Estimated reading time: 15 minutes
Just as the first jaw-dropping images of deep-sea tubeworms and clams changed our understanding of life when hydrothermal vents were discovered in the 1970s, exploring the hadal zone—the deepest region of the ocean (named after Hades, king of the underworld realm in Greek mythology)—may yield new clues about the limits of life on Earth, and possibly beyond.
This is according to Tim Shank, a deep-sea biologist at Woods Hole Oceanographic Institution (WHOI), who is on the R/V Neil Armstrong headed to a vast, underwater canyon along the New England continental shelf. There, he and his team will field test Orpheus, a bright-orange ocean robot that he and WHOI engineer Casey Machado designed to explore this dark and mysterious layer of the ocean.
“Hadal trenches are among the least explored environments on our planet,” says Shank, who heads up the institution’s HADEX (short for Hadal Exploration) deep ocean exploration program. “We know very little about what species live down in these habitats, what the biological diversity looks like, and how life there has evolved to withstand and thrive under extreme conditions.”
Orpheus, named after one of the legendary figures in Greek Mythology who made it to the underworld and back, represents a new class of autonomous underwater vehicle (AUV) that Shank says will enable access to explore this last frontier on Earth.
The ‘what’s down there?’ question is key, but his interest in this unknown universe six miles beneath the ocean’s surface runs far deeper.
“Certain novel adaptations that enable species to exist under hadal conditions could lead to promising medical treatments, and offer clues about the rise and evolution of life itself,” says Shank.
He adds that if Orpheus is successful in withstanding the extreme pressures of the deep, the technology could be leveraged to explore ocean worlds beyond Earth with similar environments, like Europa and Enceladus, the moons of Jupiter and Saturn, respectively.
Pushing the limits
The seas are calm as Neil Armstrong draws closer to a steep-sided submarine valley known as Veatch Canyon. There, Orpheus will make its first of three dives in the open ocean, a place it hasn’t been to since 2018 when Shank and his team conducted initial field tests of the vehicle aboard OceanX’s vessel, the M/V Alucia. The expedition is an incremental yet vital step in the robot’s formative stages, one aimed at garnering confidence in the vehicle’s capabilities before it makes its plunge into full-ocean depth territory in 2020.
Machado pops into the garage holding a medicine-ball-sized glass sphere. Inside is a tangle of colorful wires and cables—the circuitry of the robot’s nervous system. She and WHOI electrical engineer John Bailey spent the last half hour running it through a series of diagnostics in the ship's main lab next door. It is now time to reattach Orpheus’s brain to its body (roughly the size and shape of a mechanical bull), which is covered in a thick layer of off-white syntactic foam. The foam—donated by filmmaker and ocean explorer James Cameron—was fabricated to withstand pressures that are more extreme than those found at the full 11,000-meter (36,000-foot) depth of the ocean. Cameron had used the custom-designed material in his own human-occupied hadal vehicle, Deepsea Challenger.
“Orpheus bridges a critical gap in our nation’s ability to access and explore the deepest parts of our ocean,” says Cameron. “I’m thrilled that the technological legacy of the Deepsea Challenger is at the core of this new developing fleet of hadal AUVs.”
Using glass to house the electronics is one of many cost-saving measures Machado and her team have taken to minimize the financial risks associated with a catastrophic vehicle failure—one that the punishing pressures of the deep could cause. Nereus, a hadal robot prototype developed at WHOI in 2011, imploded after reaching a depth of 10,000 meters in the Kermadec Trench northeast of New Zealand in 2014. From Machado’s perspective, Orpheus represented a chance to scale things down.
“I did a cost analysis and tried to come up with the most cost-effective ways to do everything we really needed to do,” says Machado. “The philosophy was, everything on the vehicle had to be super-necessary or it wasn’t included.”
Shank says another reason for the cost-conscious design of Orpheus relates to one of the HADEX program’s key goals: having a fleet of low-cost, full-ocean depth vehicles. “We want an armada of these vehicles down there,” he says.
Collectively, the ocean’s hadal zone covers an area about as large as Australia—that’s a lot of space to cover. Shank says the idea is that, rather than relying on a single vehicle that costs millions of dollars, there could be twenty or more lower-cost robots exploring hadal trenches cooperatively. A second vehicle—Eurydice—has already been built to help cover more of the hadal zone in less time.
Cool your jets
A blender-like sound cuts through the air, then stops, and then whirs again. Russell Smith, a young engineer from NASA’s Jet Propulsion Laboratory (JPL), enters the garage, where the scent of ship diesel hangs in the air. With his space-gray Macbook, he starts toggling the robot’s thrusters on and off. He completes the sweep and moves on to the lights and other functions, making sure all systems are a go for Orpheus’s first dive.
JPL engineers have been collaborating with WHOI on the Orpheus project since 2017. They’re interested in autonomous vehicles that can withstand the pressures at the bottom of the ocean, an environment that Smith says is a good analog to the pressures that exist in ocean worlds beyond Earth. He and his colleagues are writing software that will allow the robot to build three-dimensional maps of the seafloor by stitching together images of features it sees, such as rocks and clams. These terrain maps will enable Orpheus to navigate the deep, and independently recognize features along the seafloor that may be of scientific interest to Shank and others.
“The big trick here is that the bottom of the ocean is super murky and dark and there’s a lot of stuff floating around in the way,” says Smith. “There’s a lot of visual distortion that you have to get rid of to create the maps, so it’s really challenging from that perspective.”
Orpheus is hanging off Neil Armstrong’s crane hoisted a dozen feet above the Atlantic. The winch motor groans as Orpheus is gently eased into the blue water. The blur of its orange body becomes obscured as the robot is tethered 10 meters below the surface. It’s not very deep for a hadal vehicle, but enough to get the robot’s systems wet to ensure nothing is malfunctioning.
An hour later, the ship's crane starts whining again as Orpheus is hauled up from the sea. On deck, it’s gently placed onto a dolly and carted back to the garage, where Machado and Bailey begin working the robot over in pit-crew fashion.
The next day, just as Orpheus is supposed to take another dunk, the sky goes from a yawn to a tantrum as a squall rolls in. Heaving seas crash over the side of Neil Armstrong as the ocean surface becomes lined with a scrim of angry indigo ribbons. A few hours later, the storm moves out and Orpheus completes dive #2. So far, so good.
The pressure to adapt
The extreme pressures of the deep may have forced hadal robots to evolve, but the real adaptations have occurred within deep-sea animals themselves. Taylor Heyl, a deep-sea biologist in Shank’s lab, says some of the most novel adaptations relate to how certain hadal creatures seem to correct for poorly-functioning proteins.
“The high pressures can make cells too small for proteins to work properly,” she says. “Some species have adapted by using enzymes called piezolytes that surround water molecules to increase space inside their cells and counteract the pressures.”
Shank says that when proteins become dysfunctional in humans, the result is often disease, such as Alzheimer's. So, he wants to take a closer look at what’s controlling the protein stability of hadal animals by bringing them up from the deep and comparing their genomes with those of healthy people and those afflicted with disease.
“There’s a strong genetic basis for use of these hadal animals in society,” he says, “so we need to look at these adaptations on a genetic level.”
Today, Orpheus will plunge more than 1,600 meters into Veatch Canyon—the deepest it’s ever gone. If all goes to plan, it will explore for a few hours and make it back up by dinnertime.
The dinner menu on the board outside the mess hall looks good—grilled mahi, roasted mixed vegetables, tossed salad, as does the weather. But no one seems to be thinking about either right now: at this point, it’s all about robot readiness.
Machado is in the staging bay pumping fluid into a junction box of wires inside the robot’s glass housing. It’s a curious sight that runs counter to the general principle of keeping circuitry dry.
“Mineral oil compensates for depth, so we use it to protect the electronics from the extreme pressures rather than physical housings, which add weight,” she says.
Once again, Orpheus is hoisted above the water by crane and slowly submerged. As the safety line is cut, the robot is swallowed whole by the canyon. The engineers head straight to the ship's computer lab, where Shank is stationed, to get an early view of the mission. The robot is dropping 30 meters per minute, and should be at the bottom within an hour.
The afternoon flies and suddenly it’s approaching 5:00 p.m. Orpheus has been surveying the submarine canyon like a grasshopper, landing on one spot, capturing video, and then jumping up and flying over to the next spot. One of the monitors in the computer lab shows the vehicle at a depth of 1,623 meters. According to Smith’s mission script, is expected to ignite a burn wire twelve minutes from now that will cause its weights to drop and the vehicle to surface.
Twelve minutes pass. The 1,623-meter figure on the monitor doesn't budge. Orpheus is on the bottom of the ocean, and it isn’t moving. The scientists and engineers watch with baited breath.
Shank is pensive as he stares at the screen. He and Machado know this feeling all too well. Losing this vehicle would be a crushing blow to the HADEX program, which has gained considerable momentum since Orpheus was built.
Did the batteries die? Did the robot get snagged in a fishing net or line? Will the sweeping canyon currents make Orpheus an irretrievable runaway vehicle? Heyl glances over at Shank, sees his lost expression, and can’t muster much beyond, “Take four deep breaths, please.”
Machado takes a shot at some much-needed humor. She asks if Eurydice, Orpheus’ twin robot, becomes the new Orpheus if the vehicle doesn’t come back up. The half joke is met with silence as she leaves the control room to re-examine the mission scripts and see if anything seems amiss.
There are mysteries of the deep, and then there are stumpers. For example, how does organic matter get from the ocean’s surface all the way down to the hadal zone? According to Shank, there is a lot of organic material down there even though there shouldn’t be. For example, if you toss a fish overboard, other fish start eating it as it makes its way down. Microbes typically munch on the remainder so by the time the remains get to the deep ocean, there should be very little, if anything, left.
The hadal zone may be rich in organic matter, but scientists still don’t know the full variety of food sources that exist down there or what sustains its organisms.
Heyl says another mystery is whether hadal animals found in different trenches are biologically connected. “We’re not certain if they’ve evolved independently of one another given the miles of separation between certain trenches, or if certain species populations are possibly connected through dispersal mechanisms,” she says. “So, we ultimately want to investigate this at the molecular level to determine if species are genetically distinct across different trenches.”
The robot stays down. At this point, no one will know anything until 7:15 pm, when a second failsafe—a tiny galvanic latch that supports the vehicle’s weights—will dissolve from corrosion. That should cause the robot to rise up like a hot air balloon, but if the vehicle is snagged, all bets are off.
With that fear in mind, Shank heads out to the deck to confer with Armstrong captain Kent Sheasley. It turns out, the captain has experience in “lassoing” instruments on the seafloor using cable spooled on the ship’s winch.
Seven o’clock rolls around. The waiting game has been painful, so even those who aren’t hungry hit the mess for their last supper. The air of tension on the ship is inescapable.
Fifteen more minutes pass, and just when the latch is expected to separate and free the robot, the 1,623-meter figure stays etched on the screen.
Then, a few seconds later, the readout miraculously refreshes.
Orpheus is rising.
Word gets around the ship fast. Forty-five minutes later, the robot pops out of the water and is greeted with cheer on deck. Without hesitation, the vehicle is hauled up and shuttled back to the staging bay, where a symphony of socket wrenches fills the air as the engineers begin working Orpheus over to investigate why it got stuck.
A view from below
Heyl grabs a memory card from one of the robot’s cameras, and she and Shank head into the main lab to watch footage of Orpheus’ last few hours on a laptop. A crowd gathers around. Orpheus is making its way down the canyon, kicking up plumes of sediment with each turn along it’s programmed track. Then, it’s flying just above the seafloor, spying on what looks like an underwater desert of single-celled creatures known as xenophyophores. Occasional sea spiders and eels wriggle their way in and out of the otherworldly landscape.
The creatures on the monitor are quickly recognizable to Shank and Heyl, but it may be a whole different story next year when they send Orpheus to the bottom of the Mariana Trench in the western Pacific Ocean—the deepest point in the ocean that extends down 11,000 meters.
“We need access to the animals there so we can get their genomes and start looking at their adaptations on a genetic level,” says Shank, with contagious excitement. “The societal relevance here is just so strong—I think it could be a complete game changer for understanding life as we know it today.”
Within 30 minutes, Orpheus discovers a patch of deep-sea mussels embedded in the soft sediment, indicating a cold seep—a chemosynthetic community that relies on methane as a food source. It’s similar to the type of chemo-communities Shank and Heyl will be looking for in the hadal zone.
Movie time is over. Shank heads back to the garage to reconnect with Machado and Bailey. They tell him that Orpheus’ batteries died at the bottom of the canyon. The thrusters were the main culprits; they had been programmed to run full throttle during the entire mission to compete with the tough currents until, ultimately, the vehicle ran out of juice.
“We pushed the boundaries of what we asked Orpheus to do,” says Shank. “And, we picked a really complex place with rough terrain to see how hard it could run. It’s exactly what these trials are for.”
In the end, he says the team learned more from the batteries failing than they would have if everything went smoothly. Which is good, because as Orpheus searches for life at 36,000 feet deep in Mariana Trench next year, it’ll need all the juice it can get.