Curiosity so that it can be placed near, or in contact with, samples of interest. The APXS works by bombarding the sample with radiation (alpha particles and X-rays), which can knock tightly bound electrons from the atoms within the sample, creating a vacancy. When the vacancy is then filled by another electron, an X-ray is emitted in the process. These X-rays are unique signatures for each element in the periodic table, allowing the APXS to determine the types and abundance of elements in the sample.

Diagram of the mechanism involved during spectroscopy at the atomic level.

The APXS team is focused on giving precise concentration values to geological experts for interpretation.  The team is constantly working to improve their ability to produce more reliable and accurate values. Gellert explains, “our scientific goal for the APXS team consists of trying to extract all possible information from data we get from Mars. This means if we know we can measure 16 elements, can we measure even more? We see trace elements that are not that abundant in terrestrial samples that we calibrated with. Can we use the data in ways that we didn’t even think about at launch?”

There is still a lot to explore on the surface of Mars. The experts working on the MSL mission are investigating Mars in a way which has never been done before, which is a learning process. Opportunities for scientific inquiry have led to many fascinating student projects at the University of Guelph, many of which have been supervised by Professor Gellert. The projects involve trying to analyze and interpret publicly available data from Mars to gain new understandings. According to Gellert, “all these 4th year projects were very interesting. Sometimes you will see stuff that experts have overlooked over the years because there is so much data.”

More details about the APXS are provided by the Canadian Space Agency: https://www.asc-csa.gc.ca/eng/astronomy/mars/apxs.asp

References

https://link.springer.com/article/10.1007/s11214-012-9892-2#Sec26 
https://link.springer.com/article/10.1007/s11214-012-9873-5?no 
NASA Science Mars Exploration Program. APXS. Retrieved from: https://mars.nasa.gov/msl/spacecraft/instruments/apxs/ 
Bruker. Handheld XRF: How it works. Retrieved from: https://www.bruker.com/products/x-ray-diffraction-and-elemental-analysis/handheld-xrf/how-xrf-works.html 
 

Research Overview

Gellert’s research is focused on designing and applying nuclear spectroscopy methods for planetary exploration. This includes developing hardware for future missions and the related analysis software. His laboratory examines radiation sources, X-ray detector technology, their readout electronics and supporting digital electronics under the rigid mechanical, radiation and temperature conditions in outer space.

Main themes of research are:

  1. Mars Exploration Rover. The twin rovers Spirit and Opportunity landed in 2004 and lasted till 2010 and 2018, respectively. The APXS was one of the in-situ instruments on board that worked until the end. Gellert led and supported the daily operation of the APXS since 2005. This included data analysis, long term calibration checks and interpretation of the results in concert with the other science instrument. Even after the rover ceased, the in-detail APXS data analysis continues, since the data from this instrument allows to combine geologic interpretation from four landing sites on Mars.
  2. Mars Science Laboratory. After coming to Guelph, Gellert and his team set up a lab for the development and calibration of the improved APXS instrument on MSL, which was built by MDA in Brampton and supported by the CSA. Since landing in 2012, the team at Guelph and other Canadian and U.S. institutions operates the APXS, does the in-detail data analysis and interpretation of the continuously returned data. 
  3. Future missions or instruments. Gellert and his team work together with other Universities and partners to improve the APXS or other instruments, e.g. X-ray diffraction, for future planetary missions. His group investigates X-ray Spectroscopy theory to fully understand the method and investigate possible improvements in instrument setup and the analysis approach.  
  4. X-ray Spectroscopy data analysis. Gellert works on various ways to further improve the quality of the APXS analysis results from Mars by combining the APXS chemical data with various other results, like mineralogy or fine-scale chemistry. 
     

Highlights

  • Several NASA MER and MSL Group Achievement Awards
  • NASA Outstanding Public Leadership Medal 2013
  • CSA Commendation for the successful landing of the MSL APXS, 2011-12
  • Breakthrough of the Year, The Journal Science and its publisher, AAAS, 2003-04
  • ESA Award for the development of the APXS on Rosetta, 2002-03
Curiosity rover selfie

Curiosity 10 years later

  • The Curiosity Rover has covered a straight-line distance of 10517.1m, and 
  • climbed 627.3m up Mt Sharp.
  • During that time, APXS has analyzed 1263 scientifically interesting targets, 
  • downlinked in 2770 discrete EDRs (Experiment Data Records).
  • To acquire these measurements, APXS was solar powered on for 255 days, 7:53:20.

Available Positions

I am always looking for motivated undergraduate students who are interested in exciting opportunities and challenging projects in an emerging research area. There are usually opportunities to become involved in research projects in the senior level research project course and through research assistantships that are available in my research group during the summer months.

I have a dynamic, well-funded research group. The students use sophisticated, state-of-the-art equipment to study the physics of polymers, biopolymers and bacterial cells at surfaces. This work involves a lot of different science, such as physics, chemistry and microbiology, and has direct technological application to a wide variety of fields including nanotechnology, optical coatings and drug delivery systems.

If you have other questions or would like to receive more information, please contact me directly.

If you are looking for exciting opportunities and challenging projects in an emerging research area, I invite you to consider joining my research group as a graduate student. I have a dynamic, well-funded research group in which students use sophisticated, state-of-the-art equipment to study the physics of polymers, biopolymers and bacterial cells at surfaces. This work involves a lot of different science, such as physics, chemistry and microbiology, and has direct technological application to a wide variety of fields including nanotechnology, optical coatings and drug delivery systems. Graduate student projects are curiosity-driven, with students being encouraged to “follow their nose” if they discover something interesting. Students graduating from my research group receive unique, interdisciplinary training that prepares them for careers in both academia and industry. If you are a highly motivated student who is interested in pursuing leading edge soft matter and biological physics in an interdisciplinary research environment, there is a place for you in the Polymer Surface and Interface (PSI) Group.

For additional information, please check out the links below, where I have attempted to answer some of the more common questions from prospective graduate students. If you have other questions or would like to receive more information, please contact me directly.

In the Dutcher lab, there are excellent opportunities for highly motivated postdoctoral fellows to lead multidisciplinary research projects involving the study of polymers, biopolymers and bacterial cells at surfaces. I guarantee exciting, leading-edge research projects with high visibility and opportunities to present results at international scientific meetings and interact with leading researchers around the world, as well as opportunities to interact with industrial researchers and experience how polymers, biopolymers and bacterial cells are studied in an industrial environment.

Postdoctoral fellows have joined us from Penn State, the University of North Carolina, the University of Freiburg, the University of Grenoble, McGill University, the University of Toronto, Dalhousie University, the University of Navarra, Jilin University and the National Academy of Sciences in Belarus. Our students and postdoctoral fellows have gone on to faculty positions at major universities (James Forrest at Waterloo, Kari Dalnoki-Veress at McMaster, Ahmed Touhami at the University of Texas, Virginia Vadillo-Rodriguez at the University of Extremadura, Chris Murray at Lakehead, Thamara Laredo at Lakehead, and Christian Gigault at Ottawa) and hi-tech companies (Chris Murray at Monteco, Oleh Tanchak at Iogen, Oleg Stukalov at Mirexus Biotechnologies, Scott Allen at eBiz Professionals and Christian Gigault at JDS Uniphase).

For additional information, please check out the links below, where I have attempted to answer some of the more common questions from prospective postdoctoral fellows. If you have other questions or would like to receive more information, please contact me directly.

Publications

Alumni

  • Scott Annett, 2022 - 2024
  • Scott VanBommel, 2017-18
  • Jeff Berger, 2016 - 19
  • Elstan Desouza, 2014-17
  • Irina Pradler, 2012-15

  • Scott VanBommel, PhD, 2018

  • Victoria Flood, MSc, 2020
  • Jordan Hanania, MSc, 2020
  • Brent Wilhelm, MSc, 2020
  • Dustin, Tesslaar, MSc, 2016
  • Shawn Stargardter, MSc, 2014
  • Scott VanBommel, MSc, 2013
  • Nick Boyd, MASc 2012 (Co-supervised with Stefano Gregory)
  • May Lee, MSc, 2010

Contact

Department of Physics, Main Office
MacNaughton Building, Room 207
1-519-824-4120 x 52261

Courier to:
488 Gordon Street
Physics, Science Complex, Rm 1110
Guelph, ON | N1G 2W1

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