A search for methane in the atmosphere of Mars using ground-based mid infrared heterodyne spectroscopy

• Published in: Journal of molecular spectroscopy 2013-09, Vol.291, p.98-101
• Main Authors: Sonnabend, G., Stupar, D., Sornig, M., Stangier, T., Kostiuk, T., Livengood, T.A.
• Format: Article
• Language: English
• Subjects: Methane; Planetary atmosphere; Remote sensing; Spectroscopy
• ISSN: 0022-2852; 1096-083X
• DOI: 10.1016/j.jms.2013.05.009

[Display omitted] •Mars was observed using ground based high resolution infrared heterodyne spectroscopy.•Two campaigns were conducted in 2010 and 2012.•No methane was detected.•We calculate an upper limit of 100ppb of methane. We report our search for methane in the atmosphere of Mars using high-spectral resolution heterodyne spectroscopy in the 7.8μm wavelength region. Resolving power and frequency precision of >106 of the technique enable identification and full resolution of a targeted spectral line in the terrestrial-Mars spectrum observed from the ground. Observations were carried out on two occasions, in April 2010 and May 2012 at the McMath-Pierce Solar Telescope and the NASA Infrared Telescope Facility, respectively. A single line in the ν4 band of methane at 1282.62448cm−1 was targeted in both cases. No absorption due to methane was detected and only upper limits of ∼100ppb for the martian atmospheric methane concentration were retrieved. Lack of observing time (due to weather) and telluric opacity greater than anticipated led to reduced signal-to-noise ratios (SNR). Based on current measurements and calculations, under proper viewing conditions, we estimate an achievable detection limit of ∼10ppb using the infrared heterodyne technique – adequate for confirming reported detections of methane based on other techniques.