Mars Infrared Laser Spectrometer (MIRLS)

Mars Infrared Laser Spectrometer (MIRLS)

Christopher R. Webster (PI, JPL), Toby Owen (U. of Hawaii), Yuk L. Yung (Caltech) Federico Capasso and Claire Gmachl (Bell Labs.), W. Steven Woodward: (U. of N. Carolina), Gregory J. Flesch (JPL), Wendy Calvin (USGS): Mars Airplane PI, Ray Morgan (AeroVironment Inc.)

MIRLS was first proposed in 1987 and developed for atmospheric and evolved gas measurements on the Soviet Mars 94/96 exobiology experiment (Webster, Owen, Hunten).

more recently, MIRLS was considered as a tunable laser spectrometer for measuring geochemical and biogenic activity on Mars from the Mars Airplane

SCIENCE OBJECTIVES:
On the 2003 Mars Airplane, MIRLS will make measurements of several geochemical (OCS, CO), biogenic (CH₄, N₂O, H₂O, OCS), and photochemical (H₂O₂, ¹³CO/CO) gases near the Mars surface up to 5 km altitude, in addition to providing laser altimetry data for surface topography and aircraft autonomous control.

To search for and identify local sources of biogenic and geochemical activity from near-surface measurement of atmospheric gases such as CH₄, N₂O, OCS, and CO, and to search for local sources of H₂O.

To quantify transport properties and boundary conditions in the Martian atmosphere through the identification of horizontal gradients in the abundances of the biogenic and geochemical gases CH₄, N₂O, and H₂O, OCS, and CO.

To test and constrain current photochemical models of the Martian atmosphere through simultaneous in situ measurements of several key species at the sub pars-per-billion level sensitivity, including: CH₄, N₂O, H₂O, H₂O₂, CO₂, OCS, and CO.

To test current hypotheses of Martian CO/CO₂ partitioning through simultaneous measurement of CO, CO₂, H₂O, and H₂O₂.

To investigate non-statistical isotope fractionation and its relation to fundamental chemical, physical, geophysical, meteorological, and biological processes, through the determination of the isotopic ratio of ¹³C/¹²C from measurements of ¹³CO and CO, and of ³⁴S/³²S from measurements of OC³⁴S and OCS.

To measure atmospheric temperature and pressure profile along the flight path from spectral line information.

To determine Martian surface topography from measurement of the aircraft altitude using laser altimetry at 5 km and below, providing canyon surface or wall ranging to autonomous control, and surface impact warning.

MIRLS INSTRUMENT SENSITIVITIES:

A. Minimum-detectable^*mixing-ratios:

Gas	Spectral region (cm^-1)	Expected Mixing-ratio	Open-path (10 km)	Open-path (100 m)	On-board cell (10 m)
CH₄	1270-1272	70 ppb	35 ppt	3.5 ppb	35 ppb
N₂O	"	30 ppb	11 ppt	1 ppb	10 ppb
H₂O	"	~300 ppm	15 ppb	1.5 ppm	15 ppm
H₂O₂	"	20 ppb
CO₂	"	96%	N/A	N/A	N/A

OCS	2068-2070	500 ppb	1 ppt	100 ppt	1 ppb
OC³⁴S	2068-2070	22 ppb	22 ppt	220 ppt	22 ppb
CO	"	0.2%	100 ppt	10 ppb	100 ppb
¹³CO	"	22 ppm	500 ppt	50 ppb	500 ppb
CO₂	"	96%	N/A	N/A	N/A

* calculated for a line-center absorption of 1 x 10^-4. Line-center absorptions ten- to one-hundred times less than this value are measured routinely in aircraft and balloon spectrometers.

C.R. Webster, 1999

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