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When I saw that picture my first thought was, "We have a new Creative Commons logo!"

Then of course I realized Creative Commons doesn't nest the Cs in their logo.

Dang, I wish I paid for the cheap, discounted space agency you apparently contract out to for great desktop backgrounds! The Cassini project actually will cost about 3.2 billion dollars. (Portions paid in Euros, because our friends in Europe decided that they, too, had too much taxpayer money on hand). See: http://saturn.jpl.nasa.gov/faq/mission.cfm

(Incidentally, 3.2 billion is also how much karma I have lost for pasting that link on Cassini stories. Let no one say that I'm unwilling to sacrifice for science.)

I like this image showing the rings of Saturn... 4088x2908 pixels large. http://photojournal.jpl.nasa.gov/jpeg/PIA08362.jpg With more information on these pages: http://www.nasa.gov/mission_pages/cassini/multimed ia/pia08362.html http://photojournal.jpl.nasa.gov/catalog/PIA08362

I like this image showing the rings of Saturn... 4088x2908 pixels large. http://photojournal.jpl.nasa.gov/jpeg/PIA08362.jpg With more information on these pages: http://www.nasa.gov/mission_pages/cassini/multimed ia/pia08362.html http://photojournal.jpl.nasa.gov/catalog/PIA08362

I like this image showing the rings of Saturn... 4088x2908 pixels large. http://photojournal.jpl.nasa.gov/jpeg/PIA08362.jpg With more information on these pages: http://www.nasa.gov/mission_pages/cassini/multimed ia/pia08362.html http://photojournal.jpl.nasa.gov/catalog/PIA08362

Now this is more "amazing" to me:
http://saturn.jpl.nasa.gov/multimedia/images/image -details.cfm?imageID=2502

Can anyone explain why in this picture Saturn obscures the rings on both the near and far sides?

Cool archive

Check out that 4th photo caption. Damn Microsoft and their interplanetary advertising campaign!!!

The linked photo site was almost immediately Slashdotted so I'm not sure what they contained, but there are pictures on NASA's site here:

http://www.nasa.gov/mission_pages/cassini/media/20 070301.html

The site seems about 10 seconds from being fully /.ed, better photos available from NASA anyway. Full size image Cool archive

The site seems about 10 seconds from being fully /.ed, better photos available from NASA anyway. Full size image Cool archive

Forget the crappy "ciclops" site, try NASA...
http://saturn.jpl.nasa.gov/multimedia/images/index .cfm

Go here http://saturn.jpl.nasa.gov/multimedia/images/index .cfm to get bigger and more images from NASA, instead of the currently ddo.. I mean /.ed news sites.

We suggest equal emphasis on an alternative, more optimistic, scenario that emphasizes reduction of non-CO2 GHGs and black carbon during the next 50 years. This scenario derives from our interpretation that observed global warming has been caused mainly by non-CO2 GHGs.

A corollary following from Figure 1 is that climate forcing by non-CO2 GHGs (1.4 W/m2) is nearly equal to the net value of all known forcings for the period 1850-2000 (1.6 W/m2). Thus, assuming only that our estimates are approximately correct, we assert that the processes producing the non-CO2 GHGs have been the primary drive for climate change in the past century.

The primary natural source of CH4 is microbial decay of organic matter under anoxic conditions in wetlands.

Non-CO2 greenhouse gases are probably the main cause of observed global warming, with CH4 causing the largest net climate forcing. There are economic incentives to reduce or capture CH4 emissions, but global implementation of appropriate practices requires international cooperation. Definition of appropriate policies requires better understanding of the CH4 cycle, especially CH4 sources.

Yet the climate simulations lead to the conclusion that the Kyoto reductions will have little effect in the 21st century (Wigley 1998), and "thirty Kyotos" may be needed to reduce warming to an acceptable level (Malakoff 1998).

The show will be effectively over by moonrise here on the Wet Coast. The weather forecast is totally dismal anyway.

Of the last three lunar eclipses visible in these parts, we were clouded out on 16 May 2003, but had fine shows on 28 October 2003 and 9 November 2004. I also saw the eclipse on 21 January 2000 from Toronto, while I was at school. Next for us: 28 August 2007.

I saw my first total solar eclipse last year from Turkey. Even though I knew exactly what was going on, it still gave me the creeps, some sort of "if nothing else makes sense then panic" reaction. It must have scared the crap out of our ancestors.

...laura

Today's Astronomy Picture of the Day has the moon passing in front of the sun, as seen by STEREO.

The eclipse starts at 3:18 p.m. EST Saturday, with the total eclipse occurring at 5:44 p.m. EST. Look east at sunset. I'll be out there for sure.

The next total lunar eclipse occurs on August 28.

The eclipse starts at 3:18 p.m. EST Saturday, with the total eclipse occurring at 5:44 p.m. EST. Look east at sunset. I'll be out there for sure.

The next total lunar eclipse occurs on August 28.

...But inflatable structures in a vacuum are extremely strong due to the pressure difference. For example, the ISS gets considerable structural strength from air pressure alone....

Between 1972 and 1977, the Apollo seismic network saw twenty-eight of them; a few "registered up to 5.5 on the Richter scale," says Neal. A magnitude 5 quake on Earth is energetic enough to move heavy furniture and crack plaster.

And how will they make money off of this? Space tourism to orbit may be on the horizon, but trips to a moon of Saturn are a long way off!

I thought the water was part of the sound suppression system:
http://www.nasa.gov/mission_pages/shuttle/launch/s ound-suppression-system.html

They had a problem with noise from the rocket engines reverberating off the platform and causing pressure variations near the nose of the shuttle.

The pad site itself is being damaged by the frequent heat-swings, causing the heat-resistant concrete to crack and come loose:
http://engineer.tamu.edu/news/story.php?p_news_id= 1220

The Shuttle does indeed have two sets of flight software, Primary Avionics Systems Software (PASS), and Backup Flight System (BFS). During critical phases of flight, PASS is loaded on four of the GPCs and BFS is loaded on the fifth. BFS doesn't have all the capabilities of PASS - it is intended to take over in case of an emergency.

The Shuttle does indeed have two sets of flight software, Primary Avionics Systems Software (PASS), and Backup Flight System (BFS). During critical phases of flight, PASS is loaded on four of the GPCs and BFS is loaded on the fifth. BFS doesn't have all the capabilities of PASS - it is intended to take over in case of an emergency.

I read an article that the software was updated multiples times. An interesting point was the stuked bits in the processor registers (bit permanentely set to 1 or 0). NASA issued a software update to go around that.
More info here: http://voyager.jpl.nasa.gov/science/thirty.html

You may want to look at the Postfix mail server, it went a long time without errors or updates.

The problem you were pondering is not solved by a transmission. It's solved this way...

Aerospike Engines (how they work)
Aerospike Engine (history)
Linear Aerospike Engine (see the "efficient at all altitudes" section)

Rocket engines are more efficient (see: specific impulse)when the exhaust velocity of the escaping gas is higher. The shape of the bell of the "traditional" rocket nozle is static and thus operates at maximium efficiency at a particular altitude. The linear aerospike engine makes one side of it's bell continuously variable -- by using the air as one side of the nozle and taking advantage of the changing atmospheric pressure as the rocket ascends. The rocket engine will then have a continuously variable, uh, "transmission", to borrow the terminology of this discussion which beats a five-speed hands down. : )

The article summary, the RP/ZDNet press release rehash, and indeed the original press release itself are all very poorly written.

The problem you were pondering is not solved by a transmission. It's solved this way...

Aerospike Engines (how they work)
Aerospike Engine (history)
Linear Aerospike Engine (see the "efficient at all altitudes" section)

Rocket engines are more efficient (see: specific impulse)when the exhaust velocity of the escaping gas is higher. The shape of the bell of the "traditional" rocket nozle is static and thus operates at maximium efficiency at a particular altitude. The linear aerospike engine makes one side of it's bell continuously variable -- by using the air as one side of the nozle and taking advantage of the changing atmospheric pressure as the rocket ascends. The rocket engine will then have a continuously variable, uh, "transmission", to borrow the terminology of this discussion which beats a five-speed hands down. : )

The article summary, the RP/ZDNet press release rehash, and indeed the original press release itself are all very poorly written.

1. In an ion engine you WANT to accelerate the propellant as fast as possible -- the satellite get the same momentum as propellant in the opposite direction, so to get best use of the same mass of propellant you should accelerate it to the maximum speed your engine allows with reasonable energy efficiency. If it's a chemical engine, the amount of energy you can use is proportional to the amount of fuel you burn, so you don't really have a choice -- from conservation of energy the maximum possible speed of escaping gas is square root of the twice energy produced by burning a unit of mass. If energy can only come from fuel, the only way to increase speed beyond that is to leave some burned fuel in the satellite yet pass its energy to the escaping gas, so even if you somehow manage to do that, you have to release burned fuel at a lower speed later, thus wasting energy, or keep it stored thus wasting energy and also increasing your mass.

If your energy comes from solar panels (so it arrives if you want it or not) or a nuclear reactor (so fuel and propellant are separate), you should try to use propellant as efficiently as possible, accelerating it to the maximum speed that the engine design allows. To control the total momentum produced by the engine you can just run it for a longer or shorter time.

2. Drawing in the article makes no sense, unless it's missing something important. If electric and magnetic fields' directions are as shown (electric along the axis, magnetic along the radius), electrons' trajectories will be, depending on the initial speed, spirals around the axis of the device, or , more likely, loops returning them to the anode, not spirals around circles shown on the drawings. They would look like those spirals if those circles were magnetic field caused by the current produced by ions, but then this field should be significantly stronger than the radial magnetic field.

3. There should be something accelerating electrons, or this engine will end up charged negatively, decelerating ions that leave it until the whole process stopped with a large cloud of positive ions hanging behind it. The drawing shows cathode that supposedly emits electrons, and direction of the electric field suggests that cathode is much larger than shown of that there is another cathode, but it still doesn't show why this cathode emits electrons. It may be in a way of the stream of ions, so it's hot from being bombarded by them, or it may be an electron cannon, like in CRTs, or both, but the drawing shows neither. If the electrons going in circles are outside the engine, as opposed to how they are shown inside it, it kinda makes sense considering that ions leaving the engine produce circular magnetic field, but then the drawing misplaces it inside the cylindrical engine, where magnetic field is in a completely different direction.

See http://www.nasa.gov/centers/glenn/about/history/ip sworks.html for comparison.

4. Any ion engine can regulate the speed of its exhaust -- it's determined by electric field's strength that is in its turn determined by voltage/position of electrodes. Maybe they have invented some other way to regulate it, for example, by changing the magnetic field, but it's not what the articles claim.

5. Ion engines can't launch satellites by themselves -- even if they are used at some point, the vast majority of the energy passed to the satellite is produced by chemical engines. Ion engines can be used to adjust orbit, or to accelerate in the process of interplanetary travel, but they are useless for initial launch that requires huge amount of energy to be released over a short time. Optimizing the use of fuel for orbit adjustment may reduce the initial mass of satellite (by the amount of fuel or ion engine propellant saved over the lifetime of the satellite), what in its turn can decrease the amount of fuel used for launch.

However at the point when satellite reaches the orbit most

And yeah, I did kind of figure that if we went to the trouble of putting a rover on mars that we might bother to keep a dish pointed at it all the time. When we send people there is it going to be too much trouble too?

Because they were originally intended to last for 90 days. There were no "long treks" planned. People assumed that maybe they'd survive a teensy bit beyond the 90 day mark and there was pretty wild celebration (for a bunch of nerds) at the 100-day mark because people thought it was really cool.

2004 press release

2006 press release - Sol 1014 - (four months prior to being front-burner'd by the ever vigilant staff here @ /. , no less - sigh).

2004 press release

2006 press release - Sol 1014 - (four months prior to being front-burner'd by the ever vigilant staff here @ /. , no less - sigh).

Still, as others have pointed out, the rover was designed to last 3-4 months. All things considered the fact that they're still going and they can be patched with new software is pretty impressive.

We're still a long way from truly useful AI.

...and factually inaccurate to boot. Surprised nobody already noted that the article claims that JPL is in Houston, TX. (It's actually located in Pasadena, CA, and as far as I know there are no JPL satellite offices anywhere else.) You'd think that ITWire could do some basic fact checking, like checking JPL's web site.

As a technical concept, this is reasonable, since NASA historically has used their own proprietary protocols, even between ground stations and on equipment buses. Spacewire is an example. In the early days of the space effort, this was necessary, but today, NASA tends to have people on staff re-inventing the wheel.

But it's not a big deal.

NASA has no where in it's mandate to do anything except research.

I would say that NASA's mandate, as a government agency, is whatever the people democratically choose for it to do. More tangibly, the National Aeronautics and Space Act of 1958, which founded NASA, declares:

(1) plan, direct, and conduct aeronautical and space activities;
(2) arrange for participation by the scientific community in planning scientific measurements and observations to be made through use of aeronautical and space vehicles, and conduct or arrange for the conduct of such measurements and observations;
(3) provide for the widest practicable and appropriate dissemination of information concerning its activities and the results thereof;
(4) seek and encourage, to the maximum extent possible, the fullest commercial use of space; and
(5) encourage and provide for Federal Government use of commercially provided space services and hardware, consistent with the requirements of the Federal Government.

Plan, direct, and conduct aeronautical and space activities is rather open to interpretation, but exploration has always been considered an element of this. Actually, this does not counter your research point, because research involves both exploration and the development of necessary infrastructure (such as a moon base) to support it. I could detail some of the 100+ research proposals NASA has for the moon, but I'll leave it for another post

Number 3 and 4 are very relevant to your post, and also very clearly supported in the Exploration Systems Architecture Study, which guides much of the current development work. NASA is very open to cooperating with other friendly nations and private industry to use the systems they're developing to land additional payloads on the moon.

As far as how a permanent stay would pan out, since the article doesn't detail it, the Constellation program would conduct a handfull of missions up to two weeks in length to points of interest. One of these will likely be an already identified crater rim near one of the poles that receives almost constant sunlight. The constant sunlight simplifies many things.

NASA would then conduct several follow up missions to the same site, each one bringing more equipment. The proposed design for the lander makes the return stage as small as possible, which maximizes the amount of hardware left behind. Being modular, the lander could also fly missions to land several tons of cargo without a crew, such as prefabricated laboratories.

After 4 or 5 missions to the same location, there would be sufficient resources on the surface to support a permanent crew. From there NASA could conduct research that may really jumpstart commerical development, such as in situ resource utilization and low gravity excavation and health effects.

http://www.nasa.gov/mission_pages/station/science/ index.html http://spaceflight.nasa.gov/station/science/experi ments/index.html

http://www.nasa.gov/mission_pages/station/science/ index.html http://spaceflight.nasa.gov/station/science/experi ments/index.html

Sorry, but I need to correct your "law of averages" figures.

Yes, Australia is a large country with a low population base. But, that density is not in anyway a uniform distribution. For a simple example see http://antwrp.gsfc.nasa.gov/apod/ap001127.html

"Highest Carbon Output" - I always love this one. What is it that is measured? What is the denominator in this case to "standardise" countries? Perhaps this model needs to be reconsidered as a large chunk of this output is used for export. Should we not use the total people consuming goods produced in a country as opposed to the population of the country?

Current solar power (in all its various configurations) is useless. Yes, it is "free energy". But the amount of resources consumed in creating these technologies make them inefficient as a whole (when taking into account of their half-life). It is still being researched heavily by countries worldwide (as it should be) but other technologies at this point look far more promising.

Not sure about the "burning a lot of coal" .... we certainly have and dig up a lot of it. If we stop digging it up, another country will start. If we have the [almost] monopoly in supply, we can start dictating terms of its usage (as we do with Uranium). We are about to start building zero emission coal plants (lead by example), we will package that technology to those buying the coal and expect users to comply with our demands. If a country does not, they pay a proportional amount more per tonne or find another supplier.

Kyoto protocol is just one for politicians to get reelected. Goals are set, but one need not meet that target. It doesn't work.

Omni-directional radio of terrestrial origin has very little chance of ever being received in another solar system.

Not nearly correct. Google for "Eavesdropping The Radio Signature of the Earth", the title of an article by W.T. Sullivan and C Wetherill in the Jan 27, 1978 issue of Science. You'll get links to a number of cached copies of it online, and also some discussions.

One of the hits is to a NASA article on the same topic with updated info and some pretty graphs. It also contains the comment "On a cosmically infinitesimal time scale, Earth has indeed become a very bright planet, outshining the Sun by orders of magnitude in certain narrow frequency ranges."

The general idea is that, first, our radio/TV/radar broadcasts aren't omni-directional; from the start our broadcasts have used antennas that broadcast most of their energy horizontally. The resulting 2-dimensional dispersion pattern reaches much farther than an omni-directional signal of the same energy would. Over time, each broadcast station does send in all directions, but from any one direction, the station appears to fade in and then fade out some minutes later, twice a day. The frequency is doppler-shifted due to the Earth's rotation, and also varies over a year due to our orbit around the sun.

And, second, with our own technology, we could detect the most powerful our own broadcasts from anywhere within the sphere that they've reached. This was the basic question in the Science article. But they also addressed a more interesting question: Assuming our own technology, and the ability to measure the signal's spectrum but not decipher program content, what could be deduced about the senders? The results were quite impressive.

Figuring out which star system the signals come from was trivial (to an astronomer). After a year or so of data collection, the planet's orbit would be known, as would the planet's size. The presence of a large satellite (including its orbit and approximate mass) would also be known. It would be clear that the senders are primarily active during the daytime and early evening.

Further study would generate a rough map of all the broadcast stations. They would be concentrated in narrow bands separating two different sorts of terrain. From the planet's orbit and the sun's brightness, the conclusion would be that the planet is roughly 3/4 water and 1/4 land, and we live on land, primarily along the coasts.

Even more study would determine from spectrum details that there were several different kinds of technology in use to generate the broadcasts, and each kind of equipment was distributed across patches of land that we might call "nations", with some kinds of hardware used by nations not close to each other, implying long-distance technological sharing among coalitions of nations.

It was interesting reading 30 years ago. (But I do remember thinking that it might be a good thing if the actual program content couldn't be decoded. ;-)

Population estimation - An estimate of the population of near-Earth objects (NEOs), including their sizes, albedos and orbit distributions, was generated using the best methods in the current literature. We estimate a population of about 1100 near-Earth objects larger than 1 km, leading to an impact frequency of about one in half a million years. To the lower limit of an object's atmospheric penetration (between 50 and 100 m diameter), we estimate about half a million NEOs, with an impact frequency of about one in a thousand years.

The weather satellite data is in part true.

http://www.ghcc.msfc.nasa.gov/MSU/msusci.html

Studies have shown the satellite data is accurate and the GCM's are not in agreement with it. There are still fundamental flaws in the current models that need to be addressed.

You mean the ice from the melting glaciers leading to more ocean ice?

Also, you're just wrong on your facts about temperatures. Check the NASA reports: http://www.giss.nasa.gov/research/news/20070208/

"Everyone is entitled to their own opinion, but not their own facts." -- Daniel Patrick Moynihan

Here is everything you want to know about this interesting satellite:

http://icesat.gsfc.nasa.gov/

There have been reports of people actually 'seeing' the laser as the satellite goes over:

http://www.satobs.org/seesat/Oct-2003/0064.html

New water holes way under the ice. Fun. I wonder if we will find even more 'new species' as was reported here:

http://science.slashdot.org/article.pl?sid=06/12/1 1/2336230

Maybe the two are linked!

> Water

http://science.nasa.gov/headlines/y2000/ast02nov_1 .htm (though they don't seem to specify the system efficiency).

The object 2007 CA19 has a better chance (as of right now) of hitting the Earth than 99942 Apophis (2004 MN4) does. The former is also about four times larger than the latter and would have more than double the velocity at impact if it were to hit.

The object 2007 CA19 has a better chance (as of right now) of hitting the Earth than 99942 Apophis (2004 MN4) does. The former is also about four times larger than the latter and would have more than double the velocity at impact if it were to hit.

This asteroid has a Palermo Technical Scale risk assessment of -2.52.

The PTS relates the impact risk to the background risk in a logarithmic way -- that is, the probability of Apophis hitting us is 0.003 times the probability that we will be struck by some other asteroid of equal or larger size first. Or, put another way, yes we should be worried about asteroid impacts, and yes we should keep watching Apophis, but it's not (by our understanding) a big cause to go and panic.

That said, Apophis is the second highest ranked asteroid we know about by the PTS, behind 2007 CA19 at -0.91 (potential impact in 2012). And if it gets the people with the budgets to start considering the problem, that's a good thing. Right now, though, it would seem that our best use of money is to spend more effort looking for asteroids -- so far, the number we find appears to be fairly well correlated to how hard we look, suggesting that we have found a very, very small fraction of the NEOs out there.

The hum ranges from 0.0037Hz to 0.0044Hz. Using the conventional MIDI frequency/pitch conversion formula p = 69 + (12 * log2(f/440)), the hum's pitch runs across almost exactly 3 semitones, a minor third, from just sharp of "B flat" to just sharp of "C sharp", 17 octaves above Middle C.

Four semitones is the range covered by a guitarist's fingers on a fretboard. The minor third is the most popular guitarist's composition interval.

Meanwhile, the Perseus Black Hole hums along a B flat. A bassline 57 octaves below Middle C, 74 octaves below the Earth's treble melody.