Ralf Gellert

Dr. Ralf Gellert
Associate Professor, Graduate Coordinator
Phone number: 
519-824-4120 x53992
MacN 450

I obtained my M.Sc. (Dipl. Phys.) in Physics in 1994 from the Darmstadt University of Technology, Germany, and a Ph.D. (Dr. rer. nat.) from the same institution in 1999.

From 1999 – 2000 I worked at the University of Mainz, Germany, as a research scientist developing the microcontroller software for the miniaturized Moessbauer spectrometer MIMOS that later flew on the NASA Mars Exploration rover mission.

From 2001-2005 I worked as a research scientist at the Max-Planck Institute for Chemistry in Mainz, Germany. During this time I was the lead engineer for the alpha-particle-x-ray spectrometer (APXS) on the European Rosetta mission and the NASA Mars Exploration rover mission. From 2003-2004 I led the calibration of the APXS in Mainz and developed the data analysis software and calibration.

After the successful landing of both MER rovers in January 2004 I spent 3 months at NASA’s JPL during the primary mission phase to operate the APXS and analyze the data. In 2004 I led the successful proposal to NASA for the Canadian contributed new APXS for MSL, which is supported by the Canadian Space Agency.

In 2005 I joined the department of Physics at the University of Guelph, ON, Canada, as an Assistant Professor.

I have been reviewing papers for the Journal of Geophysical Research and grant applications for NASA and CSA.

As the APXS Principle Investigator for MSL I’m a member of the PSG, the project science group, which heads the development and operation of the scientific investigations performed on the MSL mission.

In 2009 I was a member of the CSA science definition team for future Lunar and Martian exploration and sample return investigations.


I have received various awards from NASA and ESA for the development and operation of the APXS on board the MER rovers and the Rosetta Lander.

The research in my laboratory is focused on developing hardware and the related analysis software for instruments for planetary exploration. This includes x-ray and alpha detector technology and their readout electronics and supporting digital electronics under the rigid mechanical, radiation and temperature conditions in outer space. The investigation of the Physics principles of the method allows us to adapt and to optimize the design and the scientific return tailored to each mission.

Currently my group is working mainly on three projects:

  1. Mars Exploration Rover mission: The APXS is one of the in-situ instruments on the NASAMER rovers Spirit and Opportunity. The rovers landed in January 2004 and still operate on the surface of Mars as of December 2009. Since 2005 I am the lead scientist for these instruments responsible for their operation and data analysis. The APXS instruments on both rovers have measured so far about 400 samples along the traverse of ~ 10 kilometers. The results have brought many new insights into the composition and formation of the Martian crust and the interaction with water in the past. This data set comprises a unique set of information from the surface of another planet. Beside the daily analysis and interpretation of the data we strive to extract all possible information from the data, like current atmospheric conditions, temperature data and yet uncalibrated trace elements. As an example, my colleague Prof. Campbell was able to extract the presence of ~ 20% bound water in specific minerals from several subsurface Martian soils. He used the x-ray scatter peaks and developed a method to extract highly interesting information from these previously not well understood and neglected features in the APXS spectra.
  2. Mars Science Laboratory: In 2008 an improved version of the APXS was delivered to NASA for the new Mars rover due to launch in 2011. In our laboratory we have built up a Mars simulation chamber with an equivalent MSL APXS to calibrate the instrument with well-known standards and to perform systematical investigations of the method. In collaboration with my colleagues Prof. Campbell and Prof. O’Meara we are properly calibrating the scatter peak method to extract light element abundances that are invisible with characteristic x-rays. We are also setting up an operation center to support the activities of the APXS science team during the duration of the MSL mission on Mars.
  3. For future planetary exploration we are investigating further improvements of the APXS method and the instrument. Since the APXS has a very successful heritage in space exploration and addresses with its capabilities key scientific objectives, it has good chances of being selected again in future robotic missions to Mars, Martian moons, asteroids and our Moon. We are investigating new detectors,  new excitation sources, new miniaturized electronics and new scientific methods to further improve the suitability and scientific return of future APXS instruments in space.
Name Role
Victoria Flood MSc Candidate
Jordan Hanania MSc Candidate
Brent Wilhelm MSc Candidate