Wednesday, October 31, 2012

Citizen Scientists Discover Four-Star Planet with NASA Kepler

A Four-Star Planet: An artist's illustration of
PH1, a planet discovered by volunteers from
 the Planet Hunters citizen science project.
PH1, shown in the foreground, is the first
reported case of a planet orbiting a double
-star that, in turn, is orbited by a second
distant pair of stars. The phenomenon is
called a circumbinary planet in a four-star
Image credit: Haven Giguere/Yale
The discovery of planets continues to expand beyond the domain of professional astronomers. A joint effort of amateur astronomers and scientists has led to the first reported case of a planet orbiting a double-star that, in turn, is orbited by a second distant pair of stars.

Aided by volunteer citizen scientists using the website, a Yale-led international team of astronomers identified and confirmed discovery of the phenomenon, called a circumbinary planet in a four-star system. Only six planets are known to orbit two stars but none of these are orbited by a distant binary.

Coined PH1, the planet was identified by the citizen scientists participating in Planets Hunters, a Yale-led program that enlists the public to review astronomical data from NASA's Kepler spacecraft for signs of planets transits distant stars.

"I celebrate this discovery as a milestone for the Planet Hunters team: discovering their first exoplanet lurking in the Kepler data. I celebrate this discovery for the wow-factor of a planet in a four-star system," said Natalie Batalha, Kepler scientist at NASA Ames Research Center, Moffett Field, Calif. "Most importantly, I celebrate this discovery as the fruit of exemplary human cooperation-- cooperation between scientists and citizens who give of themselves for the love of stars, knowledge, and exploration."

A bit larger than Neptune and thought to be a gas giant, PH1 orbits its host stars every 137 days. Beyond the planet's orbit approximately 900 times the distance between the sun and Earth, a second pair of stars orbits the planetary system.

The research paper submitted to the Astrophysical Journal is scheduled to be presented today at the annual meeting of the Division of Planetary Sciences of the American Astronomical Society in Reno.

To read more about the discovery, visit and the Yale press release.

Ames Research Center in Moffett Field, Calif., manages Kepler's ground system development, mission operations and science data analysis. NASA’s Jet Propulsion Laboratory, Pasadena, Calif., managed the Kepler mission's development.

Ball Aerospace and Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.

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Monday, October 29, 2012

Studying the sun in 3D

STEREO Reaches New Milestone At Its Sixth Anniversary

Each of these images was captured from a different perspective by one of NASA's Solar Terrestrial Relations Observatory (STEREO) spacecraft on Oct. 14, 2012. The image on the left, STEREO-B, shows a dark vertical line slightly to the upper left of center. Only by looking at the image on the right, captured by STEREO-A from a different direction, is this feature revealed to be a giant prominence of solar material bursting through the sun's atmosphere. Credit: NASA/STEREO
On the evening of Oct. 25, 2006, the twin Solar Terrestrial Relations Observatory (STEREO) spacecraft launched into space, destined for fairly simple orbits: both circle the sun like Earth does, STEREO-A traveling in a slightly smaller and therefore faster orbit, STEREO-B traveling in a larger and slower orbit. Those simple orbits, however, result in interesting geometry. As one spacecraft gained an increasing lead over Earth, the other trailed further and further behind. In February of 2011, each STEREO spacecraft was situated on opposite sides of the sun, and on Sept. 1, 2012, the two spacecraft and and the Solar Dynamics Observatory (at Earth) formed an equal-sided triangle, with each observatory providing overlapping views of the entire sun.

Since its launch in 2006, the STEREO spacecraft have
 drifted further and further apart to gain different
views of the sun. Credit: NASA/GSFC
By providing such unique viewpoints, STEREO has offered scientists the ability to see all sides of the sun simultaneously for the first time in history, augmented with a view from Earth's perspective by NASA's Solar Dynamics Observatory (SDO). In addition to giving researchers a view of active regions on the sun before they even come over the horizon, combining two views is crucial for three-dimensional observations of the giant filaments that dance off the sun's surface or the massive eruptions of solar material known as coronal mass ejections (CMEs). Examine the images below to see how a feature on the sun can look dramatically different from two perspectives.    
This map of the full sun on Oct. 14, 2012, was created by images from, ­ in order from left to right,­ STEREO-A, STEREO-B and SDO. Credit: NASA/STEREO/SDO/GSFC

Bounce, Skid, Wobble - How Huygens Landed on Titan

The European Space Agency's Huygens probe, ferried to Saturn's moon Titan by NASA's Cassini spacecraft, bounced, slid and wobbled its way to rest in the 10 seconds after touching down on Titan in January 2005, a new analysis reveals. The moon's surface is more complex than previously thought.
Scientists reconstructed the chain of events by analyzing data from a variety of instruments that were active during the impact, in particular changes in the acceleration. The instrument data were compared with results from computer simulations and a drop test using a model of Huygens designed to replicate the landing.
The analysis reveals that, on first contact with Titan's surface, Huygens made a dent 4.7 inches (12 centimeters) deep, before bouncing out onto a flat surface. The Huygens probe, which had a mass of about 400 pounds (200 kilograms), hit the ground with an impact speed that was similar to dropping a ball on Earth from a height of about 3 feet (one meter). The probe, tilted by about 10 degrees in the direction of motion, then slid 12 to 16 inches (30 to 40 centimeters) across the surface. It slowed due to friction with the surface and, upon coming to its final resting place, wobbled back and forth five times. Each wobble was about half as large as the previous one. Huygens' sensors continued to detect small vibrations for another two seconds, until motion subsided nearly 10 seconds after touchdown.
"A spike in the acceleration data suggests that during the first wobble, the probe likely encountered a pebble protruding by around an inch [2 centimeters] from the surface of Titan, and may have even pushed it into the ground, suggesting that the surface had a consistency of soft, damp sand," said Stefan Schröder of the Max Planck Institute for Solar System Research in Katlenburg-Lindau, Germany, lead author of the paper reporting the results in the journal Planetary and Space Science.
Previous work measured the firmness of Titan's surface during the Huygens impact. Those results found the surface to be quite soft. The new work goes one step farther to demonstrate that if something put little pressure on the surface, the surface was hard, but if an object put more pressure on the surface, it sank in significantly.
"It is like snow that has been frozen on top," said Erich Karkoschka, a co-author at the University of Arizona, Tucson. "If you walk carefully, you can walk as on a solid surface, but if you step on the snow a little too hard, you break in very deeply."
Had the probe impacted a wet, mud-like substance, its instruments would have recorded a "splat" with no further indication of bouncing or sliding. The surface must have therefore been soft enough to allow the probe to make a sizeable depression, but hard enough to support Huygens rocking back and forth.
"We also see in the Huygens landing data evidence of a ‘fluffy' dust-like material – most likely organic aerosols that are known to drizzle out of the Titan atmosphere – being thrown up into the atmosphere and suspended there for around four seconds after the impact," said Schröder.
Since the dust was easily lifted, it was most likely dry, suggesting that there had not been any rain of liquid ethane or methane for some time prior to the landing.
"This study takes us back to the historical moment of Huygens touching down on the most remote alien world ever visited by a landing probe," added ESA's Cassini-Huygens project scientist, Nicolas Altobelli. "Huygens data, even years after mission completion, are providing us with a new dynamical ‘feeling' for these crucial first seconds of landing."
A new animation of the landing can be seen here:
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C.

Saturday, October 6, 2012

Juno's Two Deep Space Maneuvers are 'Back-To-Back Home Runs'

NASA's Juno spacecraft successfully executed a second Deep Space Maneuver, called DSM-2 last Friday, Sept. 14. The 30 minute firing of its main engine refined the Jupiter-bound spacecraft's trajectory, setting the stage for a gravity assist from a flyby of Earth on Oct 9, 2013. Juno will arrive at Jupiter on July 4, 2016.
The maneuver began at 3:30 p.m. PDT (6:30 p.m. EDT), when the Leros-1b main engine began to fire. The burn ended at 4 p.m. PDT (7 p.m. EDT). Based on telemetry, the Juno project team believes the burn was accurate, changing the spacecraft's velocity by about 867 mph (388 meters a second) while consuming about 829 pounds (376 kilograms) of fuel.
The burn occurred when Juno was more than 298 million miles (480 million kilometers) from Earth.
Juno executed its first deep space maneuver (DSM-1), one of comparable duration and velocity change, on Aug. 30. Together, both maneuvers placed Juno on course for its Earth flyby, which will occur as the spacecraft is completing one elliptical orbit around the sun. The Earth flyby will boost Juno's velocity by 16,330 mph (about 7.3 kilometers per second), placing the spacecraft on its final flight path for Jupiter. The closest approach to Earth, on Oct. 9, 2013, will occur when Juno is at an altitude of about 348 miles (560 kilometers).
"It feels like we hit back-to-back home runs here with the near-flawless propulsion system performance seen during both DSM-1 and DSM-2." said Juno Project Manager Rick Nybakken of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "These successes move us closer to being ready for our most critical mission event, the Jupiter Orbit Insertion main engine burn in July 2016. We're not in the playoffs yet, as that will come in 2016 when we arrive at Jupiter, but it does feel fantastic to have hit both of these DSMs out of the park."
Juno was launched on Aug. 5, 2011. Once in orbit, the spacecraft will circle Jupiter 33 times, from pole to pole, and use its collection of eight science instruments to probe beneath the gas giant's obscuring cloud cover. Juno's science team will learn about Jupiter's origins, structure, atmosphere and magnetosphere, and look for a potential solid planetary core.
Juno's name comes from Greek and Roman mythology. The god Jupiter drew a veil of clouds around himself to hide his mischief, and his wife, the goddess Juno, was able to peer through the clouds and reveal Jupiter's true nature.
NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. The Juno mission is part of the New Frontiers Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the spacecraft. JPL is a division of the California Institute of Technology in Pasadena.
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