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Archive for March, 2012

How the Equatorial Ridge on Saturn’s Moon Iapetus Formed

March 29, 2012 Leave a comment

Saturn’s moon Iapetus is one of the most unusual moons in our solar system. Perhaps the most bizarre feature of Iapetus is its equatorial ridge, a 20-km (12.4-mi) high, 200-km (124-mi) wide mountain range that runs exactly along the equator, circling more than 75 percent of the moon. No other body in the solar system exhibits such a feature, and as Dombard et al. show, previous models have been unable to adequately explain how the ridge formed.

The authors now propose that the ridge formed from an ancient giant impact that produced a subsatellite around Iapetus. Tidal interactions with Iapetus ultimately led to orbital decay, eventually bringing the subsatellite close enough that the same forces tore it apart, forming a debris ring around Iapetus. Material from this debris ring then rained down on Iapetus, creating the mountain ring along the equator.

Full Story: http://www.agu.org/news/press/jhighlight_archives/2012/2012-03-29.shtml#four

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‘Mount Sharp’ on Mars Links Geology’s Past and Future

March 29, 2012 Leave a comment

One particular mountain on Mars, bigger than Colorado’s grandest, has been beckoning would-be explorers since it was first sighted from orbit in the 1970s. Scientists have ideas about how it took shape in the middle of ancient Gale Crater and hopes for what evidence it could yield about whether conditions on Mars have favored life.

No mission to Mars dared approach it, though, until NASA’s Mars Science Laboratory mission, which this August will attempt to place its one-ton rover, Curiosity, at the foot of the mountain. The moat of flatter ground between the mountain and the crater rim encircling it makes too small a touchdown target to have been considered safe without precision-landing innovations used by this mission.

To focus discussions about how Curiosity will explore the mountain during a two-year prime mission after landing, the mission’s international Project Science Group has decided to call it Mount Sharp. This informal naming pays tribute to geologist Robert P. Sharp (1911-2004), a founder of planetary science, influential teacher of many current leaders in the field, and team member for NASA’s first few Mars missions. Sharp taught geology at the California Institute of Technology (Caltech), in Pasadena, from 1948 until past his retirement. Life magazine named him one of the 10 best college teachers in the nation.

Full Story: http://www.jpl.nasa.gov/news/news.cfm?release=2012-090

A Planetary System from the Early Universe

March 29, 2012 Leave a comment

Image credit: Timotheos Samartzidis

Image credit: Timotheos Samartzidis

A group of European astronomers has discovered an ancient planetary system that is likely to be a survivor from one of the earliest cosmic eras, 13 billion years ago. The system consists of the star HIP 11952 and two planets, which have orbital periods of 290 and 7 days, respectively. Whereas planets usually form within clouds that include heavier chemical elements, the star HIP 11952 contains very little other than hydrogen and helium. The system promises to shed light on planet formation in the early universe – under conditions quite different from those of later planetary systems, such as our own.

It is widely accepted that planets are formed in disks of gas and dust that swirl around young stars. But look into the details, and many open questions remain – including the question of what it actually takes to make a planet. With a sample of, by now, more than 750 confirmed planets orbiting stars other than the Sun, astronomers have some idea of the diversity among planetary systems. But also, certain trends have emerged: Statistically, a star that contains more “metals” – in astronomical parlance, the term includes all chemical elements other than hydrogen and helium – is more likely to have planets.

This suggests a key question: Originally, the universe contained almost no chemical elements other than hydrogen and helium. Almost all heavier elements have been produced, over time inside stars, and then flung into space as massive stars end their lives in giant explosions (supernovae). So what about planet formation under conditions like those of the very early universe, say: 13 billion years ago? If metal-rich stars are more likely to form planets, are there, conversely, stars with a metal content so low that they cannot form planets at all? And if the answer is yes, then when, throughout cosmic history, should we expect the very first planets to form?

Full Story: http://www.idw-online.de/en/news469865

Mapping Galaxy Formation in Dual Mode

March 29, 2012 Leave a comment

A team of astronomers led by David Sobral (Leiden Observatory and Royal Observatory of Edinburgh) has explored the synergies between the Subaru Telescope and the United Kingdom Infra-Red Telescope (UKIRT) to locate numerous distant galaxies in the ancient universe and investigate their star formation activity. By combining narrow-band filter (Note 1) observations from both the Subaru Telescope and the UKIRT, the team has been able to obtain clean panoramic maps of parts of the distant universe about 9 billion years ago. This dual mode of surveying faint galaxies provides a powerful technique for selecting and studying star-forming galaxies during their formation and evolution.

Astronomers rely on detailed observations of astronomical objects outside of our own Milky Way Galaxy to understand how galaxies developed into what they are today. By comparing the properties of galaxies at different ages of the Universe, scientists can investigate their formation and evolution. However, current samples of the distant Universe lack the size and volume to answer such questions as: When was the peak of galaxy formation activity? Which physical processes propelled such activity? The current research team has developed and applied a technique for overcoming some common problems: a) missing many galaxies by looking at only one emission line and b) contamination of findings by less accurate measurements of galaxy distance and properties.

Full Story: http://www.subarutelescope.org/Pressrelease/2012/03/27/index.html

Milky Way Image Reveals a Billion Stars

March 29, 2012 Leave a comment

More than one billion stars in the Milky Way can be seen together in detail for the first time in an image captured by an international team of astronomers. Scientists created the colour picture by combining infra-red light images from telescopes in the northern and southern hemispheres. Large structures of the Milky Way galaxy, such as gas and dust clouds where stars have formed and died, can be seen in the image. Dr Nick Cross of the University of Edinburgh will present the new work on Thursday 29 March at the National Astronomy Meeting in Manchester.

The picture represents part of a 10-year project involving scientists from the UK, Europe and Chile, who gathered data from the two telescopes. The information has been processed and archived by teams at the Universities of Edinburgh and Cambridge, who have made it available to astronomers around the world for further studies.

Archived information from the project – known as the VISTA Data Flow System – is expected to enable scientists to carry out groundbreaking research in future years without the need to generate further data.

Full Story: http://www.jodrellbank.manchester.ac.uk/meetings/nam2012/pressreleases/nam21.html

Space Weather Warnings for Earth & Forecasts for Exoplanets

March 29, 2012 Leave a comment

The UK Met Office’s weather and climate model is being adapted to help understand space weather at Earth and the atmospheres of planets orbiting other stars. Two teams of scientists will present their work at the National Astronomy Meeting in Manchester.

The Met Office plans to expand its services to provide operational space weather forecasts for the UK. It is pooling skills with the UK’s space weather research community to extend its ‘Unified Model’ upwards to include the Earth’s thermosphere, a region about 90-600km above the Earth surface. The impact of space weather events is very commonly seen in this region.

“Space weather can affect the aviation and power industries, as well as a whole range of activities that rely on GPS timing and positioning, radio communication or satellite-based observations,” said the Met Office’s Dr David Jackson, who will present the project on Friday 30th March.

“To develop a more accurate and useful advanced-warning system for space weather, we need to develop a system of interconnected models that describe the whole domain – the conditions on the Sun, interplanetary space, the layers of the Earth’s atmosphere, all the way down to the Earth’s surface. The more accurate we can be in representing interactions between the lower atmosphere and thermosphere, the more we can enhance thermospheric forecasts, and thus improve space weather forecast products for users,” Jackson continued.

Full Story: http://www.jodrellbank.manchester.ac.uk/meetings/nam2012/pressreleases/nam13.html

Flying Formation – Around the Moon at 3,600 MPH

March 29, 2012 Leave a comment

Image credit: NASA/Caltech-JPL/MIT

Image credit: NASA/Caltech-JPL/MIT

The act of two or more aircraft flying together in a disciplined, synchronized manner is one of the cornerstones of military aviation, as well as just about any organized air show. But as amazing as the U.S. Navy’s elite Blue Angels or the U.S. Air Force’s Thunderbirds are to behold, they remain essentially landlocked, anchored if you will, to our planet and its tenuous atmosphere. What if you could take the level of precision of these great aviators to, say, the moon?

“Our job is to ensure our two GRAIL spacecraft are flying a very, very accurate trail formation in lunar orbit,” said David Lehman, GRAIL project manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “We need to do this so our scientists can get the data they need.”

Essentially, trail formation means one aircraft (or spacecraft in this case), follows directly behind the other. Ebb and Flow, the twins of NASA’s GRAIL (Gravity Recovery And Interior Laboratory) mission, are by no means the first to synch up altitude and “air” speed  while zipping over the craters, mountains, hills and rills of Earth’s natural satellite. That honor goes to the crew of Apollo 10, who in May 1969 performed a dress rehearsal for the first lunar landing. But as accurate as the astronauts aboard lunar module “Snoopy” and command module “Charlie Brown” were in their piloting, it is hard to imagine they could keep as exacting a position as Ebb and Flow.

Full Story: http://www.jpl.nasa.gov/news/news.cfm?release=2012-089