Lesson Plan:
Using Remote Mössbauer Spectroscopy
Purpose:
To introduce students to the uses of Mössbauer spectroscopy to
indentify minerals on remote planetary surfaces.
Overview:
Each student picks three minerals from a list of 50 candidates likely
to be found on Mars. Students research the conditions under which their
minerals form. Mössbauer spectra of these minerals are compared,
and students decide if the spectra of their minerals will overlap, or
if their minerals have spectra that have unique features.
Key Concepts:
- Rocks are made
up of minerals. Different combinations of minerals form rocks in different
types of environments. Thus, knowing the mineralogy of a planet tells
us a great deal about the conditions under which it formed and the
starting composition of that planet.
- Based on spectra
acquired from orbiting satellites, as well as from martian meteorites,
scientists have suggested the presence of about 50 minerals likely
to be found on the surface of Mars. Some of these minerals contain
the element hydrogen. The presence of hydrogen in a mineral's composition
usually tells us that it formed in the presence of water. If water
was/is present on Mars, that may have provided a place for life to
form.
- A Mössbauer
spectrometer was included on the Mars Explorations Rovers, as well
as the Beagle 2 lander, in order to identify the iron-bearing phases
that are present. Scientists will match the spectra of mineral mixtures
(=rocks) acquired on the martian surface with data acquired in terrestrial
laboratories.
- Unfortunately,
not all Mössbauer spectra are unique; some minerals look very
similar because the iron atoms in their structures are in very similar
sites. Also, the Mössbauer effect is temperature-sensitive --
but only a handful of spectra acquired at Mars surface temperatures
exist.
Skills:
- Researching how
minerals form
- Comparing mineral
spectra
- Predicting which
minerals will be found on Mars, and whether or not they will be uniquely
recognized by Mössbauer spectroscopy
Materials:
- web access, or
printouts of spectra from Mars Mineral Spectroscopy web site
- web access,
or mineral identification handbooks
- clear transparencies
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