When it comes to charting uncharted territory, NASA ranks among the world's preeminent explorers - not just mapping distant planets and stars, but using a cosmic vantage point to shed new light on our own world. Now, a groundbreaking NASA technology adapted for commercial use could open the door to comprehensively mapping Earth's vast uncharted seafloors while protecting fragile marine ecosystems.

Developed at NASA's Jet Propulsion Laboratory and licensed to California-based Seatrec Inc., this pioneering invention provides the first entirely self-sustaining energy source for underwater robots and sensors. By harnessing the endless thermodynamic cycles of the ocean itself, it eliminates the reliance on batteries that have long constrained the reach and endurance of subsea exploration.

"Our vision has remained unchanged since we started working on Prime Air: to create a safe and scalable way to map the seafloor using highly autonomous systems that can work in the open ocean indefinitely, without any intervention," said Yi Chao, Seatrec's founder and the JPL scientist who originated the renewable ocean power concept.

Chao's eureka moment came during his previous work calibrating NASA's Aquarius satellite, which measured ocean salinity from 2011 to 2014. While the satellite effortlessly circled the globe, his team had to deploy robotic floats across vast expanses just to gather enough localized data points for calibration.

"We went out to sea for 30 days," Chao recalled. "We had to distribute robotic platforms to collect data in the middle of the Atlantic Ocean...and I really had an opportunity to know the challenges of underwater robotics, and especially energy."

Powered By the Ocean's Temperature Cycles All existing subsea robots operate on batteries with finite life, requiring costly surface vessels to periodically retrieve and recharge them - an unsustainable economics for comprehensive seafloor mapping. Chao's key innovation sidesteps those limitations by generating power from the temperature differences robots naturally encounter as they cycle between warm surface waters and the colder depths below.

The JPL-designed system relies on phase-change materials that expand upon melting and contract when refreezing. As a robotic float dives into colder depths, the material solidifies, generating kinetic energy from its volumetric contraction. This spins a generator producing electrical power to charge the onboard battery.

Resurfacing into warmer water reverses the process, with the material melting and expanding to "rewind" the generator. In this way, the float's routine vertical movements through thermoclines harness practically infinite renewable power. Seatrec has optimized the entire system for efficiency, carefully selecting ideal phase-change materials, generators, and other components.

"We use the kinetic energy from that volume expansion to spin the motor and then turn the mechanical energy into electricity, and now you can recharge your battery," Chao explains. "We are the first to go through the process end-to-end and pick the highest-efficiency components, and eventually we can generate a sufficient amount of energy for an underwater robot."

Unlocking Ocean Data for New Applications After over a decade developing and commercializing the technology, Seatrec's novel "InfiniTE" power modules are now enabling underwater robots to operate autonomously for years, surfacing only to transmit data instead of scrambling to find a charge. This ingenious energy solution is poised to usher in new realms of oceanic research and industrial applications previously dismissed as too costly or impractical.

At the top of the list is the monumental task of comprehensively mapping the 80% of Earth's seafloors that remain uncharted wilderness. Accomplishing this feat through surface ships alone would require a billion-dollar armada. But legions of self-sustaining robotic vessels could affordably map the depths globally at scale, a strategic imperative for maritime powers, offshore industries, and environmental efforts.

"So we are enabling mapping of the ocean floor from a subsea platform for the first time," Chao stated. "Many hurricane forecasters and oceanographers believe sub-surface data is the last missing piece of information we need to increase the accuracy of storm intensity prediction."

And that's just one example of the enhanced ocean monitoring Seatrec's technology could provide - delivering deeper insights into marine life, offshore operations, climate patterns, and more. Already, Chao reports strong interest from environmental groups, energy firms, telecom companies, navies, scientists and more looking to multiply their access to perpetual subsea data streams.

From mapping the seafloor to defending marine habitats, monitoring offshore infrastructure to fortifying climate prediction models, NASA's rechargeable ocean robot technology promises to expand humanity's understanding and stewardship of the final frontier on planet Earth. Once again, the aerospace pioneer's vision for exploration is extending across new boundaries.