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Galactic Cloud Map Takes Shape

By David Reneke

Dave Reneke’s wrap-up of space and astronomy news.

An international team led by University of NSW astronomers has begun to map the location of the most massive and mysterious objects in our galaxy: the giant gas clouds where new stars are born. Using the 22-metre Mopra Millimetre Wave Telescope at Coonabarabran, which narrowly escaped devastation in a recent bushfire, the team has been identifying galactic clouds of molecular gas, which can be up to 100 light-years across, from the carbon monoxide they contain.

“On Earth, carbon monoxide is poisonous, a silent killer, but in space it is the second most abundant molecule and the easiest to see,” said team leader Prof Michael Burton. “One of the largest unresolved mysteries in galactic astronomy is how these giant, diffuse clouds form in the interstellar medium. This process plays a key role in the cosmic cycle of birth and death of stars.”

The international team is also searching for “dark” galactic gas clouds that contain very little carbon monoxide. It’s assumed these clouds are mostly made up of molecular hydrogen that is too cold to detect. The team is using telescopes in Antarctica and Chile to search for the presence of carbon atoms, rather than carbon molecules, in the clouds. “Taken together, these three surveys will provide us with a picture of the distribution and movement of gas clouds in our galaxy,” Burton says.

Dark clouds could be the “missing” source of gamma rays produced when high energy cosmic rays interact with the nuclei of gas atoms or molecules they encounter when travelling through space. The source of more than 30% of gamma rays remain unidentified.

Some of the options for how large giant molecular clouds form include the gravitational collapse of small cloud groups into a larger one, or the random collision of small clouds that then agglomerate. Interestingly, about one star per year, on average, is formed in the Milky Way.

Stars that explode and die then replenish the gas clouds, as well as moving the gas about and mixing it up. Our Milky Way started out as a faint blue object with lots of gas, clouds of which eventually collapsed to form stars. At the time of peak star formation, about four billion years after the Big Bang, the Milky Way was pumping out about 15 new stars per year.

NASA’s Asteroid Capture Plan Applauded

The US National Space Society (NSS) has applauded a new NASA budget item that would provide close to US$100 million for a mission to rendezvous with a small asteroid and move it into orbit around the Moon where it could later be visited by astronauts.

“An asteroid capture mission is a tremendously important mission, and one that could not be more relevant to the challenges our civilization faces today,” said Mark Hopkins, Chairman of the NSS Executive Committee. “Robotic asteroid capture is the first step to exploiting the vast material resources of the solar system for a hopeful and prosperous future for mankind.”

The NSS Executive Vice President, Paul Werbos, said: "Even small asteroids contain tremendous wealth – precious metals, rare strategic metals important for sustainable development, raw materials for in-space construction, and volatiles for life support and propulsion in space." One medium-sized asteroid, tagged 3554 Anum, is estimated to contain US$20 trillion of platinum-group metals.

Robotic asteroid capture is also a key step toward an effective planetary defence. The mission will mature our ability to capture and deflect a hazardous asteroid protecting civilisation from suffering the same fate as the dinosaurs. The search for suitable targets will find huge numbers of smaller, currently unknown asteroids that pose a very real meteor threat to cities, as evidenced by the explosion recently over Chelyabinsk, Russia, that injured over 1000 people.

The mission also involves the development of cost-effective new technologies of value both to public and private activities in space. Robotic asteroid capture will drive improvements to solar electric propulsion, a critical enabler of cost-effective transportation in Earth lunar space and the inner solar system.

Historically, what has caused humanity to make its largest investments in exploration and in transportation has been the search for resources. It might seem like a radical concept, but scientists have been thinking about mining asteroids for longer than the space program has been running. “The NSS has been advocating the capture of asteroid resources for decades,” Hopkins said, “and is most gratified to see this important step toward the NSS Vision of people living and working in thriving communities beyond the Earth, and the use of the vast resources of space for the dramatic betterment of humanity,"

David Reneke is an astronomy lecturer and teacher, a feature writer for major Australian newspapers and magazines, and a science correspondent for ABC and commercial radio.

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