In this study, we simulated space flight of the nematode, Caenorhabditis elegans, on the ground and examined how it is affected by space radiation and G-forces. We simulated G-forces during launch in a gravity acceleration laboratory device in order to identify and isolate the effects of the G-forces. Following this, we irradiated C. elegans with accelerated protons (MC-50 Cyclotron) and gamma rays (iR 222 machine) at the same physical dose. We calculated the expected radiation dose according to Reitz [1] and simulation programs (NASA AP8MIN [2], NASA AE8MAX [2], and CREAM86 [3]) for 1 month (dose rate: 6 × 10^-3 Gy; 2.8 × 10^-2 Gy), 6 months (dose rate: 36 × 10^-3 Gy; 16.8 × 10^-2 Gy), and 2 years (dose rate: 144 × 10^-3 Gy; 67.2 × 10^-2 Gy) of space flight. There have been several trials that aimed to take C. elegans into orbit on US space shuttle missions including a mission on the shuttle Columbia. In this study, we simulated longer duration space flights and performed a whole-genome microarray analysis to observe phenotype variations whereas most such experiments were carried out during short duration space flights and focused on mutations and genotypic variations. We expect that the results of this study will be useful to predict the effects of long-term exposure of space radiation on living organisms.