(From west to east)

• Irene is in the constellation of Virgo.
• Iris is in the constellation of Sagittarius.
• Information about the Minor Planets can be found at the Minor Planet Observer website.

"As April draws to a close, the relatively infrequent Titan flybys we enjoyed earlier in 2009 seem a distant memory. Even though we only returned to sixteen-day orbits a bit over one month ago, the months start blurring together when Titan encounters come fast and furious. We started the month with a high-altitude (4150-kilometer, or 2579-mile) Titan-52 flyby. This offered our navigation and engineering teams a unique challengeÑthere were only eight days between T51 and T52! As such, we didn't have our usual calendar time to execute a series of propulsive maneuvers to target T52Ñwe had to nail it with OTM-186, a hybrid between a T51 "clean-up" maneuver and a T52 final targeting maneuver. I'm happy to tell you that our targeting for T52 was excellent despite these time pressures."

Cassini Imaging Team

"New Horizons' run to the Final Four of NASA's first "Mission Madness" tournament was a great experience -- thanks to the thousands of fans who supported the first mission to Pluto! New Horizons' bid for the title fell just short, with a semifinal loss to eventual champion Super-Pressure Balloon."

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."

"The National Space Club will award the MESSENGER team its Nelson P. Jackson Aerospace Award this evening at the 52nd annual Dr. Robert H. Goddard Memorial Dinner in Washington, D.C. The award, named in honor of the National Space Club's founder and past president, is presented annually to recognize exceptional teamwork between government and industry in the missile, aircraft, and space fields."

"PASADENA, Calif. -- Heading into a period of the Martian year prone to major dust storms, the team operating NASA's twin Mars rovers is taking advantage of eye-in-the-sky weather reports.

On April 21, Mars will be at the closest point to the sun in the planet's 23-month, elliptical orbit. One month later, the planet's equinox will mark the start of summer in Mars' southern hemisphere. This atmospheric-warming combination makes the coming weeks the most likely time of the Martian year for dust storms severe enough to minimize activities of the rovers."

"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: Another Reset and a Cleaning Event - sols 1879-1885, April 16-22, 2009:

"Spirit experienced another reset event over the weekend, but otherwise has been well-behaved.

The investigation into Spirit's recent anomalous behavior continues, but there is still no explanation. A team of experts involved in the original design and construction of the rover has been consulted. Although the anomalous behavior is frustrating, the rover continues to be healthy in terms of power, temperature and communication.

The plan going forward is to implement some enhanced data-collecting techniques in order to gather more information from any future anomalous events, and to resume near-normal operations. A short drive for Spirit has been sequenced on Sol 1886 (April 23, 2009).

Spirit also had a small dust cleaning event on her solar arrays on Sol 1881 (April 18, 2009). Solar array energy improved by more than 10 percent.

As of Sol 1885 (April 22, 2009), Spirit's solar array energy production is 306 watt-hours, about as much as is used in lighting a 100-watt bulb for three hours. Atmospheric opacity (tau) is estimated around 0.964. The dust factor has improved to about 0.377, meaning that about 37.7 percent of sunlight hitting the solar array penetrates the layer of accumulated dust on the array. Spirit's total odometry remains at 7,726.78 meters (4.80 miles)."

OPPORTUNITY UPDATE: Five Long Drives - sols 1859-1865, April 16-22, 2009:

"Opportunity has been driving "great guns" southward this week on her way to Endeavour crater, driving five out of the last seven sols and covering almost half a kilometer.

Sols 1859, 1860, 1863, 1864 and 1865 (April 16, 17, 21, 22 and 23, 2009) had drives of 62 meters (203 feet), 88 meters (289 feet), 96 meters (315 feet), 137 meters (449 feet) and 95 meters (312 feet), respectively. The right-front wheel on Opportunity remained well-behaved, with motor currents very near normal levels. More driving is planned for the sols ahead.

As of Sol 1865 (April 23, 2009), Opportunity's solar array energy production is 447 watt-hours. Atmospheric opacity (tau) is around 0.831. The dust factor is 0.607, meaning that 60.7 percent of sunlight hitting the solar array penetrates the layer of accumulated dust on the array. Opportunity is in good health, with an odometry total of 15,737.05 meters (9.78 miles)."

Landing sites

"This movie shows the southern high-latitudes region of Mars from March 19 through April 14, 2009, a period when regional dust storms occurred along the retreating edge of carbon-dioxide frost in the seasonal south polar cap. Compared with a full-hemisphere view, this view shows more details of where the dust clouds formed and how they moved around the planet."

Weather Movie, Mars Southern Hemisphere, March-April 2009

"This movie shows the full southern hemisphere of Mars from March 19 through April 14, 2009, a period when regional dust storms occurred along the retreating edge of carbon-dioxide frost in the seasonal south polar cap."

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