“…Thus, human habitats and crop-growth modules very likely will be sheltered or located underground (ACCESS Mars, 2009). Moreover, sunlight will be reduced or not available at all times due to local conditions such as long dust storms on Mars, the periodically increased distance between Mars and the Sun, or extended dark periods on most locations of the Moon (Cockell and Andrady, 1999;Cockell, 2001;Horneck et al, 2003;Rontó et al, 2003;Salisbury, 1992;Wheeler, 2004), making electric lighting a more reliable option for growing food plants in space (Massa et al, 2006). However, it has been estimated that 40 to 50 m 2 of cropping area, in continuous use, would be necessary to fully sustain each crew member (Mitchell et al, 1997), which would require considerable energy for a traditional electric croplighting scenario (Drysdale, 2001).…”