Astropaleobiology is a new concept in science with the flurry of exploration to find evidence of life in the solar system, if not the universe. It is a multidisciplinary approach, and even is in the same stride as SETI in finding intelligent life in the universe. The underlying theme to both is if life cannot be proven to exist today, it may have existed in the not to distant past or even billions of years ago.
It would appear that astropaleobiology and astrobiology are the two branches of science that will play the pivotal role in the search for life, past or present, in the universe. NASA and other organizations around the world have plans for the establishment of an Astrobiology Institute, which would also incorporate astropaleobiology. The current focus is Mars, since both Earth and Mars have similar planetary geologic histories, albeit with certain dissimilarities. The failed early NASA missions, including the Viking and Mariner spacecrafts, to find current evidence of life has turned the focus onto astropaleobiology. The goal now is to search for evidence of former life, as well as continued search for present life. The emphasis on astropaleobiology blossomed recently with the discovery of a meteorite from Mars had the fossil imprints for life on the planet in our Archaean time frame. Life is known to have been present on Earth that far back, and evidence supports it on Mars as well. Of course this still remains in debate, but the finding has fueled the focus on astropaleobiology.
This has also prompted another consideration for scientist. The studies of the meteorite has now expanded into the thinking that microbes may be able to transport between planets by meteorites, forming a connective link between planets. This is probably putting the cart before the horse, but it exemplifies the type of scientific thinking which has brought astropaleobiology to the forefront in the search for life in the universe.