Use of Photobioreactors in Regenerative Life Support Systems for Human Space Exploration

Abstract

There are still many challenges to overcome for human space exploration beyond low Earth orbit (LEO) (e.g., to the Moon) and for long-term missions (e.g., to Mars). One of the biggest problems is the reliable air, water and food supply for the crew. Bioregenerative life support systems (BLSS) aim to overcome these challenges using bioreactors for waste treatment, air and water revitalization as well as food production. In this review we focus on the microbial photosynthetic bioprocess and photobioreactors in space, which allow removal of toxic carbon dioxide (CO2) and production of oxygen (O2) and edible biomass. This paper gives an overview of the conducted space experiments in LEO with photobioreactors and the precursor work (on ground and in space) for BLSS projects over the last 30 years. We discuss the different hardware approaches as well as the organisms tested for these bioreactors. Even though a lot of experiments showed successful biological air revitalization on ground, the transfer to the space environment is far from trivial. For example, gas-liquid transfer phenomena are different under microgravity conditions which inevitably can affect the cultivation process and the oxygen production. In this review, we also highlight the missing expertise in this research field to pave the way for future space photobioreactor development and we point to future experiments needed to master the challenge of a fully functional BLSS.

Algae: Study of Edible and Biologically Active Fractions, Their Properties and Applications

“…Hydrocarbons, aldehydes, alcohols, and esters were identified in macroalgae S. thunbergii , G. lemaneiformis ( Rhodophyta ), and S. fusiforme . Hydrocarbons accounted for more than 60% of the total amount of components in the species P. yezoensis and U. pinnatifida ( Rhodophyta ) [ 211 ]. The fishy odor of these volatile compounds seriously affects consumer perception and limits the development of the edible algae industry; therefore, deodorization technologies need to be developed.…”

Shining a Light on Wastewater Treatment with Microalgae

“…Moreover, within those light wavelengths that can be used by photosynthetic microalgae, some wavelengths are better than others, and there is variation in which wavelengths are preferred by different species [ 41 , 46 ]. This means that supplying light energy of selected wavelengths can achieve the growth of microalgae more efficiently than using sunlight directly [ 37 , 47 ] and this approach has applications for growing microalgae in space as direct sunlight, especially in space, can be too intense to allow the growth of microalgae [ 48 – 50 ]. If the full spectrum of energy in sunlight were converted into electricity using solar, thermal or an equivalent technology, the resulting energy could be used to power light-emitting diode (LED) illumination 24 h per day to produce light of only selected wavelengths and at the minimum intensity required to achieve the robust growth of biofilm on surfaces that are internally illuminated.…”

The World Smallest Plants (Wolffia Sp.) as Potential Species for Bioregenerative Life Support Systems in Space

“…Arthrospira platensis (commonly referred to as Spirulina) is a current example. This filamentous cyanobacterium is the most widely cultivated photosynthetic prokaryote and is promoted as a candidate for BLSSs for space missions [3,10]. The present review focuses on additional new candidate crops, with attention to duckweeds (family Lemnaceae), and specifically the possible use of Wolffia species as plants to be cultivated in BLSSs in space.…”