The Bio-Arboretum: Building the First Cemeteries Beyond Earth

October 2025

Project Status: Open 
By Marie Roohi

Float or Moat?

On Designing Cemeteries for the Uninhabitable

The idea for this essay came to me at a funeral. Funerals have a strange way of rearranging your sense of time. Everything slows down. The air feels thicker. Even gravity seems to press differently on the body. I remember looking at the ground and realizing how much of our rituals depend on it. The simple act of burial, of placing something into the earth, only works because we live on a planet that holds us in place.

That thought stayed with me. What happens to mourning when you take away gravity? What happens to peace when nothing ever rests?

I began reading. First about the most beautiful cemeteries in the world, then about the architecture of silence, and eventually about structures built for space. Somewhere between those two worlds, between death and design, an idea started to form.

Death in space is inevitable. It sounds poetic, but it is mostly practical and terrifying. Accidents will happen. Radiation will take its toll. Human bodies will fail after long journeys. Yet burial, as we know it, cannot exist without air, soil, or microbial life. In a vacuum, bodies do not decompose.

Incineration consumes oxygen, which is too valuable to waste. Freezing and releasing bodies into orbit violates planetary protection rules and strips the act of any human meaning. A person should not become debris.

If we ever settle other worlds, we will need a place for the dead. Not digital archives or floating capsules, but real ground. A place with weight and ritual, a place that remembers stillness.

In space, nothing falls. Dust does not settle. Without gravity, even grief has no weight.

If we do not want our dead to float forever, we will have to invent gravity for them. Not mechanical gravity, but emotional gravity. A way to let matter return to matter again.

That is where the idea of the Bio Arboretum began to grow.

To answer one of the most overlooked inevitabilities of space settlement: death.

Bio-Arboretum –Extraterrestrial Memorial Ecology

The Bio-Arboretum is conceived as a bioregenerative memorial habitat for extraterrestrial environments such as the Moon, Mars, and future orbital stations. It integrates life-support engineering, biochemical processing, and human-centered design to address one of the most overlooked inevitabilities of space settlement: death.

On Earth, burial completes the biological cycle: organic matter returns to soil, microbes convert it into nutrients, and the atmosphere receives it back as oxygen and carbon. In space, none of these natural cycles exist. The Bio-Arboretum replicates this closed ecology in a controlled system. Each interment is treated not as waste but as a transfer of mass back into the settlement’s regenerative loop.

From a mission standpoint, the Arboretum fulfills both operational and psychological objectives. Operationally, it ensures safe containment of biological material while recovering usable elements like nitrogen, phosphorus, and calcium. Psychologically, it restores the human connection to ritual, continuity, and meaning, giving future settlers a place where loss feels grounded even on worlds without ground.

Environmental Integration

The Arboretum is built as a pressurized annex to the main habitat. It connects directly to the Environmental Control and Life Support System (ECLSS), sharing its air revitalization, thermal regulation, and water recovery circuits.

The internal atmosphere maintains near-Earth conditions: one atmosphere of pressure, twenty-one percent oxygen, and relative humidity around fifty percent. This controlled environment supports photosynthetic vegetation that simultaneously serves as the emotional and ecological core of the memorial space.

Thermal energy from the Arboretum’s bioprocesses is recycled through a liquid heat-exchange loop. The alkaline hydrolysis reaction that breaks down organic matter generates significant heat, which is captured and redirected to warm the habitat’s life-support systems. This design minimizes energy loss and demonstrates mass-energy conservation within a closed ecosystem.

PhaseI. Biological Conversion

When a crew member or settler passes away, remains are transferred into a sealed bioreactor pod. Each pod is fabricated from corrosion-resistant Inconel alloy to withstand temperature, alkalinity, and pressure variations.

The decomposition process uses alkaline hydrolysis, a water-based chemical reaction that dissolves organic tissue in a heated solution of potassium hydroxide. The reaction converts proteins, fats, and carbohydrates into amino acids, soaps, and simple mineral salts. Over sixteen to twenty hours, more than ninety-eight percent of soft tissue is transformed into a sterile liquid.

This method is chosen because it requires minimal oxygen, releases no greenhouse gases, and operates under complete containment. Energy consumption averages eighty to one hundred kilowatt-hours per cycle. Heat exchangers recover up to sixty percent of that energy for reuse. The remaining solid output is a small quantity of calcium-phosphate ash, which is collected for mineral recycling.

The result is a pathogen-free effluent rich in essential elements for plant life —nitrogen, phosphorus, potassium, and calcium— ready to enter the next phase of ecological processing.

Phase II. Mineral Reclamation and Nutrient Integration

After hydrolysis, the effluent undergoes neutralization. Carbon dioxide from the habitat’s air system is bubbled through the liquid to reduce its alkalinity, forming carbonate salts and restoring pH balance. This process simultaneously helps scrub excess CO₂ from the living quarters, creating synergy between human respiration and the memorial system.

The neutralized fluid is then filtered and directed into a nutrient reservoir connected to the Arboretum’s hydroponic root beds. These beds replace soil with a porous medium through which the liquid circulates. The dissolved minerals supply macronutrients for plant metabolism, while sensors continuously monitor concentration levels and adjust flow through variable-speed pumps.

Because the chemistry of each reactor output is analyzed in real time, the nutrient balance is precisely calculated. Every atom that entered the reactor as part of a human body re-emerges in measurable form inside the life-support ecology. This establishes a mass-balanced biogeochemical loop, the same principle that underlies terrestrial ecosystems, replicated on another world.

Phase III. Bio-Regenerative Growth Chamber

Above the processing units lies the memorial canopy, a greenhouse-like dome that houses vegetation sustained by the reclaimed nutrients. The plant community is selected for both symbolic and functional purposes, species capable of efficient photosynthesis and emotional resonance.

Light is provided by tunable LED arrays emitting at photosynthetic wavelengths between 440 and 660 nanometers. At full intensity, each square meter of canopy produces approximately 0.8 grams of oxygen per hour. With twenty square meters active per interment, the Arboretum offsets the oxygen consumption of one human being for several days.

Humidity from plant transpiration is condensed, filtered, and returned to the station’s potable water supply. Nothing leaves the cycle. The Arboretum becomes an oxygen generator, carbon sink, and water recovery node, transforming remembrance into active resource regeneration.

Radiation Shielding and Structural Design

All biological and human material operations occur beneath a two-meter regolith cover that provides roughly five hundred grams per square centimeter of radiation shielding. This reduces exposure to galactic cosmic rays by over ninety-five percent.

The structural shell is an aluminum-lithium pressure hull lined with polyurethane impact foam for micrometeoroid protection. An internal reflective coating maintains thermal equilibrium and disperses radiation evenly to prevent hot spots.

Temperature is maintained between eighteen and twenty-four degrees Celsius using closed-loop liquid thermal control. Sensors distributed throughout the structure continuously report thermal gradients to ensure biological stability and material safety.

This robust construction not only shields the living systems but ensures planetary protection compliance, guaranteeing that no biological material or microbe escapes containment into the external environment.

Control Architecture and Fault Tolerance

The Bio-Arboretum operates autonomously through a multi-tiered control hierarchy modeled after spacecraft flight software.

At the lowest level, radiation-hardened microcontrollers manage essential safety functions: pressure regulation, heating, and power distribution. These systems can independently execute shutdowns or restarts without external input.

Above them, industrial-grade flight computers handle advanced modeling, sensor fusion, and data management. The software architecture is modular and fault-tolerant. Each subsystem runs as an isolated service, monitored by watchdog processes that automatically restart any failed function.

Cross-communication between controllers occurs through redundant Ethernet and CAN buses. Every critical operation can continue after the loss of any single processor, cable, or power path. In the event of high radiation flux or memory corruption, the secondary system takes over within seconds.

All telemetry is serialized in protocol buffers, logged locally, and transmitted through the main communication array with forward error correction. This ensures that even over millions of kilometers, Earth operators receive precise, uncorrupted data about the state of the Arboretum.

Human Factors and Cultural Continuity

While its subsystems operate like a machine, the Bio-Arboretum is built for people. The interior experience is designed as a pressurized biophilic chamber that supports ritual and reflection. Crew members enter through an airlock, remove helmets, and encounter greenery, filtered light, and silence — elements proven to reduce stress and maintain psychological stability in isolated environments.

Each memorial tree or plant is associated with a nameplate and a digital archive stored within the station’s data system. The space serves as both oxygen farm and memorial hall, integrating utility with emotional necessity.

By merging technical precision with cultural empathy, the Bio-Arboretum transforms burial into participation in the life cycle of the habitat. It becomes proof that even in engineered environments, the human story continues in full circle — energy, matter, and memory conserved together.

Final Note

The Bio-Arboretum represents a new category of extraterrestrial infrastructure: the life-support memorial system. It converts seventy kilograms of human organic matter into oxygen, water, and plant biomass without releasing pathogens or contaminants.

From a systems engineering perspective, it demonstrates that life support and memorialization can coexist in a single closed loop. From a human perspective, it gives settlers a sense of permanence and gravity in a place that has neither.

In the long term, modules like the Bio-Arboretum could extend beyond Mars or the Moon. They could become part of generational ships, orbital colonies, or asteroid bases, where every loss sustains the continuity of the mission.

It is not only a technical innovation but a moral one, a reminder that wherever we go, we will bring both life and death with us, and it is our responsibility to design for both.

This is an open-ended, ongoing essay of thoughts written by Marie Roohi.