Cassini Doubleheader: Flying By Titan and Dione

Composite of Saturn's moons Titan and Dione Composite of two images from NASA's Cassini spacecraft of Saturn's moons Titan (left) and Dione (right). › Full image and caption (Titan) | › Full image and caption (Dione)
In a special double flyby early next week, NASA's Cassini spacecraft will visit Saturn's moons Titan and Dione within a period of about a day and a half, with no maneuvers in between. A fortuitous cosmic alignment allows Cassini to attempt this doubleheader, and the interest in swinging by Dione influenced the design of its extended mission.

The Titan flyby, planned for Monday, April 5, will take Cassini to within about 7,500 kilometers (4,700 miles) of the moon's surface. The distance is relatively long as far as encounters go, but it works to the advantage of Cassini's imaging science subsystem. Cassini's cameras will be able to stare at Titan's haze-shrouded surface for a longer time and capture high-resolution pictures of the Belet and Senkyo areas, dark regions around the equator that ripple with sand dunes.

In the early morning of Wednesday, April 7 in UTC time zones, which is around 9 p.m. on Tuesday, April 6 in California, Cassini will make its closest approach to the medium-sized icy moon Dione. Cassini will plunge to within about 500 kilometers (300 miles) of Dione's surface.

This is only Cassini's second close encounter with Dione. The first flyby in October 2005, and findings from the Voyager spacecraft in the 1990s, hinted that the moon could be sending out a wisp of charged particles into the magnetic field around Saturn and potentially exhaling a diffuse plume that contributes material to one of the planet's rings. Like Enceladus, Saturn's more famous moon with a plume, Dione features bright, fresh fractures. But if there were a plume on Dione, it would certainly be subtler and produce less material.

Cassini plans to use its magnetometer and fields and particles instruments to see if it can find evidence of activity at Dione. Thermal mapping by the composite infrared spectrometer will also help in that search. In addition, the visual and infrared mapping spectrometer will examine dark material found on Dione. Scientists would like to understand the source of this dark material.

Cassini has made three previous double flybys and another two are planned in the years ahead. The mission is nearing the end of its first extension, known as the Equinox mission. It will begin its second mission extension, known as the Solstice Mission, in October 2010.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL.

More information about the Titan flyby, dubbed "T67," is available at:
http://saturn.jpl.nasa.gov/mission/flybys/titan20100405/ .

More information about the Dione flyby, dubbed "D2," is available at:
http://saturn.jpl.nasa.gov/mission/flybys/dione20100407/

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Wind Power Could Support a Stable Grid

This is the first time a study has demonstrated that offshore East Coast wind energy can provide
“a reliable supply of smooth power”

New from ScienceNow, and it’s more good news about wind power.  So why aren’t we investing more in this, instead of in finding and using more fossil fuels?

“Individual wind turbines and even whole wind farms remain at the mercy of local weather for how much electricity they can generate. But researchers have confirmed that linking up such farms along the entire U.S. East Coast could provide a surprisingly consistent source of power. In fact, such a setup could someday replace much of the region’s existing generating capacity, which is based on coal, natural gas, nuclear reactors, and oil.

In terms of potential, wind-energy resources are tremendous. One estimate puts it at nearly five times as much as the world’s entire existing electricity demand. And for environmentalists and anticarbon advocates, wind offers an energy source that does not require drilling, mining, or enriched uranium—and its carbon footprint is essentially zero.

But wind is erratic. A region might get gale-force winds one day and dead calm the next. To balance things out, engineers have proposed linking up wind farms to take advantage of wind variability across a wider area. But until now, no one had ever quantified whether meteorological conditions would justify such a linkup.

In the new study, energy policy analyst and electrical engineer Willett Kempton of the University of Delaware, Newark, and colleagues did just that. “Instead of just looking at the statistics of connecting turbines,” he says, “we also decided to look at the meteorology.” First the researchers chose a region known for its relatively constant winds. They compiled 5 years of wind data from 11 offshore weather-monitoring stations buoyed along 2500 kilometers of the East Coast. They estimated how much power offshore wind farms could produce if they had been placed at the same locations as the monitoring stations—which would be the case under current wind-farm configurations. Then they calculated the combined power output of the farms if they were all connected into a single grid.

As the team reports online today in the Proceedings of the National Academy of Sciences, at no time during the 5-year span of the study did the winds die down completely along the hypothetical grid. That means it would have been possible for the hypothetical offshore wind-power grid to generate electricity continuously for all of that time. Moreover, Kempton explains, linking the wind farms showed “a tremendous amount of smoothing” of power output. Farms located, say, in the Northeast might be operating at full tilt under gale-force winds, while the southeastern portion of the grid languishes under sunny skies and tepid breezes. As the wind data showed, he added, the quick swings between [...]

Dan Ariely: It’s OK to cheat and steal (sometimes)

Dan Ariely is a behavioural economist. He studies irrationality and tries to understand why humans act as they do act. In this video he focuses on the role of morality. In some clever studies he looks at why we think that it’s OK to cheat and steal (sometimes).
Filed under: Behavioural Science Tagged: behavioural economy, cheat, [...]

Please change RSS feeds if you haven’tGene Expression

If you are still subscribed to:

http://feeds.feedburner.com/scienceblogs/gnxp

You are receiving updates from the new RSS feed. But at some point these updates will cease. You will need to switch to the new RSS feed:

http://feeds.feedburner.com/GeneExpressionBlog

It’s been a week since I first mentioned this issue, and the old feed still has over twice as many subscribers as the new feed. I’m sure many of them are evil people who are subscribed but no longer read the blog, but for those of you who are good please switch feeds. It is a mitzvah.

Danke.

Endangered Species Traded Online

There are many reasons to explain why some of the world's species have become endangered. Habitats have been lost to housing developments, food sources have become scarce due to overfishing, and some animals are simply hunted to extinction. Now, conservationists are saying that technology cr

March Military Campaign – Mutt vs. Mighty Mite

It's not that difficult to confuse the two. Besides the similar names, both were quarter-ton, four-wheel-drive replacements for the Jeep. The timelines for the two overlap, and both feature independent front and rear suspensions. But the differences between the two are substantial.

So le

How to Improve Plasma Cut Quality

Plasma arc cutting (PAC), or plasma cutting, is a process by which a vortex of pressurized gas is ionized to heat and melt electrically conductive materials. The PAC system's parts are configured to constrict and focus the vortex of ionized gas on an electrically conductive material so that the

The growth of ScienceBlogs & science blogsGene Expression

sbgrowthScienceBlogsTM just put out a release on their traffic growth. The trend is interesting because after a period of flattening out, 2008-2010 seems to have seen some robust growth again. As I said when I left I do wish SB and many of their bloggers well, and I continue to subscribe to several of their blogs in my RSS as well as the select feed. The network’s robust growth is a positive sign when it comes to the transition of science communication from dead tree to the internet. I know that there’s been a lot of stress on the part of science journalists as to the sustainability of their enterprise, though that is really just a domain-specific instantiation of the issues in journalism as a whole, but until that works itself out the growth and persistence of science blogging and science-related websites is a good thing. There is a calm after the storm of creative-destruction, and the current science blogosphere is laying the seedbed for future renewal. The outcome may be sub-optimal from the viewpoint of labor, but the consumer will benefit.

The growth of internet based science communication means that the pie is growing, and the tide is rising. It isn’t a zero-sum game between SB, Nature Networks, Scientific Blogging, Discover Blogs, etc. My main concern personally is that my readership is still strongly Anglospheric, literally hundreds of millions of Chinese have started using the internet while I’ve been blogging, but very few of them do and can read my content. Due to language constraints this may be a long term structural issue, though the utilization of Google translate + chart heavy posts may be a way to push beyond the Anglosphere a bit. If you want to see the geographic skew, sitemeter is sufficient even with a sample size of the last 100 visitors.

Note: Also, please note that the growth can’t be attributed only to non-science content. Obviously I can’t lay out specific numbers, but blogs which focus on science such as Tetrapod Zoology and Frontal Cortex draw lots of traffic.

(via DM)