Algae-powered bioreactor on space station could be oxygen, food source for astronauts

Astronauts are yet to try it in a meal but can definitely survive on it for protein if required.

There's a new experiment that floating into the zero-gravity environs of the Space Station laboratory. On 6 May, astronauts welcomed the 'photobioreactor' — a reactor powered by algae to convert carbon dioxide to breathable oxygen on longer flights.

The photobioreactor experiment is a big step in space research towards engineering advanced life-support systems for astronauts to survive for longer periods of time in space without the need for frequent resupply missions from Earth.

This technology could be a big part of making missions to the moon or Mars sustainable. These longer missions could last months or years on end, and call for more supplies than a spacecraft can carry. An algae-powered bioreactor could reduce the amount of machinery or power required for oxygen supply and climate control in a spacecraft, the German Aerospace Center (DLR) explains in a statement.

Algae-powered bioreactor on space station could be oxygen, food source for astronauts

The PBR@LSR experiment housed on the ISS in a standard housing called a mid-deck locker. In the middle you can see the actual bioreactor glowing green. Image credit: Airbus Defense and Space

The algae that powers the bioreactor belongs to the Chlorella vulgaris species, which is resilient and has been researched extensively on Earth. These tiny aquatic in the reactor use photosynthesis (like leaves do) to produce oxygen if it is supplied with light and a nutrient solution. The freshwater algae is also edible. Astronauts at the space station are yet to try it in a meal, but can, in principle, survive on it if required. Roughly 30 percent of an astronaut's diet can be replaced by algae due to its high protein content, according to the DLR statement.

For now, the photobioreactor works in tandem with the air-recycling system — the Advanced Closed-Loop System (ACLS), which reached the space station in 2018. The ACLS uses some of the carbon dioxide from the space station cabin to extract methane and water from it. The water made using the ACLS is then fed back into the machine to produce oxygen by splitting the hydrogen and oxygen molecules in water. Using the ACLS has minimised the need for water supplies delivered from Earth.

The algae in the photobioreactor will now process some more of the carbon dioxide and produce oxygen, complementing the ACLS system's working. This hybrid system goes by the name "PBR@ACLS" — the physicochemically-based ACLS system. For the first time, this unit will demonstrate a hybrid life-support system under real space conditions.

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