Introduction
Our mission has a two-fold goal. First, we aim to generate a systematic view of the yeast proteome in flux, in unprecedented scale for space missions, through a process that may shed light onto the effect that Low Earth Orbit (LEO) conditions have on human cells. Second, we seek to demonstrate that Lab-on-a-chip technologies can be reliably employed aboard CubeSats to multiplex experimental designs and usher in a new era of approachable, low-cost, high-throughput space biology.
The Science Unit is tasked with realizing the research mission, i.e. designing the satellite payload as well as defining all experimental procedures and subsequent data analysis. Toward that end, we utilize theoretical and engineering knowhow across a broad interdisciplinary spectrum to integrate novel technologies, while circumventing the strict limitations imposed by space conditions. A skunkworks R&D subteam at heart, we work on genetically engineering yeast cells, engineering a system-compatible microfluidic continuous culture system and an in-house miniaturized imaging system, among others.
We sincerely hope our mission will attest to the potential of CubeSats as a new scalable and reliable “chassis” for space biology research and provide a stepping stone for increased engagement from research teams across the globe, given that both the payload and the supporting platform will be open source. Every single aspect of mission design and implementation, from source code to protocols to design drawings and schematics is and will be open and accessible for all.
The members of our interdisciplinary team work on the following:
Genetically engineering yeast cells…
…to emit fluorescent signals as markers of gene expression and DNA damage. To that end, we are using the Yeast GFP Library, which is a collection of yeast strains identical to each other except that in each strain a different protein is tagged with a fluorescent protein (GFP), covering overall the entire yeast proteome. This tagging method is complemented with a systematic approach to identify the genes to be studied.
To study radiation and microgravity combined effects, the team is re-engineering a previously used DNA damage memory circuit. This is a synthetic circuit that essentially “hijacks” the cell’s DNA damage signalling cascades to actuate a positive feedback loop, leading to the production of a fluorescent protein, eventually identifying the cells in which mutations have occurred along with their progenies.
Microfluidic continuous culture system
The accommodation of the concurrent growth of multiple Library strains is realised via the use of a state of the art Lab on chip technology, namely a microfluidic chip. This platform enables the culturing of multiple yeast strains in tandem, while avoiding cross contamination.
Our microfluidic system is inspired from the biodisplay array described here and is designed for storage and culturing of over 190 different yeast strains, in duplicate. Solenoid valves and micropumps are used to control the chip and regulate the flow of sterilized growth medium along the bottom flow channels. Sterilized growth medium and waste are stored in medical-grade, sterilized bags.
Miniaturized fluorescence microscope
A digital epifluorescence microscope aims to capture real time images during in-orbit yeast culturing to measure the fluorescence intensity of each yeast strain’s population. Towards that, our imaging system is designed to perfectly fit within our nanosatellite’s space constraints. Fluorescent images comprise our mission’s scientific results and thus image processing is also a procedure our subsystem is responsible for.
Ensuring the essential conditions for cell growth in space
To withstand launch conditions and achieve long-term storage, sporulation of yeast cells is performed. The experiment is taking place in a pressurized payload container (1 atm), which takes up the space of almost 2 units and will run at 3 distinct time-points. A number of sensors are in place inside to measure pressure, temperature and humidity. The temperature required for optimal yeast growth is 30 oC and is achieved by employing a thermal control scheme, consisting of a heater, on-chip temperature sensors and a software-implemented PID controller.
