For these reasons, the existence of this organism, which is a bacterium called GFAJ-1, is being recognized as an astonishing discovery. For NASA, this information is relevant because it is allowing for the possibility of extraterrestrial life that is chemically built in a different way from life on Earth. In essence, it radically changes how we understand life to chemically be constructed, supporting the idea that extraterrestrial life does not have to resemble life on Earth.
However, this information is relevant to other areas of science as well. With respect to the idea of natural selection, the fact that GFAJ-1 is able to incorporate an otherwise dangerous element into its DNA - its most fundamental and basic component - means that it has found a way to survive when it is in an environment where phosphorus is not available.
The lack of phosphorus, as an environmental pressure, is one that otherwise would stifle all organic life as we know it. In other words, it is about as basic a requirement for life as there can be. At least this is what scientists thought until the discovery of GFAJ-1. The idea of natural selection says that environments decide which organisms are strong enough to survive, reproduce, and pass on their genetics, and which are not. If GFAJ-1 can survive by fundamentally altering its DNA so that it is unlike any other life on earth, it is filling an otherwise unoccupied niche, and therefore is securing its survival in a manner that undermines what were thought to be the limits of life.
So not only does the discovery of this bacterium greatly increase the possibility of finding life on other planets, but it demonstrates the lengths that the notion of 'survival of the fittest' can actually reach on our own planet.