ChemCam consists of two remote sensing instruments. One, a Laser-Induced Breakdown Spectroscopy (LIBS) instrument provides rapid elemental composition data on rocks and soils within 13 m of the rover. By using laser pulses, it can remove dust or profile through weathering layers remotely. The other instrument, the Remote Micro-Imager (RMI), provides the highest resolution images between 2 m and infinity. At approximately 80 Rad field of view, its resolution exceeds that of MER Pancam by at least a factor of four. The ChemCam instruments are described in a companion paper by Maurice et al. Here we present the science objectives for the ChemCam instrument package

Bridges, N.

Clark, B.

Cremers, D.

Herkenhoff, K.

Kirkland, L.

Mangold, N.

Manhes, G.

Mauchien, P.

Maurice, S.

Wiens, R.

NASA Technical Reports Server

CHEMCAM SCIENCE OBJECTIVES FOR THE MARS SCIENCE LABORATORY (MSL) ROVER 
R. Wiens1, S. Maurice2, N. Bridges3, B. Clark4, D. Cremers5, K. Herkenhoff6, L. Kirkland7,8, N. Mangold9, G. Manhés10, P. 
Mauchien11, C. McKay12, H. Newsom13, F. Poitrasson14, V. Sautter15, C. d’Uston2, D. Vaniman1, S. Shipp7; 1Los Alamos Na-
tional Laboratory (rwiens@lanl.gov), 2Centre d’Etude Spatiale des Rayonnements, 3Jet Propulsion Laboratory, 
4Lockheed Martin Astronautics, 5SDN Research, Santa Fe, 6USGS Flagstaff, 7Lunar and Planetary Institute, 8Aerospace Corp., 
9Laboratoire IDES, 10Institut de Physique du Globe, Paris, 11Commissariat á l’Energie Atomique, Saclay, 12NASA Ames, 13U. 
New Mexico, 14Laboratoire des Mécanismes de Transfer en Géologie, Toulouse, 15Museum d’Histoire Naturelle, Paris 
 
 
Overview:  ChemCam consists of two remote 
sensing instruments.  One, a Laser-Induced Break-
down Spectroscopy (LIBS) instrument provides rapid 
elemental composition data on rocks and soils within 
13 m of the rover. By using laser pulses, it can remove 
dust or profile through weathering layers remotely.  
The other instrument, the Remote Micro-Imager 
(RMI), provides the highest resolution images between 
2 m and infinity. At approximately 80 µRad field of 
view, its resolution exceeds that of MER Pancam by at 
least a factor of four.  The ChemCam instruments are 
described in a companion paper by Maurice et al. [1].  
Here we present the science objectives for the Chem-
Cam instrument package. 
Introduction:  Planetary surfaces can be difficult 
places for accurate remote sensing. Orbital remote 
sensing can obtain average spectral compositions over 
large areas.  Rover-based remote sensing can be more 
challenging for several reasons: a) individual rocks can 
be completely dust-covered, b) their suface textures 
can make them poor reflectors at wavelengths where 
telltale emission or reflectance peaks would otherwise 
be seen, and c) weathering coatings can obscure the 
true composition of the rock.  Weathering coatings on 
a regional scale may also fool orbital remote sensing 
[2]. 
The LIBS instrument uses a pulsed laser providing 
40 mJ to a small (≤1 mm) spot.  The laser produces a 
plasma from the ablated atoms.  The plasma radiates at 
visible and UV wavelengths characteristic of the ele-
ments (and in some cases molecules) present in the 
sample.  The LIBS spectrographs record the spectra 
and allow identification of the rock type and quantifi-
cation of the composition. The laser removes dust at 
up to ~1 mm/pulse [3], and can remotely profile into 
rock samples with weathering rinds at rates of ≥0.3 
µm/pulse.  The LIBS instrument can thus depth profile 
several hundred microns in twenty minutes. 
The utility for the LIBS instrument can be under-
stood by considering some of the MER Mars rover 
scenarios.  The Opportunity rover landed in Eagle Cra-
ter, within a few meters of a rock outcrop [4].  LIBS 
would have allowed immediate identification of the 
composition of the rock outcrop rather than having to 
wait many days until the rover could drive up to the 
rocks and brush them off.  Other features have re-
mained inaccessible to the rover because of the terrain.  
Likewise, the composition of the hematite spherules 
known as “blueberries” could not be determined im-
mediately because these features were much smaller 
than the APXS sensor head.  Their composition was 
eventually determined when many blueberries were 
found in a single location.  Because LIBS analyses are 
made on spots  ≤1 mm in diameter, LIBS can immedi-
ately identify the composition of small features, not 
only those similar to blueberries, but also layers, for 
example, within a finely stratified sedimentary rock. In 
such applications the remote micro-imaging function 
of ChemCam will be crucial in guiding the LIBS laser 
to specific features. 
ChemCam Science Objectives:  As a science 
team, we view the following as the current most press-
ing issues in Mars science: 
• Composition of sedimentary deposits, and what they 
tell us of Mars’ climate history. The SNC meteorites, 
Viking, and Pathfinder did not give direct informa-
tion on sedimentary materials. That the Mars surface 
has abundant sedimentary surface materials was evi-
dent from orbital imagery [5]. However, direct 
measurements were only recently made with MER. 
Critical questions include the origin, extent, and du-
ration of large bodies of water responsible for sedi-
ments in the Arabia and Meridiani regions. Micro-
imaging and trace element chemistry will greatly aid 
the interpretation of the Mars sedimentary record. 
• Nature and origin of the surficial fines and aerosol 
dust composition.  The origin of the high sulfur and 
chlorine abundances in the dust has been an open 
question ever since Viking [6]. The finding of sedi-
mentary sulfate deposits at Eagle Crater show that 
the water from which these deposits formed was also 
high in sulfur. The origin of the enrichment of these 
elements on the surface is still unknown, however 
low-temperature brines, hydrothermal fluids, and 
volcanic aerosols have distinctive minor and trace 
element chemical signatures that may allow the de-
termination of the origin of this mobile element 
component [e.g., 7].   
Lunar and Planetary Science XXXVI (2005) 1580.pdf
https://ntrs.nasa.gov/search.jsp?R=20050180758 2019-08-29T19:53:24+00:00Z
 • Composition of the Mars crust. The composition of 
the SNC meteorites, inferred to be from Mars, sug-
gests a basaltic composition for some of the Martian 
crust. But how extensive are basaltic compositions 
on Mars? The Thermal Emission Spectrometer 
(TES) observations on Mars Global Surveyor found 
two different kinds of signatures, one of which was 
associated with the basaltic compositions from Vi-
king and SNC meteorites, and the other was sug-
gested to be andesitic [e.g., 8]. The andesitic inter-
pretation was consistent with the original data from 
the Alpha-Proton X-ray Spectrometer (APXS) on 
Pathfinder [9], but the silica content of the Path-
finder site rocks was later revised downward signifi-
cantly, to make it consistent with basalt (Bruckner et 
al., 2003). The TES observations, however, could be 
caused by weathering of basalt [2] which would im-
ply that Mars’ surface volcanism is entirely basaltic.  
The recent MER results raise the question of how 
much of the near-surface material is igneous and 
how much is sedimentary. Additional rock and soil 
compositions are important because the soils may 
represent an average crustal composition due to ae-
olian erosion, even though variations exist in some 
elements based on global gamma ray data (e.g. [11]). 
• Organic content of Mars’ sediments, and evidence of 
past life. Sedimentary deposits are also exciting be-
cause of their potential for finding evidence of past 
life on Mars. Without Beagle, we must wait several 
more years to determine the presence or absence of 
organic materials in sedimentary deposits.  The 
ChemCam experiments will also help characterize 
and select samples for organic analysis by the in-situ 
MSL experiments. 
ChemCam addresses four of the five broad MSL 
mission objectives, including a) Characterize geology 
of the landing region, b) Investigate planetary proc-
esses of relevance to past habitability, including the 
role of water, c) Assess the biological potential of tar-
get environments, and d) Investigate the presence of 
materials toxic to plants or humans. 
Defined Investigations:  The ChemCam science 
team mapped the mission objectives and critical ques-
tions into eleven defined investigations. They are 
briefly described as follows: 
1. Rapid remote rock identification, for rocks within 
13 m of the rover.  These would be qualitative 
analyses looking for samples worthy of further 
study. 
2. Soil and pebble surveys.  Daily analyses of the 
soils and/or pebbles near the rover will help un-
derstand the range of compositions within any lo-
cation and regional changes in soil compositions.  
It may provide information on soil maturity at 
various locations.  RMI images collected along 
with LIBS spectra will provide an extensive data-
set of correlated images and spectra. 
3. Quantitative analysis of rocks and soils, including 
trace elements.  These less frequent analyses will 
require in-situ calibration with standards on board 
the rover. 
4. Detection of hydrated minerals by observing the H 
emission line at 656 nm. 
5. Rapid remote identification of surface ices using 
both the OH molecular band and H emission line. 
6. Analysis of weathering and depositional coatings 
or rinds on rocks, by depth profiling up to a mil-
limeter or more into rocks and observing changes 
in spectra with depth. 
7. Remotely observing rock morphologies with the 
RMI resolution of 0.08 mRad. 
8. Analysis of rocks and soils that are inaccessible to 
the rover itself. 
9. Assist in arm and drill sampling.  Both LIBS and 
RMI have close focusing capabilities (presently to 
2 m), allowing them to observe/analyze samples 
that are scooped or cored before they are fed to 
the in-situ instruments. 
10. Remote identification of organic materials.  Detec-
tion of CN and C2 molecular bands at the 20% 
composition level will allow remote detection of 
organics if present in relatively high abundances. 
11. Assist in preparation for human exploration by 
checking for abundances of Be, Pb, Cd, As well 
above hazardous limits for humans.    
To carry out these investigations, the ChemCam 
Science Team has planned a healthy strawman cam-
paign of nearly 7 “measurements” per sol consisting of 
~12 RMI images per sol (typically 1 prior to and 1 
subsequent to each LIBS analysis), 915 spectra with 
945 laser shots per sol, packaged in ~12 Mb per sol.  A 
typical measurement requires only 0.7 W-hr and 6 
minutes, including sample acquisition. 
References:  [1] Maurice S. et al. (2005) this vol-
ume. [2] Wyatt M.B. and McSween H.Y.Jr. (2002) 
Nature 417, 263-266, 2002. [3] Knight A.K. et al. 
(2000) Appl. Spectrosc. 54, 331-340. [4] Squyres S.W. 
et al. (2004) Science 306, 1698-1703. [5] Edgett K.S 
and Malin M.C. (2002) Geophys. Res. Lett. 29, 2179. 
[6] Clark B.C. et al. (1982) J. Geophys. Res. 87, B12, 
10059-10067. [7] Newsom H.E. et al. (1999) J. Geo-
phys. Res. 104, 8717-8728. [8] Bandfield J.L. et al. 
(2000) Science 287, 1626-1630. [9] Reider R. et al. 
(1997) Science 278, 1771-1774. [10] Bruckner J. et al. 
(2003) J. Gephys. Res. Planets, 108, E12, 8094. [11] Taylor 
G.J. et al. (2004) Lunar Planet Sci. XXXV, 1808. 
Lunar and Planetary Science XXXVI (2005) 1580.pdf


ChemCam Science Objectives for the Mars Science Laboratory (MSL) Rover

ChemCam Science Objectives for the Mars Science Laboratory (MSL) Rover

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