Monday, July 19, 2010

See Beautiful Ontario Lacus: Cassini's Guided Tour

Ontario Lacus, the largest lake in the southern hemisphere of Saturn's moon Titan, turns out to be a perfect exotic vacation spot, provided you can handle the frosty, subzero temperatures and enjoy soaking in liquid hydrocarbon.

Several recent papers by scientists working with NASA's Cassini spacecraft describe evidence of beaches for sunbathing in Titan's low light, sheltered bays for mooring boats, and pretty deltas for wading out in the shallows. They also describe seasonal changes in the lake's size and depth, giving vacationers an opportunity to visit over and over without seeing the same lake twice.

With such frigid temperatures and meager sunlight, you wouldn't think Titan has a lot in common with our own Earth," said Steve Wall, deputy team lead for the Cassini radar team, based at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "But Titan continues to surprise us with activity and seasonal processes that look marvelously, eerily familiar."

Cassini arrived at Saturn in 2004 when the southern hemisphere of the planet and its moons were experiencing summer. The seasons have started to change toward autumn, with winter solstice darkening the southern hemisphere of Titan in 2017. A year on Titan is the equivalent of about 29 Earth years.

Cassini first obtained an image of Ontario Lacus with its imaging camera in 2004. A paper submitted to the journal Icarus by Alex Hayes, a Cassini radar team associate at the California Institute of Technology in Pasadena, and colleagues finds that the lake's shoreline has receded by about 10 kilometers . This has resulted in a liquid level reduction of about 1 meter per year over a four year period.

Friday, July 16, 2010

NASA Sensor Completes Initial Gulf Oil Spill Flights

NASA's Airborne Visible/Infrared Imaging Spectrometer instrument collected an image over the site of the Deepwater Horizon BP oil rig disaster on May 17, 2010. Crude oil on the surface appears orange to brown. Scientists are using spectroscopic methods to analyze measurements for each point in images like this one to detail the characteristics of the oil on the surface.

AVIRIS extensively mapped the region affected by the spill during 11 flights conducted between May 6 and May 25, 2010, at the request of the National Oceanic and Atmospheric Administration. In total, AVIRIS measured more than 100,000 square kilometers of the national oil spill response. The instrument flew at altitudes of up to 19,800 meters aboard a NASA ER-2 aircraft from NASA's Dryden Flight Research Center, Edwards, Calif.

Figure 1 depicts AVIRIS imaging spectrometer measurements along the Gulf coast to measure the characteristics and condition of the ecosystem and habitat prior to possible oil contamination and impact. The location is near Johnson's Bayou and along the Gulf Beach Highway, between Port Arthur, La., to the west and Cameron, La., to the east. The west corner of the image includes part of the Texas Point National Wildlife Refuge.

AVIRIS data provide scientists with many different types of information about the spill. Researchers at the U.S. Geological Survey's Spectroscopy Laboratory in Golden, Colo., are working to determine the characteristics of the oil based upon the AVIRIS measured spectral signature.

Thursday, July 15, 2010

NASA Finds Super Hot Planet with Unique Comet-Like Tail

Astronomers using NASA's Hubble Space Telescope have confirmed the existence of a baked object that could be called a "cometary planet." The gas giant planet, named HD 209458b, is orbiting so close to its star that its heated atmosphere is escaping into space.

Observations taken with Hubble's Cosmic Origins Spectrograph powerful stellar winds are sweeping the cast-off atmospheric material behind the scorched planet and shaping it into a comet-like tail.

"Since 2003 scientists have theorized the lost mass is being pushed back into a tail, and they have even calculated what it looks like," said astronomer Jeffrey Linsky of the University of Colorado in Boulder, leader of the COS study. "We think we have the best observational evidence to support that theory. We have measured gas coming off the planet at specific speeds, some coming toward Earth. The most likely interpretation is that we have measured the velocity of material in a tail."

The planet, located 153 light-years from Earth, weighs slightly less than Jupiter but orbits 100 times closer to its star than the Jovian giant. The roasted planet zips around its star in a short 3.5 days. In contrast, our solar system's fastest planet, Mercury, orbits the Sun in 88 days. The extrasolar planet is one of the most intensely scrutinized, because it is the first of the few known alien worlds that can be seen passing in front of, or transiting, its star.

Linsky and his team used COS to analyze the planet's atmosphere during transiting events. During a transit, astronomers study the structure and chemical makeup of a planet's atmosphere by sampling the starlight that passes through it. The dip in starlight because of the planet's passage, excluding the atmosphere, is very small, only about 1.5 percent. When the atmosphere is added, the dip jumps to 8 percent, indicating a bloated atmosphere.

COS detected the heavy elements carbon and silicon in the planet's super-hot, 2,000-degree-Fahrenheit atmosphere. This detection revealed the parent star is heating the entire atmosphere, dredging up the heavier elements and allowing them to escape the planet.

The COS data also showed the material leaving the planet was not all traveling at the same speed. "We found gas escaping at high velocities, with a large amount of this gas flowing toward us at 22,000 miles per hour," Linsky said. "This large gas flow is likely gas swept up by the stellar wind to form the comet-like tail trailing the planet."
The results appeared in the July 10 issue of The Astrophysical Journal.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute conducts Hubble science operations.

Thursday, July 1, 2010

ISS Progress 38 Launches

As the Progress made its way to the orbiting complex Thursday, the Expedition 24 crew members made preparations for its arrival and worked with a variety of science experiments.

Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko had a conference with specialists on Earth to review docking procedures for the arrival of the Progress.

The Progress is scheduled to dock to the International Space Station using the automated Kurs docking system at 12:58 p.m. Friday.

To make room for the ISS Progress 38, the Expedition 24 crew relocated the Soyuz TMA-19 spacecraft from the aft end of the Zvezda service module to the Rassvet module Monday.

Flight Engineer Doug Wheelock worked with the VO2max experiment, which involves recording the oxygen intake of exercising crew members before, during and after their stays aboard the station to evaluate and document the changes in their aerobic capacity.

Flight Engineer Tracy Caldwell Dyson worked with the Coarsening in Solid-Liquid Mixtures-2 experiment, which studies the way that particles of tin suspended in a molten tin/lead mixture increase in size – a process known as coarsening – without the influence of the Earth’s gravity. This work has direct applications to metal alloy manufacturing on Earth, including materials critical for aerospace applications.

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