The following essay is reprinted with permission from The Conversation, an online publication covering the latest research.
As ships resume the search for missing Malaysian Airlines flight MH370 in the depths of the Indian Ocean this week, we often hear that the oceans are “95% unexplored” and that we know more about the surface of the Moon or Mars than the ocean floor. But is that true, and what do we really mean by “explored”?
The entire ocean floor has now been mapped to a maximum resolution of around 5km, which means we can see most features larger than 5km across in those maps. That’s the resolution of a new global map of the seafloor published recently by David Sandwell of Scripps Institute of Oceanography in San Diego and colleagues, who used some nifty tricks with satellites to estimate the landscape of the sea floor and even reveal some features of the Earth’s crust lurking beneath sea-floor sediments.
Unlike mapping the land, we can’t measure the landscape of the sea floor directly from satellites using radar, because sea water blocks those radio waves. But satellites can use radar to measure the height of the sea’s surface very accurately. And if there are enough measurements to subtract the effects of waves and tides, satellites can actually measure bumps and dips in the sea surface that result from the underlying landscape of the ocean floor.
Where there’s a large underwater mountain or ridge, for example, the tiny local increase in gravity resulting from its mass pulls sea water into a slight bump above it. If instead there is an ocean trench, the weaker local gravity produces a comparative dip in the ocean surface.
Reading those bumps and dips in the sea’s surface is an astounding feat of precision measurement, involving lasers to track the trajectory of the measuring satellite and inevitably a lot of maths to process the data. The new map uses data from the Cryosat-2 and Jason-1 satellites and shows features not seen in earlier maps using data from older satellites. The previous global map of the ocean floor, created using the same techniques and published in 1997, had a resolution of about 20km.
So we do actually have a map of 100% of the ocean floor to a resolution of around 5km. From that, we can see the main features of its hidden landscape, such as the mid-ocean ridges and ocean trenches – and, in that sense, the ocean floor is certainly not “95% unexplored”. But that global map of the ocean floor is admittedly less detailed than maps of Mars, the Moon, or Venus, because of our planet’s watery veil.
NASA’s Magellan spacecraft mapped 98% of the surface of Venus to a resolution of around 100 meters. The entire Martian surface has also been mapped at that resolution and just over 60% of the Red Planet has now been mapped at around 20m resolution. Meanwhile, selenographers have mapped all of the lunar surface at around 100 meter resolution and now even at seven meter resolution.
To map the ocean floor back home in greater detail, we have to use sonar instead of satellites. Modern sonar systems aboard ships can map the ocean floor to a resolution of around 100 meters across a narrow strip below the ship. Those more detailed maps now cover about 10%-15% of the oceans, an area roughly the size of Africa.
Mapping from ships at the level of detail achievable by ship’s sonar systems still reveals plenty of surprises. The first phase of searching for Malaysian Airlines flight MH370 in the Indian Ocean, which involved mapping from ships to plan future surveys by underwater vehicles, found underwater mountains and other features that were not shown on satellite-derived maps for the area.
But if we want to detect things just a few meters in size on the ocean floor, such as the wreckage of missing aircraft or the mineral spires of undersea volcanic vents that my team investigates, we need to take our sonar systems much closer to the sea bed using underwater vehicles or towed instruments. So far, less than 0.05% of the ocean floor has been mapped to that highest level of detail by sonar, which is an area roughly equivalent in size to Tasmania.
And of course, actually to see the sea floor using cameras or our own eyes means getting even closer, using remotely operated vehicles or manned submersibles.
So the “95% unexplored” meme doesn’t really tell the full story of our exploration of the oceans. When it comes to having a large-scale map, the ocean floor is perhaps not as unexplored as we might think, with 100% coverage to a resolution of 5km and 10%-15% coverage at around 100m resolution. That 10%-15% is similar in resolution to the current global maps of Mars and Venus.
But our exploration of the oceans depends on what we want to know about them. If our questions are: “What does it look like down there?” or: “What’s going on down there?”, then the area that has been “explored” is arguably even less than the 0.05% mapped so far at the very highest resolution by sonar.
Philosophically, when it comes to exploring anywhere on our dynamic world, how and when do we decide that somewhere has “been explored”? Do we declare “mission accomplished” once we’ve seen a location for the first time? The local woods where I walk my dog look very different in winter compared with summer, with different species flourishing at different times. Should I have considered them “explored” after my first visit in just one season? Exploring our world starts with mapping, but perhaps doesn’t really have an end.
Jon Copley receives funding from the Natural Environment Research Council.
This article was originally published at The Conversation. Read the original article.
We’ve been to the moon and just about everywhere on Earth. So what’s left to discover? In September, Future Tense is publishing a series of articles in response to the question, “Is exploration dead?” Read more about modern-day exploration of the sea, space, land, and more unexpected areas.
We shall not cease from exploration
and the end of our exploring
shall be to return where we started
and know the place for the first time
That tidbit of T.S. Eliot is stolen from Graham Hawkes, a submarine designer who really, really loves the ocean. Hawkes is famous for hollering, “Your rockets are pointed in the wrong goddamn direction!” at anyone who suggests that space is the Final Frontier. The deep sea, he contends, is where we should be headed: The unexplored oceans hold mysteries more compelling, environments more challenging, and life-forms more bizarre than anything the vacuum of space has to offer. Plus, it’s cheaper to go down than up. (You can watch his appealingly arrogant TED talk on the subject here.
Is Hawkes right? Should we all be crawling back into the seas from which we came? Ocean exploration is certainly the underdog, so to speak, in the sea vs. space face-off. There’s no doubt that the general public considers space the sexier realm. The occasional James Cameron joint aside, there’s much more cultural celebration of space travel, exploration, and colonization than there is of equivalent underwater adventures. In a celebrity death match between Captain Kirk and Jacques Cousteau, Kirk is going to kick butt every time.
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In fact, the rivalry can feel a bit lopsided—the chess club may consider the football program a competitor for funds and attention, but the jocks aren’t losing much sleep over the price of pawns and cheerleaders rarely turn out for chess tournaments. But somehow the debate rages on in dorm rooms, congressional committee rooms, and Internet chat rooms.
Damp ocean boosters often aim to borrow from the rocket-fueled glamour of space. Submersible entrepreneur Marin Bek talks a big game when he says, “We can go to Mars, but the deep ocean really is our final frontier,” but he giggles when a reporter calls him the “Elon Musk of the deep sea,” an allusion to the founder of the for-profit company Space X who is rumored to be the real-life model for Iron Man’s Tony Stark.*
Even Hawkes admits that he “grew up dreaming of aircraft”—though he means planes, not spaceships—but “then I got to look at this subsea stuff and I saw this is where aviation was all those years ago. The whole field was completely backwards, and that’s why I jumped in.”
While many of the technologies for space and sky are the similar, right down to the goofy suits with bubble heads—the main difference is that in space, you’re looking to keep pressure inside your vehicle and underwater you’re looking to keep pressure out—there’s often a sense that that sea and space are competitors rather than compadres.
They needn’t be, says Guillermo Söhnlein, a man who straddles both realms. Söhnlein is a serial space entrepreneur and the founder of the Space Angels Network. (Disclosure: My husband’s a member.) The network funds startups aimed for the stars, but his most recent venture is Blue Marble Exploration, which organizes expeditions in manned submersibles to exotic underwater locales. (Further disclosure: I have made a very small investment in Blue Marble, but am fiscally neutral in the sea vs. space fight, since I have a similar amount riding on a space company, Planetary Resources.)
As usual, the fight probably comes down to money. The typical American believes that NASA is eating up a significant portion of the federal budget (one 2007 poll found that respondents pinned that figure at one-quarter of the federal budget), but the space agency is actually nibbling at a Jenny Craig–sized portion of the pie. At about $17 billion, government-funded space exploration accounts for about 0.5 percent of the federal budget. The National Oceanic and Atmospheric Administration—NASA’s soggy counterpart—gets much less, a bit more than $5 billion for a portfolio that, as the name suggests, is more diverse.
But the way Söhnlein tells the story, this zero sum mind-set is the result of a relatively recent historical quirk: For most of the history of human exploration, private funding was the order of the day. Even some of the most famous examples of state-backed exploration—Christopher Columbus’ long petitioning of Ferdinand and Isabella of Spain, for instance, or Sir Edmund Hillary’s quest to climb to the top of Everest—were actually funded primarily by private investors or nonprofits.
But that changed with the Cold War, when the race to the moon was fueled by government money and gushers of defense spending wound up channeled into submarine development and other oceangoing tech.
“That does lead to an either/or mentality. That federal money is taxpayer money which has to be accounted for, and it is a finite pool that you have to draw from against competing needs, against health care, science, welfare,” says Söhnlein. “In the last 10 to 15 years, we are seeing a renaissance of private finding of exploration ventures. On the space side we call it New Space, on the ocean side we have similar ventures.” And the austerity of the current moment doesn’t hurt. “The private sector is stepping up as public falls down. We’re really returning to the way it always was.”
And when it’s private dough, the whole thing stops being a competition. Instead, it depends on what individuals with deep pockets are pumped about—or what makes for a good sell on a crowdfunding site like Kickstarter.
Looking for alien life forms? You probably think you’re a natural space nerd, but you’re wrong. If the eternal popularity of “Is There Life on Mars?” stories is any indication, an awful lot of people are just hoping for some company. We really have no idea what’s hanging out at the bottom of the Mariana Trench, but there are solid reasons to think the prospects for biological novelty (and perhaps even companionship for humanity) are better down there than they are in Mars’ Valles Marineris.
Want a fallback plan for when that final environmental catastrophe occurs? Underwater or floating habitats may offer fewer challenges than space colonies if you’re looking to quickly build a self-sustaining place to live when things cool down, warm up, dry out, or otherwise return to fitness for human habitation.
If you’re just looking for wide open spaces, the vastness of space may ultimately prove your final frontier, but Söhnlein has a very human take on the question: “For myself,” he says, “I’d probably go with the oceans. Humanity has millennia to explore the cosmos. But I have only decades or—depending on who you believe—centuries. And there’s plenty to discover down there to fill my lifetime.”
This article arises from Future Tense, a collaboration among Arizona State University, the New America Foundation, and Slate. Future Tense explores the ways emerging technologies affect society, policy, and culture. To read more, visit the Future Tense blog and the Future Tense home page. You can also follow us on Twitter.
*Correction, Feb. 9, 2016: This piece originally misspelled the last name of Marin Bek. (Return.)