Archive

Archive for August 2, 2012

Vaporizing the Earth

August 2, 2012 Leave a comment

Simulations of the vaporization of Earth-like planets tell planet-hunting astronomers what to look for in the atmospheres of candidate super-Earths.

In science fiction novels, evil overlords and hostile aliens often threaten to vaporize the Earth. At the beginning of The Hitchhikers Guide to the Galaxy, the officiously bureaucratic aliens called Vogons, authors of the third-worst poetry in the universe, actually follow through on the threat, destroying the Earth to make way for a hyperspatial express route.

“We scientists are not content just to talk about vaporizing the Earth,” says Bruce Fegley, professor of earth and planetary sciences at Washington University in St. Louis, tongue firmly in cheek. “We want to understand exactly what it would be like if it happened.”

And in fact Fegley, PhD, and his colleagues Katharina Lodders, PhD, a research professor of earth and planetary sciences who is currently on assignment at the National Science Foundation, and Laura Schaefer, currently a graduate student at Harvard University, have vaporized the Earth — if only by simulation, that is mathematically and inside a computer.

They weren’t just practicing their evil overlord skills. By baking model Earths, they are trying to figure out what astronomers should see when they look at the atmospheres of super-Earths in a bid to learn the planets’ compositions.

Full Story: https://news.wustl.edu/news/Pages/24087.aspx

Newest NASA Mars Mission Connects Past and Future

August 2, 2012 Leave a comment

NASA’s newest Mars mission, landing in three days, will draw on support from missions sent to Mars years ago and will contribute to missions envisioned for future decades.

“Curiosity is a bold step forward in learning about our neighboring planet, but this mission does not stand alone. It is part of a sustained, coordinated program of Mars exploration,” said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. “This mission transitions the program’s science emphasis from the planet’s water history to its potential for past or present life.”

As the Mars Science Laboratory spacecraft places the Curiosity rover on the surface of Mars next week, NASA will be using the Mars Odyssey orbiter, in service since 2001, as a relay for rapidly confirming the landing to Curiosity’s flight team and the rest of the world. Earth will be below the Mars horizon from Curiosity’s perspective, so the new rover will not be in direct radio contact with Earth. Two newer orbiters also will be recording Curiosity’s transmissions, but that data will not be available on Earth until hours later.

When Curiosity lands beside a mountain inside a crater at about 10:31 p.m. PDT, Aug. 5 (1:31 a.m. PDT Aug. 6), the 1-ton rover’s two-year prime mission on the surface of Mars will begin. However, one of the rover’s 10 science instruments, the Radiation Assessment Detector, or RAD, already has logged 221 days collecting data since the spacecraft was launched on its trip to Mars on Nov. 26, 2011.

Full Story: http://www.nasa.gov/mission_pages/msl/news/msl20120802.html

Fingering the Culprit that Polluted the Solar System

August 2, 2012 1 comment

For decades it has been thought that a shock wave from a supernova explosion triggered the formation of our Solar System. According to this theory, the shock wave also injected material from the exploding star into a cloud of dust and gas, and the newly polluted cloud collapsed to form the Sun and its surrounding planets.
Traces of the supernova’s pollution can be found in meteorites in the form of short-lived radioactive isotopes, or SLRIs. SLRIs—versions of elements with the same number of protons, but a different number of neutrons—found in primitive meteorites decay on time scales of millions of years and turn into different, so-called daughter, elements. A million years may sound like a long time, but it is actually considered short when compared to other radioactive isotopes studied by geochemists and cosmochemists, which have half-lives measured in billions of years.
When scientists find the daughter elements distributed in telltale patterns in primitive meteorites, this means that the parent SLRIs had to be created just before the meteorites themselves were formed. This presents a timing problem, as the SLRIs must be formed in a supernova, injected into the presolar cloud, and trapped inside the meteoritic precursors, all in less than a million years.

Now Boss and Keiser have extended those models to 3-D, so they can see the shock wave striking the gas cloud, compressing it and forming a parabolic shock front that envelopes the cloud, creating finger-like indentations in the cloud’s surface. The fingers inject the SLRI pollution from the supernova. Less than 0.1 million years later, the cloud collapses and forms the core of the protostar that became the Sun and its surrounding planets. The 3-D models show that only one or two fingers are likely to have caused the SLRI pollution found in primitive meteorites.

Full Story: http://carnegiescience.edu/news/fingering_culprit_polluted_solar_system

Red is the new Black

August 2, 2012 Leave a comment

Red is the new black, at least for night-time skyglow, according to scientists of the Freie Universität Berlin and the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Germany. And the color of night-time skyglow may be about to undergo a radical change worldwide. The team predicts that with increasing use of LED street lamps, the color of the night sky will become bluer. To track this change, the researchers developed a prototype measurement device, and used it to show that the sky currently contains far more red light on cloudy nights compared to clear nights. Their report, entitled “Red is the New Black”, is published in the journal Monthly Notices of the Royal Astronomical Society.

Christopher Kyba, physicist at the Freie Universität and lead author of the study, explains that innovations in lighting technology will result in changes in the color of streetlights. “The current worldwide trend of replacing gas discharge lamps with solid state lighting, such as LEDs, will affect the radiance and spectrum of urban skyglow.” In order to understand the potential impacts of this change on ecology, it will be essential to monitor the sky over the long term.

The scientists used the new instrument to study how clouds affect sky brightness in urban areas. “For almost all of evolutionary history, clouds made the night sky darker, just like they do in daytime”, said Franz Hölker, ecologist at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries, study author, and leader of the project “Verlust der Nacht” (Loss of the Night). In areas with artificial light the effect of clouds is now reversed, and the size of the effect depends on color. The researchers found that in Berlin the blue portion of skyglow is 7 times more radiant on cloudy nights than on clear, and 18 times more for the red part.

Full Story: http://www.ras.org.uk/news-and-press/219-news-2012/2156-red-is-the-new-black

Australia Is “All Ears” For Mars Landing

August 2, 2012 Leave a comment

Dishes in Australia will be the ones following NASA’s Mars Science Laboratory mission when it lands on Monday (6 August) after a nail-biting series of manoeuvres.

The Canberra Deep Space Communication Complex (CDSCC), which CSIRO manages on NASA’s behalf, will be the main tracking station for landing activities. Its 70-m and two 34-m antennas will receive signals from the spacecraft both directly and then relayed through another NASA spacecraft, Mars Odyssey, which is already in orbit around the red planet.

CSIRO’s 64-m Parkes telescope will record signals directly from the spacecraft as a backup in case there is a problem with the relaying. But as the spacecraft descends, it will drop below the Martian horizon (and out of direct sight of Earth-based antennas) about two minutes before touchdown, and Parkes will cease receiving its signals.

Full Story: http://www.csiro.au/en/Portals/Media/Australia-is-all-ears-for-Mars-landing.aspx