The image shows details of an impact crater in Mars' northern hemisphere.
Credit: NASA/JPL-Caltech/University of Arizona

NASA recently published new images of Mars, acquired by the Mars-orbiting Mars Reconnaissance Orbiter (MRO) spacecraft. MRO obtained recently 600 observations of interesting Martian terrains, applying a telescopic camera, termed HiRISE, aboard the spacecraft. The imaged surface features include gullies, ridges and steep cliffs.

Each of the new MRO observations covers an area of several square kilometers on Mars, and reveals details as small as desks. The images were taken from 5 April to 6 May 2010, and are now available on NASA's Planetary Data System and the camera team's website.

For more information about MRO, please visit the following website.
http://mars.jpl.nasa.gov/mro/

To view the new scenes of Mars, please visit the following websites.
http://pds.jpl.nasa.gov/
http://hirise.lpl.arizona.edu/

Aymen Mohamed Ibrahem
Senior Astronomy Specialist

An artist’s impression showing one of NASA’s Mars Exploration Rovers
Credit: NASA-JPL

NASA has announced that its Mars Exploration Rover Project will achieve a duration record on 20 May, as the Mars Rover Opportunity will surpass the previous duration record held by NASA's Viking 1 Lander of six years and 116 days of operation on the Martian surface.

Opportunity has a twin rover, Spirit, located on the opposite side of Mars. Spirit landed on Mars, on 4 January 2004, three weeks before Opportunity. However, Spirit has been out of communication for nearly three months. If it resumes communication, Spirit will hold the Martian surface longevity record.

The Viking 1 Lander touched down on Mars on 20 July 1976. It was the first spacecraft to land on Mars and complete its mission successfully. Before the Viking Mission, several Soviet landers failed to accomplish their missions. The Viking 2 Lander was another successful Mars probe. It landed on Mars on 3 September 1976, and remained operational for nearly four years.

Further Reading

NASA’s Press Release
http://www.nasa.gov/mission_pages/mer/news/mer20100519.html
The Viking Mission to Mars
http://nssdc.gsfc.nasa.gov/planetary/viking.html
Mars Exploration Rovers
http://marsrovers.jpl.nasa.gov/home/index.html
Aymen Mohamed Ibrahem
Senior Astronomy Specialist

Infrared mages of star-forming cosmic clouds
Credit: NASA/JPL-Caltech/Univ. of Michigan

The Sun is a solitary star, but most of the stars in the Galaxy are actually members of binary star systems. A binary star is a gravitationally-bound system of two stars, orbiting a common center of gravity.

How binary stars form is an intriguing question. Do they originate from two separate cosmic clouds? Or do they start evolving in one cloud that fragments into two? Astronomers generally believe that widely spaced binary stars form from two separate clouds, while the tight binary systems are born in one cloud. Yet, the latter mechanism remains unclear.

New observations from NASA's sophisticated Spitzer Space Telescope (SST) are revealing the early evolutionary stages of closely separated binary stars. SST is an infrared space-based telescope that can detect the structure of the dense, dusty envelopes surrounding newborn stars in amazing detail. These envelopes feed developing stars within: the material accumulates onto disks spinning around the stars, and then is pulled by the growing stars.

The SST images show blob-like, asymmetrical envelopes for 17 of 20 objects observed. Astronomers believe such irregularities might induce the formation of binary stars.

"We see asymmetries in the dense material around these proto-stars on scales only a few times larger than the size of the Solar System. This means that the disks around them will be fed unevenly, possibly enhancing fragmentation of the disk and triggering binary star formation," said John Tobin of the University of Michigan, principal author of a recently published research article.

All stars, whether they are binaries or not, form from shrinking envelopes, or clumps, of gas and cosmic dust. The clumps continue to contract, due to gravity, until pressure is high enough for atoms to fuse together, and generate energy.

Theorists have previously devised computer simulations, to show that close binary stars may form inside irregularly-shaped envelopes. The collapsing Material would be concentrated in clumps, not evenly spread out, triggering the formation of two stars instead of one. However, observational evidence for this scenario was inconclusive.

Tobin and his colleagues initially did not aim to examine this theory. They were studying the influence of interstellar jets and outflows on envelopes around young stars, when they realized that most of the envelopes were asymmetrical, rather than spherical. Also, three of the 20 envelopes under study were not as irregular as the others, but not quite round either. Many of the envelopes were already known to contain embryonic twin stars, possibly due to the irregular envelopes.

"We were really surprised by the prevalence of asymmetrical envelope structures," said Tobin. "And because we know that most stars are binary, these asymmetries could be indicative of how they form."
SST was able to acquire such detailed images of these envelopes, thanks to its high infrared sensitivity that can detect the feeble infrared emission from our Galaxy. The dusty envelopes surrounding the young stars block background light from the Galaxy, giving rise to the appearance of a shadow in images from SST.

Further Reading

SST Official Websites
http://www.nasa.gov/mission_pages/spitzer/main/index.html
http://www.spitzer.caltech.edu/spitzer/

Aymen Mohamed Ibrahem
Senior Astronomy Specialist

Credit: NASA/JPL/Space Science Institute

NASA recently published a stunning image of Saturn, acquired by the Saturn-orbiting Cassini spacecraft. The image shows a huge cloud formation, swirling in the high northern latitudes of Saturn, near the top of image.

The image was taken with Cassini’s wide-angle camera, on 14 February 2010, in an infrared filter. The spacecraft was approximately 523,000 km away from Saturn.

Saturn's turbulent atmosphere occasionally features long-lived oval clouds. In 1990, the Hubble Space Telescope observed a gigantic white cloud near Saturn's equator, and, in 1994, a smaller storm was recorded. Such storms, also known as the great white spots, resemble Jupiter’s titanic Great Red Spot, an immense Jovian storm, characterized by its reddish hue. The great white spots occur in Saturn around the start of Saturn’s northern summer, or every 30 years, approximately.

Further Reading

Saturn
http://solarsystem.nasa.gov/planets/profile.cfm?Object=Saturn
Cassini Spacecraft Website
http://saturn.jpl.nasa.gov/

Aymen Mohamed Ibrahem
Senior Astronomy Specialist

Credit: NASA/JPL-Caltech/SSI

NASA's Saturn-orbiting Cassini spacecraft has acquired rare images of lightning on Saturn, the ringed giant planet. The images have enabled scientists to produce the first movie showing lightning blazing on another planet.

Scientists have been waiting years, for Saturn to dim enough for the spacecraft's cameras to detect the flashes of lighting in the planet’s turbulent atmosphere. The movie features a soundtrack of the crackle of radio waves, emitted when lightning bolts occurred.
Lightning strikes on Earth and on Saturn generate radio waves that can be detected as noise, on an AM radio. The sounds in the Saturn lightning video approximate that noise sound, based on measurements by a Cassini's radio instrument. This is the first time that scientists obtain visual and radio data of Saturn’s lightning, which confirms the observed phenomenon is lightning.

The movie and radio data suggest extremely powerful storms with lightning that flashes as brightly as the brightest super-bolts on Earth, according to Andrew Ingersoll, a Cassini imaging science subsystem team member at the California Institute of Technology, Caltech. "What's interesting is that the storms are as powerful -- or even more powerful -- at Saturn as on Earth," said Ingersoll. "But they occur much less frequently, with usually only one happening on the planet at any given time, though it can last for months."

The first images of the lightning were captured in August 2009, during a storm that swirled from January to October 2009, and lasted longer than any other recorded lightning storm in the Solar System.
Since Cassini's arrival at Saturn, in July 2004, it has been difficult to observe the Saturnian lightning, because the planet is very bright and reflective.

Sunlight shining off Saturn's magnificent rings brightly illuminates the night side of Saturn. However, every about 14 years, during early spring or autumn in Saturn, the Sun lies in, or near to the plane of the rings, to a hypothetical Saturnian observer, and therefore, the rings are significantly fainter, and the night side of Saturn is sufficiently dark, for imaging the Saturnian lightning.

Further Reading

JPL Press Release
http://www.jpl.nasa.gov/news/news.cfm?release=2010-129
Cassini Websites
http://www.nasa.gov/cassini
http://saturn.jpl.nasa.gov

Aymen Mohamed Ibrahem
Senior Astronomy Specialist