BioHome

Did You Know?

• CELSS was first pioneered by the Soviet Union during the Space Race in the 1950s–60s.
• The concept originated with Konstantin Tsiolkovsky and was furthered by V.I. Vernadsky.
• Crewed experiments in the BIOS-3 began in 1965.

Rationale

Human space presence has been limited to the Earth–Moon system, with all life-support supplies brought from Earth. This approach is not viable for long-term missions or settlements. CELSS aims to create a regenerative environment that supports human life through agricultural means.

Components of CELSS

In non-CELSS environments, air is replenished via stored tanks and scrubbers, which require refilling or replacement. Toxic fumes from synthetic habitat materials also need processing. In CELSS, air is initially supplied externally but maintained by foliage plants that produce oxygen through photosynthesis, using human respiration waste. The goal is for plants to fully take over oxygen production, making the system closed.

Food is typically freeze-dried for storage, but in a self-sustaining ecosystem, crops are grown in dedicated areas, with more crops needed for larger groups. Water is derived from air condensate and plant moisture, then filtered naturally or mechanically. Human wastes are broken down and integrated back into the ecology; urine is processed into water for toilets and plant watering. Wastewater treatment uses aquatic plants, whose root systems process the water, and the plants grow larger with more waste. In tests like those at BioHome, plants also produced compost usable as a growth medium for crops.

Closed versus controlled

Closed systems recycle everything indefinitely with no external interaction, but their life is limited by increasing entropy unless they accept external radiant energy and reject waste heat. Earth is an example. Controlled systems depend on periodic external maintenance, such as the ISS.