Last night, the detectors of Planck's High Frequency Instrument reached their amazingly low operational temperature of -273°C, making them the coldest known objects in space. The spacecraft has also just entered its final orbit around the second Lagrange point of the Sun-Earth system, L2.

Planck is equipped with a passive cooling system that brings its temperature down to about -230°C by radiating heat into space. Three active coolers take over from there, and bring the temperature down further to an amazing low of -273.05°C, only 0.1°C above absolute zero - the coldest temperature theoretically possible in our Universe.

A new class of pulsars detected by NASA's Fermi Gamma-ray Space Telescope is solving the mystery of previously unidentified gamma-ray sources and helping scientists understand the mechanisms behind pulsar emissions.

A study to be published by an international team of scientists in the July 2 edition of Science Express describes 16 pulsars discovered by Fermi based on their pulsed emissions of high-energy gamma rays. A pulsar is a rapidly spinning neutron star, the dense core left behind after a supernova explosion. Most of the 1,800 known pulsars were found through their periodic radio emissions.

Mars gets as far as 250 million miles away, but many parts of it closely resemble places on Earth, including its landscape, history of water, soil and even its weather, says a Texas A&M University researcher in the current issue of Science magazine.

Mark Lemmon, a professor of atmospheric sciences who has been involved with Mars missions for years, says last year's Phoenix Mars Lander mission keeps revealing secrets about the planet, answering some questions but raising other big ones. He is one of several authors detailing the Phoenix discoveries.

Four papers in the journal Science this week offer new details about the history of water on Mars, gleaned from the 2008 NASA Phoenix Mars Mission that was operated from The University of Arizona.

Peter H. Smith, a scientist with the UA Lunar and Planetary Laboratory and the mission's principal investigator, is the first author of "H2O at the Phoenix Landing Site" in Science. There are 35 co-authors from six countries on the paper. Smith and his group of scientists and students used the lander to investigate the role of water and ice on Mars, as well as the changing weather patterns.

NASA's Lunar Reconnaissance Orbiter, or LRO, has transmitted its first images since reaching lunar orbit June 23. The spacecraft has two cameras -- a low resolution Wide Angle Camera and a high resolution Narrow Angle Camera. Collectively known as the Lunar Reconnaissance Orbiter Camera, or LROC, they were activated June 30. The cameras are working well and have returned images of a region a few kilometers east of Hell E crater in the lunar highlands south of Mare Nubium.

As the moon rotates beneath LRO, LROC gradually will build up photographic maps of the lunar surface.

Spirit remains positioned on the west side of Home Plate. The rover has been continuing an ambitious science campaign of extensive observations with the panoramic camera (Pancam) and miniature thermal emission spectrometer (Mini-TES) plus contact science using using all the tools on the robotic arm (instrument deployment device, or IDD).

On Sol 1948 (June 26, 2009), the IDD placed the Mössbauer (MB) spectrometer on the target called "Cyclops_Eye_3" for a multi-sol integration. On Sol 1952 (June 30, 2009), the rock abrasion tool (RAT) was calibrated. Then, a RAT grind-scan was performed on a surface target in preparation for brushing that target.

The following new images taken by the High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter spacecraft are now available:

• Martian Zambonis?
  This image of Mars' south polar area shows an amazing series of elliptical rings. Could these have been made by a Zamboni on Mars driving around and around on the ice? No, of course not! But the answer in some ways more fun.
• Gullies on Southwest Slope of Ring Trough in Noachis Terra
  Geologically young gullies are a prime target for the HiRISE camera. Gullies are located in a variety of settings and are found all over Mars.
• Layering and Faulting in Melas Chasma Layered Deposits
• Light and Intermediate Toned Material Near Morava Valles
• Light Toned Rugged Intercrater Area in Viking Images 637A36 and 635A94
• Faulting in South Polar Layered Deposits

Astronomers using ESA's XMM-Newton X-ray observatory have discovered a black hole weighing more than 500 solar masses, a missing link between lighter stellar-mass and heavier supermassive black holes, in a distant galaxy. This discovery is the best detection to date of a new class that has long been searched for: intermediate mass black holes.

Due to appear tomorrow in the journal Nature, the discovery has been made by an international team of researchers working with XMM-Newton data, led by Sean Farrell from the Centre d'Etude Spatiale des Rayonnements, now based at the University of Leicester.

In 2008, Ulysses was expected to cease functioning due to weakening power. But solid engineering know-how and on-the-fly innovation have eked out an additional year of important science returns, which came to an end yesterday.

Ulysses, the joint ESA/NASA solar orbiter mission, finally ended yesterday when ground controllers sent commands to shut down the satellite's communications. The event marks the conclusion of one of the longest and most successful space missions ever conducted.

An international team of researchers led by a UC Riverside astronomer has completed the largest ever survey designed to find very distant clusters of galaxies.

Named the Spitzer Adaptation of the Red-sequence Cluster Survey, "SpARCS" detects galaxy clusters using deep ground-based optical observations from the CTIO 4m and CFHT 3.6m telescopes, combined with Spitzer Space Telescope infrared observations.

This image was recently featured in an article in Science magazine about the evolution of Mercury's crust.

The top mosaic (A) is an enhanced-color view of the planet created from images taken through the WAC's eleven color filters during MESSENGER's first and second flybys of Mercury. White areas are those that MESSENGER has not yet observed. The bottom half of this image (B) is a map of major terrain types on Mercury.

New research led by a UK scientist indicates that Mars had significantly warmer weather in its recent past than previously thought.

The research, funded by the UK's Science and Technology Facilities Council (STFC) and published in Earth and Planetary Science Letters, is good news in our quest for life on Mars, as the shorter the time period since the last warm weather on the planet, the better the chance that any organisms that may have lived in warmer times are still alive under the planet's surface.

The latest Geostationary Operational Environmental Satellite, GOES-O, soared into space today after a successful launch from Space Launch Complex 37 at the Cape Canaveral Air Force Station in Florida.

The GOES-O spacecraft lifted off at 22:51 UTC on a Delta IV rocket. The National Oceanic and Atmospheric Administration's GOES-O satellite will improve weather forecasting and monitor environmental events around the world. The satellite is the second to be launched in the GOES N series of geostationary environmental weather satellites.

Upon receipt of the last command from Earth, the transmitter on Ulysses will switch off on 30 June, bringing one of the most successful and longest missions in spaceflight history to an end.

After 18.6 years in space and defying several earlier expectations of its demise, the joint ESA/NASA solar orbiter Ulysses will achieve 'end of mission' on 30 June 2009. The final communication pass with a ground station will start at 15:35 UTC and run until 20:20 UTC or until the final command is issued to switch the satellite's radio communications into 'monitor only' mode. No further contact with Ulysses is planned.

The following new images taken by the Imaging Science Subsystem (ISS) on the Cassini spacecraft are now available:

• Fascinating F Ring (Released 22 June 2009)
  In the lower center of this image, the Cassini spacecraft captures an intriguing feature of Saturn's tenuous F ring.
• Serene Enceladus (Released 23 June 2009)
  Saturn's moon Enceladus looks tranquil here, concealing the true nature of this active moon.
• Faint Spokes on a Ring (Released 24 June 2009)
  This high-phase image from the Cassini spacecraft shows dark areas separating faint spokes that are brighter than the rest of Saturn's B ring.
• Centered on Senkyo (Released 25 June 2009)
  The Cassini spacecraft examines the dark region of Senkyo on Saturn's largest moon, Titan.
• Exposing a Shadow (Released 26 June 2009)
  The shadow of the moon Tethys is revealed on Saturn's B and C rings in this image which also includes the planet.