2005j-936 2007g-524 2007j-905 2015b-544 adaptation adverseeffects aerospacemedicine animals astronautics astronauts cardiovascularphysiologicalphenomena cardiovascularsystem cellphysiologicalphenomena clinicalmedicine cosmicradiation diseases effectofspaceflighton erythrocytes evidence-basedmedicine exploration extraterrestrialenvironment fitness general governmentagencies governmentprograms gravitation gravity health internalmedicine juvenileliterature medical oxygenconsumption physiological physiology plantphysiologicalphenomena psychology radiationeffects reducedgravityenvironments research researchinreducedgravityenvironments riskassessment spacebiology spaceflight spacemedicine spaceradiobiology standards technology wd750b61052007 wd750i596p2005 wd751 wd751f9812006 wg102