The potential of Deception Island, Antarctica, as a multifunctional Martian analogue of astrobiological interest

Abstract

The establishment of the possible presence of life on Mars (past or present) is based on the study of planetary analogues, which allow in situ analysis of the environments in which living organisms adapt to often extreme conditions. Although Mars has been a candidate for hosting life, based on observations made decades ago, it is thanks to the characteristics identified in environments, mainly volcanic, that it has been possible to calibrate instruments and detail the features of the red planet. In this paper, we present a review of the main characteristics of different planetary analogues, particularly deepening the study of Antarctica, to later expose the factors studied in Deception Island that have contributed to considering it as an analogue of Mars from different perspectives. Although geological and geomorphological studies on the analogies of the island already exist, detailed analyses that present the approach of astrobiological analogues are required, thus allowing further research.

Introduction

Astrobiology seeks to understand how life emerged and evolved on Earth by relating the physical, chemical and geological characteristics of different environments. It also aims to explore, based on these understandings, the possibilities of life on other rocky bodies in the Solar System or outside it (Des Marais et al., 2008; Horneck et al., 2016). One of the main goals of astrobiology is to use Earth as a natural laboratory to study the emergence of life and pose models of what life, as we know it, might be like elsewhere in the universe (National Aeronautics and Space Administration (NASA), 2015; Camprubí et al., 2019). One of the ways to understand the possible habitability of other planets or satellites corresponds to the evaluation of specific places that present similar conditions to those present in rocky bodies; these places are called planetary analogues, also known as terrestrial analogues (a.k.a. terrestrial analogues) (Fairén et al., 2010; Martins et al., 2017).

Always taking into account the uniqueness and the noticeable environmental differences that the Earth has in relation to all other rocky bodies of the Solar System, from the perspective of astrobiology, it is possible to classify planetary analogues into two types: (1) field planetary analogues and, (2) laboratory planetary analogues (Martins et al., 2017). The first one corresponds to sites distributed on Earth, usually with extreme conditions of pH, temperature, pressure, radiation, salinity and water availability (Amils et al., 2007; Bendia et al., 2018a) in conjunction with some geological or geomorphological features (Martins et al., 2017; Matsubara et al., 2017). Field planetary analogues enable the development of various types of research, including: (1) understanding geological and geomorphological processes of other bodies, (2) testing and calibrating new instruments, which will be carried aboard space missions, (3) standardizing operational procedures for exploration vehicles and future human crews and (4) collecting biotic and abiotic samples to investigate relationships between life and its geological context, as well as the identification of microorganisms from extreme environments that will allow the evaluation of future methods of detection (or exploitation) of (bacterial) life, instrumentation, payload testing and selection of sites of interest with the potential to harbour life, for future missions (Gómez, 2015; Martins et al., 2017; Mouginis-Mark, 2021).

Conversely, laboratory planetary analogues correspond to laboratories used to evaluate parameters of extraterrestrial environments through a series of experiments to understand biological signatures, mechanisms of adaptation and survival of microorganisms and the interaction between life and a simulated atmosphere (Martins et al., 2017). In the development of these laboratory analogues, instrument calibration can also be performed (Motamedi Mohammadabadi, 2013). Additionally, it is possible to induce chemical processes or evaluate the behaviour of astro-materials for a broad variety of purposes (Mateo-Martí et al., 2006).

Globally, more than 30 analogue sites have been mapped (Martins et al., 2017; Cassaro et al., 2021; Dypvik et al., 2021). Most of them correspond to Mars analogues, and a few others correspond to icy satellites. In astrobiological terms, the search for sites that present extreme conditions for most living organisms has been chosen, aiming to create and evaluate models for the understanding of the adaptation of life to adverse conditions (Cavicchioli et al., 2002; Deming, 2009; Garcia et al., 2013). Additionally, understanding the different mechanical processes and petrological and mineralogical characteristics are determinants for the geomicrobiological relationships of the various microorganisms and their environment (Henry, 1998; Sajjad et al., 2022), a crucial aspect in the search for life elsewhere in the universe.

Within the different extreme environments, a place with low temperatures, strong winds, permafrost and isolation stands out on our planet: Antarctica is considered one of the most suitable analogues for Martian surface processes (Anderson et al., 1972). Three locations on the so-called icy continent have been classified as analogue sites (Martins et al., 2017). The McMurdo Dry Valleys are considered the driest cold place on the planet (Marchant and Head, 2007), reaching average temperatures of −30°C in winter and −15°C in summer. It has been possible to detect a great richness of microorganisms in the permafrost and rocks (Friedmann, 1982; Gilishinsky et al., 2007). It has been considered, since 1975 when Viking missions were launched, to be the closest climatic analogue to Mars conditions (Horowitz et al., 1972; Leal et al., 2015).

The other two Antarctic analogues are Victoria Land Mountains and Lake Vostok. Victoria Land shares characteristics with McMurdo since dry valleys are also present there, but which, being at a high altitude, promotes the presence of microorganisms resistant even to increased ultraviolet (UV) radiation (Meeßen et al., 2015). In case of Lake Vostok, it is one of the places that have been catalogued as an analogue of Enceladus (Saturn's Moon) or Europa (Jupiter's Moon) due to the presence of microorganisms in a lake covered by a layer of ice between 50 and 70 km thick (Shtarkman et al., 2013). However, when detailing the geological or petrographic characteristics of these sites, they are considerably distant from being able to be a planetary analogue of any other kind beyond the astrobiological.

Therefore, evaluating other Antarctic sites that may be considered as multifunctional analogues could enhance logistical operations, as well as combine efforts and resources to offer new astrobiological perspectives in the search for life beyond Earth. Among other potential Antarctic multifunctional analogues, Deception Island displays similar characteristics with its counterpart. The reason for selecting this stratovolcano located between the South Shetland Islands and the Antarctic Peninsula (Geyer et al., 2019) lies in its geological, geomorphological and climatological, among other characteristics. While this island has been assessed from a geomorphological standpoint (de Pablo et al., 2009; Centeno et al., 2013; Molina et al., 2013, 2014; de Pablo, 2015) and offers logistical facilities that propose it as a possible planetary analogue, allowing the evaluation of sensors for space missions (Ramos et al., 2012; de Pablo, 2015), many of its features have yet to be integrated to propose it as a multifunctional analogue of Mars.

For this reason, the present review has the following objectives:

1. (1) Identify and classify the geological, geomorphological and meteorological characteristics of Deception Island as a multifunctional analogue of Mars.

2. (2) Describe the astrobiological potential of the island as a Mars analogue.

3. (3) Identify future research opportunities and further exploration of the island as a Martian analogue.

To address these objectives, the study includes a section that discusses the criteria for the selection of multifunctional analogues, followed by a review of Deception Island's characteristics that may be of interest as an analogue. Subsequently, the island's relevance as an astrobiological Mars analogue is discussed, and finally, there is a discussion on future research perspectives and deeper exploration of the island as a Mars analogue.

Criteria for the selection of multifunctional analogue sites

According to the proposal of Foucher et al. (2021), it is possible to classify analogues according to their practical use in planetary exploration. Thus, two major classifications can be found: (1) functional analogue sites and (2) functional analogue samples. Functional analogue sites exhibit general characteristics similar to those found on another extraterrestrial body, but have specific analogous properties of interest for a particular use and are widely used in astronaut training and instrument calibration and contribute to interpreting observations made in space missions. Therefore, analogous sites can be classified according to their function: (1) planetary analogy, (2) analogy of mechanical and chemical processes, (3) petrological and mineralogical analogy, (4) analogy of astrobiological interest and (5) engineering analogy. Analogue samples can be classified into: (1) geological analogue samples, (2) chemical analogue samples, (3) biological samples and (4) technical analogue samples.

Based on the selection pathways of the most appropriate analogue site to be used according to the purpose of the study (Figs. 1 and 2), this study will evaluate Deception Island as a multifunctional analogue that can simultaneously serve as a functional site for two or more categories: engineering, biology, geology, medicine and architecture. However, priority will be given to ensuring that at least one of these corresponds to a scientific study and the other to a technical study.

Figure 1. Aspects to consider for the definition of functional analogue sites of scientific interest. Geological interest sites are marked in yellow, biological interest sites in green and medical interest sites in blue (own construction based on Foucher et al., 2021 and Heinicke and Arnhof, 2021).

Figure 2. Aspects to consider for the definition of functional analogue sites of technical interest. Geological interest sites are marked in yellow, biological interest sites in green, engineering interest sites in grey and architectural interest sites in purple (own construction based on Foucher et al., 2021 and Heinicke and Arnhof, 2021).

Characteristics of Deception Island with analogous functionality

Geology, geography and geomorphology

Deception Island is located in the South Shetland Islands archipelago, near the Antarctic Peninsula (62°57′S; 60°38′W). This island is the first planetary analogue proposed in the vicinity of the Antarctic Peninsula, given that some sectors of Antarctica have been considered planetary analogues, such as the Dry Valleys (including the Victoria Mountains and Beacon Valley) and Lake Vostok (Fairén et al., 2010; Martins et al., 2017; Dypvik et al., 2021). However, as shown in Fig. 3, the Antarctic locations classified as analogues are not situated in this region.

Figure 3. Location map of the already proposed planetary analogues in Antarctica. Data source: Quantarctica v3 (Matsuoka et al., 2018).

Deception Island is one of the three emergent volcanoes in the volcanic complex that developed along the rift axis forming the Bransfield Strait (Caselli et al., 2007). It is a stratovolcano with a caldera collapse that created a central rim with an internal ocean and the characteristic horseshoe shape, as shown in Fig. 4 (Baraldo, 1999). The last eruptive cycle occurred in 1970, after which geothermal anomalies with gas emissions of varying compositions and temperatures were generated (Caselli et al., 1994, 2007; Agusto et al., 2004). The island is a composite volcano, with a basal diameter of 30 km and an elevation of 1400 m from the ocean floor to a maximum of 540 m above sea level (Luzón et al., 2011; Geyer et al., 2019). It is estimated that the island is less than 0.75 million years old (Valencio et al., 1979), and the subaerial part would have formed in the last 0.2 million years (Martí et al., 2013). It is estimated that the caldera collapse released 60 km² of magma (Geyer and Marti, 2008), classifying it as a medium-sized caldera, and this process is believed to have occurred between 8300 and 3980 B.C. (Oliva-Urcia et al., 2016).

Figure 4. Detail map of Deception Island, the here proposed analogue. Data source: Quantarctica v3 (Matsuoka et al., 2018).

The magmas on the island range from basaltic to trachydacitic, and the rhyolitic compositions show a characteristic alkaline increase, caused by an unusual rise in sodium oxide. This alkalinity and the incompatible trace element enrichment are consistent with the data recorded in the Bransfield Rift, which also geologically corresponds to the subduction zone where the volcanic arc is formed. On the other hand, it has been identified that the magmas that erupted after the caldera collapse tend to evolve, showing a wide compositional range from basalts to rhyolites (Geyer et al., 2019).

The rocks on the island have traditionally been classified as pre- and post-caldera products (González-Ferrán and Katsui, 1970; Baker et al., 1975) and syn-caldera deposits (Geyer et al., 2019). However, later studies allowed for the classification of the rocks into lithologies (Smellie, 1988), and the pre-caldera deposits were divided into two formations: the Basaltic Shield Formation (BSF) and the Yellow Tuff Formation (YTF) (Martí and Baraldo, 1990). The BSF includes basaltic lavas, scoria deposits and palagonitized tuffs. The YTF corresponds to the oldest deposits and consists of palagonitized tuffs with a subsequent effusive lava episode (Martí and Baraldo, 1990; Baraldo, 1999).

On the island, which shows a horseshoe shape, it is possible to distinguish an inner zone and an outer zone mediated by different mountain systems that divide and isolate the exterior from the interior, among which the following stand out: Mount Kirkwood, Mount Irizar, Stonethrow Ridge, Telephone Ridge, Mount Goddard and Mount Pond. Access to the inner zone of the island is through a small opening called Neptune's Bellows. Other notable geographical features of the island include bays with their beaches, such as La Lobera beach, Colatina, Fumarole Bay, Telephone Bay, Pendulum Cove and Whalers Bay. Additionally, in some of these areas, fumaroles have been observed during low tide, as in Fumarole Bay (Fig. 5), Whalers Bay and Pendulum Cove.

Figure 5. High-temperature gas emission in Fumarole Bay (photograph taken by David Tovar in December 2022).

On the other hand, due to the intense volcanic activity, lava channels and craters can be distinguished, such as Crater 70 (Fig. 6) and others that have also filled with water, forming crater lakes such as Crater Lake, Zapatilla Crater (Fig. 7), Soto Crater, Kroner Lake and Chacao Crater. Another relevant feature is the presence of mountains and hills, such as Cerro Caliente, Mount Irizar, Cerro Crimson, Cerro Ronald and Morro Baily.

Figure 6. Area known as Crater 70, where various craters can be observed as a result of volcanic activity from 1970 (photograph taken by David Tovar in December 2022).

Figure 7. Zapatilla Crater, which has naturally filled with freshwater through precipitation and runoff processes, creating a crater lake (photograph taken by David Tovar in January 2022).

The island features numerous glaciers, which significantly alter volcanic structures (Aparicio et al., 1997). One example is the so-called Red Glacier, which consists of weathered rock that contains iron oxides, giving it a reddish colour (Fig. 8). On the other hand, there are glaciers with interlayered strata that reflect ash deposits from past eruptions, resulting in dark coloration on the glacier, which is why it has been named Black Glacier (Fig. 9). Regarding gradational processes, it is possible to identify river and stream patterns, as well as moraines (de Pablo et al., 2009).

Figure 8. Red glacier, which corresponds to glacial weathering processes of volcanic materials, resulting in the presence of iron oxides that give it its characteristic coloration (photograph taken by David Tovar in January 2023).

Figure 9. Black glacier, which features interlayered strata of glacier ice and ash deposits from different eruptive pulses (photograph taken by David Tovar in January 2023).

Climate and meteorology

Although Deception Island hosted the Argentine Deception Base in 1948 and the Spanish Gabriel de Castilla Base in 1989, records are only available from 2005 onwards. It was from this point that the Spanish Meteorological Agency (AEMET) began monitoring the area, following the installation of the meteorological station. Some of the island's most notable features include a historical maximum temperature of 13.3°C in February 2020 and a historical minimum temperature of −22.5°C in July 2007. Regarding atmospheric pressure, the highest recorded pressure was 1025.2 hPa in August 2017, while the lowest was 931.4 hPa, recorded in August 2015. In terms of wind measurements, the highest historical 10 min average was 28.3 m s⁻¹, with a maximum gust of 44.6 m s⁻¹ (AEMET, 2024).

When analysing the mean atmospheric and soil temperatures for each month, as shown in Fig. 10, it is observed that the months with the lowest temperatures, as expected, correspond to May through August. The ground acts as a buffer against abrupt temperature changes, averaging 0.95°C higher than the atmospheric temperature.

Figure 10. Mean temperature of Deception Island during the period 2005–2023, recorded at the Spanish Antarctic Base Gabriel de Castilla (source: own elaboration based on AEMET data).

Regarding average wind speed (m s⁻¹), according to AEMET (2024), the month with the highest recorded wind speed is August, with a value of 8.2, followed by June with a value of 8.0. In contrast, the months of January and December report the lowest values, 5.4 and 5.7, respectively. Conversely, in terms of average pressure (hPa), the highest reading is observed in September with an average of 998, followed by July with a value of 994 in contrast with, August and October where the lowest measurements are dominant, displaying values of 983 and 989, respectively.

Life on the island

Studies related to the presence of living organisms on Deception Island date back to the 1960s, with studies reporting the presence of spermatophytes and cryptogams (Longton, 1967), as well as the presence of bacteria and yeast (Stanley and Rose, 1967). Of course, numerous studies have been conducted on plant species such as Colobanthus quitensis and Deschampsia antarctica (Collins, 1969; Greene and Holtom, 1971; Smith, 2005), as well as on animals like Pygoscelis antarcticus, since the island hosts three colonies of this penguin (Graña and Montalti, 2012; Masello et al., 2021; Román et al., 2022).

Additionally, Cameron and Benoit (1970) report the presence of microorganisms and their respective relationship with processes associated with microbial ecology in the cinder cones of Deception Island. Studies related to the microbial population present in Antarctica highlight the presence of microorganisms under conditions of desiccation, isolation and aridity, which resemble places in the Solar System such as Mars (Gilishinsky et al., 2007; Gilichinsky et al., 2010; Nicholson et al., 2013).

Some of the microorganisms isolated from the hot soils of Fumarole Bay include Geobacillus jurassicus, Geobacillus thermoleovorans, Bacillus fumarioli, Bacillus thermantarcticus, Brevibacillus thermoruber and Thermus sp., which are thermophilic bacteria that have also been isolated from other geothermal sites in Antarctica (Muñoz et al., 2011). However, not only organisms from high-temperature environments have been studied, but also microorganisms found in the island's permafrost, demonstrating that both low and high temperatures support microbial growth. Among the representative bacterial phyla found in the permafrost are Actinobacteria, Cyanobacteria, Acidobacteria and Proteobacteria (Blanco et al., 2012). Studies conducted on rock samples from the island identified the presence of various endolithic microorganisms, with the predominant genera being Ralstonia, Gaiella and Polaromonas (Hidalgo-Arias et al., 2023).

Human life and engineering

Another aspect to consider regarding what can be found on the island includes the operational Antarctic bases, such as the Spanish Antarctic Base Gabriel de Castilla (Fig. 11) and the Argentine Antarctic Base Deception (Fig. 12), as well as the ruins of bases that were eliminated due to volcanic eruptions, such as the British Base and the Chilean Base. The two bases exhibit considerable differences in infrastructure; the Spanish installation features fully modular structures, while the Argentine installation consists of permanent facilities. Another distinguishing aspect relates to the available spaces in the living module, workshops and the presence or absence of a gym, laboratories and medical office.

Figure 11. Spanish Temporary Antarctic Station Gabriel de Castilla (photograph taken by Marcos Rozalen of the Spanish Army in January 2023).

Figure 12. Argentine Temporary Antarctic Station Decepción (photograph taken by David Tovar in January 2023).

Regarding engineering for data collection, notable is the evaluation conducted on the island during the 2008–2009 field campaign, where the REMS (Rover Environmental Monitoring Station-Mars Science Laboratory) instrument was tested under the island's conditions. This environmental station was designed by the Centro de Astrobiología (CAB-Spain) in collaboration with national and international partners. The instrument consists of five sensors: soil temperature, air temperature, wind speed and direction, pressure, humidity and UV radiation. One of the most relevant aspects of evaluating it under the island's conditions was the ability to test data collection in the active layer of permafrost and the balance in the boundary layer between soil and atmosphere, which is fundamental for conditions on Mars, where an extensive layer of permafrost exists (Esteban et al., 2009; Ramos et al., 2012).

Mars

Mars and habitability

Several factors determine the habitability of a planet. From an astrophysical perspective, the star's spectral type around which it orbits is critical. Late G to mid-K type stars are ideal since they have a half-life time that allows life to evolve and emit UV radiation in low proportions concerning O, A and B type stars that will enable some biochemical processes relevant to the emergence of life (Cuntz and Guinan, 2016); moreover, they can host planets at a distance that facilitates the presence of liquid water on the surfaces of the planets orbiting it, in the so-called habitability zone (Kereszturi and Noack, 2016). Other factors include the composition of the planet (rocky planets being those most likely for life to arise), having a sufficient size for gravity to retain an atmosphere, having a maximum orbital eccentricity of ≈0.10 (Dressing et al., 2010), axial inclination similar to that of the Earth, presence of a natural satellite as an obliquity stabilizer (Laskar et al., 1993), presence of a gas giant that can serve as a protective shield from impacts (Horner and Jones, 2008; Grazier, 2016). Additionally, the company of environmental factors such as the presence of nutrients, water (solid or liquid), energy sources, the existence of elements required for life and various factors recognized as the limits of life must be considered (Beaty et al., 2006; Kereszturi and Noack, 2016).

Based on these factors, Mars would be a potential candidate for the search for biofilms in rocky material. In addition to this, unlike other bodies of the inner Solar System, on the red planet, it has been possible to detect traces of clays distributed in some places on the Martian surface. Although they are far from the possible presence of a large-scale ocean on the planet (Leone, 2020, 2021b), they could be a source of water and hydrated minerals for some microorganisms. Besides having the presence of basalts containing olivines, pyroxenes and iron oxides (haematite) (Bandfield, 2002; McSween et al., 2009; Kasting, 2010), this clay could serve as nutrients for some microorganisms (Hersman et al., 1996; Herrera et al., 2009; McLoughlin et al., 2011) if they can survive cosmic and solar radiation, for example, is the case of organisms such as Deinococcus radiodurans, which can tolerate gamma radiation doses of more than 5000 Gy (Daly, 2009; Krisko and Radman, 2013) or Thermococcus gammatolerans, which accepts amounts of up to 30 000 Gy (Marín-Tovar et al., 2022).

On the other hand, although the red planet has neither active plate tectonics nor a present-day magnetic field, palaeomagnetism records suggest that both plates tectonic processes (Connerney et al., 1999; Yin, 2012) and the presence of a global magnetic field (Connerney et al., 1999, 2001) could have been present in Mars' past. This first hypothesis must be discarded, considering the lack of subduction zones throughout the planet. The second hypothesis is plausible, considering that a transient magnetic field could have coincided with an epoch of active volcanism between 4550 and 4100 million years ago (Leone et al., 2014). But as this intense volcanic activity ended, the magnetic field would have ended (about 4 billion years ago), suggesting that the two processes could have been related to the heat produced by a Giant Impact in the South Pole of the planet (Leone, 2021b). This hypothesis was proposed by Reese and Solomatov (2006) and Reese et al. (2011), studied with two-dimensional modelling (Golabek et al., 2011), refined with three-dimensional (3D) modelling (Leone et al., 2014) and validated with the discovery of 12 volcanic alignments that had previously been predicted with 3D modelling (Leone, 2016, 2021a).

The hypothesis of volcanic intrusions less than 20 million years old (Mitchell and Wilson, 2003) is not sustainable even with some extreme thermal models of the planet (Leone, 2020, 2021b). Although models derived from InSight's seismic data have established the possibility of the presence of currently active magma chambers in the Elysium Planitia region on Mars (Broquet and Andrews-Hanna, 2023). Furthermore, the presence of a thin CO₂ atmosphere (Banfield et al., 2020), an orbital eccentricity of 0.093 (JeongAhn and Malhotra, 2015) and a current obliquity of 25° (Holo et al., 2018), but which has not been stable over time, are not sufficient to ensure large-scale habitability as present on Earth. The lack of water, the distance from the Sun, the currently thin atmosphere, which is not suitable for aerobic organisms and the planet's low gravity that is insufficient to retain this atmosphere are the major factors that distance Mars from Earth in terms of habitability. However, it is necessary to consider that the late Hadean Earth had similar atmospheric conditions and that life was possible (Kasting, 1993; Sleep and Zahnle, 2001; Kasting and Howard, 2006); besides not knowing if, in the past, the atmosphere could have been much thicker.

Regarding ecological factors, it has been possible to find evidence of the apparent presence of liquid water at depth beneath the south-polar region of Mars (Orosei et al., 2018) and ambiguous traces of past water at the surface (Rampe et al., 2020; Moller et al., 2021). This evidence has recently been discussed due to the large amount of olivine on the planet's surface, which could indicate that it is undisturbed after its first eruption 4500 million years ago (Leone, 2020). Although the surface of Mars has the presence of nitrogen, phosphorus, sulphur, calcium, magnesium, chlorine and potassium, considered essential nutrients for life (Kounaves et al., 2014; Bohle et al., 2016; Matsubara et al., 2017; Thomas and Hu, 2019), which while not a total guarantee that life exists either now or in the past, it does facilitate the elements necessary for life. Additionally, perchlorate salts have been identified on its surface (Kounaves et al., 2010), and its soils have been catalogued as gelisols (Certini et al., 2020) that could also be the result of volcanic deposition (Leone, 2020). In terms of temperature, in summer seasons in equatorial zones and at specific times, surface temperatures could exceed 20°C (Joseph et al., 2020a, 2020b), but extremophile microorganisms could only tolerate the variation in surface temperature throughout the day. All these features make Mars a planet of interest in studies of extremophile habitability in particular protected conditions such as inside lava tubes, under CO₂ ice in the polar caps or artificial sites for space biomining experiments.

However, two hypotheses stand out of the different possibilities for past or present habitability on Mars. From one perspective, the possible presence of endolithic microorganisms, which would have protection from such an adverse environment as the one described, in addition to having different minerals required for their metabolism (Wierzchos et al., 2005; McLoughlin et al., 2011; Meslier and DiRuggiero, 2019; Sajjad et al., 2022). The other possibility lies in the case of microorganisms in the soil, which, even being a few centimetres away, could have developed radiation tolerance mechanisms (Daly, 2009; Krisko and Radman, 2013; Musilova et al., 2015; Marín-Tovar et al., 2022), to low temperatures (D'Amico et al., 2006; Allen et al., 2009; Ayala del Río et al., 2010; Bendia et al., 2018a) and nutrient deficit (Parro et al., 2019; Price et al., 2022).

Mars site analogues

Some extreme terrestrial environments can also be considered planetary analogues, given specific geological or climatological characteristics, which resemble some rocky bodies in the Solar System (West et al., 2010a, 2010b). Of the rocky bodies explored in recent decades, Mars has mainly gained increased relevance in the last decade due to the findings of liquid water reported in the subsurface of the Martian South Pole (Orosei et al., 2018) and in Ultimi Scopuli (Sulcanese et al., 2023), as well as the interest in sending human-crewed missions in the next decade (Levine et al., 2010). The most sceptical scientists could recognize the presence of liquid water in the Martian subsurface, but the depth at which it could be found is more than 1 km, which would generate problems of a practical nature (Leone, 2020). Although a large number of missions sent to the red planet have focused on geochemical, mineralogical, seismic and geothermal studies, it has not yet been possible to return samples from its surface that would allow us to quantitatively establish a detailed and broad mineralogical composition similar to that studied in terrestrial analogues (Rieder et al., 2004; Morrison et al., 2018; Pantazidis et al., 2019). However, some Martian meteorites have been used as a reference for geochemical and mineralogical examination of Martian surface, investigating the chemical composition at the laboratory (Udry et al., 2020).

Nevertheless, there are in situ analyses that have allowed us to understand that the soil composition is mainly of volcanic origin (McLennan et al., 2013; Sautter et al., 2013; Ollila et al., 2014; Cousin, 2015), although some analyses have evidenced the presence of rocks of sedimentary origin and aeolian sediments, in places like Gale Crater (Rampe, et al., 2020; Smith et al., 2021; Millan et al., 2022). Given the surface geologic processes identified on Mars, the identification and characterization of sites on Earth that exhibit diverse geologic processes, including those related to past and present volcanic activity as a priority, are critical for the establishment of terrestrial analogues (Byrne, 2019). Other geological processes are of interest in terms of the classification of terrestrial environments as terrestrial analogues; according to Lalla et al. (2015), it is necessary to consider three types of processes: (1) those developed by the activity of aeolian, periglacial, evaporitic or alteration processes in arid environments and polar zones, (2) volcanic with snow–ice interaction, effusive eruptions and hydrothermalism and (3) magmatic related to the rock formation. These environments, in conjunction with meteorites recovered on the Earth's surface, are fundamental to understanding the geological processes along the geological evolution of Mars, evaluating the geobiological conditions present to establish possible similes with geological scenarios on the red planet and the different mechanisms to be a habitable place, as well as the calibration of instruments and methodologies that are expected to be implemented in future missions (Pantazidis et al., 2019).

In addition to the above, a feature to be considered when evaluating volcanic environments is the morphometry of the volcanic edifice (Leone et al., 2022) and its eruptive products since endogenous processes usually generate expressions in the crust, while exogenous processes are directly perceived in the surface and the atmosphere (Carr and Head, 2010), conditioning both measurement instruments and the data recorded to obtain information from the relief (Beyer, 2015). It is also essential to understand the evolution of some of the astrophysical conditions to assess habitability on Mars, such as radiation levels, the flux of particles harmful to life coming from the Sun and the rest of the Galaxy, the evolution of the magnetic field, to take them into account in the perspectives of comparison of terrestrial analogues (Kasting et al., 1993; Lammer et al., 2009; Kopparapu et al., 2013; Lorenz, 2019).

Mars site analogue biological interest and analogous mission

Extreme-analogous terrestrial habitats, such as dry, cold environments or environments exposed to an intense flux of UV radiation, have allowed inferring potential oases in which life could inhabit and be sustainable on Mars, as well as their adaptations to these conditions, where the generation of cryptoendolithic communities and structural changes stand out (Horneck, 2008). Habitability can be understood as the capacity of an environment to support the activity of at least one known organism in a given time, also known as instantaneous habitability (Cockell et al., 2016). In addition, it assesses the possibilities of interplanetary human sustainability based on the ability of the species to sustain itself over a long period without depleting its resources (Losch, 2019). In order to achieve the latter condition on Mars, it has been proposed to rely not only on in situ and available resources but also on an additional biological module that can be created by microorganisms isolated from terrestrial analogues, such as Anabaena spp. (Verseux, et al., 2016).

Thus, within the sustainability capabilities is the evaluation of the viability of microorganisms, defined as the ability of a microbial population to multiply (Guerra and Castro, 2020). Plant capabilities must also be taken into account, this being the measure of the percentage of seeds with the ability to germinate and produce plants under suitable conditions (Pérez et al., 2013), thus offering an opportunity to assess the viability of terrestrial organisms as indicators for habitability and sustainability on Mars. The terrestrial analogues, in turn, allow the realization of analogous missions, advancing and deepening the possible habitability of humans on Mars and which is part of the planetary exploration plans developed by different space agencies around the world (Baum, 2010). As mentioned above, habitability is addressed in these case studies, and sustainability is a branch of habitability (Frank and Sullivan, 2014), even with technological intervention (Cockell et al., 2016). Some of these sites for the development of analogous missions are Devon Island (Binsted et al., 2010), Mauna Kea (Graham et al., 2015), Dhofar region of Oman (Gruber et al., 2019) and Rio Tinto (Orgel et al., 2014).

One of the most recognized terrestrial analogues in astrobiology is the Atacama Desert in Chile, where the presence of oxidants that inhibit the presence of microorganisms has been reported (Navarro-González et al., 2003; Navarro-González, 2005). According to Navarro-González et al. (2003), the soils of the Atacama Desert are characterized by (1) the absence of organic matter in parts per billion, (2) the rapid release of molecular oxygen when soil samples are exposed to water vapour (70–770 nmol g⁻¹) and (3) rapid disappearance of organic matter in some soil samples as if microbial life were present in these samples, which is in direct contradiction with the first result obtained. These results are similar to those obtained by the instruments of the Viking missions once the Martian soil samples were analysed (Soffen, 1977). For future manned missions to Mars, it is necessary to have solutions that will allow future explorers of the red planet to settle and sustain themselves; for this reason, the simulation of Martian soils with terrestrial parent material whose composition is similar to that reported on the Martian surface has become a priority (Certini et al., 2020). These simulated soils are mixed with organic matter to mimic the addition of residual material from previous cultivation (Wamelink et al., 2019).

Rio Tinto in Spain is another terrestrial analogue that has allowed the study of extremophile (acidophilic) microorganisms, which could be present in areas where liquid water existed on the surface or in the subsurface of Mars billions of years ago (Parro et al., 2011). Parro et al. (2011) report that using technology capable of detecting biomolecules, it is possible to establish a correlation between factors of high geological and microbiological relevance, such as microenvironments, diagenetic processes and the age of the biomarker profiles present in the analysed samples. These associations can be helpful in defining study areas for future Mars exploration missions.

As mentioned above, Iceland presents some geological similarities to the Martian Noachian period, which is associated with intense volcanic activity and an average amount of water (i.e. 1–2 wt%) naturally contained in the magma that was vapourized and that could have allowed the emergence of life (Clifford, 2001; Villanueva et al., 2015), this if we take into account that aerosol water is usable by microorganisms, and even the same microorganisms, detected in hot springs can behave as aerosols (Ellis et al., 2008; Hurwitz and Lowenstern, 2014). Additionally, studies such as Dragone et al. (2023) show that microorganisms can colonize in the early stages of volcanic island formation without needing clear liquid water at the surface. Other examples of analogues, such as the case of the European Mars Analogue for Space Exploration (MASE) project, which sought to evaluate the habitability and detection of life on the red planet, so isolations of various microorganisms were made from the Graenavatn analogue, a low-temperature acidic volcanic lake poor in nutrients, detecting the polyextremotolerant bacterium Yersinia intermedia, with the ability to tolerate low pressure, ionizing radiation, variable temperature, osmotic pressure and oxidizing chemical compounds (Schwendner et al., 2016; Gaboyer et al., 2017).

Geological site analogues

Currently, different places on Earth have been classified as planetary analogues (Martins et al., 2017; Foucher et al., 2021) in order to carry out research leading to the study and understanding of the geological evolution of the rocky bodies of the Solar System; such is the case of the volcanic Big Island of Hawaii, which has been catalogued as a terrestrial analogue that resembles some studied areas of the surface of the planet Mars (Tirsch et al., 2012; Nie et al., 2020). Mineralogical studies, including methods such as fluorescence and X-ray diffraction, visible reflectance spectroscopy, near-infrared, Mössbauer and transmission electron microscopy, have been applied to samples of palagonite tephras poor in phyllosilicates on the upper slopes of Mauna Kea volcano, has allowed establishing a geological analogy with some regions of the planet Mars at different latitudes (Morris et al., 2001). Likewise, the dust has been analysed to evaluate magnetic properties for the presence of iron oxides (magnetite) to be compared with the Mars Pathfinder Magnet Array experiment and thus understand the various surface geological processes that have occurred in Martian geological time (Seelos et al., 2010). However, Hawaii has also served as a setting for the development of numerous experiments focused on the calibration and testing of instruments that will go aboard the various Martian rovers (Pommerol et al., 2013; Rumpf et al., 2020); this constitutes another potential of the terrestrial analogues. Mainly alpha particle X-ray spectrometers have been tested, which analyse the concentration of different elements in a broad and diverse range of materials; however, because samples are not prepared beforehand, some interpretation errors may occur, so calibrating them on Earth is essential (Berger et al., 2020). Studies related to the geological evolution of the planet Mars and evidence of future habitability based on terrestrial analogues, particularly the volcanic Island of Hawaii, are currently underway (Hughes et al., 2019). The concerted effort by scientists and engineers to test hypotheses about the surface geological processes that have shaped the red planet, coupled with the need to train astronauts for eventual human-crewed travel, has made this volcanic island a global benchmark as a planetary analogue (Lim et al., 2010; Szocik et al., 2018).

Another recent example of a terrestrial analogue for planetary geology and astrobiology studies is the island of Santorini in Greece (Pantazidis et al., 2019). The classification of basaltic rocks on Santorini is based on three parameters: (1) field relations, (2) petrographic characteristics and (3) chemical characteristics. As mentioned by Marlow et al. (2008), most of the knowledge we have about Mars comes from meteorites (Bouvier et al., 2005), astronomical observations with telescopes on Earth (Yen et al., 2005) and space missions including orbiters, in situ laboratories and robotic explorers (Squyres et al., 2004; Rampe et al., 2020). The minerals reported on the island of Santorini have some compositional similarities with those found on the surface of Mars, so space agencies such as NASA, with its Planetary Science and Technology Analogue Research (PSTAR) programme, and ESA with the initiative called ESA Exploration Sample Analogue Collection (ESA2C), have this place as a reference for the testing of different Martian exploration missions as well as the collection of rock samples for further studies in planetary geology and astrobiology. As reported by Pantazidis et al. (2019), the presence of euhedral olivines and euhedral to subhedral pyroxene phenocrysts immersed in a matrix whose content varies between olivines, pyroxenes and prismatic and skeletal plagioclase crystals. Compositionally these rocks can be compared to those found in the Gusev Crater on Mars (Morris et al., 2004).

The basalts of the Gusev Crater have been classified into four classes characterized by their composition, as explained by Schmidt et al. in their study (2013) and Klingelhöfer and his team (2006). These classes are (1) Adirondack, which is characterized as massive angular blocks containing olivine and pyroxene in the Gusev Crater plains (McSween et al., 2004); (2) Backstay, which includes a floating rock (loose, not part of an outcrop) aphyric with microphenocrystic olivine, pyroxene, magnetite and ilmenite, as well as other disaggregated material identified by a Mini-TES (miniature thermal emission spectrometer) at Husband Hill (McSween et al., 2006), (3) the Irvine class, which includes massive to scoriaceous pyroxene- and magnetite-bearing rocks on the flanks of Husband Hill and the inner Columbia Hills basin and (4) the Algonquin class which have lower normative diopside than the Adirondack, Backstay and Irvine classes. The Algonquin class has a more ultramafic composition, and even pristine rocks would have a lower normative diopside (Mittlefehldt et al., 2006). Similarly, their composition is similar to Martian shergottites, characterized by olivine phenocrysts (olivine-phyric texture) (Filiberto, 2017). Martian pyroclastic-ejecta deposits have also been identified within Columbia Hills, namely the layered plateau of Homeplate (Squyres et al., 2007). The rock classes associated with these deposits are alkaline (tephrite) Wishstone (Usui et al., 2008), basaltic glass-rich Clovis (Squyres et al., 2006) and magnetite-rich Barnhill class rocks (Squyres et al., 2007), some of which have evidence of various degrees of aqueous alteration (Squyres et al., 2006; Ming et al., 2008).

These similarities between Santorini Island rocks and Martian rocks offer an excellent opportunity for local scientists, students and teachers who have research projects and need to collect samples for further analysis, as mentioned by Pantazidis et al. (2019).

For its part, Iceland and its intense volcanic activity, has served as a study site for understanding processes related to magma–ice interaction, as well as the dynamics of basaltic fissures that allow establishing a comparison with similar volcanic processes in the geological past of Mars (Hughes et al., 2020). For Hughes et al. (2020), the detailed study of the effusive-type eruptive styles reported in Iceland provides a preliminary classification that allows an evaluation of geological parameters of volcanic eruptions on Mars and other rocky bodies of the Solar System. In compositional terms, the surface of Mars presents a global distribution of pyroxene-olivine-rich basaltic (Southern Hemisphere/highlands) and possibly volcanic-glass-rich basaltic andesitic (Northern Hemisphere/lowlands) sands resulting from past volcanic action (Ruff and Christensen, 2007). However, the data of the latter composition can be also interpreted as altered/weathered basalt (Wyatt and McSween, 2002; Minitti and Hamilton, 2010; Rogers and Hamilton, 2015). This type of sand is present in Iceland, Hawaii and the Reunion Islands, so their study could contribute to the correct interpretation of the data obtained by remote sensing since the segregation of olivine must be taken into account once the extraction of the spectral composition of sandy lavas on the surface of Mars is done (Mangold et al., 2011). In this type of analysis, the overall lack of water alteration on Mars that terrestrial basalts have must be considered.

The outcrop ‘Las Arenas’ on the volcanic island of Tenerife, which corresponds to the monogenetic volcanic field of the Canary Islands (Spain), is considered a Martian analogue because of the rocks present there with varied mineralogy that resembles volcanic regions on the surface of Mars (Lalla et al., 2019), even though the alteration processes are different from those that could occur on Mars. Lava flows and associated structures (lava tubes) are processes related to the evolution of the Martian surface that can be studied in the volcanic islands of the Canary Islands. These structures play a fundamental role in planetary geology and astrobiology since, by analysing the morphological parameters, composition and distribution in volcanic fields, it is possible to determine their genesis and evolution in geological time. In addition, they are ideal scenarios for speleology and the study of environmental conditions, ecological and compositional parameters associated with desirable microbial life in the Martian subsurface (Boston et al., 2001; Sauro et al., 2020).

Deception Island as analogue of astrobiological interest

The active volcano of Deception Island, in the South Shetland archipelago of Antarctica, displays a variety of tectonic, volcanic, slope and periglacial landforms similar to those observed on Mars (de Pablo et al., 2009; Molina et al., 2013, 2014). Of particular interest are the glaciers of the island, which are covered by pyroclastic materials from the last eruptions, whose morphologies resemble the potentially covered glaciers described on Mars (de Pablo et al., 2009; de Pablo, 2015). This volcano contains basaltic rocks and andesitic basalts (Martí et al., 1996; Hopfenblatt et al., 2021), which allows for the establishment of another geochemical scenario for evaluating habitable processes. Regarding the geochemical composition of Deception Island rocks, these are similar to Gusev Crater volcanic rock compositions. Pre-caldera (volcanic) and post-caldera (pyroclastic–volcanoclastic) deposits are similar to these compositions, to a comparable degree to that of the Etna volcano and Tenerife Martian analogue terrains, respectively (Fig. 13 and Table 1). This evaluation followed the methodology of figures of merit (FOM) (Rickman et al., 2007, 2009), which has been used for evaluating the geochemical similarity of regolith simulants (e.g. Metzger et al., 2017; Fackrell et al., 2021) and analogue terrain lithologies (e.g. Tovar et al., 2024) to their intended target Martian compositions. FOM values range from 1 (100% similarity) to 0 (completely dissimilar), and values of >0.80 indicate an adequate overlap between the compared compositions (Fackrell et al., 2021).

Figure 13. Boxplot of geochemical FOM values comparison of Gusev Crater compositions, terrestrial analogue sites and Deception Island (DI) Compositions. *Post-caldera pyroclastics were compared with Gusev pyroclastic deposits (Barnhill and Clovis class rocks).

Table 1. Average FOM values of the comparison of Gusev Crater and terrestrial analogue terrains' volcanic rock compositions

^a Post-caldera pyroclastics were compared with Gusev pyroclastic deposits (Wishstone, Barnhill and Clovis class rocks). Complete geochemical data is in the Supplementary material (S1).

Guglielmin (2012) stated that hummocky-type terrain on Deception Island has been widely described concerning glacial shrinkage and permafrost aggradation and degradation. However, regarding the assessment of microbiological relationships with a view towards Mars' habitability and sustainability, this field can be further developed on the island.

This type of terrain has been identified on Mars at different latitudes (Mangold, 2005; Machado et al., 2012; Yin et al., 2021), so the interaction between permafrost and the rocks that make up the volcanic edifice of Deception Island should be considered as a fundamental process that can provide clues about the geological evolution of Mars and its relationship with certain types of extremophile organisms (Amils et al., 2007). Meteorological conditions in this Antarctic volcano are extremely cold, reaching −21°C in winter, with the average temperature in summer exceeding 2°C (Kejna et al., 2013). These conditions allow the existence of glaciers on the island despite the volcanic activity evidenced by the presence of fumaroles and areas of geothermal anomalies (Kyle, 1990; Lezcano et al., 2019). Characterizing and evaluating Deception Island geologically and geochemically to establish the parameters that would make this place a terrestrial analogue would allow the realization of different research projects on planetary geology, astrobiology and geomicrobiology without having to structure expensive projects whose costs would be unsustainable for the local environment.

In order to contextualize the importance of the Deception Island volcano, it is necessary to understand the processes associated with magma–ice interaction and their relationship with the presence of terrestrial extremophile organisms. Interactions between ice and magma have been a constant in the geological records that constitute the Earth's history (Edwards et al., 2015). As Edwards et al. (2015) and Head and Wilson (2007) described, volcano–ice interaction is formally termed glaciovolcanism. It can be described as volcanic interaction with all ice forms and associated meltwater. Some locations on planet Earth where the process of glaciovolcanism is widely distributed include Antarctica, Alaska, British Columbia and Iceland (Edwards et al., 2015; Curtis and Kyle, 2017).

Glaciovolcanism can create valuable proxies for understanding palaeoclimatic evolution (Edwards et al., 2015; Smellie and Edwards, 2016) and acts as a terrestrial analogue for understanding processes associated with some Martian environments (McKenzie and Nimmo, 1999; Ogawa et al., 2003; Head and Wilson, 2007). These real-world implications of glaciovolcanism have led to a growing interest in academia about this volcanic process, particularly in studies related to astrobiology (Wierzchos et al., 2005; Cousin, 2015; Edwards et al., 2015). Glaciovolcanism in Antarctica has been recorded as old as 28 Ma (Smellie and Edwards, 2016), making Antarctica the oldest active glaciovolcanic province on Earth. Present-day glaciovolcanism has rarely been recorded in Antarctica due to infrequency and inaccessibility (Wilson and Head, 2002; Smellie and Edwards, 2016). The 1967–1969 Deception Island subglacial eruption is the most studied on the continent (Wilson et al., 2013; Smellie and Edwards, 2016). On the other hand, the interaction of volcanic activity with glaciers, which gives rise to the Black Glacier and Red Glacier, could serve as a model for the search for habitable conditions on Mars, where it has been suggested that survival within the ice could be possible, provided it contains a layer of dust (Khuller et al., 2024).

Prieto-Ballesteros et al. (2010) mention geological and biological studies in the region of Crater Lake in Deception Island (Antarctica), whose ultimate goal is to explore the possibility of testing planetary exploration missions on planets like Mars, for which simulations and geophysical studies were conducted in the permafrost in a basaltic plain, in which cores from the borehole were analysed mineralogically and geochemically to detect biological signatures. Lezcano et al. (2019), when exploring the Cerro Caliente sector, evaluated how hydrothermal fluids buffered by low atmospheric temperatures allowed the survival of microorganisms, making this a place of interest for understanding possible life on ancient Mars. Hydrothermal zones with microbial mats have also been detected (Fig. 14), are highly relevant in astrobiology research (Vicente et al., 2021).

Figure 14. Microbial mat related to hydrothermal activity, which is relevant to the understanding of the emergence of life, one of the research areas of astrobiology (photograph taken by David Tovar in December 2022).

On the other hand, studies of the presence of perchlorates in Antarctic marine sediments showed that the highest presence of these was recorded on Deception Island, apparently related to a possible volcanic contribution to the formation of perchlorates (Acevedo-Barrios et al., 2022, 2024), which could be related to Martian perchlorates (Kounaves et al., 2014). Another potential of Deception Island is addressed by Blanco et al. (2012) by using LDChip300 technology to describe the diversity of natural microbial communities and determine their main operational metabolic pathways present in the Island's permafrost, which colonizes this type of substrate and establishes themselves there.

Bendia et al. (2018a, 2018b) refer to the relationship between Deception Island's geological and environmental conditions, particularly the volcanic activity and the presence of psychrophilic and thermophilic organisms. In these works, Bendia et al. (2018a, 2018b) highlight Deception Island as a terrestrial analogue that studies similar environments on other rocky bodies in the Solar System. Additionally, a great variety of microbial and extremophile mats (thermophiles and psychrophiles) associated with hydrothermal activity resulting from the interaction between magma and surface water in this region in Antarctica have been reported on Deception Island (Lezcano et al., 2019). Subsequent studies show a wide diversity of microorganisms present in the volcanoclastic sediments of Deception Island, whose basaltic–andesitic composition is associated with eruptive events typical of the study site (Vicente et al., 2021). Finally, in geochemical terms, a notable feature of the island is the basalt-water interaction (Elderfield et al., 1977), which could help in understanding the likelihood that Martian rocks were once in contact with water.

Considering the characteristics of Deception Island and the studies carried out in other global analogues, including those located in Antarctica, this volcanic Island offers possibilities for cataloguing as a multifunctional Mars analogue with astrobiological potential (Leal et al., 2024), for which it is necessary to increase the spatial resolution of sampling, as well as the geochemical and geomicrobiological evaluation of endolithic and radiophilic organisms, to identify specific regions of Mars with potential for life and similar characteristics to those present on the Island, as well as the study of Antarctic bases as analogous missions.

Conclusions

The characteristics of Mars and the field analogues that can be found on Earth, being candidates for the extreme environments, in particular, sectors of Antarctica that offer opportunities for this type of study so that we can conclude:

1. (1) Extreme environments for life, such as Deception Island, serve as natural laboratories to understand the development of life and examine the potential for it to have arisen in locations like Mars.

2. (2) Deception Island, as a volcanic environment, enables in situ study of geological, geomicrobiological, climatological and mission-relevant characteristics, providing valuable opportunities to understand rocky bodies within the Solar System.

3. (3) Deception Island, with its low temperatures and potential for high radiation, desiccation and environmental processes that induce weathering, is ideal for exploring the potential for life on Mars.

4. (4) Deception Island possesses astrobiological features that make it a potential Mars analogue, including the presence of perchlorates, glaciovolcanic processes, permafrost and evidence of microbial mats able to form under extreme conditions. To confirm its analogy with specific sectors and periods of Mars, a more detailed examination of the island's geochemistry, the presence of endolithic and radiotolerant microorganisms and the development of analogous missions is needed.