Well, let me briefly discuss what is presented in the paper before I go into any editorializing or critiquing. The paper examines Io as a potential abode for life, both currently and in the past, despite the obvious environmental roadblocks to the development of life. A primary focus is whether one of the known chemical components of Io's surface and shallow sub-surface, such as hydrogen sulfide, sulfur dioxide, or sulfuric acid, could be used as a solvent for an alternative form of life native to Io. Schulze-Makuch also suggests that water may have been used as a solvent for microbial life early in Io's evolution when it may have been more Europa-like (active silicate core covered with a thin layer of water and water ice). Finally, he explores possible energy sources for life, such as geothermal heat or from Jupiter's magnetic field. The authors states that, "One possible microbial survival strategy in this type of environment would be that microorganisms remain in a dormant-type of state most of the time and are reverting back to a vegetative state only when heated by nutrient rich lava flows." The authors notes that a potential habitat for life could be lava tubes in Io's sub-surface, similar to those suggested for Mars.
Well, before I rip this article a new one, let me make it clear that the author does state in his conclusion that the likelihood of life on Io "has to be considered low". This sort of article I think was intended to explore whether the assumption that there is absolutely no chance for life on Io is valid. Schulze-Makuch describes some scenarios for how life on Io might have gotten started and what kind of form it might take. He even points out a number of critical issues, such as the lack of carbon on Io, with the exception of possibly some carbon dioxide in Io's volcanic plumes. However, the low residence time for carbon-based molecules in Io's atmosphere and surface thanks to the radiation environment may have something to do with it, but still, Io is not know for its carbon, unlike Callisto.
Now is it time for me to rip into it? Oh please, can I? I ever so want to...
Now it is no secret that I am not a big fan of astrobiology. In fact, I think that it is at best a mislabeled field of science and at worst it is pseudo-science, based more on speculation and grant-hunting than on reality. Even though it would be nice to add Io to the list of places to the possible abodes for life in the Solar System, the only reason at this point would simply so that we can shoehorn Io exploration into NASA's goal of studying Solar System habitability than actually advancing Io science. I just don't see where you can go to follow-up on it without looking blatantly self-serving. Besides, do advocates for Ionian exploration such as myself want to bother with the planetary protection policies that other targets have problems with.
So go ahead, read the Schulze-Makuch article. Just take it with a grain of salt ;-)
I work for the Cassini Imaging team, usually processing Titan and Enceladus images and making maps of Titan based on our images. When I am not working or studying, I'm...I forget. I watch a lot of movies I guess.