Looking beneath the waves has always been a challenge for oceanographers. (Image: Flickr/U.S. Navy) It’s an oceanographer’s favorite aphorism, that we know more about the surface of Mars than we do our own planet’s oceans. And, in many ways, it’s true. Based largely on a compilation of data from the University of Southampton's Dr. Jon Copley (as well as other sources including HiRISE camera data and conversations with deep-sea scientists), we can see the distribution of spatial understanding in the figure below:

A schematic view of mapping resolution of various celestial bodies and the Earth's oceans. The rectangular areas are drawn to scale, with colored boxes corresponding to spatial resolutions known for different proportions of the areas. (Image: Jeffrey Marlow) The numbers indicate that, from a topographic / bathymetric perspective, we’re pretty far behind in understanding the seafloor. We have a sense of features larger than 5 kilometers in size - the most obvious marine mountain ranges, for example - but such resolution is effectively useless when considering local geophysical features or geochemical gradients. It’s like trying to sort grains of rice by feel, wearing bulky winter gloves. (Of course, we have a lot of ocean-derived data with no extraterrestrial analog, like ocean current trajectories, nutrient and chemical fluxes, and biological stocks.) It’s a problem that has plagued scientists for decades, and now, the latest XPRIZE, sponsored by Shell, is hoping to solve it once and for all. Entrants will need to map a 250 square kilometer patch of the seafloor (which may extend up to 4000 meters deep) at 5-meter horizontal and 0.5-meter vertical resolution. They must also acquire images of “biological, archaeological, and geological features of the ocean environment.” These principle aims are incentivized with $6 million in prize money; an additional $1 million ponied up by the National Oceanic and Atmospheric Administration (NOAA) will award platforms that can detect and trace chemical and biological signals. (Detailed guidelines are provided here.) Our limited knowledge of the seafloor is due to the pesky water molecule - sure, it makes all life on Earth possible, but it also soaks up most of the wavelengths of electromagnetic radiation we typically use to map surfaces and infer mineralogical composition. So, detailed mapping instruments need to get far beneath the waves, to hover near the seafloor and capture data before it’s absorbed in the water column. It’s not the most scalable approach, cruising autonomously and adaptively over 360 million square kilometers, rising periodically to offload data to a satellite. The XPRIZE hope is that a large financial incentive will attract new entrants into the field to develop a more efficient strategy of seafloor mapping. From a capacity-building perspective, prizes are a relatively efficient way to mobilize many teams in support of a given aim - after all, you only need to pay the winners for their work. This set of partners - XPRIZE, NOAA, and Shell - represents an intriguing, and potentially countervailing, set of interests. As Dr. Jyotika Virmani, a Senior Director at XPRIZE told National Geographic, “Shell, NOAA and XPRIZE are all aligned in our goals, which is really the discovery of what is down there, what’s in the deep ocean.” But the resulting knowledge will likely feed into very different applications. While one plank of NOAA’s mission is “to conserve and manage coastal and marine ecosystems and resources,” Shell is in the business of leveraging seafloor geophysical studies to pursue promising sites for hydrocarbon exploitation. From a biologist’s perspective, the NOAA million-dollar addendum is perhaps the most compelling aspect of the prize. Life requires energy, and seafloor chemical gradients are particularly juicy locations. Microbes can tap reduced (electron-rich) fluids that enter oxygen-carrying bottom water, supporting oases that rival rainforests for their scale of biological productivity. Hydrothermal vents, methane seeps, and serpentinization springs have all presented scientists with bizarre metabolisms and alien creatures, and their discovery was presaged by chemical signatures that were sniffed to their source. But given the expanse of seafloor yet to be investigated in depth, there are almost certainly additional flavors of geochemical hotspots that fuel novel forms of life. The Ocean Discovery XPRIZE may lead to newly detailed seafloor maps, but biological discovery - and the technological and medical advances that often accompany such findings - could be the program's ultimate legacy.