Mar 17 2016
From The Space Library
Science Papers Reveal New Aspects of Pluto and its Moons
A year ago, Pluto was just a bright speck in the cameras of NASA’s approaching New Horizons spacecraft, not much different than its appearances in telescopes since Clyde Tombaugh discovered the then-ninth planet in 1930.
But this week, in the journal Science, New Horizons scientists have authored the first comprehensive set of papers describing results from last summer’s Pluto system flyby. “These five detailed papers completely transform our view of Pluto – revealing the former ‘astronomer’s planet’ to be a real world with diverse and active geology, exotic surface chemistry, a complex atmosphere, puzzling interaction with the sun and an intriguing system of small moons,” said Alan Stern, New Horizons principal investigator from the Southwest Research Institute (SwRI), Boulder, Colorado.
After a 9.5-year, 3-billion-mile journey – launching faster and traveling farther than any spacecraft to reach its primary target – New Horizons zipped by Pluto on July 14, 2015. New Horizons’ seven science instruments collected about 50 gigabits of data on the spacecraft’s digital recorders, most of it coming over nine busy days surrounding the encounter.
The first close-up pictures revealed a large heart-shaped feature carved into Pluto’s surface, telling scientists that this “new” type of planetary world – the largest, brightest and first-explored in the mysterious, distant “third zone” of our solar system known as the Kuiper Belt – would be even more interesting and puzzling than models predicted.
The newly published Science papers bear that out; click here for a list of top results.
“Observing Pluto and Charon up close has caused us to completely reassess thinking on what sort of geological activity can be sustained on isolated planetary bodies in this distant region of the solar system, worlds that formerly had been thought to be relics little changed since the Kuiper Belt’s formation,” said Jeff Moore, lead author of the geology paper from NASA's Ames Research Center, Moffett Field, California.
Scientists studying Pluto’s composition say the diversity of its landscape stems from eons of interaction between highly volatile and mobile methane, nitrogen and carbon monoxide ices with inert and sturdy water ice. “We see variations in the distribution of Pluto's volatile ices that point to fascinating cycles of evaporation and condensation,” said Will Grundy of the Lowell Observatory, Flagstaff, Arizona, lead author of the composition paper. “These cycles are a lot richer than those on Earth, where there's really only one material that condenses and evaporates – water. On Pluto, there are at least three materials, and while they interact in ways we don't yet fully understand, we definitely see their effects all across Pluto's surface.”
Above the surface, scientists discovered Pluto’s atmosphere contains layered hazes, and is both cooler and more compact than expected. This affects how Pluto’s upper atmosphere is lost to space, and how it interacts with the stream of charged particles from the sun known as the solar wind. “We’ve discovered that pre-New Horizons estimates wildly overestimated the loss of material from Pluto’s atmosphere,” said Fran Bagenal, from the University of Colorado, Boulder, and lead author of the particles and plasma paper. “The thought was that Pluto’s atmosphere was escaping like a comet, but it is actually escaping at a rate much more like Earth’s atmosphere.”
SwRI’s Randy Gladstone of San Antonio is the lead author of the Science paper on atmospheric findings. He added, “We’ve also discovered that methane, rather than nitrogen, is Pluto’s primary escaping gas. This is pretty surprising, since near Pluto’s surface the atmosphere is more than 99 percent nitrogen.”
Scientists also are analyzing the first close-up images of Pluto’s small moons—Styx, Nix, Kerberos and Hydra. Discovered between 2005 and 2012, the four moons range in diameter from about 25 miles (40 kilometers) for Nix and Hydra to about six miles (10 kilometers) for Styx and Kerberos. Mission scientists further observed that the small satellites have highly anomalous rotation rates and uniformly unusual pole orientations, as well as icy surfaces with brightness and colors distinctly different from those of Pluto and Charon.
They’ve found evidence that some of the moons resulted from mergers of even smaller bodies, and that their surface ages date back at least 4 billion years. “These latter two results reinforce the hypothesis that the small moons formed in the aftermath of a collision that produced the Pluto-Charon binary system,” said Hal Weaver, New Horizons project scientist from the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, and lead author of the Science paper on Pluto’s small moons.
About half of New Horizons’ flyby data has now been transmitted home – from distances where radio signals at light speed need nearly five hours to reach Earth – with all of it expected back by the end of 2016.
“This is why we explore,” said Curt Niebur, New Horizons program scientist at NASA Headquarters in Washington. “The many discoveries from New Horizons represent the best of humankind and inspire us to continue the journey of exploration to the solar system and beyond.”
MEDIA ADVISORY M16-030 NASA TV Coverage Set for Fifth Orbital ATK Resupply Mission to Space Station
NASA commercial provider Orbital ATK is scheduled to launch its fifth mission to the International Space Station Tuesday, March 22 under the agency’s Commercial Resupply Services contract. Live launch coverage will begin at 10 p.m. EDT on NASA Television and the agency’s website.
The company’s Cygnus spacecraft is set to lift off on a United Launch Alliance Atlas V rocket at 11:05 p.m., the start of a 30-minute launch window, from Space Launch Complex 41 on Cape Canaveral Air Force Station in Florida. Coverage will resume for solar array deployment at 12:45 a.m. March 23, and a post-launch briefing will be held approximately two hours after launch.
NASA TV also will air two prelaunch briefings Monday, March 21. At 12:30 p.m., scientists and researchers will discuss some of the investigations to be delivered to the station, followed by a briefing by mission managers at 2:30 p.m. The briefings will stream live on the agency’s website.
Cygnus will carry almost 7,500 pounds of science and research, crew supplies and vehicle hardware to the orbital laboratory to support dozens of science and research investigations that will occur during Expeditions 47 and 48.
The new experiments will inspire future scientists and explorers, with experiments such as an investigation that looks at the properties and behavior of regolith, or "soil" found on asteroids, comets, the moon, and other airless worlds; an instrument for the first-ever, space-based observations of the chemical composition of meteors entering Earth’s atmosphere; a technology demonstration of an adhesive device that can stick on-command in the harsh environment of space; and, the second generation of a portable onboard 3-D printer, among others.
The spacecraft will arrive at the station on Saturday, March 26, at which time Expedition 47 Commander Tim Kopra of NASA and Flight Engineer Tim Peake of ESA (European Space Agency) will grapple Cygnus, using the space station’s robotic arm, at approximately 6:40 a.m. NASA TV coverage of rendezvous and grapple will begin at 5:30 a.m.
After Cygnus capture, ground commands will be sent from mission control in Houston to the station’s arm to rotate and install the spacecraft on the bottom of the station’s Unity module. Coverage of installation will begin at 9:15 a.m.
Cygnus will remain at the space station until May, when the spacecraft will be used to dispose of several tons of trash during its fiery reentry into Earth’s atmosphere.
Media at the agency’s Kennedy Space Center in Florida will have the opportunity to participate in special tours and briefings on March 21 and 22, as well as view the launch. The deadline for media to apply for accreditation for this launch has passed. For more information about media accreditation, contact Jennifer Horner at 321-867-6598 or jennifer.p.horner@nasa.gov.
If the launch does not occur on Tuesday, March 22, the next launch opportunity is 10:40 p.m. Wednesday, March 23, with NASA TV coverage starting at 9:45 p.m.
This will be the second flight to the station of an enhanced Cygnus spacecraft, which has an extended pressurized cargo module that increases the spacecraft’s interior volume capacity by 25 percent and enables more cargo to be delivered with each mission. Dubbed the S.S. Rick Husband, the spacecraft is a tribute to U.S. Air Force Col. Rick Husband, commander of space shuttle Columbia’s STS-107 mission, which was lost during reentry on Feb. 1, 2003.
