By MARK MARCHAND | Special to The Republican
(The Republican daily newspaper, the primary daily in Springfield, Mass. Feb. 22, 2017)
BOSTON — Pluto circles slowly at the very outer edges of our solar system. The dwarf planet is so far away that sunlight, which flickers 1,000 times dimmer on Pluto than on Earth, takes 51/2 hours to get there. Radio waves from Earth need 41/2 hours to reach the remote, celestial body. And Pluto takes 248 years to circle the Sun.
Anyone hoping to send a research probe to explore the tiny sphere less than one-sixth the size of Earth faces a daunting, multi-year task that requires almost unheard-of navigation precision.
That didn’t stop legendary planetary scientist Alan Stern and his colleagues at NASA and the Southwest Research Institute. A veteran of 29 space exploration missions, Stern and his colleagues were inspired by earlier missions to the planet Neptune, conducted by NASA and its Jet Propulsion Laboratory. Neptune is the eighth planet in the Solar System, the last stop before entering a vast field of smaller objects beyond, including Pluto.
“In the early 1990s, Pluto went from being a sort of misfit planet to one of the most well-known of a new population of planets in what’s now known as the third zone of our solar system, or the Kuiper Belt,” Stern — named one of Time Magazine’s 100 most influential people last year — said during a lecture at the American Association for the Advancement of Science annual meeting in Boston last week. “We were learning from remote observations amazing new information, including the fact that Pluto has an atmosphere, and we could also detect the presence of three chemicals: methane, carbon monoxide and nitrogen.
“That new information and other factors raised the ranking of our mission on NASA’s list, and we finally received approval,” Stern said.
The complex undertaking, involving a 67-pound probe with seven scientific instruments, was named New Horizons. Stern was named the project leader, or principal investigator.
New Horizons was launched from Earth on Jan. 19, 2006. With a gravity boost from the giant planet Jupiter a year later, New Horizons cruised for another eight years before approaching Pluto. In the process, the probe covered about 4.6 billion miles at over 36,000 miles per hour.
In July 2015, New Horizons made its closest approach to Pluto: 7,800 miles. All seven instruments trained their sensors and lenses on Pluto, collecting over 50 gigabits of valuable data. But because the probe has a small antenna and operates at low power, it took more than a year for the information to make its way back to Earth. Since October, Stern and other scientists have finally begun analyzing the photos and other data, and talking about it.
They found a rocky, cratered surface, dotted with other features, such as ice and mountains.
“What is clear to us is that instead of being a cold, lifeless planet, Pluto is still geologically active,” Stern said. “We found ancient terrain that dates back to the formation of Pluto four billion years ago, but we also found middle-aged terrain and relatively new terrain features.”
One example involved the discovery of glaciers composed of nitrogen.
“We didn’t expect that at all. We didn’t even have one glaciologist (glacier expert) on our entire team,” Stern explained. “We had to quickly bone up on glaciers and hire a few experts.”
Another key discovery involved those glaciers. While nearby, rocky, heavily cratered surfaces displayed evidence of meteor and asteroid strikes over billions of years, the glaciers displayed smooth, unblemished surfaces.
“We couldn’t see a single impact crater on the glacier. This meant the glacier was recently formed or it was somehow renewing itself,” Stern said. “We didn’t expect that. We think the glacier at one point had craters but they were somehow erased.
“This activity had us scratching our heads,” he explained. “Something is causing Pluto to still be geologically active. We even saw some down slope movement of ice from the mountains, and perhaps evidence of a large avalanche. We didn’t expect that either.
“Now, with information from New Horizons, we have come to view Pluto as complex as nearby Mars,” Stern continued. “Pluto is the new Mars.”
Other data gathered by New Horizons revealed an atmosphere made up of nitrogen and methane, stretching as high as 125 miles about the surface. Scientists also spotted a frozen lake 18 miles wide. The probe also gathered data on the smaller, nearby dwarf called Charon, which is part of a “binary system” with Pluto. Farther away, New Horizons examined four other smaller objects.
“We think we can gain some knowledge about how our own moon was created, because of how we now think Charon was created: a catastrophic collision of a large object with Pluto, which is one theory of how our moon was created,” Stern said,
Pluto is now in New Horizons’ rear-view mirror, but the work of the mission is far from over. Because the probe’s tiny plutonium-powered reactor is still supplying electricity, NASA has cleared the craft to keep heading through the Kuiper Belt. On New Year’s Day 2019, New Horizons is expected to pass by another object, now called 2014-MU-69.
Peppered with questions from other scientists after he concluded his lecture, Stern revealed some unexpected thinking about further studying Pluto.
“From everything we have gathered, a strong case could be made for an ocean deep beneath Pluto’s surface,” he said. “If that proves to be the case, it could harbor the development of some biology deep in the interior.”
(Link to original story on newspaper website.)