Indian scientists identify Martian analogue sites

Kerala University researchers identified two minerals linked to Martian analogue research: melanterite and gypsum. The discoveries matter because both minerals record interactions between water and rocks. Their presence can help scientists study environmental conditions that may once have existed on Mars.

Melanterite was found in Neyveli, Tamil Nadu. Gypsum was identified in the Atacama Desert in Chile and in the Tiruchirappalli Badlands, a semi-arid geological and paleoclimatic terrain in Tamil Nadu. These sites resemble Mars in important geological, chemical and physical ways.

The team was led by Sajin Kumar K.S., Associate Professor of Geology at Kerala University and DST-FIST project coordinator. Laser Raman spectroscopy confirmed the minerals. The researchers describe these places as useful terrestrial analogues for studying Martian water activity, possible habitability and future mission targets.

A Martian analogue site is an Earth location that shares important geological, chemical or physical features with Mars. Scientists study these places to understand minerals, water–rock interactions and environmental conditions that may also have occurred on the Red Planet. Earth sites are accessible for detailed sampling and laboratory analysis.

The research identified the Atacama Desert, Neyveli and the Tiruchirappalli Badlands as relevant locations. The Atacama Desert and the Tamil Nadu sites contain minerals associated with water-related processes. Gypsum can preserve evidence of past aqueous environments, while melanterite records short-lived wet, acidic and oxidising conditions.

These comparisons matter because orbital data alone cannot fully characterise Martian minerals. Researchers can examine analogue minerals with high-precision instruments, including a laser Raman spectrometer. The results can improve interpretations of Mars and help select promising locations for future searches for life-related evidence.

The study involves two minerals: melanterite and gypsum. They occur across three terrestrial locations that researchers consider useful Martian analogue sites. This combination links mineral evidence with different environments that can help illuminate Mars’s geological and water history.

Melanterite was identified at Neyveli in Tamil Nadu. Gypsum was identified in two places: Chile’s Atacama Desert and the Tiruchirappalli Badlands in Tamil Nadu. The Badlands are described as a semi-arid geological and paleoclimatic terrain. Together, these sites provide examples of minerals formed or preserved through water–rock interactions.

The number of sites is important because analogue research compares more than one environment. The researchers used a laser Raman spectrometer to confirm the minerals’ distinctive spectral fingerprints. Their findings were published in two papers in the Journal of Geophysical Research: Planets, supporting broader planetary-science investigations.

Gypsum and melanterite are hydrous sulphates, so they record interactions between water and rocks. Their different environmental signals make them valuable clues to Mars’s past. They do not simply show that water existed; they also indicate the kinds of conditions associated with that water.

Gypsum preserves evidence of past aqueous environments. Melanterite indicates short-lived wet conditions that were acidic and oxidising. These contrasting records can help scientists reconstruct changing environments, including episodes that may have affected the potential for habitability. The minerals were found in terrestrial sites with Martian similarities.

Such evidence is important because the researchers are seeking minerals capable of recording water activity and preserving biosignatures. Their work could guide future planetary missions toward locations most likely to preserve evidence of life beyond Earth. The findings therefore connect mineral chemistry with questions about ancient Martian environments.

A laser Raman spectrometer helped the researchers identify the minerals by detecting their distinctive spectral fingerprints. These fingerprints are instrument readings linked to the materials being examined. Matching the readings with known mineral characteristics allowed the team to confirm the identities of melanterite and gypsum.

The instrument was used on samples from Neyveli, the Atacama Desert and the Tiruchirappalli Badlands. It identified melanterite in Neyveli and gypsum in the other two locations. The facility was supported by DST-FIST, the Fund for Improvement of S&T Infrastructure in Universities and Higher Educational Institutions.

This confirmation matters because analogue research requires precise mineral identification. The researchers noted that high-precision, state-of-the-art analytical tools are essential for such investigations. Their results were published as two papers in the Journal of Geophysical Research: Planets, a leading planetary-science journal.

Terrestrial analogue sites are needed because spacecraft observations from orbit have limits. Recent studies showed that orbital data alone cannot fully characterise Martian minerals. Earth locations provide accessible material that researchers can examine directly with high-precision, state-of-the-art instruments.

The Kerala University team used terrestrial examples from Neyveli, the Atacama Desert and the Tiruchirappalli Badlands. Laser Raman analysis detected the minerals’ spectral fingerprints. The resulting evidence showed how gypsum and melanterite can record water–rock interactions and different environmental conditions, including past aqueous settings and brief acidic, oxidising episodes.

These sites strengthen interpretations of Martian data and help scientists understand past potentially habitable environments. They may also guide future planetary missions toward locations where minerals could preserve biosignatures. The team is now studying rare analogue sites in extreme conditions around the world for astrobiological research.

Hydrous sulphates are sulphate minerals that contain water within their mineral structure. That structure forms through, or records, interactions involving water and rock. Because the minerals retain chemical and physical evidence of those processes, scientists can use them to investigate environmental history and possible habitability.

In this research, gypsum and melanterite are hydrous sulphates. Gypsum preserves evidence of past aqueous environments. Melanterite records short-lived wet, acidic and oxidising conditions. These different signals show how mineral chemistry can distinguish among water-related settings rather than treating all ancient water activity as identical.

The researchers also note that minerals capable of recording water activity may preserve biosignatures. Such minerals could therefore help identify places worth examining for evidence of life beyond Earth. The article does not specify particular biosignatures or explain their precise chemical preservation, but links the minerals’ records to future astrobiological investigations.