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The Mars Science Laboratory mission’s Curiosity rover carries the tunable laser spectrometer, which is currently investigating isotope ratios in carbon, hydrogen, and oxygen to assess present-day habitability and whether Mars supported life.

MDL News & Trends

MDL TLS Instrument Vital to Mars Science Laboratory Mission

With its rover named Curiosity, the Mars Science Laboratory mission is part of NASA's Mars Exploration Program, a long-term effort of robotic exploration of the red planet. Curiosity, which successfully landed on Mars in August 2012, is designed to assess present-day habitability and whether Mars ever supported life.

The Mars Science Laboratory is the biggest, most advanced suite of instruments for scientific studies ever sent to the Martian surface. It carries the tunable laser spectrometer (TLS), which includes a new kind of semiconductor laser — the interband cascade laser — developed at MDL specifically for methane detection.

NASA’s investment in the invention of the interband cascade laser and the development and qualification of tunable diode lasers paid off richly when TLS made new measurements of methane gas and key isotope ratios in hydrogen, carbon, and oxygen for gases in the Martian atmosphere and those evolved from heated soils and rocks.

TLS has made several observations of atmospheric methane during the mission, establishing very low background levels and also observing variations not explained by our current understanding of the Martian atmosphere.

In addition, TLS has measured key isotope ratios D/H in water and 13C/12C and 18O/17O/16O in carbon dioxide at unprecedented precision (few parts in a thousand) that, in comparison with meteoritic data, has concluded that the Martian atmosphere has been largely unchanged over the last 4 billion years. More recently, measurements of the D/H ratio of water bound in the rocks during their formation have revealed that the Yellowknife bay mudstones exhibit D/H much lower than the atmosphere and were therefore formed during the Hesperian period before much of the atmospheric escape happened.

Analyses of findings were featured in the July and October issues of Science magazine in 2013:

“Low upper limit to methane abundance on Mars”, C. R. Webster, et al., Science 342, 355 (2013).

“Isotope Ratios of H, C, and O in CO2 and H2O of the Martian Atmosphere,” C. R. Webster, et al., Science 341, 260 (2013).

To learn more about Tunable Laser Spectrometers (TLS) in the Sample Analysis at Mars (SAM), please visit:

To learn more about the Mars Science Laboratory, please visit: