Should We Explore Space or the Ocean?

Framing ocean and space exploration as rivals competing for the same pot of funding misrepresents how these two frontiers actually work. The technologies, scientific questions, and even the personnel overlap so heavily that progress in one routinely accelerates progress in the other. The real question is not which to choose but how to invest in both without letting one quietly starve while the other dominates public attention. Understanding why requires looking at what each frontier uniquely offers, where they converge, and what we stand to lose by treating them as an either/or proposition.

How Little We Actually Know About Either Place

People often hear that we know more about the surface of Mars than we do about our own ocean floor. That claim oversimplifies things, but it gestures at something real. We have high-resolution maps of Mars, the Moon, and several asteroids compiled from orbital surveys. Meanwhile, much of the deep ocean has been mapped only at low resolution using satellite-derived gravity data, and direct human observation of the seafloor has covered a small fraction of its total area. Space exploration benefits from a relative advantage in remote sensing: you can photograph a planetary surface from orbit without physically going there. The ocean absorbs and scatters the electromagnetic signals that make satellite mapping possible, so getting detailed data from the deep sea means sending instruments down physically or using sonar from ships, both of which are slow and expensive.

Space, of course, has its own knowledge gaps that dwarf anything on Earth. We have never directly sampled the subsurface oceans believed to exist on moons like Europa and Enceladus. We have crude compositional data for most asteroids. The overwhelming majority of exoplanets are known only by their mass and orbital period. The point is that both frontiers remain profoundly underexplored, and the popular impression that space is “more explored” reflects media attention and public imagination more than actual scientific coverage.

Why the Engineering Challenges Are More Similar Than They Look

A crewed submarine and a crewed spacecraft face surprisingly parallel problems. A NASA comparison of nuclear-powered submarines and the planned Space Station found that both require a 90-day mission capability during which all aspects of human habitation must be accommodated, and the requirements for environmental control and failure tolerance of life-support systems are “quite similar.”¹ In both settings, engineers must scrub carbon dioxide, manage humidity, recycle water, handle waste, and maintain breathable air inside a sealed vessel surrounded by an environment that kills unprotected humans in minutes. The operating environments differ wildly, one in vacuum, the other under crushing pressure, but the design principles are the same.

The deep ocean actually introduces some engineering headaches that space does not. Communicating underwater is notoriously difficult because radio waves barely penetrate seawater. Acoustic signals travel well but suffer from severe multipath interference and Doppler shifts as water layers shift. Researchers have described the underwater acoustic channel as “the most challenging channel” for communications, driving the development of new modulation techniques just to achieve reliable data links in high-mobility underwater scenarios.² In space, by contrast, radio signals travel unimpeded once you have line-of-sight to a relay satellite or ground station. The delay can be enormous, minutes to Mars, hours to Jupiter, but bandwidth is comparatively generous. The ocean offers the inverse problem: short distances but terrible signal quality.

Exploring the subsurface oceans of icy moons like Europa or Enceladus would combine the worst of both worlds. A review of key technologies needed for such missions lists power generation, pressure resistance, radiation hardness, corrosion protection, navigation, miniaturization, autonomy, and sterilization as simultaneous requirements, calling such missions “extremely challenging.”³ Any probe that drills through kilometers of ice and then swims through an alien ocean needs to solve deep-sea engineering and deep-space engineering at the same time. This is where the false dichotomy between the two frontiers becomes most obvious: the hardest missions ahead demand mastery of both.

Underwater Habitats as Space Analog Laboratories

NASA has spent decades using the ocean floor as a rehearsal space for planetary exploration. The NEEMO program (NASA Extreme Environment Mission Operations) sends astronauts to live in the Aquarius underwater habitat off Key Largo, Florida, where they practice coordinated human and robotic exploration. During one mission, crews worked alongside autonomous underwater vehicles and single-person submersibles used as analogs of robotic systems and human-operated vehicles proposed for use on asteroids, the Moon, or Mars.⁴ The underwater setting lets teams test procedures and communication protocols in a genuinely hostile environment at a fraction of the cost of doing so in orbit.

More recently, the DIANA mission used an underwater habitat called the Hydronaut H03 DeepLab to simulate long-duration spaceflight and extraterrestrial habitation, studying crew performance, psychosocial dynamics, and technological systems in an isolated, confined, and extreme environment.⁵ These analog missions do not just benefit space programs. The sensors, communication systems, and habitat technologies developed for underwater analogs feed directly back into civilian oceanography and subsea industry. A robotic arm validated during NEEMO for asteroid surface work can be repurposed for deep-sea maintenance of oil and gas infrastructure, or for scientific sampling in ocean trenches.

What the Deep Ocean Teaches Us About Life Beyond Earth

One of the strongest scientific links between ocean and space exploration is the search for life. Earth’s deep-sea hydrothermal vents, discovered in the late 1970s, overturned the assumption that all life depends on sunlight. Entire ecosystems thrive on chemical energy from the planet’s interior, fed by reactions between seawater and hot rock. That discovery reshaped how astrobiologists think about where life could exist elsewhere.

Enceladus, a small moon of Saturn, is now considered one of the most promising targets in the search for extraterrestrial life precisely because the Cassini spacecraft detected plumes of water vapor and organic molecules erupting from its south pole, suggesting hydrothermal activity on its ocean floor. Researchers have outlined laboratory strategies to simulate prebiotic chemistry in hydrothermal vent systems on icy ocean worlds, noting that Enceladus provides an ideal test case because the pressure at its ocean floor is relatively easy to replicate in the lab.⁶ Results from Enceladus simulations can be extrapolated to understand other ocean worlds like Europa and Titan.

More broadly, origin-of-life research conducted in Earth’s oceans can guide the biosignature detection strategies of future planetary science missions, potentially advancing our understanding of how life begins in the first place.⁷ The loop is tight: study Earth’s ocean vents to learn what chemical signatures to look for, then send probes to alien oceans to test whether those signatures appear there. Neither line of inquiry makes full sense without the other.

Marine Extremophiles and the Future of Space Travel

The practical value of ocean biology to space programs goes well beyond theoretical astrobiology. Organisms that survive extreme heat, pressure, salinity, or radiation in the deep sea, collectively called extremophiles, are turning out to be useful tools for keeping astronauts alive and supplied on long missions. These organisms and the enzymes they produce have proven to be a rich source of industrial-scale manufacturing capabilities, thanks to their inherent tolerance for harsh conditions. Researchers have identified their potential to provide access to pharmaceuticals, biofuels, food supplements, and life-support chemicals within the constraints of using local resources in space, positioning extremophilic enzymes as potentially indispensable tools for sustainable space exploration.⁸

Consider what a crewed Mars mission actually requires. You cannot resupply a Mars habitat the way you resupply the International Space Station. Every kilogram launched from Earth costs tens of thousands of dollars. If extremophile-derived enzymes can convert Martian regolith or recycled waste into something useful, whether fuel, food supplements, or materials, that dramatically changes the math of deep-space missions. The organisms doing this work were discovered and characterized by marine biologists, not aerospace engineers. Defunding ocean research means losing access to these biological resources before we even fully catalog them.

Climate, Disasters, and Planetary Defense

The ocean drives Earth’s climate in ways that remain inadequately monitored. The deep ocean absorbs the vast majority of the excess heat trapped by greenhouse gases, and changes in deep circulation patterns can shift weather systems across entire continents. Satellite systems, a product of space technology, are essential for monitoring sea surface temperatures, ice coverage, and ocean color from above. But satellites cannot see below the surface. Understanding what is happening in the ocean’s interior requires in-situ instruments: floats, gliders, moored sensors, and crewed or remotely operated vehicles. The two observation systems are complementary, and gaps in either one leave climate models flying partially blind.

Disaster monitoring illustrates the same complementarity. After the catastrophic 2004 Indian Ocean tsunami, the global warning system was overhauled. Deep-ocean pressure sensors (DART buoys) now detect tsunamis in the open ocean and feed data to warning centers that use satellite communications to issue alerts. When the 2011 Japanese tsunami triggered these buoys, data from four sensors near Japan produced the world’s first forecast of tsunami flooding for locations in Hawaii six hours before the wave arrived, enabling an evacuation order that saved lives.⁹ That system depends equally on ocean-floor instrumentation and space-based communication infrastructure. Cut either leg and it falls over.

Planetary defense, the effort to detect and deflect asteroids that could strike Earth, is often cited as a uniquely space-centric priority. And it is true that the threat comes from space and must be addressed there. But the consequences of a large ocean impact, which is statistically more likely than a land impact given that water covers roughly 70% of the surface, depend heavily on how well we understand tsunami generation and propagation. Protecting coastal populations from an asteroid-generated tsunami requires the same ocean-monitoring networks that protect them from earthquake-generated ones.

The Resource and Sovereignty Question

Both the deep seabed and outer space contain mineral resources that governments and private companies are eyeing with increasing seriousness. The seabed holds polymetallic nodules rich in manganese, nickel, cobalt, and rare earth elements. Asteroids contain platinum-group metals and iron in quantities that dwarf terrestrial reserves. In both arenas, a geopolitical contest is underway. Research into the “green, blue, and black” resource frontiers, meaning land, sea, and space respectively, has warned that sovereignty creep already observed on land and at sea could extend to outer space, with the competition for mineral wealth and sovereign dominance raising the likelihood of a return to a “colder war period.”¹⁰

The governance frameworks for seabed mining (overseen by the International Seabed Authority under the UN Convention on the Law of the Sea) and for space resource extraction (loosely governed by the Outer Space Treaty and more recent national legislation like the U.S. Commercial Space Launch Competitiveness Act) face parallel challenges. Who owns resources extracted from a global commons? How do you enforce environmental protections in areas beyond national jurisdiction? The lessons learned from decades of seabed governance disputes are directly applicable to space, and vice versa. Nations that engage seriously with both frontiers are better positioned to shape the rules, while those that focus on only one may find themselves outmaneuvered on the other.

The Technology Transfer Economy

One reason the “space vs. ocean” framing persists is that space exploration has a more visible track record of returning economic value through technology spinoffs. NASA has long promoted the downstream commercial benefits of its research investments. A pilot study of fifteen companies that successfully commercialized NASA life sciences spinoff products found that value-added benefits totaled over $1.5 billion, with a NASA R&D investment of $64 million in those technologies stimulating an additional $200 million in private research and development.¹¹ Those numbers are striking, and they reflect a genuine strength of space programs: centralized, well-funded agencies with explicit mandates to transfer technology to the private sector.

Ocean research produces its own spinoffs, from anti-fouling coatings to sonar systems to biomedical compounds derived from marine organisms, but these tend to be less well-documented and less publicly celebrated. The ocean science community has historically been more fragmented across agencies and academic institutions, without a single entity playing the promotional role that NASA plays for space technology. This visibility gap skews public perception of where exploration dollars produce the best return, making it easier for politicians to frame ocean research as a lower priority than it actually is.

What Extreme Environments Do to People

Both frontiers put humans in isolated, confined, and extreme environments, and the psychological research conducted in one setting transfers to the other. A systematic review of studies on psychological growth following exposure to such environments, drawn mostly from polar expeditions, found that perceived stress, agreeableness, and openness to experience were the strongest predictors of whether individuals reported lasting personal benefits afterward.¹² People who came through these experiences often perceived lasting benefits in some areas of their lives, a finding relevant to selecting and supporting crews for both deep-sea habitats and long-duration space missions.

The overlap matters practically. Submarine crews, saturation divers, polar researchers, and astronauts all face prolonged confinement with a small group, limited communication with family, monotonous routines punctuated by moments of genuine danger, and the knowledge that the external environment is lethal. Psychological screening tools, team-building protocols, and mental health interventions developed for any one of these populations are immediately relevant to the others. Treating ocean and space exploration as separate fields means duplicating this human-factors research unnecessarily, or worse, missing insights that one community has already generated.

Where the Money Actually Goes

Public budgets tell a lopsided story. NASA’s annual budget has hovered in the range of $25 billion in recent years. NOAA, the primary U.S. agency for ocean research and monitoring, operates on roughly a quarter of that. The National Science Foundation funds substantial ocean science, but its total budget covers all scientific disciplines. Internationally, the pattern repeats: space agencies are better funded, more politically visible, and more culturally prominent than their oceanographic counterparts.

This imbalance does not reflect a careful cost-benefit analysis. It reflects historical momentum from the Cold War space race, the inspirational power of human spaceflight imagery, and the fact that rockets are more photogenic than research vessels. Ocean scientists have long argued, with considerable justification, that the return per dollar invested in ocean observation and marine biology is exceptionally high, particularly for climate forecasting, fisheries management, pharmaceutical discovery, and disaster preparedness. The argument is not that space is overfunded, it is that ocean research is chronically underfunded relative to what it delivers.

Private investment is shifting the landscape somewhat. Commercial space companies have attracted tens of billions in venture capital, while ocean technology startups are beginning to draw more interest, particularly in autonomous underwater vehicles, ocean energy, and aquaculture technology. But the gap remains wide, and the public framing of exploration as a competition between the two frontiers makes it harder, not easier, to argue for increasing funding for both simultaneously.

Deep-Sea Mining and the Precautionary Debate

One arena where the “space or ocean” question takes on real urgency is resource extraction. Proponents of deep-sea mining argue that seabed minerals are needed to build the batteries and electronics that support both the green energy transition and the space industry itself. Opponents counter that we understand deep-sea ecosystems so poorly that mining them risks destroying biological communities we have not yet discovered, including organisms that might yield valuable pharmaceutical or biotechnological applications.

The parallel with space mining is instructive. Asteroid mining faces massive logistical hurdles but almost no environmental opposition, because asteroids, as far as we know, harbor no ecosystems to damage. The deep seabed is the opposite: technically more accessible but ecologically sensitive in ways we are still mapping. Both frontiers need better baseline science before extraction begins at scale. In the ocean’s case, that means more funding for deep-sea biology and ecology. In space’s case, it means more detailed surveys of near-Earth asteroid composition. The irony is that rushing to extract resources from either frontier without adequate scientific groundwork could undermine the very industries that depend on those resources being available long-term.