French astronomers at the Observatoire de Paris have run 2,501 mathematical models of our solar system's next 5 billion years, and 25 of them end in severely disrupted orbits, often planetary collisions. These disrupted orbits don't all result in collisions with Earth, but they are all pretty disastrous for us.

In one model, Mars passes within 500 miles of Earth (that's about as far away as San Diego is from San Francisco), both planets' gravity ripping each other to pieces. In other models, either Mars or Venus careens into Earth in a fiery explosion. In all models, though, the culprit for the orbital breakdown is Mercury.

That's right, all of this possible chaos and destruction can be traced back to "orbital chaos" in Mercury's path around the sun. The models were built using old modeling techniques, but factoring in relativity effects. In the models, Mercury's orbit would start to resonate with that of Jupiter, and the combined effect would severely distort the rest of the solar system's orbits.

The odds are small (under 1% of the models have any disruption), and it wouldn't happen for billions of years. But astronomical observation shows that collisions like this might have happened before. If it did happen here, and there was anyone left to do any blaming, they should blame our diminutive near-neighbor, Mercury.

Earth-Venus smash-up possible in 3.5 billion years: study [AFP]
More concept images at Universe Today

Image artistic design: J Vidal-Madjar, provided by Nature

While space isn't likely to become an issue in the waning days of the presidential campaign, Obama has repeatedly vowed to revisit the federal budget "line-by-line." Obama would prefer the money go elsewhere: He would delay NASA’s controversial moon-to-Mars program five years in order to fund education initiatives.

The Obama Plan for Science and Innovation has a conspicuous omission:

Did I miss the word Mars in there somewhere? Most of NASA's mission, in this appraisal, seems to be focused on the ground, not the sky.

In light of the economy, the debate is also about the price tag. Coming in on schedule means the program will go from costing $300 million in 2006 to topping $1.9 billion in NASA's latest public estimate. It's not an easy choice, but you need a healthy understanding of what can be accomplished scientifically before you make that decision.

For those on the inside like Ed Weiler, the goal of the program isn't as abstract as it might be for a congressman. "The science is critical. It's a flagship mission in the Mars program and as long as we think we have a good technical chance to make it we are going to do what we have to do," he told the press.

Weiler sounds like most politicos lately, and he'll have to deal on Obama's terms by throwing in the word hyperdrive every now and then, as the Senator detailed at a Wyoming event:

"I grew up on Star Trek. I believe in the final frontier.... NASA has lost focus and is no longer associated with inspiration. I don’t think our kids are watching the space shuttle launches. It used to be a remarkable thing. It doesn’t even pass for news anymore."

What if NASA abandons its mission to explore the galaxies and focuses on new technologies and applications on Earth? Not that those two things don't have a lot in common to begin with, but wouldn't that make NASA just another government bureaucracy? Since that would be precisely what Obama says he doesn't want, NASA administrators might have to get used to sad press conferences.

What Direction Now For the U.S. Space Program [New Scientist]

Of course you do. Most of this region of the planet has never before been photographed. The stark shadows you see in the ridges here are caused by the area's proximity to the dividing line between night and day on the planet, which exists in a constant state of boiling heat or freezing cold.

Stunning New Views of Mercury [via Space]

Mercury orbits the Sun once every 88 days, and it obviously believes we're jealous that it's so close to the Sun. Wrong again, Mercury! We're tired of this constant fighting about who has more active volcanos, okay? Just stay quiet as we attempt to photograph your southern half.

NASA's Mariner 10 probe passed Mercury three times in 1974 and 1975, but this is the first extended look we've gotten at the first planet from the sun since. The Messenger's mission may be complicated by the irrefutable fact, suggested by astrologer Susan Miller, that Mercury in retrograde affects electronic devices on Earth, and took down the Hubble. This is an old theme that's been bouncing around in astrological circles for some time.

Messenger will be photographing places previously unseen, including parts of its Southern hemisphere referred to as Mercury's "junk." Mercury has been shrinking, and more images may give us a better idea of why that's happening. (Our guess is that it's dieting because of shiny new planets intruding on its turf.) A spacecraft won't get in orbit with the planet until 2011, and the resulting post-orbit period will no doubt be full of awkward recriminations and a Messenger-Mercury sextape. Here's some scandalous imagery to tide you over until then.

Mercury is about twice as big as pluto, but still is the smallest object called a "planet" orbiting the Sun. The question is: how much smaller will it get? It will never get anywhere near as small as the former ninth planet, but will the IAU see fit to demote it too as it continues shrinking? Only time will tell.

Meanwhile, Mercury's molten iron core continues to cool, shrinking the planet from the inside. Small particles of solid iron 'snow' rain down toward the ever-widening solid core. But even as the solid grows it's denser than the liquid and so takes up less space. This has been going on probably for billions of years and over time the shrinkage has caused Mercury's crust to buckle and fold up on itself, as seen here (that y-shaped fracture in the left side of the image is a huge fracture in the rock. The whole picture is about 200 kilometers wide):

(from NASA)

On the right hand side of the image, the craters with the soft-looking rims appear to be old impact basins that have been filled in with lava, indicating the Mercury once had some serious volcanoes exploding on its surface. Why did the volcanoes die off? Mercury cooled off. Just like on Mars and the Moon, Mercury was fiery when it first came into being, but lost its heat in the roughly 4.5 billion years since, silencing is volcanic activity. Earth is cooling in a similar way and in a few billion years it will get too cold for volcanoes too. When it does it will go quiet forever.

Source: Science, NASA, via LA Times

[Special note to Moff and Blakeley: Just try making dick jokes about this picture! It can't be done!] Image courtesy of NASA/JHUAPL/CIW NASA Spots Mystery Spider Scar [Space.com]

NASA's Mercury Visualization Tool includes a slider bar. You can choose the time period of black-and-white images by the minute, the second and even the hundredth of a second. For each time period, there are images from the Wide-Angle Camera, the Narrow-Angle Camera and the sensor footprint. You can also choose a "phase" of the exploration, including WAC Approach Color Imaging or WAC Departure Mosaic.

Probably the best way to find the coolest Mercury images via this site is just to set a refresh rate of 1 second and then hit "play" on the slideshow. The site will jump forward in time a minute or so at a time. Just be prepared to hit "pause" when something good pops up. And then get ready to spend a few hours in Photoshop making your images sexier. Send us your best Mercury porn and maybe we can post a gallery. [Messenger Visualization Tool]