That's because any bacteria that may once have lived on the surface have long since been exterminated by cosmic radiation sleeting through the thin Martian atmosphere.
That's because any bacteria that may once have lived on the surface have long since been exterminated by cosmic radiation sleeting through the thin Martian atmosphere.
这是因为早期存在火星表面的细菌可能早就被轻易穿越稀薄的火星大气层的宇宙射线杀死了.