Plants for a Cold Cosmos: Planetary Vegetal Thresholds

What does it mean that plants—soy, coffee, wheat, cotton, lettuce and more—are growing in Near-Earth orbit? What histories account for their presence beyond the terrestrial, and what futures might they be incubating? In this paper, to address these questions, I describe four very different planetary vegetal thresholds, which I understand as geohistoric events thick with potentials for realigning worlds. First, technoscientific cultures of space science. Second, the allying of crops and elites in late neolithic plantation agriculture. Third, the cosmic and global travels of the kumara, figuring Māori plant alliances that take us beyond colonial ideologies of space exploration. Fourth, a science fiction art installation growing plants in a prototyped Martian House. Drawing on vegetal geographies, critical plants studies and Anthropocene geophilosophy, the paper is a work in speculative planetology which argues that plants are seeking to stretch out beyond Earth and enable other planets to become otherwise: photosynthesis is a vegetal gift to the cold cosmos.

sustaining future exploration and settlement of the solar system will require plants (Stutte, Monje, and Wheeler 2015).Besides provisioning services (food, oxygen), plants are also seen as psychologically beneficial.In addition to the well-known overview effect (the psychological impact of the extra-terrestrial sublime, as astronauts orbit the Earth) and long-eye syndrome (gazing out of the space station or craft at a distant Earth in s state of anxious depression), many cosmonauts and astronauts have reported unexpectedly intense affective connection to plants they have grown in Near Earth orbit.Space psychologists emphasise how plants provide not just food or objects for experiment, but a link to diurnal rhythms and the colours and feelings of being on Earth (Haeuplik-Meusburger et al. 2014).
This all points to the fact that, from the beginning, space exploration has been a multi-species endeavour.As Aronowsky puts it in her study of NASA's 1950s experiments with algaeregulated life support systems, 'underpinning the rhetorical bravado of the preternatural cowboyastronaut are a host of interspecies and sociotechnical maintenance practices that sustain a biologically feeble human in the extreme' (Aronowsky 2017, 372; see also Battaglia 2017).Travelers into space have taken plants along for the ride: a recognition, I suggest, of a necessary alliance with plants.There are of course many reasons to be sceptical and critical of space exploration: space exploration's longstanding frontier and colonial ideology (Anker 2005;Messeri 2016;Dunnett et al. 2019); its narrowness of geopolitical vision and its claims to universality (Mandel 2021;Klinger 2021;MacDonald 2007); the role of private sector companies in space exploration (Tutton 2021).Billionaires portray themselves as sky gods pointing to a new era of humanity; they take joy rides into space, leveraging their capital and technopower to shape the vision of life beyond Earth -tweeting new cosmic Man into existence, or special delivery all the way to Mars.The vision of such 'new space' industries is to ensure humanity, or at least some selection thereof, becomes a 'multiplanetary civilisation' to hedge against extinction events on Earth, such as an asteroid collision (Valentine 2012).As contestable as the critic may find such visions, they do have cultural power to shape imaginaries of the future.
In this article, I want to sidestep critical dissection of space exploration politics and instead make the following argument.Plants, as we know, convert solar energy to create a breathing planet, and the basis for most forms of terrestrial existence (Morton 2007).Their chloroplasts link the sun to life on earth, across the cold of space.Plants have transformed-literally terraformed-Earth, most notably taking advantage of the Great Oxygenation event to spread themselves across the globe.I work from the axiom, then, that plants are agential, meaning-making beings with problem solving skills and distributed intelligence-an axiom shared across new plant sciences, plant humanities, critical plant studies and Indigenous scholarship (Lawrence 2022;Meeker and Szabari 2020;Ryan, Vieira, and Gagliano 2021;Kimmerer 2016).Humanity and many plant species are now (on an aggregate level) mutually dependent, bound together in their co-evolutionary dance through time: planetary relationality is not just a metaphor, nor is it innocent (Haraway 2016).If we accept this irreducible relationality between plants and their humans, then taking plants into space is not done by space agencies acting alone, it is done with-done with plants.
The argument I will develop in this article is that the movement of plants into space is evidence of a new stage-or at least an inflection point in a potential new stage-in the very longrun alliance humans have had with plants.In developing this argument, I make several leaps through vegetal world history, alighting on specific moments of threshold, where thresholds are thick moments of potential for transformation.Having sketched the first-the journey of plants into near-Earth orbit-in this introduction, the next reaches back to late neolithic Plantationocene origins to account for the negative relationality of human-plant alliances.Then, vegetal worlds are considered through the Polynesian settlement of New Zealand and the role of the kumara in M aori cosmology to show that alternative plant-human alliances have always been possible, and can be held open to the future.A final threshold jumps scale and history to the micro-present and an art installation in the UK, placing the vegetal in the socio-technical world of analogue, off-Earth settlement.The choice is necessarily partial: my goal is not to spin a didactic historical account, but a braided narrative about how distinct plant-human alliances resemble, echo and mutate through geography and history.These build towards the final argument on the significance of plants growing in space.The act moves plants' gift of photosynthesis across the threshold of the Earth, offering the cold cosmos a germinal spark, helping Earth-bound creatures stretch out and enable other planets to become otherwise.Might plants, millennia or more from now, have extended their gifts of photosynthesis to other planets and have made, ultimately, human Earth-bound concerns a mere cosmic footnote?Might we consider then that plants in some way want to go to space?

PLANETARY THRESHOLDS, VEGETAL GIFTS
Readers will be familiar with the many responses to ongoing epochal transformations of earth systems.These include mainstream policy frameworks responding to quantifiable planetary boundaries and earth systems science, embodying the progressive impulse of Anthropocene science/policy to diagnose and problem-solve (Rockstr€ om et al. 2009).They also include feminist care ethics, be that through staying with the trouble of ongoing multispecies living and dying (Haraway 2016) or cultivating arts of living amid ruin (Tsing 2015): such approaches eschew grand narrative in favour of patterned alliances.Theorists grapple with Enlightenment legacies in response to The New Climatic Regime (Latour 2018), or the intrusion of Gaia (Stengers 2015), in ways that seek to reformulate the political, the demos and the stakes of planetary life.Then there are updated, upgraded, and extended Marxist analyses of 400 years of planetary capitalism putting the appropriation of cheap and free nature and labour at the heart of the story (Moore 2015); for some at the vanguard of discontent critique of capitalism is the only story worth either telling or hearing (Malm 2017).Another set of responses to understanding deep time and the deep transformation of earth systems from the environmental humanities and geohumanities has been to think anew planetarity and the grounds that make thought possible, to allow thought to be altered by the deep times and spaces revealed by the Earth.As Clark and Szerszynski (2021) have argued, planetary thinking must be more than debating epochal labels, engaging in critique and asserting liberal power/knowledge.The challenge is thinking in geo-bio-techno oriented frames that have the ambition of adequately responding to the material energies of the earth, to allow thought to be "altered by the material-energetic forces it grapples with" (Clark and Szerszynski 2021, 46).Clark and Szerszynski (2021) also remind us that geoscience has told stories of deep time transformations before-the template is not new, only the addition of humans as protagonists is novel.There have been many past times when the Earth has shifted from one state to another.The paradigm shift in understanding deep time in the twentieth century moved from a foregrounding of cyclical and gradual time to one emphasising non-linear shifts, catastrophic events and abrupt changes as system thresholds changed (on climate science see Demeritt 2001; on geology see Gould 1987).Large steps-the emergence of biological life in the Precambrian explosion, or oxygenic photosynthesis, the break-up of Pangea-involved massive step changes in the flow of energy and matter.Clark and Szersynski capture this in their term "planetary multiplicity" (Clark and Szerszynski 2021, 9).By this they mean that the Earth has changed many times, being nudged from one state to another, self-differentiating through the conjunction of different Earthly powers and processes.Citing Kirby (2011), they see the Earth as differentiating, creative, inventive, even investigative, and suggest that "it is as thresholds are approached that matter-energy is at its most expressive, its most creative, its most potentially surprising" (2021,162).The threshold here is a time of, after Haraway (2016), kainos, thick potential for the way the future might unfold.The idea of planetary multiplicity implies not just an Earth that has changed many times in the past, but also a question beyond that of what the Earth might be capable of doing and becoming in the future (Clark and Szerszynski 2021).A key point here is the 'might'-the threshold might or might not be crossed, new Earthly conjugations might or might not emerge: "actualised orders and structures are only a small subset of what is possible" (Clark and Szerszynski 2021, 49).
From this perspective, the current planetary moment reveals that humans have been conjoining with various Earth powers.Not humans in general, but particular groups in particular times and places, joining to particular geo-powers.Industrial capitalism: a joining of mining labour, capitalist owners, imperial powers and fossilised energy of plants that literally burrowed through the earth (Mitchell 2011).Colonial capitalism: bodies, especially black and brown bodies, systematically put in sacrifice zones where earth powers, not only coal, but crops and minerals, were exploited (Yusoff 2018).Indigenous ways of knowing and walking the earth made, and make, different kinds of animated geo-social collectives (Mueggler 2011).Not only on earthly scales, there are multiple and forms of alliance networked across territories small or teleconnected, some violent -such as birds hunted to extinction for fashion (Patchett 2021) -some mundane-such as reading the soil for signs of fungus (Du Plessis 2022), others carnal or banal (Alaimo 2016).There is multiplicity in the many "modes of being by which human collective attune themselves to the self-differentiating dynamics … of the Earth" (Clark and Szerszynski 2021, 96).
The Earth's inhabitants present a living archive of past and present solutions to different problems of existing.Plants demonstrate Earthly life experimenting with modes of existence: 500 million years ago plants diverged from animal life, opting for stationary autotropism, and adopted a physiology where bodily function wasn't tied to organs (Mancuso and Viola 2015).Some 130 million years ago, most plants forged an alliance with insects for pollination.Plants, it is now clear, are intelligent, adaptive and even creative beings, in ways not like 'us' animals.They are non-individuated, multiple beings, forming through obligate symbiosis with other kingdoms and creatures-bacteria, fungi, animals.Plants have a primordial generosity, literally terraforming through their capture of the sun's energy, "cosmic mattering," as Natasha Myers styles it, drawing energy across the solar system and provisioning a large portion of Earthy life with "liveable, breathable, and nourishing worlds" (Myers 2018, 56).Plants have given us planetary multiplicity, making the Earth become otherwise.
What happens when geosocial collectives ally themselves to the vegetal?American writer and critic Michael Pollan is a committed gardener.As well as writing about psychedelics (Pollan 2021) and pushing plant intelligence into the limelight (Pollan 2013), he has reflected on more mundane human-plant interactions.In The Botany of Desire, Pollan (2001) compared himself to a bee-devoting his labour to the reproduction of a particular few crop species.As much as plants help meet human desires for taste, plants induce gardeners and agriculturalists to help them: a long-run process of coevolution.In aligning ourselves with some representatives of the plant kingdom (especially cereals), new forms of more-than-social organisation have emerged.Critical plants studies cautions that these forms of vegetal organisation have not always been comfortable, in the ways in which planetary vegetal systems have been undergirded by systematic slave, forced and precarious labour (Yusoff 2018).Of course, there are remainders and other modes of being-with plants that exceed the form of reductive vegetal planetarity: everyday plant wisdoms (Myers 2018), progressive soil cultures (Krzywoszynska 2020), radical urban agriculture (Ginn and Ascensão 2018).And, even from the orbit of space technoscience, new vegetal alliances might emerge to shape thresholds-planetary and beyond-to come.

PLANTATIONOCENE DEEP TIME
The story of human-plant alliances goes back a considerable way, into what can be called an early, or long, Plantationocene.The old civilizational metanarrative that at some stage humans domesticated plants and animals and crossed a special line from being hunter-gatherers and foragers to sedentary, civilized people has been thoroughly debunked.The neolithic period was not a time of inexorable intensification in agricultural civilisation, centred on independent hotspots of domestication (Maya, Eastern China, SE Asia, West Africa, Egypt), leading necessarily to a 'used planet' (Ellis et al. 2013).Rather than crossing one threshold in a singular revolutionary event, there is instead a broader, slower and much more fragmented process of landscape modification and growth in agriculture.
The big bang theory of agriculture domestication has been superseded by a gradual 'complex mosaic' of co-evolution of humans and grain plants for strategic economic ends over three thousand years or more, until widespread but modest cultivation of the foundational crops-cereals and legumes-by 6,000 BCE (Fuller, Willcox, and Allaby 2011, 644).During this time there were both settlements of up to 5000 inhabitants without any agriculture, and places where crop planting occurred without permanent settlement (Scott 2017).From at least 10,000 years ago hunter-gathers tended wild stands of grain, and evidence is now that genetically and phenotypically, plants changed after they had been cultivated for a long time (Fuller, Willcox, and Allaby 2011).In general, subsistence economies made use of multiple resources-hunting and gathering, but also cultigens and domestic animals (Zeder 2011).People practiced hunting, foraging, pastoralism and agriculture, moving between the modes of production as they needed or as circumstances dictated, being generalist experimenters with a "large portfolio of subsistence options" (Scott 2017, 59).The gap between cultivation of grains and the emergence of sedentary agrarian states stretches to 4000 years: this suggests to archaeologists that there is no necessary link between agriculture and sedentary civilisation (Scott 2017).
The co-evolution of grain and human societies did gradually transform ecologies.By 5,000 BCE, there were hundreds of permanent agricultural settlements in Mesopotamia.Over the next 4,000 years, these settlements and their human populations became increasingly reliant on grain (in Mesopotamia the crop was wheat; China's Yellow River, sorghum; in Mayan lands, maize; Egypt, barley and wheat) (McNeill and Winiwarter 2004).This unique human-plant alliance created new grain city-states, which James Scott calls "late neolithic multispecies resettlement camps" (2017, 18): "a unique and unprecedented concentration of tilled fields, seed and grain stores, people, and domestic animals, all evolving with consequences no one could possibly have foreseen" (2017,73).The grain city-state had at its core simplified landscapes of domesticated crops fed by irrigation and labour.The demands of dependable, determinate and predictable agriculture selected for self-pollinating plants that did not cross-fertilise with 'wild' kin, that were morphologically simple and robust, and harvestable at the same time-a key characteristic enabling taxation and centralisation.While much more diverse than today's monocultural and genetically narrow systems, late neolithic agricultural selection fully domesticated crops such that they could not survive without human care.This marked a significant change from piecemeal tending of semi-wild stands of crops, or periodic crop-growing to the creation of new, specific ecological niches for domesticates (Tsing 2015).From the late neolithic, the hallmark of sedentary settlement was ultimate reliance on the grain harvest.
Early city-states were crowded and disease-prone, with greater levels of malnutrition than pastoralist or hunter-gather societies (especially among women who bore the brunt of reproducing to feed the grain system's labour needs).Grain-based agriculture was labour intensive-these simplified landscapes required much care; grain had to harvested, ground, prepared and stored.The labour demands of the plant usually exceeded any stable or sensible level of population, meaning city elites traded for slaves and forced labour with non-sedentary populations around them.Lives in slavery to the grain complex were short and brutal.The routines of early city states were dictated mostly by "the demanding genetic clockwork of a few plants" (Scott 2017, 91).Early sedentary states were very fragile: two or more successive bad harvests and they usually collapsed, and their populations dispersed.As Scott (2017) argues, the collapse of these city-states should not be seen as a retrograde step back towards the primitive anarchy of huntergathering.Their collapse was usually positive for most of the populous-except the elites who benefitted most from the exploitative labour practices required for grain cultivation.Hunter-gatherer, nomadic and pastoralist peoples of the hinterland were, archaeological evidence shows, generally much healthier and longer living than city dwellers because they employed a diverse range of production strategies.The reliance on simplified grain ecologies was by no reckoning a wholly positive step.
Here then is the birth of the Plantationocene in deep time.A planetary threshold where our species, driven by elites, allied to a few grain species with long-lasting and planetary landscapeshaping consequences.The plantation-a simplified, replicable and scalable landscape worked by slave or cheap labour-became a motor of planetary history.It is also, just as importantly, a "threshold to thinking through long-standing and contemporary practices of racial violence" (McKittrick 2013, 4).Through the deadly cotton, indigo, sugar and tobacco ecologies of the Americas in the long sixteenth century, the plantation figured racial necropolitical arrangements that continue to echo in the colonial present (McKittrick 2013;Murphy and Schroering 2020).Today, the reductive logics of the plantation proliferate globally, uprooting and exploiting humans and plants as they are put to work in the service of specific capitalist natures (Chao 2022).Plantation logics worm themselves into citational practice too; the term's popularisation as a planetary heuristic epistemologically sidelined long-standing Black feminist scholarship on plantations past and present (Jegathesan 2021;cf Haraway 2016).On a planetary scale, reliance on a few genetically narrow cultivars is pushing biogeochemical earth systems to the brink, all the while showing that "alienation, interchangeability, and expansion … lead to unprecedented profits" (Tsing 2015, 40).If the deep time plantation was a threshold event, a crossing into a new form of human-plant alliance with "uninhabitable … spatiotemporal realities," then it is a threshold we must escape (Jagathesan 2021, 87).A future where the plantation logic leaves Earth and seeks to build new socio-ecologies in its image is not desirable: as we shall see in the next section, we need the help of other plants, and other stories, to do better.

M AORI TRAVELS WITH THE KUMARA
When Polynesians arrived on the New Zealand islands in the thirteenth century they brought with them various crops-taro, gourd, yam, cabbage tree, kumara (sweet potato).New Zealand was the last large landmass to be settled by humans, the culmination of several hundred years of sophisticated navigation and exploration of the Pacific by Polynesian seafarers.In successive waves, these voyages reached from SE Asia right across into the Pacific and even to the coast of South America, settling tropical and subtropical islands across the ocean.Adapting to new climatic conditions of Aotearoa New Zealand, M aori increasingly relied on the kumara as a staple crop (at least until superseded by more amenable crops, such as the potato, after European contact) (Belich 1996;Salmond 1997).Many other items brought with them (pigs, bananas, breadfruit) did not survive.In New Zealand, kumara had to be propagated from tubers, and outside the very north of the Islands, had to be grown seasonally rather than year-round.Kumara's importance was reflected in tikanga (protocols) governing its cultivation, and its prominence in song, genealogy and culture.Kumara were grown in puke (mounds) on sloping, north-facing gardens, in regular quincunx formation.They were planted on certain nights between September and November according to the moon and stars, in light, porous soil (soil was altered with sand or gravel if necessary).Planting was accompanied by ritual song, and in some traditions a long karakia (invocation) to Pani, the goddess who gave birth to the kumara (each iwi had its own set of specific protocols and rituals).A small portion of the crop was also set aside for Pani, to secure goodwill, and any large or abnormally shaped kumara were not eaten but offered by the priest to Pani.Kumara gardens were tapu (forbidden, prohibited) until they were harvested in Autumn.Some portion of each crop was eaten, another part dried and carefully stored in semi-subterranean pits where it became again tapu (Best 1976(Best /1925)).Cultivation of the kumara thus bundled together soil and ritual, stars and gods.At some point in the 1870s, North Island M aori experts came together to debate the origins of the kumara.Each speaker tried to out-do the other in their eloquence, learning and superior understanding; the debate was witnessed, transcribed and later translated into English by a government official (White 1888).The stakes of the debate were claiming, by ancestral ties to the origins of the kumara, considerable authority (or mana).This is because the kumara could be traced back to Rongo (god of peace and cultivated foodstuffs).Rongo stole the kumara from his elder brother Whanui (the name given to the star Vega) and impregnated his wife Panitinaku; Pani then birthed the varieties of kumara cultivated in New Zealand.The first speaker in this late nineteenth century debate, Ropata Wahawaha, claimed that his ancestors' canoe had sailed back from New Zealand to Hawaiki (the physical and mythological homeland of M aori) to bring the kumara.Upon their return, his ancestors deposited the kumara in various locations around the coast.He noted that these locations were part of an incantation ritual that accompanied the planting of the kumara crop.The second speaker claimed that it was in fact his ancestors' canoe, Aotea, which brought the kumara, and that the offshoots of that first kumara were still tended in his gardens.Mohi Turei, the next expert to speak, remarked that even though his ancestral canoe is recounted as the first to make landfall on New Zealand, he would not claim, as no learned man ever has, that it was the only one to bring the kumara.Surely, it was not possible that all kumara came from one canoe: "You possess your kumara, and your own ancestor, and your kumara cultivations; and I have my kumara, my ancestors, and my kumara cultivations" (cited in White 1888, 5).He accused the first orator of speaking a "myth of his own invention" (cited in White 1888, 6).In turn, Hoani Nahe tried to take the high ground in the debate by reminding the gathering that to claim that one's ancestor brought the kumara was to elevate oneself above others; the opening speakers were arrogant to assume that they were the most able and learned men to rehearse the genealogy of those who inhabit the Islands.The debate continued, with some subsequent speakers supporting Ropata's claim, citing evidence that older men had spoken similarly, tracing that story back to ancient spirits not easily dismissed.Others made their own claims and counterclaims (White 1888).
The debate does not represent a clash of competing stories or interpretations of nature, or differing versions of the past.Rather, the debate was a way in which reality was sifted into a world that was true in its own terms.In this case, ancestral ties to Rongo and other powerful ancestors, and the mana associated with the origins of the kumara were composing a common universe of association.Reality is made through whakapapa, a "way of being based on complex networks that encompass all forms of life, interlinked and co-emergent" (Salmond 2017, 3;Salmond 2019).Debate and exchange of knowledge is more than epistemological sorting; it is also a way to pass hau (the breath of life) between beings.In such exchanges, hau is passed across the pae-the "threshold between sky and earth, light and dark, local people and visitors, life and death, past and present" (Salmond 2017, 6).Hau moves through time and space.As Anne Salmond notes, the kumara grows in ways that echo the relations between land and kin, with its tangled vines and mix of ancestral belonging and mundane earthly being.The kumara encapsulates the close connections between plants, land, ancestors and kin in M aori worlds; its whakapapa makes links back and forth time and space.In a very real sense, then, the kumara has already been in the cosmos-growing kumara partakes of whakapapa traceable back to and from Rongo and his brother Wh anui (the star also known as Vega), and to their parents.
If the kumara has come from the cosmos and the gods, and maintains links back to its origins through whakapapa, what would happen were it to be grown in space?M aori cosmology is not a static, historic world.New knowledge and ties were made through the colonial period; new associations and new mauratanga (M aori knowledge) continue to grow in the present.While M aori concepts now feature in New Zealand's conservation world, most projects seldom lead to real partnership or equity of worlds, with m atauranga (M aori knowledge) treated as supplementary or second-class knowledge (Coombes, Johnson, and Howitt 2013).M aori and pakeha biologist, Mere Roberts, has worked to develop new protocols and new forms of knowledge for biotechnology and novel organisms (Roberts et al. 2004;Hudson et al. 2012).Under the Treaty of Waitangi, M aori have the right to consultation over use of, among other things, valued flora and fauna.As Roberts (2009) cautions, the representational politics are unclear-in some circumstances this might mean a single representative, in other cases a gathering of specific iwi, or in other cases a national gathering of experts.Consultations on genetic modification reveal a wider problem-not just cross-cultural barriers, but the complexities of tribal processes and claim and counterclaim over authority to speak.While the general M aori view of genetic engineering is that genes are considered taonga (highly valued possessions), with their organisms seen more as custodians than owners (gene editing thus significantly alters whakapapa), there was however no generic response, with several experts expressing much greater sanguinity about genetically engineered organisms.There is no such a thing as a singular M aori worldview.
Yet, as Hudson et al. (2012) note, new technologies create new arenas for kinds of M aori knowledge.One can speculate then, that were kumara to be grown in space, new protocols would be needed, new ancestral ties would form, and new m atauranga M aori would emerge.Of course, the contours of any such knowledge are not mine to sketch.Such speculation also runs up against the epistemic violence of the colonial present, in the context of which to suggest that M aori visions of plants in space be given the same credence as technoscientific experiments run by international space research programmes would seem fanciful at best.Nonetheless, the speculation is important and it is real, and I do not offer it as an allegory: growing kumara in space would bring new material, spiritual and genealogical futures into being.Attention to questions of kaitiakitanga (guardianship), rangatiratanga (autonomy, control) and benefit sharing would all be raised and perhaps answered (Hudson et al. 2012).There is no reason why the kumara, descendent of Rongo, should not return and voyage back out into the cold cosmos.

AN EXPERIMENT IN MARTIAN TECHNOSYMPOIESIS
Vegetal thresholds are visible in the many prototypes of systems for human inhabitation of Mars, simulating to greater or lesser technical fidelity the conditions under which life might be sustained on the Red Planet.Prior to the 1980s, such systems revolved around the search for closed loops that could circulate biotic mass and energy for long periods of time (H€ ohler 2017).Since the 1980s, such engineering experiments have been complemented by larger-scale constructions on Earth, most notably Biosphere 2. An attempt to combine ecology and cybernetics, Biosphere 2 launched in the American south-west in the late 1980s with 4,000 plant and animal species and eight humans living in sealed biospheres (Allen 1991).While its engineering failed in the short term-due to unanticipated imbalances in CO 2 and O 2 from soil and concrete, death of insects, and social conflict among the crew-its legacy endures.There is now a plethora of recent and active simulated Martian environments.The Mars Society has been running their Mars Desert Research Station in Utah since the early 2000s.NASA has HI-SEAS, an analogue space research station in Hawaii.The site is physically isolated on the Mauna Loa volcano, and mission parameters, such as communication delays, can be imposed to simulate life on Mars.The MARS 500 mission  ran as a joint Russian, European and Chinese Space Agencies programme, simulating the 520 days the journey to Mars might last.These experimental systems all follow a rational, technologically driven logic: trying to find solutions to problems preventing off-Earth settlement -and there are many challenging problems (NASA 2010).Solutions lag behind promises: China vows to go to Mars by 2033 and NASA to have permanent settlement on the Moon in the same decade, though neither have clear roadmaps to technical feasibility.Martian prototypes bring the future and the faraway into the present, making them actionable objects and inserting plants as stable, predictable elements of an overall whole.This temporality is symptomatic of modernity, visioning and actualising future risks to better understand and manage them.But there are other ways of crossing the threshold between future and present.
In summer 2022, in the city of Bristol in the southwest of England, a group of artists, architects and members of the public collaborated in the installation and running of a prototype Martian House.The ethos was different to other Martian simulations.First, the centre of a British city is a rather different setting than an isolated desert or volcanic landscape.Second, the limited budget meant a make-do build, recycling old materials (such as a shipping container) and relying on donations and pro bono contributions from companies (for example, installing a mistshower that could work on Mars, but using only very cheap materials readily purchasable in a local garden centre).Through this, the architects evoked the sense of a Martian dwelling.Third, the design of the house, and its rooms and objects, was participatory rather than expert-led, codesigned in a series of workshops with different groups of local citizens.Fourth, the project's attitude to the future was prefigurative rather than problem-solving.That is, it did not attempt a literal or material version of what a Martian house should look like but attempted to ask what one might look like; to figure in advance how the future might manifest.
Upstairs in the Martian House ran an experiment in pre-figuring liveable worlds with plants. 1  The gold-coloured tent-like structure, its walls filled with regolith to block radiation, sat on top of the main body of the building and housed a hydroponic plant system.Hydroponics, growing plants indoors in a water-based nutrient liquid with artificial light, as well as aeroponics or even aquaponics, offer one approach to the problem of growing plants off-Earth.Plants can be removed from complex ecological systems and managed through a much simpler, technologically calibrated arrangement.The project experimented with, invoking Lynn Margulis, forms of techno-sympoiesis, becoming with plants and technology.Rather than grow plants with any telos in mind, they were allowed to grow freely, intertwining and engulfing their systems.While in space experiments (and industrial hydroponic economies) a hyper-abundance of artificial light pushes plants beyond their usual growing capacity, the Martian House system patterns of mimicked diurnal and seasonal rhythms.Plants do, like animals, shape their environments: mycorrhizal associations underground, altering soil conditions, creating microclimates under their canopies (so-called tree nurseries).From continental, Western plant philosophy we understand plant being as different: they grow without purpose or desire; they sense, communicate, calculate, plan and grasp the future in ways which are not driven by the same logics as animal being.Plants are non-individuated beings: that is, they do not have a coherent self.Parts can be cut off, but the plant remains whole.Plant subjectivity also does not work with a closing off from the world; plants remain much more radically open to seasons, elements, flows of matter and energy.These differences are not weakness or markers of something less-than-human-they are the distinct mode of vegetal being (Coccia 2018;Marder 2013).They do however mean that plants are open to manipulation, to being inserted in systems designed to make them behave in certain ways-as previous thresholds discussed in this paper have shown this has often been done to extract value from plants and their work (Ernwein et al. 2021).
Rather than compartmentalising plants in simplified ecologies to harness their propensity for growth, in the Martian house they exceed their hydroponic systems; root tips spread across floor and table, communicating with kin.This offers a glimpse of plant subjectivity adapting through technics, becoming different to itself-a glimpse only, though, as they plant-as-subject is always withdrawn.Workshops invited the public to a Martian tea ceremony, harvesting and drinking lemon balm, prefiguring new naturecultures under butterscotch-coloured Martian skies.In the planning stages, people had been adamant: no nostalgia for lost Earthly natures, we needed new Martian forms of nature-culture (echoing the trajectory of Kim Stanley Robinson's [1993] Mars Trilogy).Visitors were invited to bathe underneath the artificial light, imagine themselves being elsewhere.The spirit was of curiosity and companionship-what plants would go to Mars, how would they react, how might we rely on them, and might new forms of plant being might emerge?
The plants of the Martian House were not at a cosmic threshold; denied access to the sun, they are a different sort of being than their outdoor kin.Although they were just plants-basil, hollyhock, lemon balm-growing.But they were prefiguring future transformation, living at the threshold of imagining what might be to come, and seeing that possibility immanent in the present.Sria Chatterjee (2023) reminds us that artistic renditions of multispecies vitality and plant sentience have no necessary pathway to progressive ends or wider justice; plant sentience can be, and has been, co-opted for political and economic ends.While these cautions are a useful rejoinder to apolitical optimism, the potential for artistic renditions of plants to create new pathways and new forms of multispecies alliance does still exist.While technologically mediated plant growth, as in hydroponics, can fuel emerging hyper-capitalist industrial agriculture (the fever-dream of a new urban agricultural revolution), the effects of any technology depend upon its socio-technical relations, not on its given properties.As the cyborg was repurposed by feminist science studies in the Cold War, so too can the hydroponic lab be repurposed in the bio-capitalist times of the C21st.This art project of hydroponic plant growing creates cosmic dreams of plants beyond earth: beyond instrumentalism, these plants are active partners in creating their own space.Of course, insignificant on their own by any energetic or material measure, they nonetheless are a threshold: they are incubating a form of human-plant alliance that might, conceivable, move Earthly life beyond Earth.It is a playful conjoining of technology and the restlessness of the Earth, of our planet's propensity to become otherwise.

CONCLUSION: PLANTS INTO THE COLD COSMOS
This paper has offered a geo-historical account of four germinal moments in planetary transformation.I began by suggesting that growing plants in space extends what Latour calls the Terrestrial beyond Earth and is a threshold, a bundle of potential relations and possibility, a harbinger of cosmic transformation to come.Space exploration has from the beginning been a multispecies endeavour and will continue to be so: corporate Sky Gods of the Anthropocene may rocket into orbit, but long-term survival will require plants for oxygen, food and perhaps other services.The predominant geosocial alignment between technoscientific worlding and the prevailing western ontology of plants as open, manipulable, pliant: as free labourers in space exploration.This geosocial formation has its roots in late neolithic grain cities, the prototype for exploitative, violent, hollowed out human-plant ecologies.A third threshold emphasised more than a one-world story, exploring how M aori whakapapa (genealogy) connects growers of the kumara across time to cosmic ancestors.The 1870s debate about who brought kumara to the islands of Aotearoa New Zealand showed that the braided ontologies of debate and disagreement mean the origins and endings of the kumara are never settled, nor some ossified aspect of Indigeneity, but live and contestable.What forms of sociality and vegetal being might M aori cosmology narrate beyond Earth, and might that take equal place alongside solely techno-scientific visions?Such alter-ontologies are also visible in sf worlding, in a specific artistic and practical alternative to tech-bro Martian living.Experiments in hydroponic growing sought to subvert instrumentalised uses of plants, to open up space for plants to grow their own liveable worlds in a simulated Martian house.These are geosocial formations, particular constellations of ideologies, technologies and power that have allied themselves to the vegetal.
Each of these thresholds are of course different in scale, scope and ultimately, the effects that have or might ensue.I have attempted to juxtapose them loosely, not in a sense of logical argument, but more in a desire to position plants and their attendant humans within the strata and flows of life from which they emerged.I point not to a genealogical (or genetic) history of human-plant alliance, but rather the virtual webs aligning multispecies travelers, to patterns that might repeat, echo, or mutate across geography and history.The paper hopes to have offered a speculative planetology that sees photosynthesis as an Earthly gift and a germinal spark for a New Earth, outlining four thresholds that, in very different ways, partake of the primordial generosity of plants, a generosity now being extended into the cold cosmos.
I have borrowed the juxtaposition of cold cosmos and gift from Clark (2010).For Clark, the cosmic void sets the limits to any and all relational ethics; its gift is to make the choice and possibility of ethics by acting as its negating outside.IN this paper I have inverted the direction between cold cosmos and gift.The plant extends beyond Earth, with its particular mode of vegetal life itself indifferent to the indifference of a cold cosmos.The vegetal gift is in a sense offered to a void.Future worlds may become vegetal.Yet there is a 'we' to be made here.Gifts forge connection and obligation, they draw together while simultaneously excluding and holding others apart.Exalting the vegetal requires a delicate straddling of one of Chakrabarty's (2021) chasms of Anthropocenic thought-between aggregated species history, and disaggregated human-colonial history.Straddling this chasm makes it possible to hear the blunt truism that humanity owes the vegetal a lot, from primordial conditions of existence to ongoing sustenance, at the same time as hearing the stories of how the vegetal is thoroughly threaded through the colonial appropriation and violence so foundational to our contemporary world (Ghosh 2021).It follows that Earthbound companions of the vegetal are not bystanders but are enravelled by the plant's gesturing to the cosmos.The role of space scientists, plant-inspired artists, knowers of bigger cosmologies that exist beyond reductive modernity, plant thinkers and plant do-ers of all kinds, is to avoid replicating the pernicious multispecies injustice of our current planetary threshold.This needs to be done not only by looking down to the soil, but also to the hydroponic heavens, lest the scope of possibility in space exploration be dictated by uncritically technophilic, capitalistmasculinist ideas surfing on the inertia of colonial fantasy.NOTE 1. Building a Martian House was a project by artists Nicki Kent and Ella Good in collaboration with Hugh Broughton Architects (https://buildingamartianhouse.com).The Vegetal HydroPoetics installation was a collaboration between the author and artist Katy Connor (www.katyconnor.net),funded by the University of Bristol Brigstow Institute and Research England.See Ginn and Connor (2023).