ATV Jules Verne demonstrates key capabilities

29 March 2008 - ESA's Jules Verne ATV (the first european cargo spaceship) today demonstrated its ability to navigate safely from a point 39 km behind the ISS to a stand-off point just 3.5 km away using relative GPS navigation. The vessel then executed an Escape manoeuvre commanded from the ATV Control Centre in which the craft flew off to a safe distance.

Today’s demonstration also confirmed Jules Verne is able to establish a continuous two-way data link with the ISS. Using the high-rate S-band communication link, which was switched on at a distance of 40 km from the ISS, Jules Verne for the first time conducted relative GPS (Global Positioning Satellite) measurements with the Station. Relative GPS is a navigation technique executed by computers between the ATV's GPS receiver and the ISS GPS receiver that enables ATV to navigate relative to the Station with very high accuracy.

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For both the flight control team in Toulouse, France and the ISS flight crew, this 64 kilobits/sec transmission rate also made it possible to test all the crucial data and communication connections between the two spacecraft, including some monitoring capability on both sides to send and receive communications.

When Jules Verne reached the closest holding position, at 3.5 km from the ISS, the bus-sized spaceship turned on its external tracking lights and activated the Russian-built Kurs rendezvous radar with equipment on both spacecraft. The robust and historical Kurs system, a concept which has been used for decades, provides relative distance and velocity with independent data for the crew monitoring during Jules Verne's final approach to the Station.

During the demonstration the astronauts on board ISS reported they were able to see Jules Verne with the naked eye. The spacecraft could also be seen via screens inside the ATV Control Centre.

Data collected throughout the first demonstration day will now be analysed by the ESA JADOR (Jules Verne ATV Demonstration Objectives Report) team. A report will be submitted to the ISS Mission Management Team. After an assessment and authorisation on 30 March, ATV can proceed to Demonstration Day 2 on Monday (including an approach to within 11 m of the ISS). Docking with the ISS is scheduled on Thursday (3rd of April 2008), soon after the Demo Day 2 Report.

Source : ESA

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Cassini Spacecraft Finds Ocean May Exist Beneath Titan's Crust

March 20, 2008 - NASA's Cassini spacecraft has discovered evidence that points to the existence of an underground ocean of water and ammonia on Saturn's moon Titan.

"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, Cassini radar scientist at the Johns Hopkins Applied Physics Laboratory, "Now we see changes in the way Titan rotates, giving us a window into Titan's interior beneath the surface."

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Members of the mission's 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. They 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).

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. On March 25, 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 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.

More : see NASA.gov

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The Space Quote - Dinosaurs

" The dinosaurs failed to survive due to the lack of a space program... "

Arthur C. CLARKE - Writer and inventor, author of 2001 : A Space Odyssey.