Cassini Spacecraft Finds Ocean May Exist Beneath Crust Of Saturnian Moon
The Cassini spacecraft may have discovered an underground ocean of water and ammonia on the Saturnian moon Titan, NASA announced.
Those findings, made using radar measurements of Titan’s rotation, appear in the Friday issue of the journal Science.
“With its organic dunes, lakes, channels and mountains, Titan has one of the most varied, active and Earth-like surfaces in the solar system,” said Ralph Lorenz, lead author of the paper and Cassini radar scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Md.
“Now we see changes in the way Titan rotates, giving us a window into Titan’s interior beneath the surface.”
Members of the science team used Cassini’s Synthetic Aperture Radar to collect imaging data during 19 separate passes over Titan between October 2005 and May 2007. The radar can see through Titan’s dense, methane-rich atmospheric haze, detailing never-before-seen surface features and establishing their locations on the moon’s surface.
Using data from the radar’s early observations, the scientists and radar engineers established the locations of 50 unique landmarks on Titan’s surface. They then searched for these same lakes, canyons and mountains in the reams of data returned by Cassini in its later flybys of Titan.
Scientists and radar engineers found prominent surface features had shifted from their expected positions by up to 19 miles. A systematic displacement of surface features would be difficult to explain unless the moon’s icy crust was decoupled from its core by an internal ocean, making it easier for the crust to move.
“We believe that about 62 miles beneath the ice and organic-rich surface is an internal ocean of liquid water mixed with ammonia,” said Bryan Stiles of NASA’s Jet Propulsion Laboratory (JPL) in, Pasadena, Calif. Stiles also is a contributing author to the paper.
The study of Titan is a major goal of the Cassini-Huygens mission because it may preserve, in deep-freeze, many of the chemical compounds that preceded life on Earth. Titan is the only moon in the solar system that possesses a dense atmosphere. The moon’s atmosphere is 1.5 times denser than Earth’s. Titan is the largest of Saturn’s moons, bigger than the planet Mercury.
“The combination of an organic-rich environment and liquid water is very appealing to astrobiologists,” Lorenz said. “Further study of Titan’s rotation will let us understand the watery interior better, and because the spin of the crust and the winds in the atmosphere are linked, we might see seasonal variation in the spin in the next few years.”
Cassini scientists will not have long to wait before another go at Titan. Tomorrow, just prior to its closest approach at an altitude of 620 miles, Cassini will employ its Ion and Neutral Mass Spectrometer to examine Titan’s upper atmosphere. Immediately after this closest approach, the spacecraft’s Visual and Infrared Mapping Spectrometer will capture high-resolution images of Titan’s southeast quadrant.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The mission is managed by JPL, a division of the California Institute of Technology in Pasadena. The Cassini orbiter also was designed, developed and assembled at JPL.
Sun Visor For Webb Space Telescope Finishes Design Review
The tennis court-sized sunshield built by Northrop Grumman Corp. [NOC] for the James Webb Space Telescope (JWST) completed its preliminary design review, prime contractor Northrop announced.
NASA will loft the space telescope to replace the current Hubble Space Telescope, which later this year will receive its final rescue mission, repairs and improvements.
The Webb Telescope is the next-generation space observatory, designed to explore phenomena from distant galaxies to nearby planets and stars.
From origins of the universe to formation of star systems capable of supporting life on planets such as Earth, JWST will give scientists unprecedented access to unexplored regions of space.
The five-layer sunshield consists of extremely thin, specially coated reflective membranes and a supporting structure. The sunshield blocks solar heat, keeping the telescope’s science instruments operating at cryogenic temperatures so astronomers can study distant galaxies, young stars and planetary systems at near- and mid-infrared wavelengths.
“The completion of the preliminary design review allows the detailed engineering design to move forward and maintains the delivery schedule for the Observatory,” said Martin Mohan, Northrop Grumman JWST program manager.
Completion of the preliminary sunshield design is the latest milestone. A year ago, Northrop engineers developing sunshield membrane materials demonstrated Technology Readiness Level 6, the NASA benchmark that signifies the sunshield prototype material had been successfully tested in a relevant environment (simulating space).
Navy Halts Funding For Extended Range Guided Munition
The Navy today said it will cease funding the Extended Range Guided Munition (ERGM) program, run by contractor Raytheon Co. [RTN].
Raytheon was given a letter stating that the government doesn’t plan to provide any added funding under the cost-type contract for continued development of ERGM.
The Navy will examine, through an analysis of alternatives, possible technological solutions to meet Marine Corps naval surface fire support requirements.
That need for extended range munitions reflected a requirement for a 5-inch guided projectile to provide enhanced range and accuracy. After being fired from a gun on a Navy ship, canards would deploy from the side of the ERGM round to guide it to the target.
ERGM is a 5 inch, rocket-assisted projectile guided by a coupled Global Positioning System / Inertial Navigation System delivering a unitary warhead at ranges in excess of 41 nautical miles.