&lt;p&gt;BioSentinel technology will provide critical information about how living systems, from humans down to cells, adapt, respond and survive in deep space, beyond LEO furthering our understanding of radiation effects on biological systems and the potential countermeasures needed to enable future deep space exploration missions.&amp;nbsp; Using autonomous 6U Cubesats is an innovative, low-cost, low-risk, high pay-off approach to conduct research and technology investigations.&lt;/p&gt;&lt;p&gt;DNA double-stranded-breaks (DSB) repair exhibits striking conservation of repair proteins from yeast to humans.&amp;nbsp; The BioSentinel project uses yeast not only because of its similarity to cells in higher organisms, but also because of 1) the well-established history of strains engineered to measure DSB repair, 2) yeast&amp;rsquo;s flight heritage, and 3) the wealth of available ground and flight reference data. &amp;nbsp;&lt;/p&gt;&lt;p&gt;One &lt;em&gt;S. cerevisiae&lt;/em&gt; flight strain will contain engineered genetic defects to prevent growth and division until a radiation-induced DSB near (~1000 bases) the target genes activates the yeast&amp;rsquo;s DNA repair mechanisms: culture growth and metabolic activity will indicate directly a DSB and its successful repair.&amp;nbsp; In parallel, a different yeast strain that cannot repair DSBs will provide survival curves: increased space radiation-induced DSBs cause decreased cell survival. &amp;nbsp;Each of the multiple yeast strains is carried in multiple independent culture wells, subgroups of which are activated at multiple time points over a 6 &amp;ndash; 18-month mission.&amp;nbsp; The instrument monitors each subgroup of 12 culture wells continuously for 4 weeks, tracking cell growth via optical density and metabolic activity using a viability dye: &lt;em&gt;growth indicates DNA damage and repair&lt;/em&gt;.&amp;nbsp; A payload containment designed for minimal shielding of the cells provides biologically significant radiation doses in orbits beyond LEO.&amp;nbsp; Far higher doses can be expected during a solar particle event (SPE), triggering additional measurements by our biosensors.&amp;nbsp; The DSB rate in space will be compared to (a) physically measured radiation dose, (b) studies conducted in terrestrial radiation facilities, and (c) models of expected DNA damage-and-repair rates.&amp;nbsp; Due to the unique composition, flux, and energy distribution of space radiation, it is expected that the radiation-induced responses in space will differ from ground-based data.&lt;/p&gt;&lt;p&gt;The results will be critical for improving interpretation of the biological effects of space radiation exposure, and to reduce risk associated with long-duration human exploration.&amp;nbsp;&lt;/p&gt;&lt;p&gt;&amp;nbsp;&lt;/p&gt;