There's a galaxy of life 400 meters beneath the sunlit surface of the Alenuihaha Channel near Maui: luminous, spiral corals sprouting like giant whiskers from the seabed, brilliant red crabs, black fish adorned with diamond-like lights. When I returned from a visit there in 1979, I felt like I had seen another world. And yet I knew it was nothing compared to what we'll find when we truly explore the deepest parts of the ocean. If we get there.
Nearly a decade before Apollo 11 delivered the first two people to the surface of Earth's moon, two men touched down 11,000 meters below the ocean surface. In the ensuing three and a half decades, a dozen people have returned to the moon; hundreds have viewed Earth from space. But no one has returned to the deepest point in the sea. Exploration of our inner space has lagged behind efforts to understand the wild blue yonder.
We have increased our knowledge of the ocean dramatically in recent decades, but much of our intelligence has come by studying the surface of our oceans from space. Satellites orbiting hundreds of kilometers high gather sweeping overviews of surface temperatures, currents, salinity, plankton blooms, winds, and even the movements of large sea creatures. We can now detect slight variations in the sea surface, indicating the topography of hills and valleys hundreds or thousands of meters below sea level. But what lives beneath the surface remains largely unknown. Scientists estimate that, conservatively, there are 10 million undiscovered species in the oceans. The real number could easily be 10 times that. Until we commit to exploring the entire 3-D seaspace, we'll never know.
Not knowing could be disastrous. The oceans hold the answers to many mysteries of the history of life - earthbound and maybe extraterrestrial. Deep-ocean life thrives in conditions that can be extreme beyond imagination. Numerous creatures have been discovered thriving around mineral-laden hot water vents, including microbes that are distinctly different from anything we have previously known. Many of us wonder if similar microbes might prosper on Mars or deep under the icy surface of Jupiter's moon Europa.
It's not as if we don't have the ability or the technology to explore the depths. Kaiko, a remotely operated vehicle from Japan, recently dived to the deepest part of the ocean - the Challenger Deep in the Mariana Trench - armed with instruments, sensors, powerful lights, and specialized cameras. Before the robot was lost in a storm, it documented a rich assemblage of creatures living in 16,000 pounds per square inch of pressure, near-freezing temperatures, low oxygen concentration, and eternal darkness. China is building a three-person sub capable of diving 7,000 meters. And in a few years, the Woods Hole Oceanographic Institution will have a 6,500-meter system to replace the all-time champion of research submarines, Alvin, a 40-year-old workhorse that can submerge to 4,000 meters. Various unmanned vehicles, tethered and free-swimming, can go down 6,000 meters, and Woods Hole will soon begin construction of a vehicle that will submerge as deep as 11,000 meters and swim at the end of a fiber-optic tether receiving commands from surface operators and transmitting images and data in real time.
This may sound like a lot of equipment, but it's the equivalent of trying to explore all Earth's continents with a few jeeps. Ninety-five percent of our vast, deep waters have yet to be seen, much less explored. Our oceans contain nearly 60,000 kilometers of mountain ranges and many thousands of isolated sea peaks that are at least 1,000 meters tall. We know little about these ranges beyond their location. But the few hundred that have been sampled reveal a large percentage of unique species.
The more we understand about life in extreme environments, the greater chance we'll know where to look in space. Finding another place in the universe that's hospitable to life - either because we want to go or because we have no choice - starts with finding water. But that alone can't sustain us. It has taken Earth + the ocean + life + 4.5 billion years of fine-tuning to achieve what we now take for granted. As astronauts say about their life-support system, we should do everything we can to learn how it works, and then do everything we can to take care of it. The truth isn't out there. It's down there, in Earth's great blue under.
