Exploring Mars' Lost-Water Narrative Using Raman Spectroscopy and X-ray Fluorescence

At the American Chemical Society (ACS) Fall 2026 Meeting coming up from August 23^rd to the 27^th, an upcoming talk will discuss some of the latest orbital and rover data from Mars. The new analysis, according to Eva Scheller, a planetary scientist and researcher at Stanford University, suggests that substantial portions of the planet's early water and carbon dioxide were sequestered into crustal minerals rather than lost entirely to space.^1,2 Scheller will present the findings on Wednesday, August 26, from 10:235 to 11:05 am local time at McCormick Place Convention Center as part of her talk, which is titled "Unveiling Planetary Habitability Through Volatile Cycles: From Spacecraft Spectroscopy to Chemical Identifiability."²

Why is Scheller’s talk important for planetary science?

Scheller’s talk addresses a current widely accepted assumption about Mars’ ancient water. Currently, most scientists accept the premise that Mars’s water was lost almost entirely through atmospheric escape to space.² Scheller’s talk will challenge this assumption. Scheller will explain that her analysis of the hydrogen isotope data indicates that a significant fraction of that water was instead absorbed into the planet's crust through mineral formation.² However, she cautions in her abstract that current isotopic measurements cannot precisely determine how much water went into rock versus how much escaped to space, which is a limitation with direct consequences for how researchers model the planet's climate history and habitability.²

Another aspect to this upcoming talk is how spectroscopy can unveil new information about the Red Planet’s carbon cycle. By using Raman spectroscopy and X-ray fluorescence data collected by NASA's Perseverance rover, Scheller's team identified widespread carbonate minerals within olivine-rich rocks in the Jezero Crater.² When extrapolated across the planet, the rover-based measurements suggest that crustal carbonation may have removed a larger share of Mars' early carbon dioxide atmosphere than orbital surveys had indicated.²

Together, the two findings point to a broader methodological issue for the field: instruments that fail to detect a compound at orbital scale do not prove its absence at the surface, and single measurements are often compatible with more than one geological explanation. Scheller is developing a formal framework intended to help researchers quantify this kind of observational ambiguity and identify what combination of new data, models, or mission instrumentation would be needed to narrow the range of possible interpretations.

Why should planetary scientists and engineers attend this talk?

Scheller’s talk will touch upon some of the work that planetary scientists and engineers are currently working on, making this a talk they might find interesting. The talk also raises several important implications for workers in these fields. For example, instrument selection and landing-site targeting for missions to Mars, Venus, the Moon, and icy moons, several of which Scheller said her Stanford group is now studying using the same framework, depend on knowing which chemical signatures a given instrument can and cannot reliably detect.² Underestimating a planet's mineral-bound water or carbon reservoirs could skew assessments of its past habitability, a factor mission planners weigh when prioritizing targets for sample collection and astrobiology investigations.²

Scheller's presentation is part of the ACS Fall 2026 meeting's planetary and geochemistry programming, which runs alongside sessions on Earth-based climate and materials chemistry research.

What is the American Chemical Society Fall 2026 Meeting and what is the theme of this conference?

ACS is hosting its Fall 2026 conference in Chicago from August 23rd to the 27^th. What makes this upcoming conference unique is that ACS will be celebrating its 150^th anniversary.¹ As part of this celebration, the theme of the conference is “Chemists Making History,” and because of this reason, four Nobel Laureates will give presentations that cover advancements in growing fields such as super-resolution microscopy and battery analysis.¹

References

1. Wetzel, W. Why Spectroscopists Should Attend the ACS Fall 2026 Conference. Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/why-spectroscopists-should-attend-the-acs-fall-2026-conference (accessed July 13, 2026).
2. Scheller, E. Unveiling Planetary Habitability Through Volatile Cycles: From Spacecraft Spectroscopy to Chemical Identifiability. Presented at the American Chemical Society Fall 2026 Meeting, Chicago, Illinois, August 26, 2026. Available at: https://acs.digitellinc.com/live/37/page/1374?search=spectroscopy&tags=475&page=5&window-25otkn