10.6092/issn.2038-3460/17563
This paper describes the conceptual effort and scientific practices though which space analogues – i.e., material settings in which one or more analogies between Earth and outer space are embedded – are built, sustained and experienced. Based on my ethnographic study of astrobiologists’ and speleologists’ analogue fieldwork activities in Sardinian subsurface environments, I claim that analogues are part of the process of making astrobiology as a discipline: they do not only constitute fundamental heuristics to understand Earthly – and perhaps one day extra-terrestrial – life, but they also reframe disciplinary boundaries and imagined futures on Earth and elsewhere in the Universe.
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2038-3460
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Valentina Marcheselli
https://creativecommons.org/licenses/by-nc-sa/2.5/
Tecnoscienza – Italian Journal of Science & Technology Studies
scientific fieldwork
The Exploration of the Earth Subsurface as a Martian Analogue
Text.Serial.Journal
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Essays
2022-07-07
2023-06-30
2022-07-07
2023-10-26
25-45
TS
Valentina Marcheselli
2022/07/07
10.6092/issn.2038-3460/17563
25
Università of Trento
2038-3460
1
scientific fieldwork
en
45
The Exploration of the Earth Subsurface as a Martian Analogue
https://tecnoscienza.unibo.it/article/download/17563/16414
13
                                                                               Essay
The Exploration of the Earth Subsurface
as a Martian Analogue

Valentina Marcheselli
Università of Trento


     Abstract: This paper describes the conceptual effort and scientific practic-
     es though which space analogues – i.e. material settings in which one or
     more analogies between Earth and outer space are embedded – are built,
     sustained and experienced. Based on my ethnographic study of astrobiolo-
     gists’ and speleologists’ analogue fieldwork activities in Sardinian subsurface
     environments, I claim that analogues are part of the process of making as-
     trobiology as a discipline: they do not only constitute fundamental heuris-
     tics to understand Earthly – and perhaps one day extra-terrestrial – life, but
     they also reframe disciplinary boundaries and imagined futures on Earth and
     elsewhere in the Universe.

     Keywords: extreme environment; space analogues; astrobiology; scientific
     fieldwork.

     Submitted: September 10, 2021 – Accepted: May 26, 2022
     Corresponding author: Valentina Marcheselli, University of Trento,
     Dept. of Sociology and Social Research, Via Giuseppe Verdi 26, Trento, Ita-
     ly. Email: v.marcheselli@unitn.it



1. Introduction

     The breeze was warm and filled with the subtle aroma of the myrtle that
     in the late spring punctuates the gentle slopes of the southern Sardinian
     hills. The bushes and short trees did not offer much of a shelter from the
     sun shining high in the clear sky constantly swept by the Mediterranean
     air currents. Earlier in the morning, we had been warned to wear heavy
     clothes as the mine temperature is significantly lower than the tempera-
     ture outside; in the rocky darkness of the mine, it barely varies between
     winter and summer. The water, copiously dripping from the rocky walls,
     keeps the humidity high and covers the muddy floor with stagnant water,
     creating the conditions for bacteria to recolonize what humans had ap-

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TECNOSCIENZA
Italian Journal of Science & Technology Studies
13 (1) pp. 25-45 - ISSN 2038-3460
www.tecnoscienza.net                              2022
26                                                                 Tecnoscienza – 13 (1)


     propriated in 1880s and then abandoned a century later. The Su Zurfuru
     (“sulphur” in the Sardinian language) mine had been depleted of lead,
     iron, and fluorine for decades, before being deserted along with the adja-
     cent small village where miners used to live and process the raw materials
     extracted from the nearby deposits1.
     Our hiking boots were already sinking into the muddy soil just in front of
     the tunnel mouth, a regular opening excavated in the rock, almost com-
     pletely covered in Mediterranean vegetation. Gabriele2, an experienced
     member of the local speleological team, started the engine of his jeep,
     packed with scientists and their equipment, and slowly turned the car to-
     ward the entrance. The wheels sank into a deep puddle as the car moved
     into the tunnel, plunging into the reddish water. A small wave preceded
     us, rippling the silky surface of the water lit by the car’s headlamps. Thus,
     we moved onwards, deeper and deeper into the abandoned mine.
     When the car stopped, we heard the voices of the group that entered the
     mine before us. “Don’t walk alone” Gabriele said with an affable smile, “it
     takes nothing to get lost here”. Then he turned the car and drove back to
     the entrance to carry the last group of scientists still waiting outside.
     Somebody approached us, lighting the space where we were standing with
     a cone of light shining from the top of her helmet. Laura, one of the or-
     ganizers, joined our small group and showed us how to switch on the light
     on our hats and then led us to where the others were gathered, in a differ-
     ent tunnel, where the walls had been further excavated to almost form a
     chamber. John, a geologist from the University of Bologna, was casting his
     helmet light on a white and blue jelly substance formed around the groove
     excavated by the water gushing through a crack. He poked his finger into
     it; “this is biology”, he claimed.

    This paper is based on the second workshop organized by the Geo-
Biology for Space Exploration (GESE) ESA topical team and held in
Sardinia3 (Italy) in the Spring 2015. The workshop, titled “Extraterrestri-
al Subsurface Exploration and Geomicrobiology”, aimed to encourage
the development of a new interdisciplinary community focused on the
study of possible uses and implication of mineral-microbe interactions in
subsurface environments. These processes have a number of applications
that can be linked to a broad range of space-related activities such as the
search for evidence of life elsewhere in the universe; human and robotic
space exploration of celestial bodies; and long-term settlement scenarios.
This variety mirrors the multiplicity of scientific and technological en-
deavours funded by space agencies. By putting together experts in such
different fields, ESA hopes, on the one hand, to optimise financial re-
sources invested in emerging realms of inquiry and, on the other hand, to
create or strengthen research collaborations. The participants to the
workshop – biologists, biochemists, geologists, speleologists, astrobiolo-
gists, astronaut trainers, etc. – were charged with the compiling of a road
Marcheselli                                                              27

map that would both set the direction of further studies and make the
case for additional investments in this polyhedric field.
     I participated to this workshop as part of my multi-sited ethnographic
project on astrobiology. i.e a discipline committed with the study of life
elsewhere in the universe. After eight months of participant observation
of astrobiology laboratory activities, I had the opportunity to join two
fieldwork training events attended by some of the laboratory members.
Astrobiology fieldwork activities have often been framed in semiotic and
representational terms (for example using the Peircean vocabulary of
signs and indexes, see e.g. Helmreich 2006); in my project, I aimed at
moving beyond such frameworks to pay attention to the situated and em-
bodied dimension of practitioners’ knowing (e.g., Goodwin, 2000; Gher-
ardi, 2000). Fieldwork training activities opened a window on how partic-
ipants practice experiencing their objects of interest through the socio-
material infrastructures by which they are surrounded. I consider the
analogies described in this article as a fundamental dimension of these
infrastructures. Such narratives are produced and reproduced in astrobio-
logical practice-based knowledge.
     Astrobiologists often describe the quest for extra-terrestrial life as
something that has only recently been included within the realm of scien-
tific investigation. For centuries, philosophers and fiction writers in-
dulged in bold speculations about exotic forms of life and civilizations
that might populate distant celestial bodies (Blake 2006; Crossley 2011;
Dick 1982). The situation changed during the 20th century, when extra-
terrestrial life increasingly came to be considered an object of scientific
inquiry; toward the end of the century, astrobiology, the study of life in
the universe, was born4. As often happens, this process was more com-
plex than it may seem at first glance. For several decades the discipline,
once called exobiology, the study of extra-terrestrial life (Lederberg 1963,
1126), was blamed for being a field of inquiry that “has yet to demon-
strate that its subject matter exists!” (Simpson 1964, 769) and therefore,
according to some, did not have the status of a science at all. When
NASA funded the National Astrobiology Institute at the end of the 90s,
the term exobiology was partially discarded and a new one, in which the
prefix exo- (outside) had been replaced with astro-, was adopted (Dick
and Strick 2005). What appeared to be just a mere rephrasing was in fact
due to – and at the same time contributed to draw people into – a differ-
ent way of studying and searching for life in the cosmos, defining the dis-
cipline in a way that would also include Earthly life as an object of inter-
est. To pursue the study of life in the cosmic context, astrobiologists be-
come equipped with “at least one data point of the life that we know: life
on Earth” (Cockell 2015, 1).
     Today, the study of extreme (i.e., unusual and unfriendly from a hu-
man perspective, requiring microorganisms to adapt and develop efficient
physiological mechanisms to survive) environments5, shapes the design of
28                                                          Tecnoscienza – 13 (1)


space missions and how the data collected during those missions are in-
terpreted6. Despite being considered to be hostile for most of the forms
of life we know, these environments revealed that they could host thriving
ecologies sustained through a number of adaptations. Extreme environ-
ments have become an object of intense scrutiny to understand how life
behaves in circumstances that, even if very unusual on Earth, might be
comparable to average conditions on other planets.
     Because many of the microorganisms living in extreme environments
are still unknown or very hard to culture in the laboratory under standard
conditions, the study of extremophiles (i.e., organisms able to live in ex-
treme environments) has required astrobiologists to periodically vacate
their lab benches to set foot (and hands, eyes and all the rest of their bod-
ies and instruments) onto their chosen field sites.
    In fact, not every astrobiologist engages in long and adventurous field
trips: some of them focus on computer models and simulations, others are
satisfied with doing experiments in the laboratory with samples that other
scientists collected in the field. Nevertheless, a growing portion of those
who would call themselves astrobiologists have started engaging in field
work activities, and the resulting knowledge has been used to confirm the
validity and legitimacy of what is done in other experimental spaces. “The
field”, Paxson and Helmreich note, relies “on the promise of microbes as
revelatory entities that might reveal life’s universals with reference to un-
expected particulars.” (2004, 181). The astrobiologists’ engagement with
extreme environments as analogue field sites thus informs the establish-
ment of a new paradigm for what constitutes astrobiological research to-
day. The present work investigates one of these analogue field sites and
the experience of analogue making that scientists engage with.
    By drawing on my ethnographic study of astrobiologists’ and speleol-
ogists’ fieldwork activities, I am looking into the use of space analogues,
material settings in which one or more analogies between Earth and outer
space are embedded. In particular, I will focus on how the analogies
through which these scenarios are turned into epistemic tools to investi-
gate life in the universe are built, sustained and experienced. I will argue
that it is the multiplicity and redundancy7 of the analogies that the field
site is imbued with that keep its validity as a heuristic tool in place. Anal-
ogies between specific Earthly environments and their Martian counter-
parts are not a given a-priori; they are negotiated and made relevant
through the scientists’ experience of them which, at the same time, cre-
ates a dialogic space to envision, explore and negotiate tensions and
alignments between alternative futures for space exploration.
    During the time I spent with astrobiologists working, talking, and
thinking through terrestrial analogues of Mars, I came to realize that as-
trobiology is a discipline deeply infused with a sense of place: researchers,
research practices and the material settings mutually define each other. By
taking the conceptual efforts and scientific practices that turn Earthly en-
Marcheselli                                                                29

vironments into space analogues as the focus of this paper, I investigate
this process of mutual production.
    By examining the embodied dimension of analogue making, I join
scholars pursuing two contemporary projects. On the one hand, this arti-
cle brings together experience, embodiment, and the communitarian di-
mension of science in the context of knowledge making practice. The Sci-
ence and Technology Studies (STS) traditional focus on the laboratory
has helped deconstructing the purported universality of science by cast-
ing a light on the social construction of the laboratory’s rigid boundaries,
oversimplifications and standardizations (Latour and Woolgar 1979;
Knorr-Cetina 1981; 1995; Crabu 2014; Sormani 2014). On the contrary,
with only few exceptions (for example Kohler 2002; Livingstone 2003),
field sciences have enjoyed scarce attention. Fieldwork-oriented disci-
plines can tell a different (and complementary) story about science, a sto-
ry in which the body of the scientist cannot be easily removed from the
picture, and in which rhetoric and practice are stitched back together.
    On the other hand, I join the debate about the sociological im-
portance of space exploration and outer space technological activities.
Olson and Messeri have recently problematized the spatial “inner/outer
split” (Olson and Messeri 2015), the supposed division between what
counts as the normative terrestrial sphere of human experience and what
counts as outer space. They have argued for the inclusion of all those
non-Earthly places (and maybe, one day, non-Earthly beings) whose con-
ceptualization has been fundamental for the creation of contemporary
perspectives on Earth but that, paradoxically, have been neglected be-
cause of the current “Earthbound turn”, the inward orientation of what
counts as the environment. To question the contemporary inner/outer
dichotomy and its rhetorical topologies it is important to pay attention to
how knowledge is made, to the contingency of what counts as Earthly or
otherworldly, but also to what “does not quite fit” (Bertoni 2016) in the
contemporary discourses about perceptions of the environment and the
possibility of knowing Earthly and alien microbes. More generally Space
analogues present an interesting case because of the twofold process
through which scientists get to understand certain environments and
through which their physical presence and lived experience of these very
environments makes their identity as astrobiologists.
    The embodied experience of analogues – and more in general, of
knowledge making practices – is at the very core of this paper. Embodied
experience, nevertheless, is not just an object of analytic interest, but also
the dimension that substantiates this piece of research methodologically.
The emphasis on embodied experience is thus echoed in how the ethno-
graphic data were collected and how they are presented to the reader: this
paper’s argument is never detached from the embodied experience of the
ethnographic fieldwork, which is granted a central role throughout the
entire article. In drawing extensively from my fieldnotes, I hope to convey
30                                                          Tecnoscienza – 13 (1)


the sense of curiosity and affection toward what we have not understood
yet that strikes the ethnographer from the field to the writing of her find-
ings – what Jane Guyer (2013) called the “epistemology of surprise”. In
turn, this approach finds its parallel in the purposeful search for what we
have not encountered yet, what is not-known (see also Marcheselli 2020)
and unforeseen, that characterizes astrobiological fieldwork.


2. Analogies and Space Analogues
     Analogies are ubiquitous in science8. We all – scientists included –
think about gravitational waves in terms of ripples in the fabric of time,
evolutionary phylogeny in terms of branches of a tree and light in term of
waves and particles, to mention just a few examples. “Without models”,
Mary Hesse wrote in 1966, “theories cannot be genuinely predictive”.
Analogies, she claimed, provide the only effective way to search and test
for new hypothesis to expand the explanatory power of a theory. Similari-
ties and differences between the two terms of an analogy are not fixed,
but they are object of testing and debate and in this very process lies the
predictive power of analogical reasoning (1966, 51-100). Nancy Leys Ste-
pan reminds us that scientific metaphors and analogies, unlike those used
in literature, must not be considered arbitrary nor merely personal to
come to count as valid epistemic tools. On the contrary, they require to
be agreed upon by a community and their cultural sources have to be
made unrecognizable. “Nevertheless,” Stepan writes, “because a meta-
phor or analogy does not directly present a pre-existing nature, but in-
stead helps construct that nature, the metaphor generates data that con-
form to it, and accommodates data that are in apparent contradiction to
it, so that nature is seen via the metaphor and the metaphor becomes part
of the logic of science itself” (1986, 274).
     In their sociological analysis of scientific knowledge, Barnes and col-
leagues (1996) emphasize that, despite seeming obvious, the identification
of modelling9 in science as a contingent action is crucial. “When it is over-
looked, the result is typically a purely formal account of modelling, which
fails to grasp its purposive and goal-oriented character, and hence how it
comes to be recognized as successful or unsuccessful. There is no perfect
model […] A successful model is a pragmatic accomplishment, some-
thing which those who evaluate it take to serve their purposes” (1996,
108-109).
     The literature on outer space analogies that emerged in the last decade
is broad (for example Battaglia 2005; Helmreich 2009; Launius 2014;
Praet and Salazar 2017; Salazar 2017), but caves and mines as analogue
field sites for space exploration and settlement are fertile terrain to carry
on with the work of unpacking the set of related questions on the inher-
ently cultural sources of scientific analogies (Battaglia 2005), their role in
Marcheselli                                                                31

making forms of life and life forms (Helmreich 2012), their normative
consequences (Olson 2012), and the ongoing process by which they are
agreed upon or changed. Because analogies are not found, but made –
and, at the same time, making what counts as valid and legitimate – in as-
trobiological practice, the investigation of their conditions of possibility
cannot be conclusively settled. On the contrary, the social scientists inter-
ested in how knowledge is made out of experience can extend the princi-
ple of finitism (Barnes et al. 1996, 53-59), which states that future applica-
tions of a term are open ended and no application is indefeasibly correct,
to the making and use of analogue sites and the analogies embedded into
them.10 Space analogues raise continuous problems of correspondence
and reconciliation between the meaningful relationships among the fea-
tures of the surrounding environment and the ones that can be found
within another – real or imagined – setting. Indeed, despite their being
“extreme”, no place on Earth is inherently Mars-like (or Moon-like or
like any other body of the Solar System). Earth’s atmosphere, soil compo-
sition, gravity, tectonic dynamics, just to mention a few features, are not
the same11. Nevertheless, a number of these extreme environments are
today used as analogues of other outer space environments12, Mars in par-
ticular. These analogue sites are said to have characteristics that are so
similar to the ones we would find on the red planet, that they can be con-
sidered valid Mars analogues. But how similar is similar enough? There is
no one single answer to this question. Indeed, as it emerged during my
field research, each analogue field site has its own history of why, how
and when it was selected, and “its own stories about life to be told”13.


3. Three Analogies between Outer Space and Subsurface
Environments on Earth

     There might seem to be an unbridgeable distance between the depth
of a cave and the deep space where astrobiologists hope, one day, to find
life. To understand how these loci have become thinkable within the same
astrobiological discourse, we need to disentangle the narratives14 – a rhe-
torical device that “unsettles landscapes as static images” and “structures
both place and time as they manifest in landscape” (Messeri 2016, 31) –
that are deployed by scientists when talking about and experiencing caves
as Mars analogues.
     Fieldwork is rarely a solitary experience: a small handful of scientists
from a wide spectrum of disciplinary backgrounds join forces to under-
stand multiple aspects of the environment and make them significant for
reasoning about life beyond Earth. Very often, their collaborations are
driven by logistics and by the necessity of optimizing resources as reach-
ing remote and barely accessible sites requires laborious planning and
preparation. Nevertheless, once in the field, their collaboration becomes
32                                                          Tecnoscienza – 13 (1)


part of how the science is done. The interaction among people with het-
erogeneous experience and expertise often leads to the mingling and in-
tertwining of several analogies.

     3.1 Caves as Microbial Habitats

    The presence and activity of microorganisms underground became an
object of interest in astrobiology when decades of data on the Martian
soil and atmospheric composition made scientists agree that it is today
very unlikely to find either presence of extant or traces of extinct forms of
life on the surface of the red planet (Westall et al. 2021). The atmosphere
on Mars is today about a hundred times thinner than the one shielding
the Earth. Because of the low pressure, what was a landscape shaped in
ancient times by rivers and lakes does not, at present, offer the conditions
for liquid water anymore – except for flowing brines saturated in perchlo-
rates, highly oxidizing salts that only very rarely form on Earth. What is
more, the amount of UV radiation would constitute a severe threat for the
stability of any organic compounds. Even if there was, once upon a time,
life on Mars, astrobiologists think it would be very hard to find any trace
of it left on the surface. Nevertheless, based on observations of how life
behaves on Earth, they consider the possibility that there were residue
colonies hidden underground for much longer after the surface had be-
come uninhabitable, and their traces might be better preserved (for ex-
ample Cockell 2003). Some astrobiologists have actually made the claim
that some microorganisms might still be there, adapted to a niche where
UV radiation is lower and where there seem to be reservoirs of liquid wa-
ter (for example Mhlmann 2003; Bandfield 2007).
    Astrobiologists are thus interested in the cave as an environment in
which most of the solar radiation is filtered out and in which microorgan-
isms have lived undisturbed and isolated for thousands or millions of
years. On Earth, these conditions are extreme, while on Mars they are
seen as the last bulwark to offer refuge from even more hostile surface
conditions. Despite what every microorganism living on the Earth’s sur-
face would consider highly hostile conditions, caves are teeming with life
forms capable of optimizing the resources available. If they do so on
Earth, why they shouldn’t act the same way on Mars, astrobiologists
wonder. This unexpected multitude of microorganisms adapted to the
deep darkness of Earth’s caves reinforced the hopes of many astrobiolo-
gists. They conceive them as instances of life’s great capacity for survival,
despite the darkness, isolation, and lack of nutrients – conditions that
might all be similar to those in the Martian subsurface. The differences,
for example the copious presence of water which is indeed the primary
force giving shape to caves on Earth, are considered negligible, and thus
disappear into the background of what astrobiologists observe within the
framework of the analogy.
Marcheselli                                                                            33

    3.2 Caves as Human Shelters

    In the early 2000s, for the first time, satellites orbiting Mars sent pic-
tures of possible cave entrances back to Earth (Cushing 2012). Speleolo-
gists suggested these might be used as shelters in the future human explo-
ration of the red planet. The lava tubes, caves formed during volcanic
eruptions, might offer a cost-effective solution to the danger of UV radia-
tion exposure which is one of the main obstacles that will have to be
faced when planning the establishment of long-term settlements on Mars
(Boston et al. 2004). From 2002 to 2004, NASA funded the Caves of
Mars Project, as part of the Institute for Advanced Concepts15 to assess
the best place to situate the research and habitation modules that
a human mission to Mars would require. Microbiologists’ and speleolo-
gists’ interests have always been deeply rooted in understanding adaptive
solutions that would allow microbes to thrive in caves. But to investigate
them, they had to develop a parallel branch of expertise: during the long
expeditions bringing these teams to still unexplored hollows, they live in-
side the cave for several days. In building up a network of people inter-
ested both in speleological themes and in the possibility of extending
their technical and scientific expertise to space exploration, they had
traced a second relationship between exploring caves and inhabiting oth-
er planets.

    3.3 Caves as Topoi for Astronaut Training and Exploration

    Sardinian caves have become periodically populated by groups of as-
tronauts for training purposes16. In 2011 ESA established a training pro-
gram called CAVES, acronym of “Cooperative Adventure for Valuing
and Exercising human behaviour and performance Skills”. Every year,
the training happens in a different cave; avoiding contamination and
keeping the environment pristine is one of the imperatives of the training.
The depth of the caves had been chosen for their “dark and alien under-
ground environment with many analogies to space” (“Why caves?”). The
analogies here mentioned have nothing to do with microbes or UV radia-
tion; they were relative to the astronauts’ training needs.

    One of the terrestrial environments which best mimics a planetary world,
    such as the one on Mars, is without any doubt the cave: darkness, constant
    temperature, limited visibility, physical obstacles, strict safety rules, isola-
    tion, loss of temporal cognition, difficulty in supplying materials and food,
    the necessity of working in a team. If exploration and documentation
    tasks and scientific sampling and experiments are added to those factors,
    the similarity of a cave mission to an extraterrestrial one becomes even
    more striking. (Bessone 2013, 56-57)
34                                                          Tecnoscienza – 13 (1)


    Since the beginning of the space program, astronauts have been se-
lected according to criteria that evaluate both technical skills and person-
al temperament17. Because of the stressful conditions they will be contin-
uously exposed to during space missions, among all the applicants only
those who demonstrate a high tolerance to demanding endeavours are
considered for selection. Yet, for training purposes, they have to be ex-
posed to conditions that exceed their tolerance, which are very hard to
simulate in a controlled environment that does not present any real dan-
ger. As demonstrated by Olson (2010), during their career, astronauts are
re-made into environmental subjects, or bodies whose performance re-
quire to be evaluated within the context of its functioning (namely, the
hyper-technical space of the International Space Station). One of the
strategies adopted is to bring small groups of them into unfamiliar con-
texts, where they feel uncomfortable, “where they have to adapt”18. Plac-
ing them in these alien conditions is, indeed, another form of “ecobiopoli-
tics” (Olson 2010), that is the disciplining of the astronauts’ bodies
through the temporary remaking of their relation to a new and other-
worldly environment.
    During the six days of cave mission, the astronauts cannot be left idle,
as this would be too inconsistent with the tight schedule of a space mis-
sion. For this purpose, ESA trainers asked speleologists to provide a
number of scientific goals the trainees would have to achieve once into
the cave. Each year the team is thus given a series of scientific projects
they need to learn how to carry out to completion. The assignments usu-
ally take the form of collecting samples and specimens and making maps
of the chambers that are still uncharted. What is at stake is not merely the
survival in a cave by following standardized safety procedures, but being
able to apply them while exploring. “Who’s the real explorer?” asked
Laura, one of the ESA trainers. Her goal is to turn the engineers into ex-
plorers, teaching them how to be attuned to what is new and surprising,
to step inside the unfamiliar, inhabiting – sensing and dwelling in – an
isolated space, with no weather or days, alien and alienating.

    Through the experience in these particular field sites in Sardinia, the
scientists were involved in the production of these three analogies at the
same time: i) they were thinking about the field sites we visited as isolated
subsurface microbial habitats; ii) as shelters protecting humans from the
dangers of the Martian atmosphere, and; iii) as isolated enclosed spaces
that reproduce some of the features specific of space journeys. The three
analogies, in the lived experience, overlapped and became, at times, al-
most indistinguishable.
    The workshop talks and presentations were carried in the auditorium
of the local mining school, founded in 1871 in the attempt to improve the
economy of a region still considered poor, but rich in raw materials. Min-
ing represented, for several decades, the only industry of the region that
Marcheselli                                                                  35

employed and sustained the local people. The Art Deco building hosts, in
the basement, the museum of mining. Established during the decline of
the extractive sector, the museum is located in multiple smaller rooms
and is arranged around different aspects of local mining life. It includes
the 400m practice mine tunnel excavated by the students under the
school and the nearby square. During the Second World War, the tunnel
was used as an air raid shelter, infirmary and operating theatre, directly
connected to the old hospital. More than only in strictly economical
terms, mining and survival, in Iglesias, were deeply interrelated. During
the 1990s almost all the mines of the district closed down and today the
mining industry has mostly disappeared. The old buildings and tunnels
remain there as ruins for industrial archaeologists, and attraction for the
rampant tourist sector.
    Lisa Messeri describes analogues as the successful super-imposition of
planetary and local. In the Mars simulation facility based in the Utah de-
sert that she gives an account of, this overlapping carves out “a unique
place to inhabit and consequently forge a novel connection to or under-
standing of another world” (Messeri 2016, 26). The analogue is not just a
simulation: the new way of thinking about outer space, both considered
place-less and nevertheless deeply situated, is, according to Messeri, gen-
erative: “it creates a history even as it simulates the future” (ibid.). In cre-
ating a geo-microbiological history of the Earth within the broader Solar
System, it makes it possible to think about the future inhabitation of oth-
er planets. Double exposure can be, in fact, multiple. By means of the
first-hand experience and the group interaction, astrobiologists can
quickly shift from one narrative to another and build up a shared vocabu-
lary of adaptation, isolation and exploration, with which they can refer to
all the three analogies, making the shift between one and the following
even more immediate. The analogue was redundant in that even when
one narrative failed to convince those involved in the analogue-making
activity, others could support the legitimacy of the field site as a space of
knowledge production about extra-terrestrial environments. In fact, the
analogies drawn between a terrestrial cave and Mars might not have al-
ways been very strong or very obvious; but in the lived interaction the
analogies were substantiated and tied together. Subsurface and survival –
of microbes or humans – were superimposed in the analogue experience.


4. Co-presence, Colonization, Contamination
    The GESE topical team’s aim was to explore new research avenues
and the ways in which mineral-microbe interactions might be put into use
in future space exploration and settlement. Nevertheless, looking for life
and establishing new settlements on Mars are based on different practic-
es: biological (either astrobiological or speleological) approaches rely on
36                                                          Tecnoscienza – 13 (1)


keeping life forms apart to validate their findings (Metzer 2011), whereas
human spaceflight practices focus on putting life forms – not only hu-
mans, but entire ecosystems designed to sustain micro- and macro-
biological communities – elsewhere.
    The high vulnerability of some of these Earthly environments requires
scientists and astronaut trainees to pay attention to the consequences
(both on the epistemic and the ethical level) of their physical presence
and calls for reflections about both the future of the human exploration
of space (see, for example, Cockell 2007) and the present use of these en-
vironments as spaces of knowledge production. As Stepan (1986, 268)
suggested, a metaphor is not a one-way knowledge-making device; on the
contrary “by their interactions and evoked associations both parts of a
metaphor are changed”.
    Caves and mines are, in this respect, very different settings which en-
courage different considerations. Mines are human made spaces, whose
astrobiological relevance is due to the resistance and resilience of the mi-
croorganisms inhabiting them, which have survived the depletion of their
environments and then re-appropriated the newly created surfaces and
the cracks as soon as they became available. Astrobiologists observe their
resilience and are keen on not changing the conditions that make the mi-
crobial re-colonization possible. Caves are valued for their pristine and
isolated conditions instead. Access to pristine caves is highly regulated;
for scientific as well as logistic reasons, the scientists do not spend more
than a few days inside caves, and no long-term settlement is established in
their depths. During these exploration trips, it is imperative to bring back
outside everything that has been introduced as part of the astrobiologists’
and speleologists’ gear. Nevertheless, there are a few things that cannot
be removed: footprints and marks (for example those created by the hik-
ing equipment), and microbes. The former can be considered within a
framework of geological dynamism: footprints and small blemishes will
be, given enough time, eroded by the same processes that have carved the
cave out of the rock. The latter, microbial contamination, has a different
status, which has to do with the ambiguities of “colonization” when con-
sidered at the microbiological level to describe the opportunistic and effi-
cient entering and settling of new organisms within a certain ecosystem,
which might not have been previously inhabited. The potential for colo-
nization is in fact twofold: the scientists’ bodies could be infected by bac-
teria from the cave, and the cave could be colonized by bacteria spread by
the scientists’ presence (their touching, breathing, sweating). The body
and the cave are thus two habitats for microbial communities19. The ten-
sion between the value they attribute to these field sites’ being pristine
and the threat to this very condition posed by the scientists’ physical
presence in the analogue sites, mirrors the same ethical concerns that
trouble the astrobiologists about outer space missions20. These tensions
are materialized during the fieldwork experience: space analogues often
Marcheselli                                                                37

raise both concerns and enthusiasm about the colonization of outer
space, and they open up a discursive space within and outside the scien-
tific community (McKay 2009; McKay and Zubrin 2002), a space where
to negotiate alternatives and tame challenges to the science.


5. Back to Planet Earth
     At the end of a walk in Is Zuddas, a show cave whose first kilometre
has been equipped with steel stairs and neon light to become a tourist at-
traction, we were told that the key of the gate securing the entrance had
been lost and the gate could not be re-opened to let us out until someone
would come and fix it. A group of us stopped and waited on a terrace a
few meters below the cave mouth. We started jokingly talking about how
would we survive in the cave for a long time: would we need to hunt bats,
collect bugs, drink the water dripping from the walls? Would our grand-
children evolve to see in the dark? Would we, like in Jules Verne’s Voy-
age to the Centre of the Earth, discover prehistoric landscapes in the
depth, moving in space and travelling in time? The expert guide looked at
our faces and laughed: when the astronauts come for the training, she al-
ways plays the same trick to see their reactions. After many days of isola-
tion, how do they cope with the impossibility of getting outside, meta-
phorically returning to Earth? For us, the gate had always been open an-
yway; we got out of the cave and started walking in the large path under
the tree shade. Some veteran speleologists chat about how getting out of a
cave makes the surface feel different and indeed very chaotic: the wind
moves the leaves, birds tweet and insects fly and land on our clothes; the
warm sun, high in the sky, suggests that it is time for lunch. I wonder
whether we are back on Earth, or if we have travelled even further on a
terraformed Mars, “This cannot be Mars,” someone tells me, “too many
mosquitoes. Who would want to put mosquitoes on Mars?!” The ana-
logue experience overturned our idealistic conceptions of both Earth and
other possible habitats. Earth is the only planet we know we can live on,
but indeed what makes it feel unique are its many (perhaps imperfect)
environmental relations.
     This brings us back to the above-mentioned principles of finitism: if
the first thesis says that the future applications of terms are open-ended,
the last thesis says that the applications of different kind terms are not in-
dependent of each other. It follows that any act of use of a term “is liable
to condition all subsequent acts of use of all those associated terms.”
(Barnes et al. 1996, 58-9) Even when stepping outside the analogue field
site, the analogy keeps on its generative work: it has not only made Mars a
little closer, but also the Earth surface and atmosphere unfamiliar and
new, and a cave in southwestern Sardinia richer in interesting life forms.
38                                                          Tecnoscienza – 13 (1)


Su Zurfuru mine does not seem abandoned anymore, but repopulated and
given new life by different communities of microbial miners and dwellers.
    Thinking about ecological futures in outer space unsettles visions of
the Earth as well, in a way that is not dissimilar from the so-called “over-
view effect” (White 1987), the cognitive shift of awareness reported by
some astronauts that, in the late sixties and seventies provided one of the
conceptual bases for environmental movements21. Astrobiology and hu-
man space flight overlapped again in unexpected ways. “The [extra-
terrestrial] realm is not ‘other’ than earthly but acts back on and unsettles
assumptions about commonplace brands of knowledge” (Battaglia 2005,
11), as a resource to articulate different ways of being humans on Earth,
and also being humans on a planet shared with other micro- and macro-
biological life forms. If ecological understandings of space are continu-
ously being negotiated through analogues field sites (among other things),
so is the other term of the analogy: Earth.


6. Conclusions
    This essay focused on the ethnographic account of astrobiologists’ and
speleologists’ analogue making activities. By moving beyond analogies as
rhetorical tools and focusing on the lived, practical, situated and embod-
ied experience of analogy making, this essay aims to cast a light on ana-
logue making practices as fundamental tools to (re)define a discipline and
to explore and negotiate tensions and alignments between different (and
not always compatible) directions for future space exploration.
    The first part of the essay focused on three scenarios that scientists
embraced when exploring caves and mines in Sardinia during the GESE
workshop, i.e., caves and mines as: 1) microbial habitats; 2) shelters and;
3) sites for astronaut training. I investigated their overlaps and conse-
quences of the multiplicity and redundancy that keep the validity of the
analogy as a heuristic tool in place. I then explored some of the issues and
social dynamics involved in the shared experience of analogue fieldwork.
    It is in the collective experience of otherworldly scenarios that ana-
logues are negotiated and turned into collectively relevant epistemic tools.
Once descended into the darkness of a cave, peripheral vision is com-
pletely inaccessible and what could be seen is always and only a sharp
cone of light pointing straight. Seeing is a combination of the skilled art
of pointing one’s light in the right direction and involuntary movements,
for example when stumbling on a rock and pointing the light downward,
maybe to notice the presence of something unexpected, standing out
against the surrounding darkness such as the unexpected view of a jelly
substance, triggering the astonishment of the scientists who immediately
claimed “this is biology”. The possibility of unexpected findings is not
unique to the field as opposed to the lab – even in the controlled and
Marcheselli                                                              39

standardized space of the laboratory people are sometimes led to unex-
pected breakthroughs. What fieldwork provides is the possibility of pur-
posefully searching for the unforeseen and unforeseeable. In fact, seren-
dipity plays a significant role in laboratory or archival research as well,
and nevertheless, in these contexts, the dominant narrative reconstructs
findings (often in retrospect) as obtained through hypothesis testing. As-
trobiological fieldwork (like many other field disciplines), on the contra-
ry, rejects this narrative in favour of a more open-ended and less deter-
ministic research trajectory. The non-trivial combination of skilled obser-
vations and serendipity is considered one of the features that make field-
work experience a valuable analogue for the search for life in space.22 The
field, which represents the renewed encounter with a nature not allowed
within the strictly filtering boundaries of the laboratory, “is believed to
harbour a surplus of multiplicity, abundance, and potentiality humans
have not yet discovered or characterized” (Paxson and Helmreich 2004).
It is through the scouting for what is still unknown (Marcheselli 2020)
that astrobiologists carve a space for their discipline within the broader
academic landscape.
    Accordingly, one of the issues that caves and mines uncover, is the
question of how disciplinary boundaries are defined or blurred in analogy
making. The boundaries between disciplines, as well as between science
and other realms of action, are social phenomena; they are a “contextually
contingent and interests-driven pragmatic accomplishment drawing selec-
tively on inconsistent and ambiguous attributes” (Gieryn, 1995:393). In
making different analogies coexist, merge or conflict, caves and mines as
space analogues are trading zones (Galison 1997) in which different re-
search directions and priorities are discussed, explored and opened up
for future negotiation.
    Training to prioritize microbe detection and protection techniques
and stories of mining, survival and change provide resources to further
articulate the analogies, aligning visions or taming challenges. Extreme
environments turned into space analogues are crucial sites for “examining
practices of future imagining in social terms, and for anthropological en-
gagement with these practices” (Salazar 2017, 72). What in the collective
experience becomes a common imaginary mixes intentions and different
timescales. The ESA astronauts training in caves, for example, includes
exercises on how to collect astrobiologically relevant samples in sterile
conditions, even before the existence of an actual proposal for manned
space missions on other planets. The trainers are “testing the training” for
those who, in an indefinitely far future, will become the first (European)
astronauts on other planetary surfaces but, at the same time, are also in-
forming the astronauts’ view of Earth, space and ecosystems.
    But analogue-making work is never completed: agreement on what
constitutes a good analogue setting is an ongoing negotiation between the
epistemic practices that are implemented by those who identify them-
40                                                                    Tecnoscienza – 13 (1)


selves with the emerging discipline of astrobiology and what counts as a
meaningful present and future for space exploration. This opens up a
space for sociological inquiry about the particular social processes
through which analogue practices require collaborations to be made, al-
low for new interactions and evoke previously unforeseen associations,
and thus constantly unsettle and reframe all the terms of the analogy and
the actors involved (Stepan 1986; Franklin 2014).
    Exploration of space, exploitation of its resources and settlement es-
tablishment are not necessarily compatible goals or perhaps joinable by
the thread of mineral-microbe interaction, but they are made so when
seen through the lens of Sardinian caves and mines as analogue field site.
Finding life on Mars and establishing a human presence on it (either as
scientific outpost or long-term settlement) are often thought of as incom-
patible tasks, since the economic profitability and colonization of space as
an exercise of political power is at odds with the ethical concerns about
these environments. But strategically, astrobiologists align with geomi-
crobiologists and position themselves as to be relevant actors in any of
these possible alternatives. At the same time, they do not exclude any al-
ternative, but they order them chronologically: it is shown in practice how
microbes can both be invaluably useful to humans, and at the same time
understanding them depends on prioritizing a certain empirical approach
which privileges “surprise” over scrupulous planning, and human sensi-
bility over robotic functionality. Conflicting futures are not neglected,
they are performed and tamed.


Notes
    1
      A brief introduction to the history of the Su Zurfuru mine can be found at
http://www.parcogeominerario.eu/images/files/pagina%20633(1).pdf (in Italian).
    2
      All the people mentioned have pseudonyms.
    3
      The location, Iglesias, was chosen in function of the three sites we visited during
the field trips: two caves, Su Mannau and Is Zuddas and an old mine, Su Zurfuru. The
vignette refers to the last one.
    4
      For a comprehensive account of the history of exobiology and astrobiology, see
Strick 2004; Dick and Strick 2005; see also Impey 2010.
    5
      A popular definition of this concept can be found in Rothschild and Mancinelli
2001.
    6
      Some good examples of this feedback process can be found in the JGR-
Biogeosciences Special Issue “Field Investigations of Life in the Atacama Desert” avail-
able at https://agupubs.onlinelibrary.wiley.com/toc/21562202g/2007/112/G4.
    7
      The word “redundancy” is intended here with a meaning similar to the one the
Oxford English Dictionary attributes to the engineering use of the word: “the deliber-
ate duplication of parts in a system so that its function is not impaired in the event of a
malfunction or failure” http://www.oed.com/view/Entry/160537?redirectedFrom=
redundancy - eid.
Marcheselli                                                                             41

    8
      Different perspectives on analogies in science can be found in Hofstadter and
Sander 2013; Lakoff and Johnson 2013; Holyoak and Thagard 1995.
    9
      Modelling is defined as the establishment of a link between two things – which
might range from mathematical structures to verbalized systems – by means of resem-
blance or analogy (Barnes et al. 1966, 107-9).
    10
       As above, I define analogue sites as material settings in which one or more analo-
gies are embedded and analogies as the correspondences between Earth and outer
space.
    11
        “Especially important to the functioning of interactive metaphors” Stepan
writes, “is their ability to neglect or even suppress information about human experi-
ence of the world that does not fit the similarity implied by the metaphor. In their
‘similarity-creating’ capacity, metaphors involve the scientist in a selection of those as-
pects of reality that are compatible with the metaphor” (Stepen 1986, 272).
    12
       The same use of the word “environment” to designate other planetary surfaces
has not to be taken for granted. Planets have not always been considered places, but
what is considered the correct way of thinking about planets has changed over time.
See for example Alexander et al. 2009; Messeri 2010.
    13
       Interview with BW (astrobiologist) 21/10/2015.
    14
       Messeri proposes narrative as a device that “unsettles landscapes as static imag-
es” and “structures both place and time as they manifest in landscape” 2016:31.
    15
       The Institute encouraged creative and innovative thinking about space explora-
tion related issued. See http://www.niac.usra.edu/.
    16
        More details on ESA’s astronaut activities in caves can be found at:
http://www.esa.int/Our_Activities/Human_Spaceflight/Caves/.
    17
       The astronaut selection processes and the “American hero” narrative it repro-
duces is deeply normative. Most astronauts are white males, often with a military train-
ing or a degree in engineering. Despite the effort to reverse this trend, its limits are
enduring.
    18
       25/05/2015 private conversation with LB (astronaut trainer).
    19
         An interesting parallel with reference to the ISS can be found at
http://www.sciencemag.org/news/2015/10/international-space-station-home-
potentially-dangerous-bacteria.
    20
       For further historical insight on this, see Wolfe 2002, Anker 2005, Daly and
Frodeman 2008.
    21
       Despite looking at the planet Earth from orbit seemed objective because de-
tached, this perspective has been shown to be inherently situated, like any other per-
spective. See Helmreich 2011 and Poole 2010.
    22
       When astrobiologists imagine what it takes to find life in an alien environment,
they acknowledge that they should probably not expect to find exactly what they look
for – but they rely on the idea, often repeated in formal and informal settings alike,
that they will recognize life, despite the different forms it might take, once they en-
counter it.
42                                                                 Tecnoscienza – 13 (1)


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