Search for hydrogen peroxide in the Martian atmosphere by the Planetary Fourier Spectrometer onboard Mars Express
Journal
Date Issued
2015
Author(s)
Aoki, Shohei
•
•
Kasaba, Yasumasa
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Nakagawa, Hiromu
•
•
Geminale, Anna
•
Formisano, Vittorio
Description
Acknowledgments This work was supported by the Grant-in-Aid Fellows program of the Japan Society for the Promotion of Science (JSPS) ( #233113 ). This work was also supported by a Grant-in-Aid for Scientific Research from the JSPS ( #22340142 ) and by the Tohoku University Global Center of Excellence program titled Global Education and Research Center for Earth and Planetary Dynamics. The PFS activities were funded by the Agenzia Spaziale Italiana (ASI) in the context of Italian participation in the European Space Agency (ESA) Mars Express mission. We would like to thank Dr. M. Smith and an anonymous reviewer for reviewing the manuscript and providing useful comments.
Abstract
We searched for hydrogen peroxide (H2O2) in the Martian atmosphere using data measured by the Planetary Fourier Spectrometer (PFS) onboard Mars Express during five martian years (MY27-31). It is well known that H2O2 plays a key role in the oxidizing capacity of the Martian atmosphere. However, only a few studies based on ground-based observations can be found in the literature. Here, we performed the first analysis of H2O2 using long-term measurements by a spacecraft-borne instrument. We used the ν4 band of H2O2 in the spectral range between 359 cm-1 and 382 cm-1 where strong features of H2O2 are present around 362 cm-1 and 379 cm-1. Since the features were expected to be very weak even at the strong band, sensitive data calibrations were performed and a large number of spectra were selected and averaged. We made three averaged spectra for different seasons over relatively low latitudes (50°S-50°N). We found features of H2O2 at 379 cm-1, whereas no clear features were detected at 362 cm-1 due to large amounts of uncertainty in the data. The derived mixing ratios of H2O2 were close to the detection limits: 16 ± 19 ppb at Ls = 0-120°, 35 ± 32 ppb at Ls = 120-240°, and 41 ± 28 ppb at Ls = 240-360°. The retrieved value showed the detection of H2O2 only for the third seasonal period, and the values in the other periods provided the upper limits. These long-term averaged abundances derived by the PFS generally agreed with the ones reported by ground-based observations. From our derived mixing ratio of H2O2, the lifetime of CH4 in the Martian atmosphere is estimated to be several decades in the shortest case. Our results and sporadic detections of CH4 suggest the presence of strong CH4 sinks not subject to atmospheric oxidation.
Volume
245
Start page
177
Issn Identifier
0019-1035
Ads BibCode
2015Icar..245..177A
Rights
open.access
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