Friday, October 21, 2016

New Horizons Shows Possible Clouds on Pluto, Target KBO Reddish

Pluto’s present, hazy atmosphere is almost entirely free of clouds, though scientists from NASA’s New Horizons mission have identified some cloud candidates after examining images taken during July 2015. Photo Credit: NASA / JHUAPL / SwRI

Data presented by New Horizons mission scientists at the current American Astronomical Society (AAS) Division for Planetary Sciences (DPS) Conference suggest possible clouds in Pluto’s hazy atmosphere, and also show the spacecraft’s second target, Kuiper Belt Object (KBO) 2014 MU69, to have the same reddish color as Pluto.

At the Pasadena, California, conference, which was also sponsored by the European Planetary Science Congress (EPSC), mission scientists revealed the latest discoveries about Pluto and Charon as well as a preview of MU69.

Most of Pluto’s atmosphere is free of clouds, but scientists found a few isolated, low-lying features that could be clouds in images taken by New Horizons’ Long Range Reconnaissance Imager (LORRI) and Multispectral Visible Imaging Camera (MVIC).

Scientists cannot confirm these are clouds with current stereo images. The last of the Pluto system flyby data is set to be returned on Oct. 23.

“If there are clouds, it would mean the weather on Pluto is even more complex than we imagined,” said Alan Stern, principal investigator from the Southwest Research Institute in Boulder, Colorado.

New Horizons science team co-investigator Bonnie Buratti of NASA’s Jet Propulsion Laboratory in Pasadena, California, noted that Pluto’s surface, which varies in brightness, is among the most reflective in the Solar System. Significantly, the brightest areas, such as the heart-shaped region known as Tombaugh Regio, are the most geologically active.

“That brightness indicates surface activity. Because we see a high pattern of surface reflectivity equating to activity, we can infer that the dwarf planet Eris, which is known to be highly reflective, is also likely to be active,” Buratti said.

The most recent mission data also shows evidence of landslides on the surface of Charon, Pluto’s largest moon, considered by some a binary companion to Pluto since both objects orbit a common center of gravity between them.

Landslides have been seen elsewhere in the Solar System, such as on Mars and on Saturn’s moon Iapetus. Those on Charon are the first detected in the Kuiper Belt at such a great distance from the Sun, according to science team researcher Ross Beyer of the SETI Institute’s Sagan Center and the NASA Ames Research Center in California.

“The big question is, will they be detected elsewhere in the Kuiper Belt?” Beyer said.

Evidence of past landslides is present on Charon’s Serenity Chasma in an image taken by LORRI from a distance of 48,912 miles (78,717 kilometers) on July 14, 2015. Mission scientists marked the image with red and yellow arrows pointing to features that suggest past landslides.

While the mission team is still analyzing data from the Pluto system, the spacecraft has already taken its first photographs of its extended mission target, MU69.

Surprisingly, the small KBO, located a billion miles (1.6 billion kilometers) beyond Pluto, is the same red color as Pluto, possibly even redder.

Its red color provides the first hint of its surface properties and composition and indicates it is made up of the most ancient material in the Solar System.

“The reddish color tells us the type of Kuiper Belt Object 2014 MU69 is,” explained Amanda Zangari, a post-doctoral researcher with the mission who is based at the Southwest Research Institute. “The data confirms that on New Year’s Day 2019, New Horizons will be looking at one of the ancient building blocks of the planets.”

Far too small to be spherical like Pluto and Eris, MU69 is the smallest KBO to have its color measured. That measurement confirms it is a member of the cold classical region of the Kuiper Belt, which contains the Solar System’s oldest pristine material.

New Horizons has imaged other KBOs from a distance as it travels at a speed of 9 miles (14 kilometers) per second. Now 340 million miles (540 million kilometers) past Pluto, the spacecraft is about one-third of the way to MU69.

The New Horizons team was just given the Cosmos Award for Outstanding Public Presentation of Science by the Planetary Society for its engagement of the public in the Pluto flyby. They are already looking ahead to a possible follow-up mission to Pluto to answer the many questions raised by the data that New Horizons has collected.

“We’re excited for the exploration ahead for New Horizons, and also what we are still discovering from Pluto flyby data,” Stern said. “Now, with our spacecraft transmitting the last of its data from last summer’s flight through the Pluto system, we know that the next great exploration of Pluto will require another mission be sent there.”

Early, informal discussions favor a return mission that includes a Pluto orbiter and lander.

Written by: Laurel Kornfeld
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