The search for life is a major aspect of astrobiology that many researchers are still trying to grasp the concept of, and the complexity of the entire endeavour begs a critical question as to where we are to search. Exploring our Solar System versus exploring interstellar space and other worlds, have varying pros and cons to supplement their respective arguments, and will be explored in this blog post.
Sullivan and Carney (2007) attempt to make light of the numerous definition-theories for what life is, but in conclusion there is no real current standing definition that becomes a general consensus for all. Without a complete qualitative, or even quantitative, framework to guide our search, it leaves us with these two broad options with no real ability to narrow down our search to the level we would like.
The Solar System has an attraction to it from an exploratory perspective. On astronomical distances and timescales, our backyard is appealing due to the ability we have to send humans to places like Mars or even the Moon. Arguably, the outer Solar System is a stretch from our current technological standpoint but is within reach in comparison to exoplanets. Major missions such as the 2020 Mars mission, and Elon Musk’s vision to send humans to Mars by 2030, are the forefront of our exploratory ability to search for life in our Solar System. While they are not exactly a ‘cost-effective’ approach to searching for life and whilst we have not definitively found a definition for life, it provides an advantage from a scientific perspective with the ability we have to conduct more in-depth studies.
Expanding on the Solar System, there are prospects such as Enceladus or even Europa which many researchers such as McKay et al. (2014) and Lorenz (2016) suggest are appropriate targets for the search for life. Whilst an issue of sending manned missions on a relatively reasonable timescale, the ability to send probes to these icy moons with the appropriate equipment is something we are able to do. Understanding the processes on these icy moons and comparing them to that of Earth-like processes may give us just as great insight into the search for life, as a manned mission to Mars.
The boom of exoplanet discoveries in the past two decades has allowed astrobiology to flourish in correlation as an interdisciplinary scientific field. Seager and Bains (2015) illustrate interplay between scientific disciplines in the assessment of habitability on exoplanets and compliments this notion with remote sensing techniques currently serving our best bet in assessment. While distances between Earth and these exoplanets are extremely large and unfeasible in reaching from technological constraints, the assessment of these worlds largely increases our chances of not only detecting life but can remove variability factors from our framework which may alleviate the problem of defining what life, and its constituent processes, is.
Where does this leave us in terms of searching for life? Whilst exoplanetary research is beginning to pick up and shows promise in terms of widening our scope for ascertaining what life is, there is always the lingering notion of uncertainty as being so far away increases this factor ten-fold. In comparison, the Solar System, whilst not as biologically or chemically variable as the millions and billions of exoplanets in the Universe, will still provide the necessary insight into our search, particularly with where we stand technologically. It will still have a factor of uncertainty as to how definitively we could conclude something is life, if we were to find anything at all, but is significantly reduced by our ability to be physically present for in-depth searches particularly on Mars. I particularly believe that the search should start in our Solar System, and from there, until we are able to define what life is, or at least constrain its definition a little more, we can then narrow our prospective exoplanetary searches.
I enjoyed reading your post, you did good leave nothing out. You presented two ideas and explored them both with resources. I agree that "our back yard" is more appeasing yet exploring exoplanets increases the probability.
I agree with you on Solar system exploration first, and like dominoes everything will fall into place. Everything we learn and engineer from exploring our solar system can be applied to meaningful exoplanet exploration.