First Scientific Paper Published on Pluto Flyby Is Just the Beginning

10-15-15 Pluto
This high-resolution image captured by NASA’s New Horizons spacecraft combines blue, red and infrared images taken by the Ralph/Multispectral Visual Imaging Camera (MVIC). The bright expanse is the western lobe of the “heart,” informally called Sputnik Planum, which has been found to be rich in nitrogen, carbon monoxide and methane ices. NASA/JHUAPL/SwRI

Just over three months ago on July 14, the New Horizons spacecraft zoomed past Pluto, reaching its long-awaited closest approach and marking the first-ever flyby of the dwarf planet. By the time the first week of August came around, the crew of scientists receiving and analyzing the data being returned had submitted a paper for review.

"The Pluto system: Initial results from its exploration by New Horizons" was published online Thursday and is the cover story of the October 16 issue of the journal Science. It covers all the major findings from data received leading up to the flyby and data sent back from the spacecraft during the second half of July, says Alan Stern, principal investigator for the New Horizons mission and lead author on the paper. After his name, the list of authors goes on for nearly two dozen lines.

"In my view it's the belle of the ball of the outer solar system," Stern says of Pluto. "It is scientifically just spectacular." There are about 100 different discoveries reported in the new paper, which includes both Pluto and its satellites.

One of the most intriguing is that Pluto has some areas—like the 1,000-kilometer wide icy plain informally called Sputnik Planum that forms the western section of its "heart"—that seem to indicate recent geological activity. Stern and his colleagues were surprised by this discovery, since geophysical models indicate that by this point in their history, small planets like Pluto should have ran out of energy and ceased to be geologically active. The finding, he says, could have implications for other small planetary objects in the Kuiper belt.

Pluto's surface is also much more complex than scientists previously thought. The paper describes some of the observations made so far like those of glacial flow and a large number of tectonic features. In addition to Sputnik Planum, scientists have found heavily cratered terrain and other landforms on a surface that varies in color, composition and reflectivity.

"The New Horizons mission completes our initial reconnaissance of the solar system, giving humanity our first look at this fascinating world and its system of moons," Jim Green, director of planetary science at NASA Headquarters in Washington, is quoted as saying in the agency's press release about the paper. "New Horizons is not only writing the textbook on the Pluto system, it's serving to inspire current and future generations to keep exploring—to keep searching for what's beyond the next hill."

New Horizons' "next hill" is another potential flyby in January 2019, Stern says: Starting next week, the spacecraft will begin a series of four engine burns to retarget for a flyby of a small Kuiper belt object roughly 1 billion miles past Pluto over three years from now.

In the meantime, scientists are working on a second "wave" of five papers—which will go into much greater depth on Pluto's geology and atmosphere, on Pluto's satellites and more—to be submitted in mid-November, Stern says. He expects a third set of papers to be submitted for review in January.

The New Horizons spacecraft will continue sending down data for several months. The highest-resolution images captured, for example, have yet to make it back to Earth, Stern says. "It will take us until next September to finish that job of just getting everything on the table here on Earth so that we can start to unravel the whole story."