NASA News: NASA To Unveil Full-Frame Image Of Vesta At News Conference

WASHINGTON -- NASA will host a news conference on Monday, Aug. 1, at 2
p.m. EDT, to discuss the Dawn spacecraft's successful orbit insertion
around Vesta on July 15 and unveil the first full-frame images from
Dawn's framing camera. The news conference will be held in the Von
Karman auditorium at NASA's Jet Propulsion Laboratory (JPL), 4800 Oak
Grove Dr., Pasadena, Calif. Journalists also may ask questions from
participating NASA locations or join by phone. To obtain dial-in
information, journalists must contact JPL's Media Relations Office at
818-354-5011 by 9 a.m. PDT on Aug. 1.

NASA Television and the agency's website will broadcast the event. It
also will be carried live on Ustream, with a live chat box available, at:


The news conference panelists are:
-- Colleen Hartman, assistant associate administrator, Science Mission
Directorate, NASA Headquarters, Washington
-- Charles Elachi, director, JPL
-- Marc Rayman, chief engineer and mission manager, JPL
-- Christopher Russell, Dawn principal investigator, University of
California, Los Angeles
-- Holger Sierks, framing camera team member, Max Planck Society,
Katlenburg-Lindau, Germany
-- Enrico Flamini, chief scientist, Italian Space Agency (ASI), Rome, Italy

Although Dawn is collecting some science data now, the mission's
intensive collection of information will begin in early August.
Observations of the giant asteroid Vesta will provide unprecedented
data to help scientists understand the earliest chapter of our solar
system. Dawn is the first spacecraft to orbit an asteroid in the main
asteroid belt between Mars and Jupiter. After spending one year
orbiting Vesta, Dawn will travel to a second destination, the dwarf
planet Ceres, and arrive there in February 2015.

For more information about Dawn, visit:


For NASA TV streaming video, downlink and schedule information, visit:



NASA's Chandra Observatory Images Gas Flowing Toward Black Hole

WASHINGTON -- The flow of hot gas toward a black hole has been clearly
imaged for the first time in X-rays. The observations from NASA's
Chandra X-ray Observatory will help tackle two of the most
fundamental problems in modern astrophysics: understanding how black
holes grow and how matter behaves in their intense gravity.

The black hole is at the center of a large galaxy known as NGC 3115,
which is located about 32 million light years from Earth. A large
amount of previous data has shown material falling toward and onto
black holes, but none with this clear a signature of hot gas.

By imaging the hot gas at different distances from this supermassive
black hole, astronomers have observed a critical threshold where the
motion of gas first becomes dominated by the black hole's gravity and
falls inward. This distance from the black hole is known as the "Bondi radius."

"It's exciting to find such clear evidence for gas in the grip of a
massive black hole," said Ka-Wah Wong of the University of Alabama,
who led the study that appears in the July 20th issue of The
Astrophysical Journal Letters. "Chandra's resolving power provides a
unique opportunity to understand more about how black holes capture
material by studying this nearby object."

As gas flows toward a black hole, it becomes squeezed, making it
hotter and brighter, a signature now confirmed by the X-ray
observations. The researchers found the rise in gas temperature
begins about 700 light years from the black hole, giving the location
of the Bondi radius. This suggests the black hole in the center of
NGC 3115 has a mass about two billion times that of the sun, making
it the closest black hole of that size to Earth.

The Chandra data also show the gas close to the black hole in the
center of the galaxy is denser than gas further out, as predicted.
Using the observed properties of the gas and theoretical assumptions,
the team then estimated that each year gas weighing about 2 percent
the mass of the sun is being pulled across the Bondi radius toward the black hole.

Making certain assumptions about how much of the gas's energy changes
into radiation, astronomers would expect to find a source that is
more than a million times brighter in X-rays than what is seen in NGC 3115.

"A leading mystery in astrophysics is how the area around massive
black holes can stay so dim, when there's so much fuel available to
light up," said co-author Jimmy Irwin, also of the UA in Tuscaloosa.
"This black hole is a poster child for this problem."

There are at least two possible explanations for this discrepancy. The
first is that much less material actually falls onto the black hole
than flows inside the Bondi radius. Another possibility is that the
conversion of energy into radiation is much less efficient than is assumed.

Different models describing the flow of material onto the black hole
make different predictions for how quickly the density of the gas is
seen to rise as it approaches the black hole. A more precise
determination of the rise in density from future observations should
help astronomers rule out some of these models.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the
Chandra program for the agency's Science Mission Directorate in
Washington. The Smithsonian Astrophysical Observatory controls
Chandra's science and flight operations from Cambridge, Mass.

More information, including images and other multimedia, can be found at:





NASA Safety Chief Bryan O'Connor To Retire

WASHINGTON -- Bryan O'Connor, NASA's chief of safety and mission
assurance since 2002, has announced plans to retire from the agency on Aug. 31.

"Bryan is a fellow Marine, trusted advisor and friend I have been
privileged to serve with off and on since our years as plebes at the
U.S. Naval Academy," NASA Administrator Charles Bolden said. "I am
deeply grateful for his vigilance over the safety and well-being of
NASA's people and its work. His concern and commitment have
encompassed not just the space shuttle and the astronaut corps, but
every mission, large or small, and every member of the NASA family.
He'll be sorely missed."

O'Connor announced his plans to members of his staff in NASA's Office
of Safety and Mission Assurance on Tuesday. In his current role, he
is responsible for the safety, reliability, maintainability and
quality assurance of all NASA programs.

"Even though good practice suggests shorter tours for senior leaders,
I did not want to pass the safety baton until after the STS-135 crew
left Atlantis on the runway," O'Connor said. "This transition is a
great time to let someone new take on this wonderful role you've
permitted me to serve in."

Atlantis completed STS-135, the last mission of the space shuttle
program, with a landing at NASA's Kennedy Space Center in Florida on July 21.

O'Connor held management positions in NASA's space shuttle,
International Space Station, and Shuttle-Mir programs, and played
prominent safety management roles in the agency's recovery from two
space shuttle accidents, the loss of Challenger in 1986 and the loss
of Columbia in 2003. Prior to that, he joined NASA's astronaut corps
in 1980 and flew two missions aboard the space shuttle.

For O'Connor's complete biography, visit:


For information about NASA and agency programs, visit:



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