Volume 8 (2020): Issue 1 (May 2020)

In this work, we report on the construction, training and functional assessment of an electronic nose (called ‘E-Nose’) that is capable of monitoring the microbial contamination onboard space ships under microgravity conditions. To this end, a commercial electronic nose was modified to allow for the sampling of microbial volatile organic compounds (MVOCs) emitted from relevant bacterial and fungi species. Training of the modified ‘E-Nose’ was performed by establishing an MVOC database consisting of two Gram-positive bacteria strains (Bacillus subtilis and Staphylococcus warneri) and two fungi strains (Aspergillus versicolor and Penicillium expansum). All these strains are known to exist onboard the International Space Station (ISS) and to form important parts of its microbial contamination. All cultures were grown on four kinds of structural materials also in use onboard the ISS. The MVOCs emitted during the different growth phases of these cultures were monitored with an array of ten different metal oxide gas sensors inside the ‘E-Nose’. Principal component analysis of the array data revealed that B. subtilis and S. warneri form separate clusters in an optimized score plot, while the two fungi strains of A. versicolor and P. expansum form a large common cluster, well discriminated against to the bacteria clusters.

NASA is planning to launch robotic landers to the Moon as part of the Artemis lunar program. We have proposed sending a greenhouse housed in a 1U CubeSat as part of one of these robotic missions. A major issue with these small landers is the limited power resources that do not allow for a narrow temperature range that we had on previous spaceflight missions with plants. Thus, the goal of this project was to extend this temperature range, allowing for greater flexibility in terms of hardware development for growing plants on the Moon. Our working hypothesis was that a mixture of ecotypes of Arabidopsis thaliana from colder and warmer climates would allow us to have successful growth of seedlings. However, our results did not support this hypothesis as a single genotype, Columbia (Col-0), had the best seed germination, growth, and development at the widest temperature range (11–25 °C). Based on results to date, we plan on using the Columbia ecotype, which will allow engineers greater flexibility in designing a thermal system. We plan to establish the parameters of growing plants in the lunar environment, and this goal is important for using plants in a bioregenerative life support system needed for human exploration on the Moon.

Cell culture on orbit is complicated by numerous operational constraints, including g-loads on the ascent, vibrations, transit time to International Space Station, and delays in experiment initiation. Cryopreserving cells before launch would negate these factors. However, defrosting these cells is problematic, since the traditional method of employing a water bath is not possible. We here describe a unique apparatus designed to accomplish this in a microgravitational environment. This apparatus resulted in rapid defrost of cryopreserved cell cultures and allowed successful tissue culture operations on the station for periods of up to 21 days.

Recycling systems aboard spacecraft are currently limited to approximately 80% water recovery from urine. To address challenges associated with odors, contamination, and microgravity fluid flow phenomena, current systems use toxic pretreatment chemicals, filters, and rotary separators. Herein, a semipassive and potentially contaminant- and biofouling-free approach to spacecraft urine processing is developed by combining passive liquid–gas separation, nanophotonic pasteurization, and noncontact Leidenfrost droplet distillation. The system aims to achieve >98% water recovery from wastewater streams in zero, Lunar, Martian, and terrestrial gravitational environments. The surfaces of the phase separator are coated with carbon black nanoparticles that are irradiated by infrared light-emitting diodes (LEDs) producing hyperlocal heating and pasteurization during urine collection, separation, and storage. For the prescribed flow rate and timeline, the urine is then introduced into a heated 8.5-m-long helical hemicircular aluminum track. The low pitch and the high temperature of the track combine to establish weakly gravity-driven noncontact Leidenfrost droplet distillation conditions. In our technology demonstrations, salt-free distillate and concentrated brine are successfully recovered from saltwater feed stocks. We estimate equivalent system mass metrics for the approach, which compare favorably to the current water recovery system aboard the International Space Station.