There are many extremophiles on Earth, some that roam the Sahara Desert and come out only for the hottest parts of the day and some that scale the coldest parts of the arctic. Extremophiles are an interesting phenomenon with applications to discovery of other life in the universe. If these organisms can survive in these extreme circumstances on Earth, who is to say that there are not similar organisms capable of survival in extreme conditions in space? Surviving in space is certainly a different feat than the Sahara or arctic, as space conditions are unpredictable, reaching extreme high and low temperatures and pressures. There are however, polyextremophiles, such as water bears which can survive a variety of extreme conditions. Water bears have even survived exposure to space, including radiation, solar winds, and an oxygen deprived vacuum. The existence polyextremophiles leads us to question if life on other planets is more likely than we think, given the evidence that some unique organisms can survive in such extreme conditions.
Sources: Tardigrades: Water bears in space