New Scientist reports on a new paper from David Smith at the University of Arizona in Tucson and the University of Texas, Austin's John Scalo that declares that the sun's heliosphere protection shrinks as the solar system passes through very dense gas and dust clouds, exposing us to harmful space dust and cosmic rays. Smith notes that planets orbiting red dwarf stars aren't affected by similar shrinkage due to their closeness to the star:

The bottom line is that habitable planets around red dwarfs are better protected from climate catastrophes than Earth is.

Don't feel too under threat, however; according to the paper, Earth is only being exposed to cosmic rays between one and ten times every billion years.

Sun leaves Earth wide open to cosmic rays [New Scientist]

The termination shock is where the solar wind runs into the interstellar medium, which is astronomy jargon for "whatever is in space beyond our solar system." We learned a lot about this region of space when Voyager II passed through it last year, but IBEX will be able to study the interactions happening out there in far greater detail. Particles called energetic neutral atoms are ejected from the termination shock at high speed. IBEX will measure these particles as they strike it, and piece together an image of what's going on as the solar wind slows and ripples. NASA likes to compare it to an Impressionist painting in their IBEX press releases, but it's really more like...well, science. IBEX has been in orbit for more than a month, but it needed time to push itelf into a very high-altitude orbit and run some tests. Now it's ready to rock.

So what will IBEX find out there? It's such an unexplored region of space that scientists really have no idea. They believe that the termination sock filters out cosmic rays that would otherwise bombard the solar system, and they have some rough ideas of the heliosphere's irregular dimensions, thanks to the Voyagers, but beyond that, it's an unknown frontier. Image by: NASA.

NASA Launches IBEX Mission to Outer Solar System. [NASA]

Vinge describes the galaxy in terms of "zones of thought." Near the center of the galactic core are "the unthinking depths," where spaceships must use analog technologies and travel is very slow. In the "slow zone," which includes Earth and most of the galactic disk, FTL doesn't work, nanotech is crude, and mind-machine interfaces are impossible. Then there is the Beyond, an egg-shaped volume perpendicular to the galactic disk that functions like the galaxy's heliosphere. There, FTL is possible (though expensive), AI and nanotech work, and human-machine interfaces are everyday technology. Most creatures live in the Beyond, because the tech is so much better there. Yet another region, basically the deep space beyond the galactic sphere, is called the Transcend. There FTL is cheap, and tech works even better.

Obviously Vinge was partly creating a kind of sociological landscape with his imagining of these galactic spheres — each corresponds to a stage or potential stage in human development. But I have always wondered whether there might be a grain of truth in there. Could it be that when the Voyager probes finally travel beyond the heliosphere (in about 10 years), scientists will get data back showing that Voyager is suddenly able to travel faster using the same amount of energy? Or perhaps other physical constants will shift?

Solar System is Shaped Like an Egg [Daily Telegraph]