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Comment Magma ocean != 100% melt (Score 2) 48

A magma ocean is not a 100% liquid rock layer beneath the surface.

The observations made by this team are consistent with a 50 km-thick layer about 50 km below the surface (that is, within the mantle) with >=20 volume% melt fraction. This work is based on how Io affects Jupiter's magnetic field.

Other research teams have demonstrated, since the 1990s that Io should have a mantle with a >= 20 volume% melt fraction at some depth in the mantle--it was never clear where this magma ocean was located. This work is based on observations of the surface eruptions and models for how quickly silicate lavas cool.

The fact that these agree is significant.

A substantial portion of Io at 100 volume% melt would actually not work because pure liquid does not dissipate enough of the energy from the tidal forces to maintain 100 volume% melt. That is there's a feedback loop between Io's interior and the tidal flexing:

* Too much liquid in the interior and the energy dissipation will decrease significantly, allowing the liquid to cool enough to solidify significantly.
* Too little liquid and the interior would quickly dissipate enough tidal energy (in the form of friction) to significantly melt the interior.

So, Io's orbital resonances keep a small part of its mantle molten at between 20 volume% and 50-70 volume.

That there's now a depth associated with this magma ocean is actually quite significant. We can start better understanding the role volatiles play in Io's volcanism now that we know where the molten rock is coming from.

The Internet

Clinton Calls For "Ground Rules" Protecting Internet 205

dbune writes "Hillary Clinton has called for ground rules to protect the World Wide Web against wrongdoing and harm after the world watched as Egyptian authorities cut Internet access during its recent political crisis. She said 'For the United States, the choice is clear; on the spectrum of Internet freedom, we place ourselves on the side of openness.'"
The Almighty Buck

Science Programs Hit Hard By Proposed Budget 395

BJ_Covert_Action writes "The House of Representatives Committee on Appropriations has released a list of proposed spending cuts for the US Federal Government. The proposed cuts include reductions in spending on many science organizations and funds such as NASA, NOAA, nuclear energy research, fossil fuel energy research, clean coal research, the CDC, the NIH, and numerous EPA programs. There are also quite a few cuts proposed on domestic services, such as Americorps and high speed rail research. The House Appropriations Chairman, Hal Rogers, acknowledges that the cuts go deep, and would hurt every district across the country. But they are still deemed necessary to rein in Congressional spending. Notoriously absent from the proposed budget cuts are two of the largest spending sinks in the federal budget: the Department of Defense and Social Security."
United States

Congresswoman Writes On Broadband, Net Neutrality 125

An anonymous reader writes "Anna G. Eshoo, a California Democrat representing parts of Silicon Valley, has written an op-ed defending net neutrality and pushing the administration to take more steps to speed up US broadband. From the article: 'A climate of openness and innovation has been the hallmark of the Internet. A decade ago, it's what allowed a startup named Google to compete with better-funded, less technologically advanced competitors. Today, Congress has the responsibility to preserve this climate for the next Google, and for the consumers and the economy that will benefit from its success.'"

Senator Wyden Asks DHS To Explain Domain Seizures 243

An anonymous reader writes "With Homeland Security continuing to seize domain names without warning and without giving site operators a chance to respond to charges, it appears that at least some people in the US government are quite concerned about this turn of events. Techdirt has a copy of the full letter Senator Wyden has sent to both Attorney General Eric Holder and ICE director John Morton, asking a series of pointed questions concerning the domain seizures and how they impact due process, free speech and sovereign rule in foreign countries."

Comment Re:Okay, hold on a minute. (Score 2, Interesting) 184

Venus is basically the same size as the Earth.
Earth's mean radius is 6,371 km. Venus' mean radius is 6052 km.
The masses are also similar, as are their compositions.

A more likely control on whether plate tectonics may be initiated is the existence of liquid water at the surface and within the lithosphere of the planet in question. Water greatly reduces the yield strength of plates (by as much as 62% when going from low to moderate temperatures compared with a drop of only 39% for dry olivine). So, while plate tectonics seems to be necessary for life, water (necessary for life) may be necessary for plate tectonics. Venus is just at the range from the Sun where it could have lost all of its water too quickly for plate tectonics to initiate (especially if it lost the water long before the planet was mostly still molten).


Internet Kill Switch Back On the US Legislative Agenda 376

suraj.sun points out a story at Wired that US lawmakers have revived the idea of a government-controlled "Internet Kill Switch," which reads, in part: "The bill, which has bipartisan support, is being floated by Sen. Susan Collins, the Republican ranking member on the Homeland Security and Governmental Affairs Committee. The proposed legislation, which Collins said would not give the president the same power Egypt's Hosni Mubarak is exercising to quell dissent, sailed through the Homeland Security Committee in December but expired with the new Congress weeks later. 'My legislation would provide a mechanism for the government to work with the private sector in the event of a true cyber emergency,' Collins said in an e-mail Friday. 'It would give our nation the best tools available to swiftly respond to a significant threat.'"

Senators Bash ISP and Push Extensive Net Neutrality 427

eldavojohn writes "Remember when Verizon sued the FCC over net neutrality rules? Well, Senators Maria Cantwell (D-WA) and Al Franken (D-MN) see it a bit differently and have authored a new working bill titled 'Internet Freedom, Broadband Promotion, and Consumer Protection Act of 2011 (PDF).' The bill lays out some stark clarity on what is meant by Net Neutrality by outright banning ISPs from doing many things including '(6) charge[ing] a content, application, or service provider for access to the broadband Internet access service providers' end users based on differing levels of quality of service or prioritized delivery of Internet protocol packets; (7) prioritiz[ing] among or between content, applications, and services, or among or between different types of content, applications, and services unless the end user requests to have such prioritization... (9) refus[ing] to interconnect on just and reasonable terms and conditions.' And that doesn't count for packets sent over just the internet connections but also wireless, radio, cell phone or pigeon carrier. Franken has constantly reiterated that this is the free speech issue of our time and Cantwell said, 'If we let telecom oligarchs control access to the Internet, consumers will lose. The actions that the FCC and Congress take now will set the ground rules for competition on the broadband Internet, impacting innovation, investment, and jobs for years to come. My bill returns the broadband cop back to the beat, and creates the same set of obligations regardless of how consumers get their broadband.'"

Comment So? (Score 5, Insightful) 463

So, someone represented a company that has different ideas than you do...and that's a problem because?
Do /.ers really believe that their employer is their sole identity defining characteristic?
Are all of you who work for asshole-bosses also assholes?
It sure seems that that's what you're all saying when you go on these witch-hunts.


Obama Nominates RIAA Lawyer For Solicitor General 463

Xiph1980 writes "President Barack Obama on Monday nominated former Recording Industry Association of America lawyer Donald Verrilli Jr. to serve as the nation's solicitor general. The solicitor general is charged with defending the government before the Supreme Court, and files friend-of-the court briefs in cases in which the government believes there is a significant legal issue. The office also determines which cases it would bring to the Supreme Court for review. Verrilli is best known for leading the recording industry's legal charge against music- and movie-sharing site Grokster. That 2003 case ultimately led to Grokster's demise when the US Supreme Court sided with the RIAA's verdict."

Comment Re:'habitable zone' .. (Score 1) 97

I'm not sure what you mean when you talk about 10% of a planetary surface and AUs.

Earth's surface area is 5.1x10^8 km^2. 10% of that is, obviously, 5.1x10^7 km^2. The land area of the US is about 9.8x10^6 km^2, so we're talking about 5-times the land area of the US. None of this has anything to do with distance from the star, just to do with the radius of the planet.

But, as you say, the point of 10% isn't that it's a special number; it's a starting point. Notice that this definition explicitly excludes any gaseous planets from the get-go. That's not necessarily fair, of course, but we've got to start somewhere, and rocky planets are a LOT simpler to understand w.r.t. possibilities of life.

Earth's average albedo isn't really all that controversial or problematic. For example, we can say that the poles probably had such and such an albedo at such and such a time (based on climate models based on core samples), the clouds are difficult for a specific times (decades or so), but again the climate will dictate some average cloud cover that is relatively accurate over long periods over the entire Earth.

Going into more detail would require an actual climate model (such as the Hadley model), which doesn't make much sense for extrasolar planets since we know next to nothing about atmospheres (especially their composition) on most extrasolar planets. Of course, we can speculate and use places like Titan, Mars, Venus, Earth, and Triton as jumping-off points for planets that are certain distances from their parent star.

Milankovitch cycles are certainly included in long-term habitability or continuous habitability zone research, but we're really limited by not knowing anything about the obliquity/precession cycles of extra-solar planets, which are quite dependent on specific circumstances of those planets.

The T-tauri phase of the pre-main sequence stars would strip almost any magnetic field-protected atmosphere from most planets, so we're fairly confident that any planets found orbiting such stars are uninhabitable. In fact, there are a lot of stars that can be ruled out (of having any sort of habitable zone) just by looking at them.

Habitability zones are for "well-behaved" stars with well-behaved planets. Some researchers are looking at double or triple star systems, so we'll have a better understanding of the possibility of life in such systems as time goes on.

Comment Re:'habitable zone' .. (Score 1) 97

Yes, the moon is within the habitable zone, but it's not habitable. If we discover a rocky planet in the habitable zone of another star, the first thing we'll be looking for is an atmosphere (which is quite a bit more difficult than finding the planet, but techniques are being developed and tested). If we discover evidence for an atmosphere, the habitability of that planet jumps into a realm that is much more interesting. Then we start looking for evidence of certain gases in the atmosphere (water vapor, CO2, Nitrogen, etc.).

Comment Re:'habitable zone' .. (Score 1) 97

Well, first, let's go into some history.

A habitable zone around a main sequence star was originally (1959) defined as a (virtual) ring around that star in which at least 10% of the surface of a planet, with an Earth-like atmosphere, in that zone had a mean temperature of between 0 and 30 C with extremes not exceeding -10 and 40 C. This is appropriate for humans to survive.

The zone was quickly expanded to mean wherever liquid water was stable. The term "biostable" was employed to mean where liquid water was stable and the term "habitable" was restricted to mean a place suitable for humans. Soon, though, "habitable" was expanded to replace "biostable" and to include anywhere that liquid water is stable.

All (peer-reviewed) models since the original definition have used one type of atmosphere or another, usually an atmosphere chemically similar to Earth's. Most have also considered planetary albedo (surface brightness), solar evolution (as a star moves along the main sequence, the habitable zone changes or disappears, depending on the details), etc.

Several models have pessimistic estimates to the width and/or lifetime of a habitable zone, most often because an atmosphere like the Earth's is only metastable and it could collapse with only a few % change in solar energy input (distance from or luminosity of the sun, for example can greatly affect the stability of an atmosphere). Other models have included climate stabilization by linking CO2 and surface processes such as the creation/weathering of certain types of rock that remove/add CO2 from/to the atmosphere. There are a lot of these kinds of details that are included in most models of the habitable zone. A lot of the work is in determining which details are more important than others.

For my graduate work, we had to define the habitable zone around the sun, at the beginning of the solar system (4.556 Ga), and now. To do so, we had to start from the proplyd, condense all of the elements at the right distances from the sun, build the planets (we were allowed to assume that they formed in their current positions unless we wanted to make our work more difficult), allow atmospheres to condense or form, depending on where the planets were, etc., and finally determine which planets were possibly in the habitable zone as the sun evolved (Venus, Earth, and Mars, depending on the details and assumptions), and then determine whether the planets that are here now are in the habitable zone, and why or why not.

We, of course, used some pretty simple 1-D models for atmosphere, or used published models and argued why they were valid. We used simple models for planetary albedo, didn't evolve the albedo unless the atmosphere collapsed or changed dramatically in some other way (ignored Earth-like clouds, for example), etc. We used simple estimates for the concentrations of radioactive elements that could contribute to the surface temperature, used a simple model for luminosity evolution, etc., etc., etc.

For these kinds of simple models, the inner edge of the habitable zone is defined by when water will be lost from the atmosphere (through photolysis of the water vapor and escape of the hydrogen) and the outer edge is defined by when CO2 condenses and causes runaway glaciation.

Technically, the Moon is within the habitable zone, but it's obviously not habitable. Neither are Venus or Mars. This is because they don't have the right atmosphere, and may never have had the right conditions.

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