During a two-week demonstration expedition, onboard a National Oceanic and Atmospheric Administration (NOAA) ship, a new deep-sea exploration technology that might one day search for life in subsurface oceans on the moons of Jupiter and Saturn will be put to the test. Orpheus, NASA’s latest underwater vehicle, uses autonomous navigation software developed by JPL in California for the Mars Perseverance rover and the Ingenuity helicopter.
According to the Woods Hole Oceanographic Institution (WHOI) in Massachusetts, the mini-primary submarine’s mission would be to advance humanity’s knowledge of the ocean’s deepest regions, known as the hadal zone. The hadal field, with trenches and troughs ranging in depth from 20,000 to 36,000 feet (6,000 to 11,000 meters), poses similar challenges to those faced by exploration vehicles on other worlds, according to Russel Smith, a roboticist at JPL, during an online news conference on May 5.
Perseverance Teachable Moments
“There are a number of parallels between Earth’s deep ocean and space exploration,” Smith said, citing “data-constrained connectivity, which necessitates a lot of autonomy, but also daunting environmental circumstances that necessitate a lot of engineering work.” Orpheus will use Terrain Relative Navigation (TRN) technologies developed by NASA for the Mars 2020 mission to navigate in the dim, uncharted depths. TRN led the Ingenuity helicopter on its groundbreaking flights and assisted Perseverance in landing safely in Jezero Crater on Feb. 18. “The car then navigates using certain features. It’s as if you stroll into a living room and immediately recognize a sofa and a television. Robots do the same thing.”
Seeking for life in depths.
During a two-week expedition on the NOAA ship Okeanos from May 14 to 27, Orpheus will be put through its paces, but not to the extreme depths. As the ship sails from Cape Canaveral, Florida, to Norfolk, Virginia, the space launch mini-submarine can run 24 hours a day, exploring the seafloor. The autonomous submarine would also put new environmental DNA (eDNA) technologies to the test, extracting DNA samples from animals living in water and soil. Orpheus is expected to open a new chapter in deep-sea discovery and shed light on the mysterious universe where the pressure reaches a thousand times that at sea level, according to WHOI marine biologist Tim Shank, the mission’s lead scientist.
“We know there’s a lot of organic material and biodiversity in the hadal region, animals that have evolved extraordinary adaptations to living in the high-pressure climate,” Shank said in the briefing. “However, we didn’t have a car to get there right now.” The fate of Orhpeus’ forefather, Nereus, demonstrates the difficulties of deep-sea exploration. The vehicle imploded in the Kermadec Trench near New Zealand in 2014, 6.2 miles (9,990 meters) below the sea surface, most likely due to the extreme pressure of about 16,000 pounds per square inch (2,860 kilograms per square centimeter).
Shank and his collaborators had to reconsider their approach to hadal zone discovery after the death of Nereus. Orpheus was planned to be smaller and less expensive than WHOI’s previous deep-sea exploration vehicles. Orpheus is just around a tenth of the mass of Nereus, weighing about 550 pounds (250 kilograms). The development, construction of a six-foot-long (2 m) mini-submarine cost about $2 million, or about a fourth of the cost of Nereus. The scientists will be able to repair the vehicle in the event of a malfunction and build an entire exploration fleet by using what WHOI refers to as a CubeSat theory, which involves developing new technologies quickly and at a lower cost.
“Our grand idea is to provide a network of a dozen or so of these vehicles with base stations,” Shank said. “They’d discuss their employment, what they’re doing, and what they’re sampling with one another.” When looking for signs of life, the autonomous submarines would float above the ocean floor, taking high-resolution images that would be combined into a 3D map of the seafloor.
Next destination: Europe
On the other hand, Shank has his sights set on other seas in the solar system, including Jupiter’s moon Europa and Saturn’s moon Enceladus. In reality, as Shank pointed out during the briefing, the pressure underneath Europa’s 7-mile-thick (12-kilometer) ice crust would be similar to that found in the hadal zone’s deepest trenches. Furthermore, Orpheus’ environmental DNA sensors will be helpful for a mission looking for microbial life on a moon with an ocean.
“The hadal ocean on Earth is an upright analogy for what we are going to see on Europa,” Shank said. “It’s only natural that we use Orpheus as a testbed for instruments and sensors because he operates at the same depths as humans.” We’ll learn how to maneuver and run in a self-contained manner.” According to Smith, NASA will tap into a reservoir of expertise and experience by working with the ocean exploration group, which would otherwise take too long to build up from scratch.
Smith said, “NOAA and WHOI have a lot of experience studying Earth’s oceans, which are a perfect test ground for exploring other ocean worlds.” “Our backgrounds are really complementary, and by working together, we can create vehicles that will take a lot of trial and error to create on our own. Both Earth submersibles and these potential ocean-world explorers are being developed at a rapid pace.”
According to Smith, Orpheus is a good starting point for iterations that might lead to a mini-submarine visiting other ocean realms because of its limited scale. Engineers would have to shrink the technology by at least a factor of ten to make it fit for an interplanetary journey.
“Things should be smaller,” Smith said, “because launching heavy vehicles into space is a huge expense.” “We Should be sure that the instruments can withstand being bombarded by radiation in space, as well as on moons that don’t have an atmosphere to shield them.”
The assurance of hydrothermal vents
Finding life on Europa or Enceladus, according to Shank, does not surprise him. The discovery of hydrothermal vents in 1977 revolutionized biologists’ understanding of life on Earth. Miles below the ocean’s surface, these cracks in the seafloor emit acidic, mineral-rich water, resulting in flourishing environments of unique bacteria, mollusks, and fish. These ecosystems can thrive in the absence of light.
“I don’t see why such kinds of ecosystems do not exist on Europa,” Shank said. “All you need is a comfortable heart, which you get from gravitational force. The stretching and contraction fractures the seafloor, allowing fluid to enter and be heated by the seafloor’s movements; if you have rock, a heat source, and hot water, you can have microbial life.”