(From west to east)

• Iris is at opposition on the 4th in the constellation of Sagittarius.
• Psyche is in the constellation of Capricornus.
• Juno is in the constellation of Pisces.
• Melpomene is in the constellation of Pisces.
• Information about the Minor Planets can be found at the Minor Planet Observer website.

"PASADENA, Calif. -- For the first time, scientists working on NASA's Cassini mission have detected sodium salts in ice grains of Saturn's outermost ring. Detecting salty ice indicates that Saturn's moon Enceladus, which primarily replenishes the ring with material from discharging jets, could harbor a reservoir of liquid water -- perhaps an ocean -- beneath its surface.

Cassini discovered the water-ice jets in 2005 on Enceladus. These jets expel tiny ice grains and vapor, some of which escape the moon's gravity and form Saturn's outermost ring. Cassini's cosmic dust analyzer has examined the composition of those grains and found salt within them.

"We believe that the salty minerals deep inside Enceladus washed out from rock at the bottom of a liquid layer," said Frank Postberg, Cassini scientist for the cosmic dust analyzer at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. Postberg is lead author of a study that appears in the June 25 issue of the journal Nature."

Cassini Imaging Team

"Things are going well out in the cold space between Saturn and Uranus where New Horizons is now. We're deep in planning for our spacecraft's annual checkout this summer, which begins on July 7. But that's not what I want to write about today: instead, it's something called EPDR.

Despite still being more than six years and just over 18 astronomical units from the Pluto system, the New Horizons project team is conducting the second and final portion of our Pluto Encounter Preliminary Design Review (EPDR) today and tomorrow (May 20-21) at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md.

We conducted the first portion of the EPDR on January 7-8. EPDR part two is another two-day confab, in which the New Horizons technical and management teams will present the detailed, minute-by-minute timeline of our planned 2015 Pluto encounter to a review team of expert planetary planners from across the nation. EPDR represents the culmination of almost two years of intense encounter planning involving the entire New Horizons science and mission team, and the stakes are high — this is the main technical review of what will take place when we conduct the first exploration of Pluto and its satellites."

New Horizons gallery

"Mission controllers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., have received a transmission from the Dawn spacecraft confirming it has re-ignited its ion propulsion system. For those of you scoring at home, Thruster # 1 received the honors. Over the course of its eight-year mission, first to asteroid Vesta and then off to dwarf planet Ceres, Dawn's three ion engines will accumulate 2,000 days of operation."

"Brian Anderson, Louise Prockter, and Thomas Zurbuchen have been appointed MESSENGER Co-Investigators by NASA Science Mission Directorate Associate Administrator Edward Weiler.

"Each of these individuals has served admirably as MESSENGER Instrument Scientists, and each has led an important aspect of the analysis and interpretation of MESSENGER observations from the first two Mercury flybys," notes MESSENGER Principal Investigator Sean Solomon.

As a MESSENGER Deputy Project Scientist, Anderson, of the Johns Hopkins University Applied Physics Laboratory (APL), oversees the orbital operations planning to ensure that observations from all of the instruments are coordinated to meet the mission objectives. He formerly served as the Magnotometer Instrument Scientist. In his additional role as Co-Investigator, Anderson will provide scientific direction to the operation of the Magnetometer instrument in orbit, including in-flight calibration, data validation, science product generation, and coordination with the operation of and data returned from other instruments closely related to investigation of Mercury's magnetic field. In addition, he will lead aspects of the science analysis of data from the Magnetometer and other instruments in understanding Mercury's internal magnetic field and magnetosphere, particularly efforts to identify and quantify the magnetospheric contributions to the observations so as to recover the structure of Mercury's internal magnetic field to the highest fidelity possible.

Prockter, also of APL, serves as the Instrument Scientist for the Mercury Dual Imaging System (MDIS). In her new role as Co-Investigator, she will provide scientific direction to the operation of MDIS in Mercury orbit, including instrument calibration, data validation, science product generation, and coordination with the operation of and data returned from other instruments related to observations of Mercury's surface. In addition, she will lead aspects of the science analysis of MDIS observations to improve our understanding of the geological evolution of Mercury, particularly the study of impact melting during the formation of large craters and basins on Mercury and the contribution of impact melts to smooth plains deposits.

Zurbuchen, of the University of Michigan, is the Instrument Scientist for the Energetic Particle and Plasma Spectrometer. As a Co-Investigator, he will provide scientific direction to the operation of the Fast Imaging Plasma Spectrometer (FIPS) sensor in orbit, including calibration, data validation, science product generation, and coordination with the operation of and data returned from other instruments sensitive to the exosphere and magnetosphere. He will also lead aspects of the science analysis of data from FIPS and other instruments in understanding Mercury's charged particle environment, particularly the analysis of the distribution of plasma ions in Mercury's vicinity and the implications of their energies and compositions for magnetosphere-solar wind interaction at Mercury."

"PASADENA, Calif. - NASA's long-lived Mars Odyssey spacecraft has completed an eight-month adjustment of its orbit, positioning itself to look down at the day side of the planet in mid-afternoon instead of late afternoon. 



This change gains sensitivity for infrared mapping of Martian minerals by the orbiter's Thermal Emission Imaging System camera. Orbit design for Odyssey's first seven years of observing Mars used a compromise between what worked best for the infrared mapping and for another onboard instrument.



"The orbiter is now overhead at about 3:45 in the afternoon instead of 5 p.m., so the ground is warmer and there is more thermal energy for the camera's infrared sensors to detect," said Jeffrey Plaut of NASA's Jet Propulsion Laboratory, Pasadena, Calif., project scientist for Mars Odyssey."

"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: Studying Troy - sols 1941-1947, June 18-24, 2009:

"Spirit is continuing her ambitious remote sensing and in-situ (contact) science observations at the location called "Troy" on the west side of Home Plate.

Using the rover robotic arm (instrument deployment device, IDD), the rover has been exploring a set of surface targets that hold clues to the past geologic history at this location.

On Sol 1941 (June 18, 2009), a Microscopic Imager (MI) stack of images was collected on target Penina3, then the Alpha Particle X-ray Spectrometer (APXS) was placed for an overnight integration. On the next sol, the Mössbauer Spectrometer (MB) was placed on a different target for a multi-sol integration. The next few sols included some late-day activities where the rover imaged the Earth and Venus in the night sky.

On Sols 1945 and 1946 (June 22 and 23, 2009), Spirit investigated another set of surface targets, again with MI stacks and APXS overnight integrations. On Sol 1946 (June 23, 2009), another solar array dust cleaning event occurred, increasing the available energy each sol even more.

At JPL, a special test form has been installed for ground testing with the surface system testbed (SSTB) rover to guide the eventual extraction activities on Mars for Spirit. The materials for the soil simulant to be used in the test form have been delivered and are in the process of being formulated and mixed. As of Sol 1947 (June 24, 2009), solar array energy production increased to 945 watt-hours with atmospheric opacity (tau) of 0.480 and an improved dust factor of 0.834. Total odometry remains at 7,729.93 meters (4.80 miles)."

OPPORTUNITY UPDATE: Moving to Outcrop - sols 1920-1926, June 18-24, 2009:

"Opportunity has been moving toward a candidate patch of rock outcrop in preparation for a rest of the mobility system over the coming holiday. There continues to be concern with the elevated motor currents seen in the right front wheel.

On Sol 1920 (June 18, 2009), Opportunity drove backwards about 63 meters (207 feet) south. The right front wheel currents were elevated but were not divergently increasing. After a few sols, Opportunity drove another 7 meters (23 feet) to a nearby outcrop.

Robotic arm activities on surface targets with the microscopic image (MI) and the alpha particle X-ray spectrometer (APXS) were performed on Sols 1924 and 1925 (June 22 and 23, 2009).

Further drives are planned to reach a large region of rock outcrop. Also, the week saw further implementation of the miniature thermal emission spectrometer (Mini-TES) mirror dust mitigation. The Mini-TES shroud is left open overnight to see if the environment will clean the elevation mirror.

As of Sol 1924 (June 22, 2009), the solar array energy production was 450 watt-hours with an atmospheric opacity (tau) of 0.480 and a dust factor of 0.530, indicating that 53 percent of sunlight hitting the solar array penetrates the layer of accumulated dust on the array. As of Sol 1926 (June 24, 2009), Opportunity's total odometry remains at 16,639.71 meters (10.3 miles)."

Landing sites

Mars Reconnaissance Orbiter Mission Status Report

"PASADENA, Calif. -- NASA's Mars Reconnaissance Orbiter is examining Mars again with its scientific instruments after successfully transitioning out of a precautionary standby mode triggered by an unexpected June 3 rebooting of its computer.

Engineers brought the spacecraft out of the standby mode on June 6. Cameras and other scientific instruments resumed operation June 9.

The Mars Reconnaissance Orbiter reached Mars in 2006 and has returned more data about the planet than all other Mars missions combined.

The June 3 rebooting resembled a Feb. 23 event on the spacecraft. Engineers are re-investigating possible root causes for both events. The new investigation includes reconsidering the likelihood of erroneous voltage readings resulting from cosmic rays or solar particles hitting an electronic component."

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