Two recent articles from New Scientist highlight the fact that our universe remains, despite all our advances, a complex place with many mysteries yet to be unraveled.
First (see title link above) Japan's Hayabusa probe to the asteroid Itokawa shows it's a "loosely packed pile of rubble" resulting from a collision between larger asteroids. The problem is that it's too small (only 535 meters long) and too loose - it has a porosity of 40% (meaning that much of its volume is empty space) and appears racked by internal stresses and quakes as well as further collisions. That leaves scientists stumped as to just why this thing, with its fragmented structure and miniscule gravity, is still holding together.
Meanwhile, Slava Turyshev of NASA's Jet Propulsion Laboratory (JPL) is trying to solve another mystery - the Pioneer Anomaly. The space probe Pioneer 10, at last contact in 2003, was about 400,000 km off course, and Pioneer 11 (still in contact) shows a smaller deviation, even after factors like the gravitation of the Sun and planets, pressure of sunlight, the outgassing of onboard materials, and all the other factors in the amazingly complex world of deep-space trajectories were apparently accounted for. Turyshev will "refly" the Pioneer 10 and 11 missions virtually, using computer models, in an attempt to see where the course deviation began and look for hitherto-unsuspected causes.
http://www.newscientist.com/article/mg19025541.800.html
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