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All posts for the month April, 2011

Come on Down to the Carnival of Space

Every week, the work of a hardy band of science writers, specializing mostly in space and astronomy topics, is featured in a roving blog entry called “The Carnival of Space.”  We all take turns hosting it, highlighting the writings of  16 of us spacey scriveners.  This week, the Carnival is playing out over at The Next Big Future blog.  Check it out!  You never know what you’re going to learn as you surf the cosmic midway at the Carnival!

Sun’s Up!

This close-up view of a prominence high above the Sun_s surface shows the twisting and swirling motions caused by magnetic forces over about 10 hours on April 17, 2011. While some of the material seems to break away from the Sun, much of it appears to return to the surface by the end of the clip. This event was observed in the extreme ultraviolet light of ionized Helium and is being shown with time-lapse images every three minutes. Courtesy NASA/SDO Mission.

On the mountain where I live, we’ve been getting blasted with snow off and on the past week or so.  It’s the last gasp of winter, even as we’re truly into spring. While the snow is much-needed (it’s very dry here and the specter of forest fires is looming already this year), it means that we don’t get to see much of the Sun, so I turn to my online solar sources for some virtual sunlight.

Two sites I visit pretty regularly are the STEREO mission Web pages and the Solar Dynamics Observatory (SDO) web pages. These two space-borne missions are studying our star and sending back some really spectacular images of its busy surface and atmosphere.

The next couple of years should be exciting times for solar observers, as the Sun moves into its period of maximum activity. We’ve already seen some pretty spectacular outbursts, and there’s more to come.

A substantial coronal mass ejection blasted out from the Sun from an active region (Apr. 3, 2011) as seen by the STEREO (Ahead) COR2 coronagraph. The eruption hurled a billion tons of mass into space at over a million miles per hour. In coronagraphs an occulting disk (black) blocks out the Sun (represented by the white circle) so that we can see faint features of the expanding cloud of particles beyond that point.

Even though we evolved in the light of the Sun, and despite the fact most life on Earth thrives on heat and warmth from this nearby star — and despite the great knowledge we have about the Sun —  there’s still much to be explained about its behavior, its evolution, and its eventual demise.

Yet, that demise is billions of years in the future — what concerns many of us is the Sun of today.

Missions like STEREO and SDO tell us a great deal about the Sun’s activities, and help us understand its influence on our part of the solar system. The Sun and Earth are linked together not just as star and planet, but as members of a coupled geomagnetic system. The solar wind (that stream of charged particles that continually blows from the Sun), tangles with the magnetic field of our planet. The stronger the solar wind, the stronger our magnetic field reacts.

The local effects are sometimes no more than a beautiful display of northern or southern lights. But sometimes, the Sun’s belches affect technology on Earth.

Understanding the Sun is important in the grand scheme of human concerns. It warms us, but it can also take away our telecommunications and electricity.

So, marvel in the Sun. Enjoy its light. Revel in the fact that it keeps life going even as it poses a threat to our planet with its fiery outbursts.

And, remember that we’re still learning many new things about our nearest star every day.

The Answer to the Question…

How do you search out unusual types of “cosmic stuff” such as dark matter and antimatter?  The response:  you do particle physics.  Now, what’s particle physics?  It’s the science of understanding the makeup and actions and effects of particles (atoms and their constituent components the electrons, quarks, etc.) that make up matter in the universe.

Cosmic rays are a big part of particle physics. They are pieces of atoms called “subatomic particles” that are very energetic.  They zip around the universe at high speeds, they can penetrate our planet’s atmosphere and the surface,  and even your body.

The Alpha Magnetic Spectrometer at KSC before launch. Courtesy NASA.

The next shuttle launch (the last one for Endeavour) will take a unique experiment into space called the Alpha Magnetic Spectrometer (AMS for short).  It will be left on the International Space Station and spend some time doing particle physics.  In its search for antimatter (which is the “anti” version of regular matter), the AMS will look for what’s called an “antihelium” nucleus occurring naturally in the universe. This “stuff” has been observed before in collider experiments where they have been created briefly during high-speed particle collisions.  The instrument is sensitive enough to detect such antimatter at tremendous distances — out to the limits of the expanding universe (where, in its early  moments, there may have been antimatter created as a part of the birth of the cosmos).

The AMS also sets its sensitive sights on the detection of dark matter, that stuff that appears to make up some 95 percent of the mass of the entire universe.  There’s a LOT of it out there, and eventually we’re going to find out what it is.  The AMS will look at the background amounts of positron, anti-proton, or gamma-ray flux (or type of flow). If there are peaks (or jumps) in the flux, then this may tell us about the presence of dark matter (and what it is).

Of course, since the AMS will be in space, studying space, it will give us a lot of information on the cosmic ray counts we encounter in near-Earth space. Cosmic rays come from a variety of sources (including supernova explosions, the Sun, and so on), and knowing the cosmic ray environment at both normal and peak levels helps us understand their role and existence.  In addition, anybody venturing off Earth — whether to the Moon, the ISS, Mars or wherever — has to be continually aware of the cosmic ray levels. These babies are lethal in high doses!

So, how does this weird-looking instrument do its work? It has a set of detectors that are “interested” in various particles.  For example, the transition radiation detector clocks the speeds of very high-energy particles, as does the ring-imaging Cherenkov detector. The AMS also has a superconducting magnet that is strong enough to bend the path of a charged particle and allows it to be identified. Other instruments measure the energy of the particles as they pass through, and give some indication of their coordinates in the magnetic field of the superconducting magnet.  This all makes sense once you understand that these particles are creatures of their magnetic environments and so using speed detectors and magnets to measure their characteristics is the way to go.

While much subatomic physics can be done on the ground at places like CERN and Fermilab and Brookfield National Laboratory (among others), such experiments are usually better conducted in space, away from the Earth’s environment and where the conditions can be more easily understood.  This flight of the AMS module (officially called AMS-02) is another step in stretching our understanding of the smallest particles (and their actions).  For more information about AMS-02, visit the instrument Web page, where you’ll find introductory material, images, and videos.