A Young Island On Earth May Reveal Clues To How Water Shaped Mars
Four years ago, an underwater volcano erupted in the South Pacific, creating a new island. And NASA took notice.
The island’s evolution could hold clues to how water might have shaped similar features on Mars billions of years ago, NASA officials believed, so the space agency began collecting satellite photos to track how the elements were carving and clawing away at the land.
The images yielded insights into how the island was eroding, but the story they told was limited. NASA could wring more information from those photographs with measurements taken from the ground, but James Garvin, the chief scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md., could not justify the cost of sending a team. Then an opportunity presented itself.
Dr. Garvin jumped at the chance, sending along Dan Slayback, a research scientist for NASA who had been working on the effort to track the island’s progression.
Dr. Slayback sailed on that trip last fall, finding an island of black rock that was, to his surprise, also teeming with life.
“It was very dramatic,” he said. “Just beautifully dramatic.”
The island, part of Tonga, is about 500 acres in size and about 1,300 miles northeast of New Zealand. It has not yet been named, but is unofficially referred to as Hunga Tonga-Hunga Ha’apai, a combination of the names of the two older, uninhabited islands it sits between. (A land bridge connects all three.)
Its most prominent features are a turquoise lake and a croissant-shaped ridge — the remnants of a cone made from hardened ash — that stretches about 400 feet high and about a mile across, Dr. Slayback said.
After spending years staring at satellite photographs of the island, he was overwhelmed to finally see the breathtaking landscape up close in early October. He was also eager to get to work.
The satellite photos reveal how the island has eroded over time, but their level of detail is limited without three-dimensional points of reference as context. So, with the help of the students, Dr. Slayback roamed the island with a finely tuned GPS device, recording the location of various features visible in the photographs with an accuracy of a few inches.
Those measurements will allow the NASA team to refine the models it had created and more narrowly track erosion going forward, Dr. Garvin said.
“Instead of a map with a resolution the size of a chair that you’d sit at your desk in, we have a map of the topography, the three-dimensionality, of this new island that’s good to the size of a few fingers,” he said.
With those finer models, scientists can better compare the changing shape of Hunga Tonga-Hunga Ha’apai to volcanic shapes and erosion patterns on Mars to better understand the degree to which water was present there and the role it might have played in shaping the landscape.
In addition to helping Dr. Slayback with the measurements, the students and faculty collected rock samples and documented the vegetation growing on the island. They were also surprised to find a thriving bird population.
“The number of birds, the number of bird eggs, the number of baby chicks was astounding,” Rachel Scudder, the chief scientist for the Sea Education Association, said. “There were places where we could not actually get up to the wall of the caldera for fear of stepping on baby chicks.”
The birds included nesting sooty terns and at least one barn owl, Dr. Slayback said. The group also found grass and beach morning glories sprouting from soil-like patches on the island’s otherwise barren, rocky surface.
They came across signs of human life, too: Garbage was strewn about parts of the island. Most was likely churned up last year by Tropical Cyclone Gita, though some of the trash might have been left behind by visitors from nearby islands, according to Jeffrey Wescott, an anthropology professor with the program. The students filled and removed about a dozen bags of trash, most of it plastic bottles.
The volcanic eruption that birthed the island occurred in December 2014, sending ash as high as 30,000 feet into the air and disrupting flights. The island was formed in part when that ash fell back to earth and hardened after mixing with warm water, Dr. Garvin said.
When the island was created, the NASA team thought it might not survive much longer than a decade. (That was part of the reason it could not justify sending a team there.) Now, after sampling rocks from the island, visiting it and watching it weather the elements, the team expects it to remain for anywhere from a few decades to hundreds of years.
“Right now, things look good,” Dr. Garvin said. “The island may be cementing itself.”