Eu:CROPIS (Euglena and Combined Regenerative Organic-Food Production in Space) was a life science satellite developed by the

German Aerospace Center The German Aerospace Center (german: Deutsches Zentrum für Luft- und Raumfahrt e.V., abbreviated DLR, literally ''German Center for Air- and Space-flight'') is the national center for aerospace, energy and transportation research of Germany ...

(DLR) and intended to investigate the possibility of growing plants (specifically

tomatoes The tomato is the edible Berry (botany), berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to th ...

) in different levels of gravity, such as that of the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

and

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

, as a

sustainable food A sustainable food system is a type of food system that provides healthy food to people and creates sustainable environmental, economic and social systems that surround food. Sustainable food systems start with the development of sustainable agr ...

source using human urine for moisture and as the source of fixed nitrogen.

Overview

This orbital mission was intended to simulate and teste two

greenhouse A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of Transparent ceramics, transparent material, such as glass, in which plants requiring regulated climatic condit ...

s that could be scaled up and assembled inside a lunar or Martian habitat to provide the crew with a local source of fresh food, while recycling human urine into

fertiliser A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...

. Some microorganisms would be added to convert synthetic urine into easily digestible fertilisers for the tomatoes. The aim was to develop a stable, closed-loop, bio-regenerative

life support system A life-support system is the combination of equipment that allows survival in an environment or situation that would not support that life in its absence. It is generally applied to systems supporting human life in situations where the outsid ...

functioning in low gravity. In more detail, porous lava stones were fitted in trickle filters and dried soil containing normal soil microbial colonies. Microbes would then use nitrite () to convert the harmful ammonia ( ) into nitrate (), which is then added to six

tomato The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word ...

seeds as liquid fertiliser. In addition, the system incorporated a colony of the single-cell microorganism '' Euglena gracilis'', a

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...

algae able to produce oxygen and

biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...

while protecting the entire system against high ammonia concentrations. This oxygen is necessary for the conversion of urine to nitrate until the photosynthetic oxygen production by the tomatoes is sufficient. The spacecraft was designed replicate lunar gravity on one greenhouse for a period of six months before simulating Martian gravity on the second greenhouse for the next six months. The level of gravity on the Moon (0.16 g) and Mars (0.38 g) was simulated by rotating the spacecraft's cylindrical body around its longitudinal axis. The various payload experiments were placed in different areas within the cylinder. Tomato seed germination and plant growth were monitored with 16 cameras, while the RAMIS (RAdiation Measurement In Space)

radiometer A radiometer or roentgenometer is a device for measuring the radiant flux (power) of electromagnetic radiation. Generally, a radiometer is an infrared radiation detector or an ultraviolet detector. Microwave radiometers operate in the microwave w ...

s monitored the radiation inside and outside the spacecraft. The greenhouse was made of clear

polycarbonate Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, tough materials, and some grades are optically transparent. They are easily work ...

, with an approximate volume of . The closed system featured moisture, pH, oxygen, pressure and temperature sensors, and was capable of controlling these parameters. Four small fans created airflow through a cooling device to maintain a stable "atmospheric" temperature. On top of the greenhouse, three lamps provided light in the correct spectrum for photosynthesis. Scanners and fluorometers measured cell density and photosynthetic yield. The fluids were to be monitored with seven electrodes to measure ammonium, nitrite, nitrate, pH, chloride, sodium, and potassium. To monitor the health of ''Euglena gracilis'', the system also analysed the microbes'

mRNA In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of Protein biosynthesis, synthesizing a protein. mRNA is ...

to determine which proteins —and therefore which

genes In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

— were being commanded into action.

Objectives

The aim was to develop a stable, and

symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

biological

while being exposed to gravity levels similar to those on the lunar surface as well as the surface of Mars. Both phases of experimentation would last for six months. With water being the only component that has been recycled so far and all other components being extracted and disposed, processing of urine is an issue in human space flight. Eu:CROPIS was intended to examine the possibility of using previously disposed waste to grow fruits and vegetables after proper conversion. Two life support systems (a nitrifying trickle filter system and the single-celled algae '' Euglena gracilis'') within the satellite were to be used for producing

out of artificial urine in a closed system. Furthermore, the algae ''Euglena gracilis'' would protect the biosystem against high levels of ammonia present in urine.

Supporting science payloads

* PowerCell (Payload 2, from NASA Ames Research Center) will investigate the performance of microbial mini-ecologies. These will contain the carbohydrate (sugar) products of photosynthesis, which will feed ''Bacillus subtilis'', a robust bacterium commonly found in soil and the gut, which has already proven that it can withstand the rigors of space while in the spore form. A second objective of the PowerCell Payload is to conduct synthetic biology remotely in outer space. The basic technique for introducing genetic material into a living cell, called

transformation Transformation may refer to: Science and mathematics In biology and medicine * Metamorphosis, the biological process of changing physical form after birth or hatching * Malignant transformation, the process of cells becoming cancerous * Trans ...

, involves the transfer across a cells encasing membrane of genetic material. The PowerCell payload will examine if and how reduced gravity levels affect transformation processes. The third objective is to test protein production under different gravity regimes. Using the tools of synthetic biology, ''B. subtilis'' was engineered to produce several proteins which will be produced at the three different space gravity regimes. The ability to make proteins in space will be fundamental for human exploration, as proteins will be used to produce a range of critical substances, from on-demand food and vaccines to building materials. * Radiation Measurement in Space (Payload 3) has the goal of collecting data on long-term exposure to

cosmic radiation Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...

over the course of the space flight * SCORE (Payload 4) is a technology demonstrator for next generation on-board computing in hardware and software developed by the DLR Institute of Space Systems. It is complemented by a set of three cameras that are commanded via SCORE.

Satellite characteristics

Both the satellite and the experiment are called Eu:CROPIS. The satellite features four

gyroscope A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rota ...

s, two

magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, o ...

s, three magnetic torque rods and a sun sensor in combination with a single-frequency Phoenix

GPS receiver A satellite navigation device (satnav device) is a user equipment that uses one or more of several global navigation satellite systems (GNSS) to calculate the device's geographical position and provide navigational advice. Depending on the s ...

for

attitude control Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle ...

. The power for the satellite is provided by an Electrical Power Subsystem, which includes a

lithium-ion battery A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It also se ...

and four deployable fixed solar arrays delivering an average of 520 W of power.

Results

The Eu:CROPIS mission ended on 31 December 2019. The three supporting payloads generated large amounts of data, but the eponymous Eu:CROPIS experiment failed to activate due to a software problem. The satellite is expected to slowly de-orbit over the next two decades before reentering Earth's atmosphere.

References