In 2002, NASA and the National Research Council, at the National Academy of Science, attempted to throw open the doors of publicly organized space science research through the Solar System Exploration Survey, also known as the SSE Survey. Anyone was allowed to provide input, although the emphasis was on polling the planetary science community to try and get a sense of what the most important items for NASA research should be going forward. Currently, another report is being prepared for 2011, with public and scientist input, known as the SSE Survey (after the original) but technically as the Decadal Survey project.
– About the SSE Survey –
According to SSE survey committee chairman Michael Belton, the original survey succeeded in identifying twelve basic questions of overriding importance, grouped into four themes: the origins of the solar system and the planets, the origins of life, the evolution of worlds capable of supporting life, and some of the fundamental dynamics of how planets and solar systems function.
In practice, of course, these areas of inquiry overlap significantly. First, the survey recommended investigating how planets and moons first formed (a second question specifically asked how Jupiter formed, and what distinguishes gas giants Jupiter and Saturn from the ice giants, Neptune and Uranus), and how – and how quickly – the extremely high rate of bombardment by asteroids and comets in the early system declined to the relatively slow and stable rate today.
Second, the survey report suggested that scientists develop a history of water in the solar system, and also of organic compounds, generally recognized as the fundamental chemical building blocks of life. In order to do this, planetary scientists would need to build new planetary histories with a focus on how the prevalence of such volatile materials developed, or did not, on various planets. All of these questions indirectly involve the origin of life, although the survey did not leap further to the question of how having these building blocks present might have transitioned into actual formation of life (from a planetary science perspective, this is a biological matter which is simply assumed to occur, more or less often, once the building blocks are present).
Third, the survey turned to questions about how life could thrive, asking for a more realistic understanding of where in the solar system (other than Earth) life might plausibly develop, and what planetary processes are basic necessities for habitability. As a corollary, it also asked what features of the solar system could threaten life, including life on Earth. The most obvious threat, of course, is posed by asteroids or comets which could collide with a planet or moon and threaten the life on its surface. This has happened on Earth in the past, causing massive extinction events. Why, moreover, does Earth seem to be so different from Mars and Venus? So far as we knew a decade ago, all of them were more or less within the thin, life-supporting band where the Sun’s heat is neither too hot to fry the planet (e.g. Mercury) or too insufficient to warm it (everything past the Asteroid Belt).
Finally, the survey asked about planetary dynamics, inquiring into how the planets interact today as well as how the dynamics of our own solar system compare to what we are now beginning to learn about other solar systems.
– The Same Dilemma: Search for Life, or Survival? –
There are scientists who have built their entire careers focussing on subjects which only fit within one or two of these questions, so, of course, there are going to be widely differing opinions as to which is most important. Nevertheless, looking at the questions as a whole, deciding which is most important leads straight back to an ancient debate about the whole purpose of space science – one which has echoes in most other controversies, including whether SETI is a good idea. In short, given a still-limited amount of funding for and public interest in space research, should we be focussing on the short-term survival of the human race, or should we be trying to find out whether the human race is unique?
If it’s survival that takes priority (and there are good reasons why it should), then the most important question is one tucked into the section on habitability: what threats does Earth face? Actually, we have a reasonably good idea of the most important of those threats: near-Earth objects colliding with the planet and causing global devastation. However, we still have little more than vague theories about what to do if we find such objects, our catalogue of potentially Earth-threatening objects is still woefully incomplete, and no political effort at all has gone into building international structures to coordinate a response in advance. Ultimately, this is more than a scientific question, of course, which is why it is easy to have it shuffled aside.
On the other hand, if the most important reason to look at other planets is to try and guess whether there is other intelligent life out there like us (and there are many who feel this is one of the most important meaning-of-life questions we can ask at this point in our evolution), then other questions must take priority. In particular, we absolutely must know whether life exists beyond Earth, although we can get to the point of asking those questions, some more fundamental ones – those about the history of water and of organic compounds, both of which life as we know it cannot exist without – need to be answered first.
Other questions clearly, if reluctantly, may be of somewhat lesser priority. A longer-term view could legitimately argue that we can’t ask questions about life and habitability (the second and third themes) until we know more about planetary and solar system dynamics (the first and fourth themes). However, until we have better means of studying other solar systems, these may be questions we simply cannot answer as easily.
