Maybe life isn't so far away

Where should we look for life? 

Some exoplanets might be very good candidates for life, but why look so far away? There is one celestial body really close by that might hold some of our cousins. Mars is a great option, but only second best to Europa. Together with his three brothers, this Jupiter moon made a very important contribution to modern science. By observing them Galileo Galilei understood that not every celestial body orbited the Earth as was thought in his time. That led to the Heliocentric model and a better perspective of our place in the universe.
The potential of the next big Europa discovery might have a very similar effect as the Heliocentric model, and NASA plans to get us closer to finding life on this natural satellite. Europa holds such high hopes because it most likely has liquid water, and lots of it! Europa is basically an ocean world with a solid rock core an outer ice crust and a middle layer made of H2O, either in 'warm' solid or 'cool' liquid form. Although Europa is pretty far from the sun and thus not in the habitable zone (more on that later on) the gravitational pull of Jupiter together with the slight ellipticity cause the whole moon to expand and contract during its three and a half day orbit around Jupiter. This breathing cycle causes the icy crust to crack, allowing gases (oxygen, for example) to flow in and out from the inner layers, the moon scale 'pulse' also heats its inner areas, thus allowing the temperatures needed for running water. Unlike Earth, Europa has been very environmentally stable for the last 4 billion years, and if life on Earth can withhold 5 great extinction events think what could evolve in such constant living conditions. 

The fascinating tale of Europa was told to us by Dr. Jim Green, the head of NASA's Planetary Science division and basically the guy who decides on NASA's next missions to the solar system. In our discussion we also talked about the possibility of microbial life on Mars thanks to some liquid water the may lay just beneath the surface. We also talked a bit about terraforming some of our close neighbours like Mars or Venus. The second and fourth rocks from the Sun are just outside of our solar system's habitable zone, Venus is a little too close and Mars too far. But, perhaps, mankind could do to them what, for better or worse, we are best at - reforming the environment around us.

Every star has a habitable zone. This ring perimeter is fondly called the Goldilocks area, where the distance from the star is not too close, not too far, but just right to have liquid water. The bigger the star, the hotter it is, the farther away we'd find Goldilocks. The galaxy actually also has it's Goldilocks area, but that is a discussion for another day. As mentioned before M class stars are smaller and more abundant than our G class sun. Their size makes them cooler (4000 vs 5800 Kelvin) and thus puts their habitable zone closer in. This means a habitable planet would have a shorter yearly cycle because of the small orbital radius and thus would transit the star often, allowing transit detector telescopes to find them. But the problem with M class solar systems is that the proximity of the habitable planets to their host stars sets them in a place where they're bombarded with solar radiation, so the life that might be found on these planets would be very immune to radiation. The M class system search is the objective of the K2 'second light' mission, but Kepler's original mission was to find planets, hopefully habitable, around G class stars like our own Sun, and that process takes longer with the transit method because of the longer year cycles. 

So the question arises - what kind of systems should we look for first? And I hope our exoplanet team project would be able to rate the planetary search desirers.          

Another angle I believe we should look at in our exoplanet TP is revisiting planets that have already been found and learning more about them. This will first broaden our planetary knowledge base and secondly help us to improve our exoplanet detection methods, and maybe even find new ones.    

The Hertzprung-Russell Diagram mapping star temperature, luminosity and size  

This week also included a discussion on the recent 'Pathway to Exploration' report (abbreviated version). The report deals with the US approach to human space activity in the near future (up to 2050), its goals and destinations. I have not read this 280 page report, but from we've been told it has two main sections, chapters two and three were written by (lower level) policy makers and chapter four was written by scientists and engineers. While the fourth chapter is rather optimistic with its technical description of how mankind (or US-kind) would get to Mars by 2050, the earlier chapters are rather depressing with their explanation of 'why not' and 'why not now'. The main consensus of the panel members was that the current US pathway to Mars throw a manned mission to an near Earth passing asteroid isn't the right one, and that the US should align with the rest of the world's efforts of getting back to the Moon as a scientific and engineering stepping stone to Mars. This report is the latest of a long list of reports that basically say what can be done with a limited amount of public money and what would be the public opinion on the space activity. What I got from this discussion and from smiler ones we has previously is that in order of farther exploring space it takes a lot of politics. Sadly space as a global and national cause isn't as high as some other things, and that is despite the fact that modern life would not exist without some space applications that were initialized by government activity. In regards to commercial space, at the moment the real commercial space is somewhat limited to telecommunications and basically most of the other commercial space activities are services provided to governments. The current state of national investment (which has basically been the same since the last days of the Cold War) is that space activities are not a major part of the budget. I believe that these numbers should increase so we can do what we do best - explore and expand to new frontiers, not just for the scientists and engineers whims, but for progressing instead of stagnating, or even regressing. And I think that the discovery of any kind of life inside or outside of our solar system would change our perspective and turn space exploration to a leading goal for humanity. 

One point about 'why the US?' - There are other space exploring nations, but the US space budgets is much larger than the rest of the world combined and there is some understanding that in the near future the US will take the lead on reaching new frontiers (although, ironically the US does not launch people to space by itself at the present).    

Possible pathways to Mars

In the quote section of this week - Lagrange points are basically nice parking spots in space.