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Next ISS crew lifts off
A Russian Soyuz spacecraft safely launched from Baikonur Cosmodrome Friday night with the International Space Station's twelfth resident crew and a paying tourist aboard.
Discovery crew's movies
The seven astronauts of space shuttle Discovery's return to flight mission recently gathered for a public celebration of their mission. They narrated an entertaining movie of highlights and personal footage taken during the mission.
GPS satellite launched
The Boeing Delta 2 rocket roars off Cape Canaveral's launch pad 17A carrying the first modernized Global Positioning System satellite for the U.S. Air Force.
Back to the Moon!
NASA unveils the agency's blueprint for building the future spacecraft and launch vehicles needed for mankind's return to the lunar surface in the next decade.
Distant space explosion
Astronomers announce the detection by NASA's Swift satellite of the most distant explosion yet, a gamma-ray burst from the edge of the visible universe, during this media teleconference held Monday, September 12. (54min 01sec file)
Hill-climbing Mars rover
The Mars Exploration Rover Spirit has reached the summit of Husband Hill, returning a spectacular panorama from the hilltop in the vast Gusev Crater. Scientists held a news conference Sept. 1 to reveal the panorama and give an update on the twin rover mission.
Planes track Discovery
To gain a new perspective on space shuttle Discovery's ascent and gather additional imagery for the return to flight mission, NASA dispatched a pair of high-flying WB-57 aircraft equipped with sharp video cameras in their noses.
Rocket booster cams
When space shuttle Discovery launched its two solid-fuel booster rockets were equipped with video cameras, providing dazzling footage of separation from the external fuel tank, their free fall and splashdown in the sea.
Discovery ferried home
Mounted atop a modified Boeing 747, space shuttle Discovery was ferried across the country from Edwards Air Force Base, California, to Kennedy Space Center, Florida.
Shuttle tank returned
Shuttle fuel tank ET-119 is loaded onto a barge at Kennedy Space Center for the trip back to Lockheed Martin's Michoud Assembly Facility in New Orleans. The tank will be used in the investigation to determine why foam peeled away from Discovery's tank on STS-114 in July.
Delta 4 launch delayed
Launch of the GOES-N weather observatory aboard a Boeing Delta 4 rocket is postponed at Cape Canaveral, Florida.
Mars probe leaves Earth
The Mars Reconnaissance Orbiter lifts off aboard a Lockheed Martin Atlas 5 rocket from Cape Canaveral's Complex 41.
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Moon discovered orbiting solar system's 10th planet
CALIFORNIA INSTITUTE OF TECHNOLOGY NEWS RELEASE
Posted: October 2, 2005
The newly discovered 10th planet, 2003 UB313, is looking more and more like one of the solar system's major players. It has the heft of a real planet (latest estimates put it at about 20 percent larger than Pluto), a catchy code name (Xena, after the TV warrior princess), and a Guinness Book-ish record of its own (at about 97 astronomical units-or 9 billion miles from the sun-it is the solar system's farthest detected object). And, astronomers from the California Institute of Technology and their colleagues have now discovered, it has a moon.
The moon, 100 times fainter than Xena and orbiting the planet once
every couple of weeks, was spotted on September 10, 2005, with the
10-meter Keck II telescope at the W.M. Keck Observatory in Hawaii by
Michael E. Brown, professor of planetary astronomy, and his
colleagues at Caltech, the Keck Observatory, Yale University, and the
Gemini Observatory in Hawaii. A paper about the discovery was
submitted on October 3 to Astrophysical Journal Letters.
The discovery of the moon of the 10th planet from the W.M. Keck Observatory. The planet appears in the center, while the moon is the small dot at the 3 o'clock position. Credit: W.M. Keck Observatory
"Since the day we discovered Xena, the big question has been whether
or not it has a moon," says Brown. "Having a moon is just inherently
cool-and it is something that most self-respecting planets have, so
it is good to see that this one does too."
Brown estimates that the moon, nicknamed "Gabrielle"-after the
fictional Xena's fictional sidekick-is at least one-tenth of the size
of Xena, which is thought to be about 2700 km in diameter (Pluto is
2274 km), and may be around 250 km across.
To know Gabrielle's size more precisely, the researchers need to know
the moon's composition, which has not yet been determined. Most
objects in the Kuiper Belt, the massive swath of miniplanets that
stretches from beyond Neptune out into the distant fringes of the
solar system, are about half rock and half water ice. Since a
half-rock, half-ice surface reflects a fairly predictable amount of
sunlight, a general estimate of the size of an object with that
composition can be made. Very icy objects, however, reflect a lot
more light, and so will appear brighter-and thus bigger-than
similarly sized rocky objects.
Further observations of the moon with the Hubble Space Telescope,
planned for November and December, will allow Brown and his
colleagues to pin down Gabrielle's exact orbit around Xena. With that
data, they will be able to calculate Xena's mass, using a formula
first devised some 300 years ago by Isaac Newton.
"A combination of the distance of the moon from the planet and the
speed it goes around the planet tells you very precisely what the
mass of the planet is," explains Brown. "If the planet is very
massive, the moon will go around very fast; if it is less massive,
the moon will travel more slowly. It is the only way we could ever
measure the mass of Xena-because it has a moon."
The researchers discovered Gabrielle using Keck II's recently
commissioned Laser Guide Star Adaptive Optics system. Adaptive optics
is a technique that removes the blurring of atmospheric turbulence,
creating images as sharp as would be obtained from space-based
telescopes. The new laser guide star system allows researchers to
create an artificial "star" by bouncing a laser beam off a layer of
the atmosphere about 75 miles above the ground. Bright stars located
near the object of interest are used as the reference point for the
adaptive optics corrections. Since no bright stars are naturally
found near Xena, adaptive optics imaging would have been impossible
without the laser system.
Artist's concept of the 10th planet and its moon. The sun and other planets appear in the distance. Credit: R. Hurt, IPAC
"With Laser Guide Star Adaptive Optics, observers not only get more
resolution, but the light from distant objects is concentrated over a
much smaller area of the sky, making faint detections possible," says
Marcos van Dam, adaptive optics scientist at the W.M. Keck
Observatory, and second author on the new paper.
The new system also allowed Brown and his colleagues to observe a
small moon in January around 2003 EL61, code-named "Santa," another
large new Kuiper Belt object. No moon was spotted around 2005 FY9-or
"Easterbunny"-the third of the three big Kuiper Belt objects recently
discovered by Brown and his colleagues using the 48-inch Samuel
Oschin Telescope at Palomar Observatory. But the presence of moons
around three of the Kuiper Belt's four largest objects-Xena, Santa,
and Pluto-challenges conventional ideas about how worlds in this
region of the solar system acquire satellites.
Previously, researchers believed that Kuiper Belt objects obtained
moons through a process called gravitational capture, in which two
formerly separate objects moved too close to one another and become
entrapped in each other's gravitational embrace. This was thought to
be true of the Kuiper Belt's small denizens-but not, however, of
Pluto. Pluto's massive, closely orbiting moon, Charon, broke off the
planet billions of years ago, after it was smashed by another Kuiper
Belt object. Xena's and Santa's moons appear best explained by a
"Pluto once seemed a unique oddball at the fringe of the solar
system," Brown says. "But we now see that Xena, Pluto, and the others
are part of a diverse family of large objects with similar
characteristics, histories, and even moons, which together will teach
us much more about the solar system than any single oddball ever