Het Astronomie Topic #3

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Will NASA Sail the Great Lakes of Titan?

_{Bron: Wikimedia Commons. Maker: NASA/JPL/GSFC. Publiek Domein.
Vergelijking tussen een meer op Titan en Lake superior}
The world's astrobiology community is all abuzz over one of NASA's most exciting Discovery Mission proposals ever considered to explore the vast methane lakes in the Northern Polar region of Saturn's moon, Titan. This Titan ocean "Lake Lander" will be an Apollo-mission-like bell-shaped capsule that would be dropped directly into one of the Titan target lakes with a mast to hold a camera. The lake-born probe would use a nuclear-powered engine to run experiments and return data to Earth. When interviewed recently on National Public Radio (listen to the audio below).

Saturn's orange moon Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth, according to data from NASA's Cassini spacecraft. The hydrocarbons rain from the sky, collecting in vast deposits that form lakes and dunes. Titan is a big laboratory where several of the world's leading space scientists get to play with atmospheres on a planetary scale.

At an eye popping minus 179 degrees Celsius (minus 290 degrees Fahrenheit), Titan has a surface of liquid hydrocarbons in the form of methane and ethane with tholins believed to make up its dunes. The term "tholins," coined by Carl Sagan in 1979, describe the complex organic molecules at the heart of prebiotic chemistry.

Before the first Cassini Mission flyby's Robert Brown who led Cassini's visual and infrared mapping spectrometer (VIMS) team, said: "We know VIMS will see through the haze to Titan's surface. At closest approach - 1,200 kilometers (745 miles) - we'll have 600-meter-pixel resolution. We'll be able to see very small geologic features. We'll get very high resolution looks at atmospheric phenomena, too. But from my perspective, the really important thing about this encounter is really digging down below the atmosphere and getting our first real glimpse of Titan geology.

Bron: Daily Galaxy, lees meer…

Interview op NPR.org

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Peering far beyond our solar system, NASA researchers have detected the basic chemistry for life in a second hot gas planet, advancing astronomers toward the goal of being able to characterize planets where life could exist. The planet is not habitable but it has the same chemistry that, if found around a rocky planet in the future, could indicate the presence of life.

"It's the second planet outside our solar system in which water, methane and carbon dioxide have been found, which are potentially important for biological processes in habitable planets," said researcher Mark Swain of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Detecting organic compounds in two exoplanets now raises the possibility that it will become commonplace to find planets with molecules that may be tied to life."

Swain and his co-investigators used data from two of NASA's orbiting Great Observatories, the Hubble Space Telescope and Spitzer Space Telescope, to study HD 209458b, a hot, gaseous giant planet bigger than Jupiter that orbits a sun-like star about 150 light years away in the constellation Pegasus. The new finding follows their breakthrough discovery in December 2008 of carbon dioxide around another hot, Jupiter-size planet, HD 189733b. Earlier Hubble and Spitzer observations of that planet had also revealed water vapor and methane.

The detections were made through spectroscopy, which splits light into its components to reveal the distinctive spectral signatures of different chemicals. Data from Hubble's near-infrared camera and multi-object spectrometer revealed the presence of the molecules, and data from Spitzer's photometer and infrared spectrometer measured their amounts.

"This demonstrates that we can detect the molecules that matter for life processes," said Swain. Astronomers can now begin comparing the two planetary atmospheres for differences and similarities. For example, the relative amounts of water and carbon dioxide in the two planets is similar, but HD 209458b shows a greater abundance of methane than HD 189733b. "The high methane abundance is telling us something," said Swain. "It could mean there was something special about the formation of this planet."

Other large, hot Jupiter-type planets can be characterized and compared using existing instruments, Swain said. This work will lay the groundwork for the type of analysis astronomers eventually will need to perform in shortlisting any promising rocky Earth-like planets where the signatures of organic chemicals might indicate the presence of life.

Rocky worlds are expected to be found by NASA's Kepler mission, which launched earlier this year, but astronomers believe we are a decade or so away from being able to detect any chemical signs of life on such a body.

If and when such Earth-like planets are found in the future, "the detection of organic compounds will not necessarily mean there's life on a planet, because there are other ways to generate such molecules," Swain said. "If we detect organic chemicals on a rocky, Earth-like planet, we will want to understand enough about the planet to rule out non-life processes that could have led to those chemicals being there."

"These objects are too far away to send probes to, so the only way we're ever going to learn anything about them is to point telescopes at them. Spectroscopy provides a powerful tool to determine their chemistry and dynamics."

You can follow the history of planet hunting from science fiction to science fact with NASA's PlanetQuest Historic Timeline at http://planetquest.jpl.nasa.gov/timeline/ .

This interactive web feature, developed by JPL, conveys the story of exoplanet exploration through a rich tapestry of words and images spanning thousands of years, beginning with the musings of ancient philosophers and continuing through the current era of space-based observations by NASA's Spitzer and Kepler missions. The timeline highlights milestones in culture, technology and science, and includes a planet counter that tracks the pace of exoplanet discoveries over time.

More information about exoplanets and NASA's planet-finding program is at http://planetquest.jpl.nasa.gov .

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency and is managed by NASA's Goddard Space Flight Center in Greenbelt, Md. The Space Telescope Science Institute, Baltimore, Md., conducts Hubble science operations. The institute is operated for NASA by the Association of Universities for research in Astronomy, Inc., Washington, D.C.

JPL manages the Spitzer Space Telescope mission for NASA. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA

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Op zaterdag 24 oktober 2009 01:13 schreef ExperimentalFrentalMental het volgende:
23-10-2009

NASA wil maanatmosfeer onderzoeken

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Het Amerikaanse ruimteagentschap NASA wil, voor het te laat is, onderzoek doen aan de bijzonder ijle atmosfeer van de maan.

Naar verwachting zal de menselijke activiteit op het maanoppervlak de komende decennia namelijk flink toenemen. En waar mensen zijn, dwarrelt stof op, worden raketten gelanceerd en treden allerlei vormen van vervuiling op.

De onderzoekers willen dat vóór zijn, omdat anders nooit meer kan worden vastgesteld wat de natuurlijke samenstelling van de maanatmosfeer is. Vandaar hun plannen voor de Lunar Atmosphere and Dust Environment Explorer (LADEE), die in 2012 gelanceerd zou moeten worden.

De maan heeft zijn atmosfeer overigens voor een belangrijk deel te danken aan de zon: zijn oppervlak staat bloot aan een bombardement van ultraviolet zonlicht en geladen deeltjes van de zonnewind, waardoor atomen en moleculen vrijkomen. Ook inslagen van micrometeorieten en gassen uit het inwendige van de maan dragen een steentje bij.

De instrumenten van LADEE zullen de concentraties van 18 verschillende stoffen in de maanatmosfeer meten.

© Eddy Echternach (www.astronieuws.nl)

(allesoversterrenkunde)

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Astronomen hebben licht waargenomen dat 13,1 miljard jaar onderweg geweest is naar de aarde. Van verder weg hebben telescopen nog nooit iets waargenomen, schrijven de astronomen in Nature.
Het licht kwam van een ster die op een afstand van 13,1 miljard lichtjaar explodeerde. Een internationaal team van astronomen zag het licht gedurende tien dagen door telescopen op Hawaï.

Volgens experts is het een belangrijke ontdekking, die een doorbraak kan zijn in het onderzoek naar de 'kosmische middeleeuwen'. Daaronder wordt de tijd verstaan tussen de Big Bang en het ontstaan van de eerste sterrenstelsels.