[Germany] Is space an alternative when the City of the Future becomes too crowded? Years will have passed by the time astronauts embark on their way to Mars. But scientists at the University of Stuttgart are already developing life-sustenance systems to ensure nourishment and oxygen during missions which may last for years.
It looks so easy in the movies: astronauts sit there comfortably in a stylish lounge, and if one of them has sudden hunger pangs, he just presses a button. After a few seconds of humming and buzzing, a tasty meal is in front of him. Jens Bretschneider and his colleagues at the University of Stuttgart’s Institute of Space Systems (IRS) can only smile at such Hollywood ideas. The reason: astronauts on their way to Mars will probably have to do without veal cutlets with French fries and salad.
Researchers at the IRS are coming step by step closer to the optimum space diet: not least in importance on the menu will be: algae, fresh-grown on board the spaceship! Bretschneider reaches into his desk drawer and pulls out a package of dark-green granulated material. “These are spiruline algae, try them!” says Bretschneider, a doctoral student from Dresden, and shakes out a few grains into the visitor’s hand. The dried algae taste nutty and a little salty. Nothing that would rejoice a gourmet, but certainly an important, natural source of protein.
Bretschneider uses a simple example to answer the question why nutrients like algae, unusual at least for the European palate, should be part of the basic menu during space flights: a flight to Mars will take about 300 days, after which the astronauts will conduct research on the planet for about the same length of time and then fly back for nearly another year. That quickly makes it clear that it will be impossible to send up enough provisions with them into space, especially since spaceships always have a dearth of room. Thus the idea is almost automatic that astronauts should also become part-time food producers. Algae can make this especially effective.
Two “photobioreactors” currently make soft blubbering sounds to themselves in the research group’s laboratory. When this clumsy name is broken down, it turns out to reveal containers in which living microorganisms flourish under the influence of light. In the reactors, which resemble strange-looking bathwater boilers, gas bubbles move about through a dark-green liquid – or to put it more precisely, a mixture of micro-algae and a nutrient culture. “Here is our favorite alga, the Chlorella vulgaris“, says Bretschneider. A single-cell green alga, it is very easy to care for and eat, with a high percent of protein. The algae are irradiated in the laboratory with artificial light. How they can receive sufficient photons later on in space to spur them to multiply abundantly has still not been decided. Approaches that include coating the reactor’s surfaces with organic light-emitting-diodes (OLEDs) are under discussion.
A single-cell green alga, it is very easy to care for and eat, with a high percent of protein. The algae are irradiated in the laboratory with artificial light. How they can receive sufficient photons later on in space to spur them to multiply abundantly has still not been decided. Approaches that include coating the reactor’s surfaces with organic light-emitting-diodes (OLEDs) are under discussion.
Tested under Weightlessness
Currently, however, the researchers have other challenges. As Bretschneider explains, “This kind of test reactor would be far too small to provide a human being with protein.” In addition, the test reactor and its spontaneously rising gas bubbles could not function without gravity. For that reason another reactor system in which a pump carefully stirs the nutrient culture was tested in 2014 during about 30 seconds of weightlessness in a parabolic flight. The aim now is to improve the pump’s performance to a point where the algae and the nutrient solution (similar to seawater in the case of Chlorella vulgaris) flow uniformly. In addition, the system’s footprint must be reduced to a minimum and must run so stably that the astronauts need to check it at most only occasionally.
Other research efforts are underway parallel to this, especially since the photosynthesis upon which algae production is based has welcome side effects: it absorbs carbon dioxide from respiratory air on board and simultaneously generates oxygen. This can not only be added to the respiratory air but can also be converted with hydrogen in fuel cells to electrical energy and heat.
Bretschneider thinks that in a few years these systems could be far enough advanced for a test flight to the International Space Station (ISS). It will be 2025 at the earliest before they are mature enough for use in a long-term flight in space – but in any case there will not be a Mars mission before that time.
Photo: IRS team member Jens Bretschneider at a photo-bioreactor in which living microorganisms flourish with the help of light. © Jens Eber
View original article at: Scientists in Stuttgart are developing sustenance systems for life in space