NASA’s Webb To Examine Objects in the Graveyard of the Solar System

Pluto and its largest moon, Charon, are two of the best-known residents of the Kuiper Belt. This composite of enhanced color images of Pluto (lower right) and Charon (upper left), was taken by NASA's New Horizons spacecraft as it passed through the Pluto system on July 14, 2015. The color and brightness of both Pluto and Charon have been processed identically to allow direct comparison of their surfaces, and to highlight the similarity between Charon's polar red terrain and Pluto's equatorial red terrain. Pluto and Charon are shown with approximately correct relative sizes, but their true separation is not to scale. Credits: NASA/JHUAPL/SwRI.  Link to image

Beyond the orbit of Neptune, a diverse collection of thousands of dwarf planets and other relatively small objects dwells in a region called the Kuiper Belt. These often-pristine leftovers from our solar system's days of planet formation are called Kuiper Belt Objects, or Trans-Neptunian Objects. NASA's upcoming James Webb Space Telescope will examine an assortment of these icy bodies in a series of programs called Guaranteed Time Observations shortly after its launch in 2021. The goal is to learn more about how our solar system formed.

"These are objects that are in the graveyard of solar system formation," explained Cornell University's Jonathan Lunine, a Webb Interdisciplinary Scientist who will use Webb to study some of these targets. "They're in a place where they could last for billions of years, and there aren't many places like that in our solar system. We'd love to know what they're like."

By studying these bodies, Lunine and his colleagues hope to learn about which ices were present in the early solar system. These are the coldest worlds to display geologic and atmospheric activity, so scientists are also interested in comparing them with the planets.

Kuiper Belt Objects are very cold and faint, yet they glow in infrared light, which is at wavelengths beyond what our human eyes can see. Webb is specifically designed to detect infrared light. To study these distant objects, scientists mainly will use a technique called spectroscopy, which divides light into its individual colors to determine the properties of materials that interact with that light.

This global color mosaic of Neptune's moon Triton, likely a captured KBO, was taken in 1989 by Voyager 2 during its flyby of the Neptune system. Triton is by far the largest satellite of Neptune. Credit: NASA/JPL/USGS.  Link to image

 A Wide Assortment

The denizens of the Kuiper Belt come in various shapes and sizes. Some reside in pairs or multiples, while others have rings or moons. They exhibit a wide range of colors, which may indicate different formation histories or different exposure to sunlight.

"Some seem to be redder in color, others are bluer. Why is that?" said Heidi Hammel, a Webb Interdisciplinary Scientist for solar system observations. She is also Vice President for Science at the Association of Universities for Research in Astronomy (AURA) in Washington, D.C. "Using Webb, we will be able to get information about surface chemistry that might be able to give us some clues into why there are these different populations in the Kuiper Belt."

Kicked out of the Club

Between Jupiter and Neptune, and crossing the orbit of one or more of the giant planets, lies a different population of objects called centaurs. These are small solar system bodies that have been ejected from the Kuiper Belt. In addition to observing current Kuiper Belt Objects, these Webb programs will study such solar system bodies that have been "kicked out of the club." These former Kuiper Belt Objects have orbits that have been dramatically disturbed, bringing them significantly closer to the Sun.

"Because they cross the orbits of Neptune, Uranus, and Saturn, centaurs are short-lived. So they are typically only around for about 10 million years," explained John Stansberry of the Space Telescope Science Institute in Baltimore, Maryland. Stansberry is leading a different team that will use Webb to study Kuiper Belt Objects. "By that point, they have an interaction with one of the major planets that's very strong, and they either get thrown into the Sun or thrown out of the solar system."

Another body that Webb will study is Neptune's moon Triton. The largest of the ice giant's 13 moons, Triton shares many similarities with Pluto. "Even though it's Neptune's moon, we have evidence to suggest that it is a Kuiper Belt Object that got too close to Neptune sometime in its past, and it was captured into orbit around Neptune," said Hammel. "Triton was studied by the Voyager 2 probe in 1989. That spacecraft data will provide us very important 'ground truth' for our Webb observations of Kuiper Belt Objects."

Though not on Webb's target list, Arrokoth is probably exemplary of a lot of objects in the Kuiper Belt. The farthest object ever visited by a spacecraft, it is composed of two conjoined planetesimals. Arrokoth was photographed by the New Horizons spacecraft in December 2018 and January 2019. Credits: NASA/JHUAPL/SwRI/Roman Tkachenko.  Link to image

 

A Sampling of the Targets

Here is a small sampling of some of the dozens of current and former Kuiper Belt Objects that Webb will observe:

• Pluto and Charon: The dwarf planet Pluto and its largest moon, Charon, are two of the most well-known residents of the Kuiper Belt. Pluto boasts an atmosphere, haze, and seasons. It has geologic activity on its surface and may have an ocean in its interior. In addition to Charon, it hosts four other moons: Nix, Hydra, Styx, and Kerberos. The Webb data will complement the observations made by NASA's New Horizons spacecraft when it flew by the Pluto system in 2015.

• Eris: Nearly the size of Pluto, Eris is the second-largest known dwarf planet in the solar system. At its farthest point, mysterious Eris is more than 97 times as far from the Sun as the Earth is. Because of its distance, it is difficult to observe, but Webb will tell scientists quite a bit about what kinds of ices are on its surface.

• Sedna: With its deep red hue, Sedna is actually located beyond the main Kuiper Belt. It takes approximately 11,400 years to complete one orbit, and the farthest point of that highly elongated orbit is estimated to be 940 times Earth's distance from the Sun.

• Haumea: This large, rapidly spinning body is egg-shaped, and scientists would like to know why. In addition to moons, it also seems to have a ring system. With Webb, scientists hope to learn more about how those rings formed.

• Chariklo: The largest centaur, Chariklo is also the first asteroid found to have a ring system. It was the fifth ring system found in our solar system—after Saturn, Jupiter, Uranus and Neptune. The rings are believed to be between two and four miles wide.

Another program, called a Target of Opportunity, will observe a Kuiper Belt Object passing in front of a star, if such an alignment should occur during the first two years of Webb's lifetime. Called an occultation, this type of observation can reveal an object's size.

The few spacecraft that have flown by Kuiper Belt Objects could only study these intriguing objects for a very short period of time. With Webb, astronomers can target more Kuiper Belt Objects over an extended time. The result will be new insights into our solar system's earliest history.

The James Webb Space Telescope will be the world's premier space science observatory when it launches in 2021. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

For more information about Webb, visit www.nasa.gov/webb.

By Ann Jenkins
Space Telescope Science Institute, Baltimore, Md.

Editor: Lynn Jenner

 

Source: NASA/Webb Telescope

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Pluto 'Paints' its Largest Moon Red

NASA's New Horizons spacecraft captured this high-resolution, enhanced color view of Pluto’s largest moon, Charon, just before closest approach on July 14, 2015. The image combines blue, red and infrared images taken by the spacecraft's Ralph/Multispectral Visual Imaging Camera (MVIC); the colors are processed to best highlight the variation of surface properties across Charon. Scientists have learned that reddish material in the north (top) polar region – informally named Mordor Macula – is chemically processed methane that escaped from Pluto’s atmosphere onto Charon. Charon is 754 miles (1,214 kilometers) across; this image resolves details as small as 1.8 miles (2.9 kilometers). Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute . Hi-res image

In June 2015, when the cameras on NASA's approaching New Horizons spacecraft first spotted the large reddish polar region on Pluto's largest moon, Charon, mission scientists knew two things: they'd never seen anything like it elsewhere in our solar system, and they couldn't wait to get the story behind it.

Over the past year, after analyzing the images and other data that New Horizons has sent back from its historic July 2015 flight through the Pluto system, the scientists think they've solved the mystery. 

As they detail this week in the international scientific journal Nature, Charon's polar coloring comes from Pluto itself - as methane gas that escapes from Pluto's atmosphere and becomes "trapped" by the moon's gravity and freezes to the cold, icy surface at Charon's pole. This is followed by chemical processing by ultraviolet light from the sun that transforms the methane into heavier hydrocarbons and eventually into reddish organic materials called tholins.

"Who would have thought that Pluto is a graffiti artist, spray-painting its companion with a reddish stain that covers an area the size of New Mexico?" asked Will Grundy, a New Horizons co-investigator from Lowell Observatory in Flagstaff, Arizona, and lead author of the paper. "Every time we explore, we find surprises. Nature is amazingly inventive in using the basic laws of physics and chemistry to create spectacular landscapes."

The team combined analyses from detailed Charon images obtained by New Horizons with computer models of how ice evolves on Charon's poles. Mission scientists had previously speculated that methane from Pluto's atmosphere was trapped in Charon's north pole and slowly converted into the reddish material, but had no models to support that theory.

The New Horizons team dug into the data to determine whether conditions on the Texas-sized moon (with a diameter of 753 miles or 1,212 kilometers) could allow the capture and processing of methane gas. The models using Pluto and Charon's 248-year orbit around the sun show some extreme weather at Charon's poles, where 100 years of continuous sunlight alternate with another century of continuous darkness. Surface temperatures during these long winters dip to -430 Fahrenheit (-257 Celsius), cold enough to freeze methane gas into a solid.

"The methane molecules bounce around on Charon's surface until they either escape back into space or land on the cold pole, where they freeze solid, forming a thin coating of methane ice that lasts until sunlight comes back in the spring," Grundy said. But while the methane ice quickly sublimates away, the heavier hydrocarbons created from it remain on the surface.

The models also suggested that in Charon's springtime the returning sunlight triggers conversion of the frozen methane back into gas. But while the methane ice quickly sublimates away, the heavier hydrocarbons created from this evaporative process remain on the surface.

Sunlight further irradiates those leftovers into reddish material - called tholins - that has slowly accumulated on Charon's poles over millions of years. New Horizons' observations of Charon's other pole, currently in winter darkness - and seen by New Horizons only by light reflecting from Pluto, or "Pluto-shine" - confirmed that the same activity was occurring at both poles.

"This study solves one of the greatest mysteries we found on Charon, Pluto's giant moon," said Alan Stern, New Horizons principal investigator from the Southwest Research Institute, and a study co-author. "And it opens up the possibility that other small planets in the Kuiper Belt with moons may create similar, or even more extensive 'atmospheric transfer' features on their moons." 

Source:  New Horizons/News Center

NASA Releases New Visualization of Space Environment at Pluto

This video shows a simulation of the space environment all the way out to Pluto in the months surrounding New Horizons’ July 2015 flyby. At the time, scientists at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, worked with the New Horizons team to test how well their models—and other models contributed by scientists around the world—predicted the space environment at Pluto. Understanding the environment through which our spacecraft travel can ultimately help protect them from radiation and other potentially damaging effects. Visualizers at Goddard recently updated the movie of the model, creating this new release. Credits: NASA's Goddard Space Flight Center Scientific Visualization Studio, the Space Weather Research Center (SWRC) and the Community-Coordinated Modeling Center (CCMC), Enlil and Dusan Odstrcil (GMU). Download this video in HD formats from NASA Goddard's Scientific Visualization Studio

This artist's concept depicts the New Horizons spacecraft during its July 2015 encounter with Pluto and one of the dwarf planet's moons, Charon.  Credits: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

Though the vacuum of space is about a thousand times emptier than a laboratory vacuum, it’s still not completely empty. The sun releases a constant stream of particles called the solar wind—as well as occasional denser clouds of particles known as coronal mass ejections, or CMEs—both containing embedded magnetic fields. The density, speed, and temperature of these particles, as well as the direction and strength of the embedded magnetic fields, make up the space environment.

To map the space environment at Pluto, scientists combined the predictions of several models—and looked at events that had long since passed Earth.

"We set the simulation to start in January of 2015, because the particles passing Pluto in July 2015 took some six months to make the journey from the sun," said Dusan Odstrcil, a space weather scientist at Goddard who created the Enlil model. The Enlil model, named for the Sumerian god of the wind, is one of the primary models used to simulate the space environment near Earth and is the basis for the New Horizons simulation.  

The new, combined model tracks CMEs longer than ever before. Because particles must travel for many months before reaching Pluto, the CMEs eventually spread out and merge with other CMEs and the solar wind to form larger clouds of particles and magnetic field. These combined clouds stretch out as they travel away from the sun, forming thin ring shapes by the time they reach Pluto—quite different from the typical balloon shape of CMEs seen here at Earth.


Related Links 

• Feature: “Scientists Simulate the Space Environment During NASA's New Horizons Flyby” (July 10, 2015)
• Download HD-quality multimedia related to this story from NASA Goddard’s Scientific Visualization Studio
• NASA's New Horizons mission website

Sarah Frazier
NASA’s Goddard Space Flight Center, Greenbelt, Md.

Source: NASA/New Horizons

Hubble Finds Two Chaotically Tumbling Pluto Moons

Artist's Illustration of the Chaotic Spin of Pluto's Moon Nix

This set of artist's illustrations of Pluto's moon Nix shows how the orientation of the moon changes unpredictably as it orbits the "double planet" Pluto-Charon. This illustration is based on dynamical models of spinning bodies in complex gravitational fields — like the field produced by Pluto and Charon's motion about each other. Astronomers used this simulation to try to understand the unpredictable changes in reflected light from Nix as it orbits Pluto-Charon. They also found that Pluto's moon Hydra also undergoes chaotic spin. The football shape of both moons contributes to their wild motion. The consequences are that if you lived on either moon, you could not predict the time or direction the sun would rise the next day. (The moon is too small for Hubble to resolve surface features, and so the surface textures used here are purely for illustration purposes.)   Credit: NASA, ESA, M. Showalter (SETI Institute), and G. Bacon (STScI)

Nix, Hydra, Kerberos, Styx and Charon

This artist's illustration shows the scale and comparative brightness of Pluto's small satellites, as discovered by the Hubble Space Telescope over the past several years. Pluto's binary companion, Charon (discovered in 1978), is placed at the bottom for scale. Two of the moons are highly oblate. The reflectivity among the moons varies from dark charcoal to the brightness of white sand. Hubble cannot resolve surface features on the moons and so the cratered textures seen here are purely for illustration purposes. Credit: NASA, ESA, M. Showalter (SETI Institute), and A. Feild (STScI)

Release Images - Release Video

If you lived on one of Pluto's moons Nix or Hydra, you'd have a hard time setting your alarm clock. That's because you could not know for sure when, or even in which direction, the sun would rise.

A comprehensive analysis of all available Hubble Space Telescope data shows that two of Pluto's moons, Nix and Hydra, are wobbling unpredictably. Scientists believe the other two small moons, Kerberos and Styx, are likely in a similar situation, pending further study.

"Hubble has provided a new view of Pluto and its moons revealing a cosmic dance with a chaotic rhythm," said John Grunsfeld, associate administrator of NASA's Science Mission Directorate in Washington, D.C. "When the New Horizons spacecraft flies through the Pluto system in July we'll get a chance to see what these moons look like up close and personal."

Why the chaos? Because the moons are embedded inside a dynamically shifting gravitational field caused by the system's two central bodies, Pluto and Charon, whirling about each other. The variable gravitational field induces torques that send the smaller moons tumbling in unpredictable ways. This torque is strengthened by the fact the moons are football shaped rather than spherical.

The surprising results of the Hubble research, conducted by Mark Showalter of the SETI Institute in Mountain View, California, and Doug Hamilton of the University of Maryland at College Park, are appearing in the June 4 issue of the British science journal Nature.

"Prior to the Hubble observations nobody appreciated the intricate dynamics of the Pluto system," Showalter said. "Our report provides important new constraints on the sequence of events that led to the formation of the system."

Hubble's monitoring of Pluto's four outer moons has also revealed that three of them, Nix, Styx, and Hydra, are presently locked together in resonance where there is a precise ratio among their orbital periods. "This ties together their motion in a way similar to that of three of Jupiter's large moons," noted Hamilton. "If you were sitting on Nix you would see that Styx orbits Pluto twice for every three orbits made by Hydra."

Hubble provides observational evidence that the satellites are also orbiting chaotically. "However, that does not necessarily mean that the system is on the brink of flying apart," Showalter added. "We need to know a lot more about the system before we can determine its long-term fate."

To the surprise of astronomers, Hubble also found that the moon Kerberos is as dark as a charcoal briquette, while the other satellites are as bright as white sand. It was predicted that pollution by dust blasted off the satellites by meteorite impacts should overcoat all the moons, giving their surfaces a homogeneous look. "This is a very provocative result," Showalter said.

NASA's New Horizons probe, which will fly by the Pluto-Charon system in July 2015, may help settle the question of the asphalt-black moon as well as the other oddities uncovered by Hubble. These new discoveries are being used in the science planning for New Horizons's observations.

The chaos in the Pluto-Charon system offers insights into how planets orbiting a double-star might behave. "We are learning that chaos may be a common trait of binary systems," Hamilton said. "It might even have consequences for life on planets in such systems." NASA's Kepler space observatory has found several planetary systems orbiting double stars.

Clues to the Pluto chaos first came when astronomers measured variations in the light reflected off of the two moons Nix and Hydra. Their brightness changed unpredictably. "The data were confusing; they made no sense at all. We had an inkling something was fishy," Showalter said. His team analyzed Hubble images of Pluto taken during 2005-2012. They compared the unpredictable changes in the moons' reflectivity to dynamical models of spinning bodies in complex gravitational fields.

Virtually all large moons, as well as small moons in close-in orbits, keep one hemisphere facing their parent planet. This means that the satellite's rotation is perfectly matched to the orbital period. This is not coincidental, but the consequence of gravitational tides between moon and planet. (Hyperion, which orbits Saturn, is the only other solar-system example of chaotic rotation; it is due to the combined gravitational tugs of the planet and it largest moon, Titan).

Pluto's moons are hypothesized to have formed by a collision between the dwarf planet and another similar-sized body early in the history of the solar system. The smashup flung material that coalesced into the family of satellites observed around Pluto today. Its large binary companion, Charon, was discovered in 1978. The object is almost half the size of Pluto. Hubble discovered Nix and Hydra in 2005, Kerberos in 2011, and Styx in 2012. These little moons, measuring just tens of miles across, were found as part of a Hubble search for potential hazards to the New Horizons spacecraft flyby.

Pluto and Charon are called a double planet because they orbit about a common center of gravity that is located in the space between the bodies. Some regard the Earth-moon system as a double planet, too, although the center of gravity falls beneath Earth's surface. (Our moon has 1/80th of Earth's mass, whereas Charon has 1/8th of Pluto's mass.)

Researchers say that a combination of monitoring data from Hubble, New Horizons's brief close-up look, and eventually, observations with the James Webb Space Telescope will help settle many mysteries of the Pluto-Charon system. No ground-based telescopes have yet been able to detect the smallest moons.

"Pluto will continue to surprise us when New Horizons flies past it in July," Showalter said. "Our work with the Hubble telescope just gives us a foretaste of what's in store."

Contacts:

Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4514
villard@stsci.edu

Felicia Chou
NASA Headquarters, Washington, D.C.
202-358-0257
felicia.chou@nasa.gov

Mark Showalter
SETI Institute, Mountain View, California
605-810-0234
mshowalter@seti.org

Doug Hamilton
University of Maryland, College Park, Maryland
301-405-1548
dhamil@astro.umd.edu

Source: HubbleSite

New Horizons Spots Pluto’s Faintest Known Moons

New Horizons Spots Pluto’s Faintest Known Moons
Download the .mov file

For the first time, NASA's New Horizons spacecraft has photographed Kerberos and Styx – the smallest and faintest of Pluto's five known moons. Following the spacecraft's detection of Pluto's giant moon Charon in July 2013, and Pluto's smaller moons Hydra and Nix in July 2014 and January 2015, respectively, New Horizons is now within sight of all the known members of the Pluto system. 

"New Horizons is now on the threshold of discovery," said mission science team member John Spencer, of the Southwest Research Institute in Boulder, Colorado. "If the spacecraft observes any additional moons as we get closer to Pluto, they will be worlds that no one has ever seen before." 

Drawing even closer to Pluto in mid-May, New Horizons will begin its first search for new moons or rings that might threaten the spacecraft on its passage through the Pluto system. The images of faint Styx and Kerberos shown here are allowing the search team to refine the techniques they will use to analyze those data, which will push the sensitivity limits even deeper. 

Kerberos and Styx were discovered in 2011 and 2012, respectively, by New Horizons team members using the Hubble Space Telescope. Styx, circling Pluto every 20 days between the orbits of Charon and Nix, is likely just 4 to 13 miles (approximately 7 to 21 kilometers) in diameter, and Kerberos, orbiting between Nix and Hydra with a 32-day period, is just 6 to 20 miles (approximately 10 to 30 kilometers) in diameter. Each is 20 to 30 times fainter than Nix and Hydra. 

The images detecting Kerberos and Styx shown here were taken with New Horizons' most sensitive camera, the Long Range Reconnaissance Imager (LORRI), from April 25-May 1. Each observation consists of five 10-second exposures that have been added together to make the image in the left panel, and extensively processed to reduce the bright glare of Pluto and Charon and largely remove the dense field of background stars (center and right panels), in order to reveal the faint satellites, whose positions and orbits, along with those of the brighter moons Nix and Hydra, are given in the right panel. 

"Detecting these tiny moons from distance of over 55 million miles is amazing, and a credit to the team that built our LORRI long-range camera and John Spencer's team of moon and ring hunters," added New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute. 

Kerberos is visible in all of the images, though is partially obscured in the second image. Styx is not visible in the first image, only in subsequent ones; on April 25 it was obscured by electronic artifacts in the camera – the black and white streaks extending to the right of the extremely overexposed images of Pluto and Charon in the center of the frame. These artifacts point in different directions in different images due to the varying orientation of the spacecraft. Other unlabeled features in the processed images include the imperfectly removed images of background stars and other residual artifacts. 

Although Styx and Kerberos are more visible in some frames than others, perhaps due to brightness fluctuations as they rotate on their axes, their identity is confirmed by their positions being exactly where they are predicted to be (in the center of the circles in the right panel). 

The Johns Hopkins University Applied Physics Laboratory (APL) designed, built, and operates the New Horizons spacecraft, and manages the mission for NASA's Science Mission Directorate. SwRI leads the science team, payload operations and encounter science planning. New Horizons is part of the New Frontiers Program managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. 

Source:  New Horizons/NASA's Mission to Pluto

ALMA Pinpoints Pluto to Help Guide NASA’s New Horizons Spacecraft

The cold surface of Pluto and its largest moon Charon as seen with ALMA on July 15, 2014. 

Credit: NRAO/AUI/NSF

Animated image of ALMA data showing the motion of the moon Charon around the icy dwarf planet Pluto. 

Credit: B. Saxton (NRAO/AUI/NSF)

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) are making high-precision measurements of Pluto's location and orbit around the Sun to help NASA’s New Horizons spacecraft accurately home in on its target when it nears Pluto and its five known moons in July 2015.

Though observed for decades with ever-larger optical telescopes on Earth and in space, astronomers are still working out Pluto's exact position and path around our Solar System. This lingering uncertainty is due to Pluto's extreme distance from the Sun (approximately 40 times farther out than the Earth) and the fact that we have been studying it for only about one-third of its orbit. Pluto was discovered in 1930 and takes 248 years to complete one revolution around the Sun.

“With these limited observational data, our knowledge of Pluto’s position could be wrong by several thousand kilometers, which compromises our ability to calculate efficient targeting maneuvers for the New Horizons spacecraft,” said New Horizons Project Scientist Hal Weaver, from the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

The New Horizons team made use of the ALMA positioning data, together with newly analyzed visible light measurements stretching back to Pluto's discovery, to determine how to perform the first such scheduled course correction for targeting, known as a Trajectory Correction Maneuver (TCM), in July. This maneuver helped ensure that New Horizons uses the minimum fuel to reach Pluto, saving as much as possible for a potential extended mission to explore Kuiper Belt objects after the Pluto system flyby is complete.

To prepare for this first TCM, astronomers needed to pinpoint Pluto's position using the most distant and most stable reference points possible. Finding such a reference point to accurately calculate trajectories of such small objects at such vast distances is incredibly challenging. Normally, stars at great distances are used by optical telescopes for astrometry (the positioning of things on the sky) since they change position only slightly over many years. For New Horizons, however, even more precise measurements were necessary to ensure its encounter with Pluto would be as on-target as possible.

The most distant and most apparently stable objects in the Universe are quasars, galaxies more than 10 billion light-years away. Though quasars appear very dim to optical telescopes, they are incredibly bright at radio wavelengths, particularly the millimeter wavelengths that ALMA can see.

“The ALMA astrometry used a bright quasar named J1911-2006 with the goal to cut in half the uncertainty of Pluto's position,” said Ed Fomalont, an astronomer with the National Radio Astronomy Observatory in Charlottesville, Virginia, and currently assigned to ALMA’s Operations Support Facility in Chile.

ALMA was able to study Pluto and its largest moon Charon by picking up the radio emission from their cold surfaces, which are about 43 degrees Kelvin (-230 degrees Celsius).

The team first observed these two icy worlds in November 2013, and then three more times in 2014 -- once in April and twice in July. Additional observations are scheduled for October 2014.

"By taking multiple observations at different dates, we allow Earth to move along its orbit, offering different vantage points in relation to the Sun," said Fomalont. "Astronomers can then better determine Pluto's distance and orbit." This astronomical technique is called measuring Pluto's parallax.

"We are very excited about the state-of-the-art capabilities that ALMA brings to bear to help us better target our historic exploration of the Pluto system," said New Horizons Principal Investigator Alan Stern of the Southwest Research Institute in Boulder, Colorado. "We thank the entire ALMA team for their support and for the beautiful data they are gathering for New Horizons."

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by the European Southern Observatory (ESO), on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

New Horizons is the first mission to the Pluto system and the Kuiper Belt of rocky, icy objects beyond. The Johns Hopkins University Applied Physics Laboratory (APL) manages the mission for NASA’s Science Mission Directorate; Alan Stern, of the Southwest Research Institute (SwRI), is the principal investigator and leads the mission. SwRI leads the science team, payload operations and encounter science planning; APL designed, built and operates the New Horizons spacecraft. New Horizons is part of the New Frontiers Program managed by NASA's Marshall Space Flight Center in Huntsville, Ala. 

For more information, visit http://pluto.jhuapl.edu.

Contact: 

Charles Blue,
NRAO Public Information Officer
(434) 296-0314;
cblue@nrao.edu

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Kerberos and Styx: Welcome to the Pluto System! Pluto's Smallest Moons Receive Official Names

 

Hubble Space Telescope image of the Pluto system, taken in July 2012  

The names of Pluto's two smallest known moons, previously referred to as "P4" and “P5,” have been formally approved by the International Astronomical Union (IAU). P4 has been named Kerberos, after the three-headed dog of Greek mythology. P5 has been named Styx, after the mythological river that separates the world of the living from the realm of the dead. They join Pluto's previously known moons Charon, Nix and Hydra. According to IAU rules, Pluto's moons are named for characters associated with the Underworld of Greek and Roman mythology.

Mark Showalter, senior research scientist at the SETI Institute in Mountain View, Calif., led the team of astronomers that discovered Kerberos and Styx. Both were first seen in lengthy exposures of the Pluto system obtained by the Hubble Space Telescope. Kerberos was discovered in 2011 and Styx in 2012. The images were obtained in support of NASA's New Horizons mission, which will fly past Pluto in July 2015.

The names were selected based on the results of an unprecedented Internet vote that was held during February 2012. The ballot at plutorocks.seti.org received almost 500,000 votes, including 30,000 write-in suggestions. "I was overwhelmed by the public response to the naming campaign," says Showalter, adding that the website received international attention and half the votes came from outside the U.S. 

Kerberos is the Greek form of the name Cerberus, which ranked second in the voting. Styx ranked third. The top vote-getter was "Vulcan," based on a suggestion from actor William Shatner of TV's “Star Trek” fame. Vulcan was the name of the home planet of Star Trek character Mr. Spock. The IAU gave serious consideration to this name, which happens to be shared by the Roman god of volcanoes. However, because the name has already been used in astronomy, and because the Roman god is not closely associated with Pluto, this proposal was rejected. "I am grateful to the IAU for giving such careful consideration to our suggestions," says Showalter.

New Horizons will provide up-close looks at Kerberos, Styx and their companion moons in 2015, when it becomes the first spacecraft to fly through the Pluto system. "The discoveries of Kerberos and Styx add to the mysteries surrounding the formation of the Pluto system,” says New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute. 

During the flyby, the spacecraft will also search for additional moons, which might be too small for the Hubble telescope to detect. Afterward, New Horizons will go on to explore the more distant Kuiper Belt.

Source: New Horizon Web Site

Sharpest-ever Ground-based Images of Pluto and Charon: Proves a Powerful Tool for Exoplanet Discoveries

 

Speckle image reconstruction of Pluto and Charon obtained in visible light at 692 nanometers (red) with the Gemini North 8-meter telescope using the Differential Speckle Survey Instrument (DSSI). Resolution of the image is about 20 milliarcseconds average. This is the first speckle reconstructed image for Pluto and Charon from which astronomers obtained not only the separation and position angle for Charon, but also the diameters of the two bodies. North is up, east is to the left, and the image section shown here is 1.39 arcseconds across. Credit: Gemini Observatory/NSF/NASA/AURA .  Full Resolution JPEG

Despite being infamously demoted from its status as a major planet, Pluto (and its largest companion Charon) recently posed as a surrogate extrasolar planetary system to help astronomers produce exceptionally high-resolution images with the Gemini North 8-meter telescope. Using a method called reconstructive speckle imaging, the researchers took the sharpest ground-based snapshots ever obtained of Pluto and Charon in visible light, which hint at the exoplanet verification power of a large state-of-the-art telescope when combined with speckle imaging techniques. The data also verified and refined previous orbital characteristics for Pluto and Charon while revealing the pair’s precise diameters.

 “The Pluto-Charon result is of timely interest to those of us wanting to understand the orbital dynamics of this pair for the 2015 encounter by NASA's New Horizons spacecraft,” said Steve Howell of the NASA Ames Research Center, who led the study. In addition, Howell notes that NASA’s Kepler mission, which has already proven a powerful exoplanet discovery tool, will benefit greatly from this technique.

 Kepler identifies planet candidates by repeatedly measuring the change in brightness of more than 150,000 stars to detect when a planet passes in front of, or affects the brightness of, its host star. Speckle imaging with the Gemini telescope will provide Kepler's follow-up program with a doubling in its ability to resolve objects and validate Earth-like planets. It also offers a 3- to 4-magnitude sensitivity increase for the sources observed by the team. That’s about a 50-fold increase in sensitivity in the observations Howell and his team made at Gemini. “This is an enormous gain in the effort underway to confirm small Earth-size planets,” Howell added.

 To institute this effort Howell and his team –– which included Elliott Horch (Southern Connecticut State University), Mark Everett (National Optical Astronomy Observatory), and David Ciardi (NASA Exoplanet Science Institute/Caltech) –– temporarily installed a camera, called the Differential Speckle Survey Instrument (DSSI), among the suite of instruments mounted on the Gemini telescope.

 "This was a fantastic opportunity to bring DSSI to Gemini North this past July," said Horch. "In just a little over half an hour of Pluto observations, collecting light with the large Gemini mirror, we obtained the best resolution ever with the DSSI instrument –– it was stunning!"

 The resolution obtained in the observations, about 20 milliarcseconds, easily corresponds to separating a pair of automobile headlights in Providence, Rhode Island, from San Francisco, California. To achieve this level of definition, Gemini obtained a large number of very quick “snapshots” of Pluto and Charon. The researchers then reconstructed them into a single image after subtracting the blurring effects and ever-changing speckled artifacts caused by turbulence in the atmosphere and other optical aberrations. With enough snapshots (each image was exposed for only 60 milliseconds or about 1/20 of a second) only the light from the actual objects remains constant, and the artifacts reveal their transient nature, eventually canceling each other out.

 DSSI was built at SCSU between 2007-2008 as a part of a United States National Science Foundation Astronomical Instrumentation grant and mounted on the Gemini North telescope for a limited observing run. The instrument is likely to return to Gemini North for observations in mid-2013 for general user programs from across the international Gemini partnership. Any such arrangement will be announced along with the call for proposals for Semester 13B, in February 2013.

 This work was funded in part by the National Science Foundation and NASA’s Kepler discovery mission and will be published in the journal Publications of the Astronomical Society of the Pacific in October 2012.

Science Contacts:

Steven Howell
 NASA Ames Research Center
 Moffett Field, CA
 Desk: 605-604-4238
 Cell: 520-461-6925
Steve.b.howell@nasa.gov

Elliott Horch
 Southern Connecticut State University
 New Haven, CT
 Phone: 203-392-6393
Horche2@southernct.edu

Media Contact:

Peter Michaud
 Public Information and Outreach Manager
 Gemini Observatory, Hilo, Hawai'i
 Desk: (808) 974-2510
 Cell: (808) 936-6643
pmichaud@gemini.edu

Background History of DSSI

 The Differential Speckle Survey Instrument (DSSI) was built at Southern Connecticut State University (SCSU) between 2007-2008 as a part of a NSF Astronomical Instrumentation grant on which Elliott Horch was the principal investigator. Together with student collaborators, Horch designed and assembled the instrument, and wrote the instrument control software. In 2008 DSSI was shipped to the WIYN Observatory at Kitt Peak, where it has been used since September 2008 for both Kepler follow-up observations and a NSF-funded project to study binary stars discovered by Hipparcos. In late 2009, the detectors for the instrument were upgraded from two low-noise CCDs to two electron-multiplying CCDs, one purchased by the Kepler Science Office and the other by SCSU. DSSI is the world's first two-channel speckle imaging instrument.