23 December 2008

NASA news I

NASA has published several press releases this month which I haven't noted yet. To begin with, ZUI this press release dated 4 Dec 08:
Next NASA Mars Mission Rescheduled for 2011

NASA's Mars Science Laboratory will launch two years later than previously planned, in the fall of 2011. The mission will send a next-generation rover with unprecedented research tools to study the early environmental history of Mars.

A launch date of October 2009 no longer is feasible because of testing and hardware challenges that must be addressed to ensure mission success. The window for a 2009 launch ends in late October. The relative positions of Earth and Mars are favorable for flights to Mars only a few weeks every two years. The next launch opportunity after 2009 is in 2011.

"We will not lessen our standards for testing the mission's complex flight systems, so we are choosing the more responsible option of changing the launch date," said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. "Up to this point, efforts have focused on launching next year, both to begin the exciting science and because the delay will increase taxpayers' investment in the mission. However, we've reached the point where we can not condense the schedule further without compromising vital testing."


The advanced rover is one of the most technologically challenging interplanetary missions ever designed. It will use new technologies to adjust its flight while descending through the Martian atmosphere, and to set the rover on the surface by lowering it on a tether from a hovering descent stage. Advanced research instruments make up a science payload 10 times the mass of instruments on NASA's Spirit and Opportunity Mars rovers. The Mars Science Laboratory is engineered to drive longer distances over rougher terrain than previous rovers. It will employ a new surface propulsion system.


The mission will explore a Mars site where images taken by NASA's orbiting spacecraft indicate there were wet conditions in the past. Four candidate landing sites are under consideration. The rover will check for evidence of whether ancient Mars environments had conditions favorable for supporting microbial life and preserving evidence of that life if it existed there.

Next ZUI this press release dated 9 Dec:
Hubble Telescope Finds Carbon Dioxide on an Extrasolar Planet

NASA's Hubble Space Telescope has discovered carbon dioxide in the atmosphere of a planet orbiting another star. This breakthrough is an important step toward finding chemical biotracers of extraterrestrial life.

The Jupiter-sized planet, called HD 189733b, is too hot for life. But the Hubble observations are a proof-of-concept demonstration that the basic chemistry for life can be measured on planets orbiting other stars. Organic compounds also can be a by-product of life processes and their detection on an Earthlike planet someday may provide the first evidence of life beyond our planet.

Previous observations of HD 189733b by Hubble and the Spitzer Space Telescope found water vapor. Earlier this year, Hubble found methane in the planet's atmosphere.


Mark Swain, a research scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., used Hubble's near infrared camera and multi-object spectrometer to study infrared light emitted from the planet, which lies 63 light-years away. Gases in the planet's atmosphere absorb certain wavelengths of light from the planet's hot glowing interior. Swain identified carbon dioxide and carbon monoxide. The molecules leave a unique spectral fingerprint on the radiation from the planet that reaches Earth. This is the first time a near-infrared emission spectrum has been obtained for an exoplanet.


This successful demonstration of looking at near-infrared light emitted from a planet is very encouraging for astronomers planning to use NASA's James Webb Space Telescope after it is launched in 2013. These biomarkers are best seen at near-infrared wavelengths. Astronomers look forward to using the James Webb Space Telescope to look spectroscopically for biomarkers on a terrestrial planet the size of Earth or a "super-Earth" several times our planet's mass.

Thirdly, ZUI this press release dated 11 Dec:
Mars Orbiter Completes Prime Mission

NASA's Mars Reconnaissance Orbiter has completed its primary, two-year science phase. The spacecraft has found signs of a complex Martian history of climate change that produced a diversity of past watery environments.

The orbiter has returned 73 terabits of science data, more than all earlier Mars missions combined. The spacecraft will build on this record as it continues to examine Mars in unprecedented detail during its next two-year phase of science operations.

Among the major findings during the primary science phase is the revelation that the action of water on and near the surface of Mars occurred for hundreds of millions of years. This activity was at least regional and possibly global in extent, though possibly intermittent. The spacecraft also observed that signatures of a variety of watery environments, some acidic, some alkaline, increase the possibility that there are places on Mars that could reveal evidence of past life, if it ever existed.

Since moving into position 186 miles above Mars' surface in October 2006, the orbiter also has conducted 10,000 targeted observation sequences of high-priority areas. It has imaged nearly 40 percent of the planet at a resolution that can reveal house-sized objects in detail, 1 percent in enough detail to see desk-sized features. This survey has covered almost 60 percent of Mars in mineral mapping bands at stadium-size resolution. The orbiter also assembled nearly 700 daily global weather maps, dozens of atmospheric temperature profiles, and hundreds of radar profiles of the subsurface and the interior of the polar caps.


The Mars Reconnaissance Orbiter has found repetitive layering in Mars' permanent polar ice caps. The patterns suggest climate change cycles continuing to the present. They may record possible effects of cyclical changes in Mars' tilt and orbit on global sunlight patterns. Recent climate cycles are indicated by radar detection of subsurface icy deposits outside the polar regions, closer to the equator, where near-surface ice is not permanently stable. Other results reveal details of ancient streambeds, atmospheric hazes and motions of water, along with the ever-changing weather on Mars.

Most observations from the orbiter will be discontinued for a few weeks while the sun is between Earth and Mars, which will disrupt communications. In December, the orbiter will begin a new phase, with science observations continuing as Mars makes another orbit around the sun, which takes approximately two Earth years.

And ZUI this press release dated 15 Dec:
Saturn's Dynamic Moon Enceladus Shows More Signs of Activity

The closer scientists look at Saturn's small moon Enceladus, the more they find evidence of an active world. The most recent flybys of Enceladus made by NASA's Cassini spacecraft have provided new signs of ongoing changes on and around the moon. The latest high-resolution images of Enceladus show signs that the south polar surface changes over time.

Close views of the southern polar region, where jets of water vapor and icy particles spew from vents within the moon's distinctive "tiger stripe" fractures, provide surprising evidence of Earth-like tectonics. They yield new insight into what may be happening within the fractures. The latest data on the plume -- the huge cloud of vapor and particles fed by the jets that extend into space -- show it varies over time and has a far-reaching effect on Saturn's magnetosphere.

"Of all the geologic provinces in the Saturn system that Cassini has explored, none has been more thrilling or carries greater implications than the region at the southernmost portion of Enceladus," said panel member Carolyn Porco, Cassini imaging team leader at the Space Science Institute in Boulder, Colo.


"Enceladus has Earth-like spreading of the icy crust, but with an exotic difference -- the spreading is almost all in one direction, like a conveyor belt," said panelist Paul Helfenstein, Cassini imaging associate at Cornell University in Ithaca, N.Y. "Asymmetric spreading like this is unusual on Earth and not well understood."

"Enceladus has asymmetric spreading on steroids," Helfenstein added. "We are not certain about the geological mechanisms that control the spreading, but we see patterns of divergence and mountain-building similar to what we see on Earth, which suggests that subsurface heat and convection are involved."

The tiger stripes are analogous to the mid-ocean ridges on Earth's seafloor where volcanic material wells up and creates new crust. Using Cassini-based digital maps of the moon's south polar region, Helfenstein reconstructed a possible history of the tiger stripes by working backward in time and progressively snipping away older and older sections of the map, each time finding that the remaining sections fit together like puzzle pieces.

Images from recent close flybys also have bolstered an idea the Cassini imaging team has that condensation from the jets erupting from the surface may create ice plugs that close off old vents and force new vents to open. The opening and clogging of vents also corresponds with measurements indicating the plume varies from month to month and year to year.


With water vapor, organic compounds and excess heat emerging from Enceladus' south polar terrain, scientists are intrigued by the possibility of a liquid-water-rich habitable zone beneath the moon's south pole.

Cassini's flybys on Aug. 11 and Oct. 31 targeted Enceladus' fractured southern region. An Oct. 9 flyby took the spacecraft deep into the plume of water vapor and ice shooting out of the moon's vents. Cassini's next flyby of Enceladus will be in November 2009. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.

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