Spaceflight hardware allowing unilateral irradiation and chemical fixation in petri dishes

Abstract

To accommodate a spaceflight experiment with moss (SPM), experiment-unique equipment (EUE) was developed by engineers at Kennedy Space Center. The hardware allows sterile culture for an extended period of time in commercial petri dishes, lateral illumination of each culture with light of a specific wavelength (660 nm; other wavelengths are possible) and a range of intensities (0.05–5 μMol photons m−2s−1), incubation in complete darkness, and chemical fixation to terminate the experiment under conditions of microgravity. The use of a fixative required triple containment to protect the astronaut crew. An external panel on the experiment container allowed the timing of illumination and fixation to be controlled by the crew. Light quality is provided by light emitting diodes (LEDs) that are located in the lid of the outer container, the BRIC (Biological Research In Canisters)-LED. Each canister accommodates 6 Petri Dish Fixation Units (PDFUs), and each PDFU holds one 6 cm petri dish. All components are autoclavable. LED illumination is piped through a transparent glass rod. Each PDFU contains fixative in a reservoir that is released by the depression of an actuator. This hardware performed well during its first flight, the 16-day STS-87 mission in Nov./Dec., 1997 as part of the Collaborative USA and Ukrainian Experiment (CUE). It supported vigorous and sterile moss growth, cells were maintained in position and were well-fixed, and there was a vigorous and consistent response to light. Although here used for moss, in future flight experiments this unique new hardware can be used for many types of organisms normally grown in petri dishes, with or without a requirement for illumination.