(From west to east)

• Vesta is in the constellation of Taurus.
• Pallas is in the constellation of Monoceros.
• Amphitrite is in the constellation of Virgo.
• Irene is at opposition on the 20th in the constellation of Virgo.
• Information about the Minor Planets can be found at the Minor Planet Observer website.

"The Cassini spacecraft reveals a remarkable amount of structure in the outer portion of Saturn's A ring. The granular look of the outer edge of the A ring, first discovered soon after Cassini's orbit insertion, is likely created by gravitational clumping of particles there. As ring particles round the planet in their orbits in this region, they also become perturbed by the gravitational forcing of Saturn's two moons, Janus and Epimetheus. The resulting gravitational resonance at the A ring's outer edge periodically forces the particles close together, promoting clumping (see Scrambled Edge). Similar clumping is seen at the outer edge of the B ring where a resonance with Mimas has a similar effect on the ring particle orbits (see Perturbed Edge).

The view was obtained at a distance of approximately 206,000 kilometers (128,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 108 degrees. This view looks toward the sunlit side of the rings from about 64 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 2, 2008. Image scale is 901 meters (2,960 feet) per pixel."

Cassini Imaging Team

"Add another moon to the New Horizons photo gallery: the spacecraftÕs Long Range Reconnaissance Imager detected Triton, the largest of NeptuneÕs 13 known moons, during the annual spacecraft checkout last fall.

New Horizons was 2.33 billion miles (3.75 billion kilometers) from Neptune on Oct. 16, when LORRI, following a programmed sequence of commands, locked onto the planet and snapped away.

"We wanted to test LORRIÕs ability to measure a faint object near a much brighter one using a special tracking mode," says New Horizons Project Scientist Hal Weaver, of the Johns Hopkins University Applied Physics Laboratory, "and the Neptune-Triton pair perfectly fit the bill." LORRI was operated in 4-by-4 format (the original pixels are binned in groups of 16), and the spacecraft was put into a special tracking mode to allow for longer exposure times. "We needed to achieve the highest possible sensitivity," Weaver adds."

New Horizons gallery."

Mission Status Report: NASA's Dawn Mission

"With Mars disappearing in its metaphorical rearview mirror, NASA's Dawn spacecraft's next stop is the asteroid belt and the giant asteroid Vesta. Dawn got as close as 549 kilometers (341 miles) to the Red Planet during its Tuesday, Feb. 17, flyby.

Dawn's navigators placed the spacecraft on a close approach trajectory with Mars so the planet's gravitational influence would provide a kick to the spacecraft's velocity. If Dawn had to perform these orbital adjustments on its own, with no Mars gravitational deflection, the spacecraft would have had to fire up its engines and change velocity by more than 9,330 kilometers per hour (5,800 miles per hour).

The achieved goal of the flyby was to obtain this orbital pick-me-up, making possible its voyage to asteroid Vesta and, later, the dwarf planet Ceres. But Dawn's science teams used this massive target of opportunity to also perform calibrations of some of the scientific instruments. Calibration images were taken by Dawn's framing camera, and the Gamma Ray and Neutron Detector also observed Mars for calibration. These data will be compared to similar observations taken by spacecraft orbiting Mars."

"Mario H. Acuña, a senior astrophysicist at NASA Goddard Space Flight Center and Co-Investigator on the MESSENGER mission, died on March 5, 2009, after a long battle against multiple myeloma. During his four decades at NASA, he played a critical role in many NASA endeavors, serving as principal investigator or key developer of experiments flown on more than 30 missions to every planet in the solar system, as well as the Sun.

Acuña had been involved in the MESSENGER from its inception, 13 years ago. "He became an enthusiastic participant as soon as I mentioned MESSENGER to him, when it was just an idea without an acronym," notes Stamatios M. Krimigis, chair of MESSENGER's Atmosphere and Magnetosphere Group. "His deep technical knowledge and scientific insight, coupled with his absolute honesty and integrity made him an indispensable member of any technical review and a critical player when hard decisions had to be made."

Acuña contributed to the development of the Magnetometer (MAG) and the analysis of MAG observations from MESSENGER's first two flybys of Mercury. "He brought with him a wealth of experience that was truly irreplaceable," says Brian Anderson, MESSENGERÕs Deputy Project Scientist. "He was a fountain of knowledge about anything concerning magnetic fields and magnetometer instrumentation. His breadth of understanding was astonishing. From arcane properties of materials to the intricacies of the electronics design in his instruments, you could count on Mario to have gems of wisdom to offer. To work with Mario on any project was to learn from him. We did our best to be good students, but it will be difficult knowing that we can no longer pick up the phone when we feel the need of his advice."

"PASADENA, Calif. -- NASA's Mars Odyssey orbiter properly followed commands today to shut down and restart, a strategy by its engineers to clear any memory flaws accumulated in more than five years since Odyssey's last reboot.

The procedure also restored Odyssey's onboard set of backup systems, called the spacecraft's "B side," allowing its use in the future when necessary.

"For nearly two years, we have not known for certain whether the backup systems would be usable, so this successful reboot has allowed us to ascertain their health and availability for future use," said Odyssey Project Manager Philip Varghese of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Odyssey has been orbiting Mars since 2001 and has never switched from its primary set of components, the "A side," to the backup set, which includes an identical computer processor, navigation sensors, relay radio and other components. In March 2006, the B-side spare of a component for managing the distribution of power became inoperable. Analysis by engineers identified a possibility that rebooting Odyssey might restore that component, which proved to be a side benefit of today's procedure to refresh onboard memory."

"A simulated fly-through using the newly assembled imagery is available online.

The fly-through plus tools for wandering across and zooming into the large image are at THEMIS."

Daily Mars Odyssey THEMIS Images
Can be found at the Thermal Emission Imaging System (THEMIS) website.

The Odyssey data are available through a new online access system established by the Planetary Data System.

SPIRIT UPDATE: Distance Record for Five-Wheel Driving - sols 1852-1858, March 19-25, 2009:

"Spirit is making good progress around Home Plate to the west. After getting clear of troublesome rocks, Spirit drove 13.8 meters (45.3 feet) on Sol 1854 (March 21, 2009). The next drive, on Sol 1856 (March 23, 2009), achieved a new distance record for five-wheel driving. Spirit drove 25.82 meters (84.7 feet), beating the old record by about a meter. Spirit completed another drive of 12.9 meters (42.3 feet) on Sol 1858 (March 25, 2009).

The sol ahead will see the building of the new R9.3 flight software on board the rover. The rover will boot the new software on the subsequent sol.

As of Sol 1858 (March 25, 2009), Spirit's solar array energy production is 233 watt-hours. Atmospheric opacity (tau) remains elevated at 1.15. The dust factor on the solar array, 0.309, means that 30.9 percent of sunlight hitting the solar array penetrates the layer of accumulated dust on the array. The rover is in good health in spite of dusty skies. Spirit's total odometry is 7,665.02 meters (4.76 miles)."

OPPORTUNITY UPDATE: Brushing and Examining an Outcrop - sols 1852-1858, March 19-25, 2009:

"Opportunity remains positioned on an exposed rock outcrop, continuing an "in situ" (contact) science campaign with the robotic arm (IDD).

On Sol 1832 (March 20, 2009), the first part of a rock abrasion tool (RAT) brushing activity was performed. Using a new work-around for the failed RAT Z-encoder, the RAT successfully performed a seek-scan to locate the rock surface. On the next sol, the RAT successfully brushed the surface. The Microscopic imager (MI) took images to document the brushing. The Mšssbauer (MB) spectrometer was placed on the brushed target, and several sols of integration were performed. On Sol 1836 (March 24, 2009), the alpha particle X-ray spectrometer (APXS) was placed on the brushed target to measure the elemental composition. On Sol 1837 (March 25, 2009), another RAT seek-scan was performed to set up for a RAT grind on the next sol.

As of Sol 1837 (March 25, 2009), Opportunity's solar array energy production is 336 watt-hours. Atmospheric opacity (tau) remains elevated at 1.145. The solar array dust factor is 0.497, meaning that 49.7 percent of sunlight hitting the solar array penetrates the layer of accumulated dust on the array. Opportunity is in good health. Its total odometry remains at 15,051.44 meters (9.35 miles)."

Landing sites

"New images from the high-resolution camera on NASA's Mars Reconnaissance Orbiter show intriguing patterns where dusty gas released by thawing dry ice bursts through overlying ice near Mars' south pole.

Mars' seasonal cap of carbon dioxide ice has eroded many beautiful terrains as it sublimates (goes directly from ice to vapor) every spring. In the region where the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter took this image, we see troughs that form a starburst pattern. In other areas these radial troughs have been refered to as spiders, simply because of their shape. In this region the pattern looks more dendritic as channels branch out numerous times as they get further from the center.

The troughs are believed to be formed by gas flowing beneath the seasonal ice to openings where the gas escapes, carrying along dust from the surface below. The dust falls to the surface of the ice in fan-shaped deposits."

MARS RECONNAISSANCE ORBITER HIRISE IMAGES
All of the HiRISE images are archived here.

"The team that developed and operated NASA's Phoenix Mars Lander mission will receive the 2009 John L. "Jack" Swigert Award for Space Exploration from the Space Foundation.

During five months of operations at a Martian arctic site after landing on May 25, 2008, the Phoenix spacecraft confirmed the presence of frozen water just below the surface, identified potential nutrients and other substances in the soil, and observed snow in the atmosphere.

The Space Foundation, based in Colorado Springs, Colo., announced Feb. 19 that it will present the award to the Phoenix team on March 30, during the foundation's 25th National Space Symposium, in Colorado Springs."
Full image and caption