Exploring Science in Space: Why Experiments in Space Matter for Humanity

In the last decade or so, we've been observing the growing challenges of an increasing population and the effects of climate change, like frequent rains, floods, and droughts. These changes pressure us to feed more people while threatening how much food we can grow. This raises important questions for humanity: Can we sustain life beyond Earth? What does the future hold for life here on Earth?

In response, leading space agencies are working hard to find answers by combining knowledge from various fields, such as biology and engineering. This collaboration has led to the creation of a new field titled astro-bioengineering. For instance, experiments at institutions like the Ames Research Centre have examined how humans and plants can survive long stays in space. These studies are helping us figure out how to support long missions in space and even the idea of colonising other planets.

One interesting solution to the problem of feeding astronauts in space is microalgae-tiny organisms that pack a nutritional punch. Algae are rich in proteins, vitamins, minerals, healthy fats, and antioxidants. They grow quickly and are easy to handle, making them great candidates for space travel. Remarkably, algae also produce about half of the oxygen we breathe on Earth. By capturing sunlight, algae convert carbon dioxide and water into oxygen and biomass-a process known as photosynthesis. 

Interestingly, compared to other photosynthetically capable higher plants with a photosynthetic efficiency (PE) of just over 1%, these microalgae have a PE of 5.7%, indicating a CO2 conversion efficiency of over 6%. Algae are reported to convert carbon dioxide to microbial biomass, regulating the C: N ratio, potentially producing ~951 and ~909 191 g/day/ member of biomass and O2, respectively, which are significantly closer to the human metabolic requirements.  

The first time scientists confirmed that algae could thrive in space was in the early 1960s aboard the Soviet spacecraft Korabl-Sputnik 2. During various space missions, researchers have mainly studied different types of algae, including Chlorella and Chlamydomonas. While there are many challenges to growing living things in space-such as radiation, low gravity, extreme temperatures, and a vacuum-there are opportunities to utilise algae. Most experiments with algal sources have validated the hypothesis that photosynthetically active and inactive states can survive extended radiation, microgravity, and even vacuum (up to 12 months).

According to NASA Marshall Space Flight Centre reports, each human needs 0.84 kg of oxygen, 0.62 kg of food solids, and 29 kg of water daily. Autonomous biological LSS (BLSS) is believed to be the key to human long-term presence in space. Microbiologists are targeting the identification of superior strains of algae that can act as a good source for BLSS. 

Microbiologists have a crucial role in artificially selecting superior microalgae strains that can survive in these stressful conditions in space. A microbiologist's role involves screening for potentially superior microalgae strains by exposing algal strains to a new sub-lethal stressor. Some cells within a population may survive this challenge, adapt, and proliferate, passing on heritable variations to the next generation that could withstand the space environment. 

Microalgae have various natural metabolic pathways and precursors similar to those in higher plants. However, the range of metabolite types and synthesis processes in microalgae is limited. For example, a large-scale genomic study found no terpene synthesis genes in green algae. Microbiologists can use genetic engineering, synthetic biology, and antisense techniques to enhance metabolic pathways. In 2022, Zhao introduced the isopentenol utilisation pathway into Chlamydomonas through genetic engineering. NASA astronauts aboard the International Space Station (ISS) have been working to identify the genetic traits necessary to optimise the growth of Chlamydomonas in space. 

Additionally, NASA has initiated a project to utilise Haematococcus pluvialis to produce astaxanthin, a potent antioxidant that can support astronauts' health in the space environment. These experiments are exciting developments, and the expertise of microbiologists is invaluable in this research!

A microalgae system in space has the potential to reclaim substantial amounts of life-support materials that are essential for human survival. It could produce approximately 93% of the oxygen needed and contribute between 44% and 85% of food requirements. While these estimates may be unreal, they underscore the promising possibilities of sustainably integrating microalgae in space environments.

Algae are unique organisms with extraordinary potential to thrive in extreme environments. Microalgae, in particular, can recycle carbon dioxide into bioenergy and are 400 times more effective at fixing carbon dioxide than terrestrial plants. Research on microalgae in space has significant implications for sustainable growth on Earth and can aid in the fight against climate change by utilising resources from microbial systems. The biomass produced from algal biosystems can pave the way for a sustainable approach (Sustainable Development Goals, SDGs) to using biomass for biofuels.

Recommended Readings:

• Revellame, E.D. etal. Microalgae cultivation for space exploration: assessing the potential for a new generation of waste-to-human life-support systems for long-duration space travel and planetary human habitation. Algal Res. 55, 102258 (2021).

• Saei AA, Omidi AA and Barzegari A. Screening and genetic manipulation of green organisms to establish biological life support systems in space. Bioengineered 4: 65–71 (2013).

• Xie, X., Jaleel, A., Zhan, J., & Ren, M. (2024). Microalgae: towards human health from urban areas to space missions. Frontiers in Plant Science, 15, 1419157.

• Niederwieser, T., Kociolek, P., & Klaus, D. (2018). A review of algal research in space. Acta Astronautica, 146, 359-367.

• Hosny, S., Elshobary, M. E., & El-Sheekh, M. M. (2025). Unleashing the power of microalgae: A pioneering path to sustainability and achieving the Sustainable Development Goals. Environmental Science and Pollution Research, 1-31.