If you hear an ambulance in the distance, stand perfectly still. Listen
closely, and you will hear the pitch of the siren change as it moves. It
will start out higher than its stationary pitch, slide down as it
passes, and continue lower as it gets farther away. The movement of the
sound source changes its frequency. This vibration process is called the
Doppler effect. The Mössbauer effect is similar, but it has to do
with light instead of sound. Our newest Way Cool Scientist, Paulo Souza,
has a special place in his heart for the Mössbauer Spectrometer. On
Mars, the Mössbauer Spectrometer emits an invisible light into the
iron-bearing minerals — the very iron that makes the Red Planet
red — and, since minerals absorb light at different frequencies,
this instrument can determine their composition and abundance by
observing light wavelengths. The Mössbauer Spectrometer is also
capable of examining the magnetic properties of surface materials and
identifying minerals formed in hot, watery environments that could
preserve fossil evidence of Martian life.
Paulo is a Payload Downlink Lead (PDL) and the Long-Term Documentarian
for the Mars Exploration Rover (MER) mission. As a PDL, he receives the
Mössbauer data from the rovers, verifies that it meets the
scientists’ expectations, and makes sure that the data is
complete. The PDL is also responsible for analyzing data and reporting
the results to the other scientists in daily meetings. As the
documentarian for the Long-Term Planning Science Group, he addresses
relevant science hypotheses, and keeps tabs on the status of the mission
in relationship to long-term objectives.
Paulo is also a tutor for the Athena Student Interns Program (ASIP), an
organization that involves students from around the country in the MER
mission. Thirteen teams of high school students and their teachers
worked with mentors from the Athena Science Team from May 2003 through
May 2004 and were part of the Science Team at the Jet Propulsion Lab
(JPL) during real-time operations on Mars. His students measured the
influence of temperature on the Mössbauer spectrum recorded on
Mars. This data provided important information about the health status
of the instrument, and was used in the formal calibration process.
The planet’s volcanoes, polar ice caps, and canyons captivate
Paulo, but he’s particularly interested in the similarities
between Mars and Earth. Hematite, the mineral that is supposedly
responsible for putting the “Red” in “Red
Planet” is native to Earth as well — and we know that on
Earth, hematite was formed in a very wet environment. This gives
scientists reason to believe that this mineral, along with many others,
could be instrumental in the process of understanding the planet’s
mysterious past, especially regarding water and the implications of
life. “The minerals of Mars in both rock and soil are like the
planet’s history books,” says Paulo.
Paulo is also excited about applying space technology to earthly
inquiries. For example, he uses an engineering version of MIMOS II (a
miniaturized Mössbauer Spectrometer) for air pollution studies in
Brazil. “In the field of archaeology,” says Paulo, “we
can use this technology to learn more about the materials used in
ancient Greek pottery, masks used by Gladiators in the Roman Empire, and
manuscripts from the Middle Ages.”
Paulo is a physicist with a master’s degree in mechanical
engineering, and is currently working on his dissertation for his Ph.D.
He is a technical analyst for a mining company called CVRD in Brazil.
He’s always been a curious person, always interested in the
whys and hows. He believes that discipline, organization,
and patience are the three most important attributes for pursuing a
career in science. Paulo believes that for him, becoming a scientist was
one part natural progression, one part hard work.
Each day, Paulo learns more and more about the mineralogy of Mars
through his work on the MER mission. He believes that the more
information we can gather, the closer we will be to addressing that
million-dollar question — or perhaps I should say, a host of
questions: how much liquid water was there, for how long, and when did
it disappear? The next step will be to look at potential life forms and
possible associations between life on Mars and life on Earth. While we
don’t yet have conclusive answers, Paulo, with the help of his MER
colleagues and some pretty cool technology, is working hard to put the
puzzle pieces together.
