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Thursday, November 30, 2017

#Astronomy

#Astronomy


New radio image reveals the true grace of nearby dwarf galaxy

Posted: 30 Nov 2017 02:20 AM PST

CSIRO's ASKAP telescope has mapped the atomic hydrogen gas within the Small Magellanic Cloud. Image credit: ANU/CSIRO

The Small Magellanic Cloud, one of the Milky Way's orbiting dwarf galaxies, has had its radio emission imaged in unprecedented detail. Astronomers at the Australian National University (ANU) used CSIRO's new radio telescope, the Australian Square Kilometre Array Pathfinder (ASKAP), to decipher clues as to how the galaxy evolved and what will happen to it in the future.

The new and powerful ASKAP telescope consists of thirty-six 12-metre antennas spanning across the Australian Mid West. By using its innovative radio camera technology, also known as phased array feeds, ASKAP was able to collect large amounts of radio observations from the Small Magellanic Cloud, which appears exclusively in the southern hemisphere.

The Small Magellanic Cloud is tiny in size and mass in comparison to the Milky Way, hence the term 'dwarf galaxy'. However this neighbouring galaxy appears to have a very complex structure as well. This is likely due to interactions with the Milky Way and it's galactic companion, the Large Magellanic Cloud, according to Professor Naomi McClure-Griffiths of ANU Research School of Astronomy and Astrophysics.

“The new image captured by CSIRO’s Australian Square Kilometre Array Pathfinder telescope reveals more gas around the edges of the galaxy, indicating a very dynamic past for the Small Magellanic Cloud,” says McClure-Griffiths. “These features are more than three times smaller than we were able to see before and allow us to probe the detailed interaction of the small galaxy and its environment.”

The Small Magellanic Cloud is normally visible with the naked eye in the southern hemisphere. Image credit: NASA/ESA/Hubble Heritage Team (STScl/AURA)

This image was created as part of a survey that aims to investigate galactic evolution. It appears that these distortions to the Small Magellanic Cloud are due to prior interactions with much larger galaxies and internal stellar explosions pushing gas out of the galaxy. It is also in for a very turbulent and unpleasant future.

“The outlook for this dwarf galaxy is not good, as it’s likely to eventually be gobbled up by our Milky Way,” explains McClure-Griffiths. “Together, the Magellanic Clouds are characterised by their distorted structures, a bridge of material that connects them, and an enormous stream of hydrogen gas that trails behind their orbit – a bit like a comet.”

Our neighbouring galaxy has been studied extensively in the recent past by infrared telescope such as NASA's Spitzer Space Telescope and ESA's Herschel Telescope. However, infrared only reveals the nature of the dust and stars within the galaxy, whereas ASKAP has been investigating the behaviour of the most ubiquitous gas in the universe, hydrogen.

“The new radio image finally reaches the same level of detail as those infrared images, but on a very different component of the galaxy’s make-up: its hydrogen gas,” says McClure-Griffiths. “Hydrogen is the fundamental building block of all galaxies and shows off the more extended structure of a galaxy than its stars and dust.”

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XMAS OFFER: Get All About Space magazine for up to 49% less this Christmas!

Posted: 29 Nov 2017 06:49 AM PST

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NASA gets stuck into building its next Mars rover

Posted: 29 Nov 2017 05:38 AM PST

This artist’s rendition depicts NASA’s Mars 2020 rover studying a Mars rock outrcrop. Image credit: NASA/JPL-Caltech

In just a few years, NASA's next Mars rover mission will be flying to the Red Planet.

At a glance, it looks a lot like its predecessor, the Curiosity Mars rover. But there's no doubt it's a souped-up science machine: It has seven new instruments, redesigned wheels and more autonomy. A drill will capture rock cores, while a caching system with a miniature robotic arm will seal up these samples. Then, they'll be deposited on the Martian surface for possible pickup by a future mission.

This new hardware is being developed at NASA's Jet Propulsion Laboratory, Pasadena, California, which manages the mission for the agency. It includes the Mars 2020 mission's cruise stage, which will fly the rover through space, and the descent stage, a rocket-powered "sky crane" that will lower it to the planet's surface. Both of these stages have recently moved into JPL's Spacecraft Assembly Facility.

Mars 2020 relies heavily on the system designs and spare hardware previously created for Mars Science Laboratory's Curiosity rover, which landed in 2012. Roughly 85 per cent of the new rover's mass is based on this "heritage hardware."

"The fact that so much of the hardware has already been designed – or even already exists – is a major advantage for this mission," says Jim Watzin, director of NASA's Mars Exploration Program. "It saves us money, time and most of all, reduces risk."

Despite its similarities to Mars Science Laboratory, the new mission has very different goals. Mars 2020's instruments will seek signs of ancient life by studying terrain that is now inhospitable, but once held flowing rivers and lakes, more than 3.5 billion years ago.

To achieve these new goals, the rover has a suite of cutting-edge science instruments. It will seek out biosignatures on a microbial scale: An X-ray spectrometer will target spots as small as a grain of table salt, while an ultraviolet laser will detect the "glow" from excited rings of carbon atoms. A ground-penetrating radar will be the first instrument to look under the surface of Mars, mapping layers of rock, water and ice up to 30 feet (10 metres) deep, depending on the material.

The rover is getting some upgraded Curiosity hardware, including colour cameras, a zoom lens and a laser that can vaporise rocks and soil to analyse their chemistry.

"Our next instruments will build on the success of MSL, which was a proving ground for new technology," says George Tahu, NASA's Mars 2020 program executive. "These will gather science data in ways that weren't possible before."

The mission will also undertake a marathon sample hunt: The rover team will try to drill at least 20 rock cores, and possibly as many as 30 or 40, for possible future return to Earth.

"Whether life ever existed beyond Earth is one of the grand questions humans seek to answer," said Ken Farley of JPL, Mars 2020's project scientist. "What we learn from the samples collected during this mission has the potential to address whether we're alone in the universe."

JPL is also developing a crucial new landing technology called terrain-relative navigation. As the descent stage approaches the Martian surface, it will use computer vision to compare the landscape with pre-loaded terrain maps. This technology will guide the descent stage to safe landing sites, correcting its course along the way.

A related technology called the ranger trigger will use location and velocity to determine when to fire the spacecraft's parachute. That change will narrow the landing ellipse by more than 50 per cent.

"Terrain-relative navigation enables us to go to sites that were ruled too risky for Curiosity to explore," says Al Chen of JPL, the Mars 202 entry, descent and landing lead. "The range trigger lets us land closer to areas of scientific interest, shaving miles – potentially as much as a year – off a rover's journey."

This approach to minimising landing errors will be critical in guiding any future mission dedicated to retrieving the Mars 2020 samples, Chen says.

Site selection has been another milestone for the mission. In February, the science community narrowed the list of potential landing sites from eight to three. Those three remaining sites represent fundamentally different environments that could have harboured primitive life: an ancient lakebed called Jezero Crater; Northeast Syrtis, where warm waters may have chemically interacted with subsurface rocks; and a possible hot springs at Columbia Hills.

All three sites have rich geology and may potentially harbor signs of past microbial life. A final landing site decision is still more than a year away.

"In the coming years, the 2020 science team will be weighing the advantages and disadvantages of each of these sites," Farley says. "It is by far the most important decision we have ahead of us."

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