Strong water isotopic anomalies in the martian atmosphere: Probing current and ancient reservoirs

Abstract

We measured maps of atmospheric water (H2O) and its deuterated form (HDO) across the martian globe, showing strong isotopic anomalies and a significant high deuterium/hydrogen (D/H) enrichment indicative of great water loss. The maps sample the evolution of sublimation from the north polar cap, revealing that the released water has a representative D/H value enriched by a factor of about 7 relative to Earth's ocean [Vienna standard mean ocean water (VSMOW)]. Certain basins and orographic depressions show even higher enrichment, whereas high-altitude regions show much lower values (1 to 3 VSMOW). Our atmospheric maps indicate that water ice in the polar reservoirs is enriched in deuterium to at least 8 VSMOW, which would mean that early Mars (4.5 billion years ago) had a global equivalent water layer at least 137 meters deep.

The Main Belt Comets and ice in the Solar System

“…We show the NIR-radio spectrum of a model MBC atmosphere that comprised water, generated using the Goddard Planetary Spectrum Generator 3 (Villanueva et al 2015), in Fig. 3.…”

New measurements of D/H on Mars using EXES aboard SOFIA

“…Many observations have been performed since 1988 (Bjoraker et al 1989;Krasnopolsky et al 1997;Encrenaz et al 2001), all consistent with the first detection. More recently, attempts to map D/H on Mars as a function of latitude and season have been performed by Novak et al (2011), Villanueva et al (2015), Krasnopolsky (2015), Aoki et al (2015) and Encrenaz et al (2016).…”

New hydrogen-isotope measurements refine the picture of water on Mars

“…Now Melike Lakadamyali, Maria Pia Cosma, and their colleagues at the Institute of Photonic Sciences (ICFO) and the Center for Genomic Regulation (CRG), both in Barcelona, Spain, are using superresolution microscopy to get a closer look at the structure of chromatin. 1 What they've found so far argues against the textbook view: Rather than being evenly spaced, nucleosomes are grouped into clusters, which the researchers call "clutches," as shown in figure 1b. Furthermore, the average number of nucleosomes per clutch differs between stem cells and ordinary, or somatic, cells.…”

“…Comparing the historical D/H ratio to the poles' modern-day enriched value, Villanueva and colleagues infer that the planet must have had a global-equivalent layer of at least 140 m in its early history. 1 Current models of hydrogen loss suggest that's a hard lower bound. During the "Noachian" period of Mars's history (prior to 3.8 billion years ago), both volcanism and asteroid impacts delivered new water to the surface, which could have rejuvenated the atmosphere's D/H.…”

“…1 The researchers adopted the same remote spectroscopic approach as in the earlier work: They used powerful telescopes to collect sunlight reflected from Mars's face. But instead of measuring only a hemispherically averaged value, the team stepped the rectangular entrance slit of an IR spectrometer eastward across the face of the planet and sampled dozens of spectra spaced along the North-South length of the slit for a few minutes at each position.…”