Category: Pluto

Pluto & Charon viewed from the surface of one of Pluto’s newly discovered candidate satellites. Image credit: David A. Aguilar (CfA). Click to enlarge
Mercury is boiling. Mars is freezing. The Earth is just right. When it comes to the temperatures of the planets, it makes sense that they should get colder the farther away they are from the Sun. But then there is Pluto. It has been suspected that this remote world might be even colder than it should be. Smithsonian scientists now have shown this to be true.

Scientists continue to discuss whether Pluto is a planet or should be considered a refugee from the Kuiper belt. Whatever its classification, Pluto and its moon Charon are certain to harbor secrets about the early history of planet formation. Charon is roughly half the diameter of the planet itself, and they form a unique pair in our solar system. How they came to be together remains a mystery.

Located thirty times farther away from the Sun than the Earth, sunlight reaching the surface of Pluto is feeble at best, with daytime resembling dark twilight here at home. Pluto’s temperature varies widely during the course of its orbit since Pluto can be as close to the sun as 30 astronomical units (AU) and as far away as 50 AU. (An AU is the average Earth-Sun distance of 93 million miles.) As Pluto moves away from the Sun, its thin atmosphere is expected to freeze and fall to the surface as ice.

Reflected sunlight gathered with instruments such as the Keck telescope in Hawaii and the Hubble Space Telescope suggested the surface of Pluto might be colder than it should be, unlike Charon’s. However, no telescope capable of directly measuring their thermal emission (their heat) was able to peer finely enough to distinguish the two bodies. Their close proximity presented a formidable challenge since they are never farther apart than 0.9 arcseconds, about the length of a pencil seen from 30 miles away.

Now, for the first time, Smithsonian astronomers using the Submillimeter Array (SMA) on Mauna Kea in Hawaii have taken direct measurements of thermal heat from both worlds and found that Pluto is indeed colder than expected, colder even than Charon.

“We all know about Venus and its runaway greenhouse effect,” said Mark Gurwell of the Harvard-Smithsonian Center for Astrophysics (CfA), co-author on this study along with Bryan Butler of the National Radio Astronomy Observatory. “Pluto is a dynamic example of what we might call an anti-greenhouse effect. Nature likes to leave us with mysteries – and this was a big one.”

During the observations, the SMA utilized its most extended configuration to obtain high-resolution interferometric data, allowing separate “thermometer” readings for Pluto and Charon. It found that the temperature of the ice-covered surface of Pluto was about 43 K (-382 degrees F) instead of the expected 53 K (-364 degrees F), as on nearby Charon. This fits the current model that the low temperature of Pluto is caused by equilibrium between the surface ice and its thin nitrogen atmosphere, not just with the incoming solar radiation. Sunlight (energy) reaching the surface of Pluto is used to convert some of the nitrogen ice to gas, rather than heat the surface. This is similar to the way evaporation of a liquid can cool a surface, such as sweat cooling your skin.

“These results are really exciting and fun as well,” said Gurwell. “Imagine taking something’s temperature from almost three billion miles away without making a house call!”

This research will be presented at the 207th meeting of the American Astronomical Society in Washington, DC.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Original Source: CfA News Release

NASA’s New Horizons spacecraft. Image credit: NASA/KSC Click to enlarge
NASA is preparing to launch the first spacecraft to distant Pluto and its moon Charon. The January 2006 launch of New Horizons will complete the initial reconnaissance of the planets in the solar system.

“New Horizons will study a unique world, and we can only imagine what we may learn. This is a prime example of scientific missions that complement the Vision for Space Exploration,” said Mary Cleave, associate administrator for NASA’s Science Mission Directorate.

The Vision for Space Exploration is a bold new course into the cosmos, a journey that will return the space shuttle safely to flight, complete the construction of the International Space Station, take humans back to the moon and eventually to Mars and beyond.

The National Academy of Sciences has ranked the exploration of Pluto-Charon and the Kuiper Belt among the highest priorities for space exploration, citing the fundamental scientific importance of these bodies to advancing understanding of our solar system.

Different than the inner, rocky planets (like Earth) or the outer gas giants, Pluto is a different type of planet known as an “ice dwarf,” commonly found in the Kuiper Belt region billions of miles from the sun.

“Exploring Pluto and the Kuiper Belt is like conducting an archeological dig into the history of the outer solar system, a place where we can peek into the ancient era of planetary formation,” said Alan Stern, New Horizons principal investigator, Southwest Research Institute Department of Space Studies, Boulder, Colo.

Designed and built at the Johns Hopkins University Applied Physics Laboratory, Laurel, Md., pending launch approval, New Horizons is set to launch from Cape Canaveral Air Force Station, Fla., no earlier than Jan. 17, 2006. The launch window extends until Feb. 14, 2006.

The compact, 1,050-pound piano-sized probe will launch aboard an Atlas V expendable launch vehicle, followed by a boost from a kick-stage solid propellant motor. New Horizons will be the fastest spacecraft ever launched, reaching lunar orbit distance in just nine hours and passing Jupiter 13 months later.

Launch before Feb. 3 allows New Horizons to fly past Jupiter in early 2007 and use the planet’s gravity as a slingshot toward Pluto. The Jupiter flyby trims the trip to Pluto by five years and provides opportunities to test the spacecraft’s instruments and flyby capabilities on the Jupiter system.

The New Horizons science payload, developed under direction of Southwest Research Institute, includes imaging infrared and ultraviolet spectrometers, a multi-color camera, a long-range telescopic camera, two particle spectrometers, a space-dust detector and a radio science experiment. The dust counter was designed and built by students at the University of Colorado, Boulder.

Depending on its launch date, New Horizons could reach the Pluto system as early as mid-2015, conducting a five-month-long study possible only from the close-up vantage of a spacecraft. It will characterize the global geology and geomorphology of Pluto and Charon, map their surface compositions and temperatures, and examine Pluto’s atmospheric composition and structure. New Horizons also will study the small moons recently discovered in the Pluto system.

The spacecraft will “sleep” in electronic hibernation for much of the cruise to Pluto. Operators will turn off all but the most critical electronic systems and monitor the spacecraft once a year to check out critical systems, calibrate instruments and perform course corrections, if necessary.

The spacecraft will send back a beacon signal each week to give operators an instant read on spacecraft health. The entire spacecraft, drawing electricity from a single radioisotope thermoelectric generator, operates on less power than a pair of 100-watt household light bulbs.

For more information about NASA and the New Horizons mission on the Web, visit: http://www.nasa.gov/newhorizons

Original Source: NASA News Release

Update: Is Pluto still a planet? No.

Pluto and its possible new moons. Image credit: Hubble. Click to enlarge.
Using NASA’s Hubble Space Telescope to probe the ninth planet in our solar system, astronomers discovered that Pluto may have not one, but three moons.

If confirmed, the discovery of the two new moons could offer insights into the nature and evolution of the Pluto system, Kuiper Belt Objects with satellite systems, and the early Kuiper Belt. The Kuiper Belt is a vast region of icy, rocky bodies beyond Neptune’s orbit.

“If, as our new Hubble images indicate, Pluto has not one, but two or three moons, it will become the first body in the Kuiper Belt known to have more than one satellite,” said Hal Weaver of the Johns Hopkins Applied Physics Laboratory, Laurel, Md. He is co-leader of the team that made the discovery.

Pluto was discovered in 1930. Charon, Pluto’s only confirmed moon, was discovered by ground-based observers in 1978. The planet resides 3 billion miles from the sun in the heart of the Kuiper Belt.

“Our result suggests that other bodies in the Kuiper Belt may have more than one moon. It also means that planetary scientists will have to take these new moons into account when modeling the formation of the Pluto system,” said Alan Stern of the Southwest Research Institute in Boulder, Colo. Stern is co-leader of the research team.

The candidate moons, provisionally designated S/2005 P1 and S/2005 P2, were observed to be approximately 27,000 miles (44,000 kilometers) away from Pluto. The objects are roughly two to three times as far from Pluto as Charon.

The team plans to make follow-up Hubble observations in February to confirm that the newly discovered objects are truly Pluto’s moons. Only after confirmation will the International Astronomical Union consider names for S/2005 P1 and S/2005 P2.

The Hubble telescope’s Advanced Camera for Surveys observed the two new candidate moons on May 15, 2005. “The new satellite candidates are roughly 5,000 times fainter than Pluto, but they really stood out in these Hubble images,” said Max Mutchler of the Space Telescope Science Institute and the first team member to identify the satellites. Three days later, Hubble looked at Pluto again. The two objects were still there and appeared to be moving in orbit around Pluto.

“A re-examination of Hubble images taken on June 14, 2002 has essentially confirmed the presence of both P1 and P2 near the predicted locations based on the 2005 Hubble observations,” said Marc Buie of Lowell Observatory, Flagstaff, Ariz., another member of the research team.

The team looked long and hard for other potential moons around Pluto. “These Hubble images represent the most sensitive search yet for objects around Pluto,” said team member Andrew Steffl of the Southwest Research Institute, “and it is unlikely that there are any other moons larger than about 10 miles across in the Pluto system.”

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The Space Telescope Science Institute in Baltimore conducts Hubble science operations. The Institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington, under contract with Goddard.

The other team members for this observation are: William J. Merline, John R. Spencer, Eliot Y. Young, and Leslie A. Young, Southwest Research Institute.

Original Source: Hubble News Release

Update: Why isn’t Pluto a planet?

New Horizons arrives at Cape Canaveral. Image credit: JHU APL. Click to enlarge.
NASA’s New Horizons spacecraft arrived at the Kennedy Space Center (KSC), Fla. , for fi nal preparations and testing for the probe’s decade-long journey. It will be the first spacecraft to visit Pluto and its moon, Charon.

New Horizons arrived Saturday at KSC’s Shuttle Landing Facility aboard a U.S. Air Force C-17 cargo plane. The spacecraft is in a clean room at KSC. It is scheduled to launch on a Lockheed Martin Atlas V rocket in January 2006. New Horizons recently completed four months of space-environment tests at NASA’s Goddard Space Flight Center, Greenbelt , Md. , and the Johns Hopkins University Applied Physics Laboratory (APL), Laurel , Md. , where it was designed and built.

Carrying seven scientific instruments the compact, nearly 1,000 pound probe will fly by Pluto and Charon as early as summer 2015. Its mission is to characterize the global geology and geomorphology of the bodies, map their surface compositions, record temperatures and examine Pluto’s complex atmosphere. Flybys of ancient rocky objects farther out in the solar system may be undertaken during an extended mission.

In October, New Horizons will undergo a series of functional tests, readiness checks, and an “end-to-end” test with the tracking facilities of NASA’s Deep Space Network. In November, hydrazine fuel for attitude control and course correction maneuvers will be loaded and the spacecraft will undergo a final spin-balance test.

At the Atlas Space Operations Center on Cape Canaveral Air Force Station, processing has begun on the Atlas V. Stacking of the vehicle will begin in early October and completed in late October or early November. In November, a launch countdown rehearsal will be performed. In December, the flight-ready spacecraft will be transported to Launch Complex 41 for hoisting a top the Atlas V.

Following final launch approval, liftoff is scheduled for Jan. 11, 2006 , during a two-hour launch window that opens at 2:07 p.m. EST. Launch windows are also available daily from Jan. 12 through Feb. 14, 2006 .

New Horizons is the first mission in NASA’s New Frontiers program of medium-class planetary missions. APL will operate the spacecraft for NASA’s Science Mission Directorate. Principal Investigator Alan Stern of the Southwest Research Institute (SwRI) leads the New Horizons science and mission team. SwRI directed development of the mission’s seven science instruments.

The National Research Council ranked the first reconnaissance of Pluto and the Kuiper Belt at the top of its priority list for planetary missions to be launched in this decade. A close-up look at these mysterious worlds will provide new information about the origin and evolution of our solar system.

For information on the mission, visit http://pluto.jhuapl.edu.

Original Source: JHU APL News Release

Artist illustration of SMART-1. Image credit: ESA. Click to enlarge.

An artist’s conception of Pluto and its moon Charon. Image credit: NASA. Click to enlarge
On a clear summer night, the stars aligned for MIT researchers watching and waiting for one small light in the heavens to be extinguished, just briefly.

Thanks to a feat of both astronomical and terrestrial alignment, a group of scientists from MIT and Williams College succeeded in observing distant Pluto’s tiny moon, Charon, hide a star. Such an event had been seen only once before, by a single telescope 25 years ago, and then not nearly as well.

The MIT-Williams consortium spotted it with four telescopes in Chile on the night of July 10-11.

The team expects to use data from this observation to assess whether Charon has an atmosphere, to measure its radius and to determine how round it is.

The data and results from the observation will be presented at the 2005 meeting of the American Astronomical Society’s Division of Planetary Sciences meeting to be held in Cambridge, England, in September.

MIT team leader James L. Elliot headed the group at the Clay Telescope at Las Campanas Observatory in Chile.

“We have been waiting many years for this opportunity. Watching Charon approach the star and then snuff it out was spectacular,” said Elliot, a professor in the Department of Earth, Atmospheric and Planetary Science and the Department of Physics at MIT in Cambridge, Mass.

Jay M. Pasachoff, team leader from Williams College in Williamstown, Mass., and a professor in that school’s Department of Astronomy, said, “It’s amazing that people in our group could get in the right place at the right time to line up a tiny body 4 billion miles away. It’s quite a reward for so many people who worked so hard to arrange and integrate the equipment and to get the observations.”

With the Clay Telescope’s 6.5-meter mirror (more than 21 feet across, the size of a large room) the researchers were able to observe changes throughout the event, which lasted less than a minute. While their electronic cameras sensitively recorded data, the light of the faint star was seen to dim and then, some seconds later, brighten. This kind of disappearance of a celestial body behind a closer, apparently larger one is known as an occultation.

Studying how the light dimmed and brightened will let the MIT-Williams consortium look for signs that Charon has an atmosphere. It has very little mass and thus little gravity to hold in an atmosphere, but it is so cold (being some 40 times farther from the sun than the Earth) that some gases could be held in place by the small amount of Charon’s gravity.

Other telescopes around Chile used by the MIT-Williams consortium included the 8-meter (more than 26 feet across) Gemini South on Cerro Pachon, the 2.5-meter (more than 8 feet across) DuPont Telescope at Las Campanas Observatory and the 0.8-meter (almost 3 feet across) telescope at the Cerro Armazones Observatory of Chile’s Catholic University of the North near Cerro Paranal.

The team had searched for a distribution of telescopes along a north-south line in Chile since the predictions of the starlight shadow of Charon were uncertain by several hundred kilometers. Since the star that was hidden is so far away, it casts a shadow of Charon that is the same size as Charon itself, about 1,200 kilometers in diameter. To see the event, the distant star, Charon and the telescopes in Chile had to be perfectly aligned. All of these telescopes had clear views of the event.

Other MIT affiliates involved in the observation were MIT graduate students Elisabeth Adams, Michael Person and Susan Kern and postdoctoral associate Amanda Gulbis.

The images from three telescopes in Chile, including the Clay Telescope, and one in Brazil, were taken with new electronic cameras and computer control obtained by MIT and Williams with an equipment grant from NASA. The expeditions were sponsored by NASA’s Planetary Astronomy Program.

A video showing the star dimming as Charon passes in front of it and then brightening again is posted on the Web at http://occult.mit.edu/research/occultations/Charon/C313.2/C313OccMovie.html.

Teams from the Observatory of Paris at Meudon and from the Southwest Research Institute in Boulder, Colo., also observed the occultation.

Original Source: MIT News Release

Artist illustration of New Horizons with Pluto and Charon. Image credit: JHUAPL/SwRI. Click to enlarge.
The first spacecraft designed to study Pluto, the last planet in our solar system, arrived at NASA?s Goddard Space Flight Center (GSFC) in Greenbelt, Md., today for a series of pre-launch checkouts.

“We are extremely proud to have the NASA’s New Horizons mission make Goddard the first stop in its journey to the last planet,” said Dr. Ed Weiler, GSFC Center Director. “The New Horizons mission to Pluto is an historic journey of exploration to unlock secrets from a mysterious planet so distant that the Sun is just a bright star in the sky.”

The spacecraft will be at Goddard for the next three months where team members will check New Horizons? balance and alignment in a series of spin tests; put it before wall-sized speakers that simulate the noisy vibrations of launch; and seal it for several weeks in a four-story thermal-vacuum chamber that duplicates the extreme cold and airless conditions of space. After departing Goddard in the Fall, the spacecraft will make its way to the Kennedy Space Center, Fla. for final launch preparations.

New Horizons is the first mission to Pluto and its moon, Charon. As part of an extended mission, the spacecraft would head deeper into the Kuiper Belt to study one or more of the icy mini worlds in that vast region. New Horizons is scheduled for launch in January 2006 from Cape Canaveral Air Force Station, Fla., aboard a Lockheed Martin Atlas V. New Horizons should begin its five-month-long flyby reconnaissance of Pluto-Charon in summer 2015.

New Horizons is carrying an extensive complement of science instruments. Goddard has a major role in the Southwest Research Institute?s Ralph instrument. Ralph’s main objectives are to obtain high resolution color and surface composition maps of the surfaces of Pluto and Charon. The instrument has two separate channels: the Multispectral Visible Imaging Camera (MVIC) and the Linear Etalon Imaging Spectral Array (LEISA). A single telescope with a 3-inch (6-centimeter) aperture collects and focuses the light used in both channels. MVIC, provided by Ball Aerospace in from Boulder Colo., operates at the visible wavelength to produce color maps. LEISA operates at infrared wavelengths. LEISA, provided by Goddard, will be used to map the distribution of frosts of methane, molecular nitrogen, carbon monoxide, and water over the surface of Pluto and the water frost distribution over the surface of Charon.

New Horizons is the first mission in NASA?s New Frontiers program of medium-class, high-priority solar system exploration projects. The spacecraft is managed by the John Hopkins University Applied Physics Laboratory in Laurel, Md. The Principal Investigator Dr. Alan Stern, is from the Southwest Research Institute, San Antonio, TX. The mission team includes Goddard Space Flight Center, APL, Ball Aerospace Corporation, the Boeing Company, the Jet Propulsion Laboratory, Pasadena, Calif. Stanford University, Calif. KinetX, Inc., Tempe, AZ, Lockheed Martin Corporation, University of Colorado at Boulder, the U.S. Department of Energy and a number of other firms, NASA centers and university partners.

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

Original Source: NASA News Release

Update: Pluto is not a planet