Astronomy.

Shuttle tragedy The space shuttle Columbia disintegrated minutes before it was scheduled to land on Feb. 1 (163: 83 *). All seven of its crew members died. Tests revealed that the shuttle had been doomed since liftoff, when a piece of loose insulation punctured a hole in its left wing (163: 308; 164: 21). NASA's plan to return space shuttles to flight next year came under intense scrutiny (164: 203 *). Researchers are working on more heat-tolerant materials and designs for vehicles that might ultimately replace the shuttle (163: 215 *).

Dark doings Astronomers found new evidence that a mysterious substance, dubbed dark energy, is ripping the cosmos apart, causing the universe to expand at an ever-faster rate (164: 67 *, 227 *). The most precise map of galaxy clusters confirmed that most of the cosmos is in the dark, consisting of 70 percent dark energy, 25 percent dark matter, and 5 percent ordinary matter (164: 275).

Precocious cosmos A new portrait of the infant cosmos pinned down its age with unprecedented precision, providing new evidence that the universe began with a brief but humongous growth spurt and that the cosmos already contained a plethora of stars when it was just 200 million years old (163: 99 *). Other evidence indicated that massive galaxies were in place and forming stars at a prolific rate when the universe was less than a billion years old (163; 51, 139 *).

Alien Planets Astronomers found a planet that's the closest one known to its parent star, whipping around the star every 28.5 hours (163: 301). Scientists also discovered the oldest and most distant known planet in the universe (164: 19 *). A star 90 light-years from Earth harbors the closest known multiplanetary analog to our solar system (164: 174).

Galactic clash A tiny, newly discovered galaxy being shredded by the gravity of the Milky Way is our galaxy's closest known neighbor (164: 307).

Strange rain Thousands of alien stars are raining down on the solar neighborhood (164: 382).

Violent neighbor The most detailed visible-light picture ever taken of the heavens revealed that the nearby Andromeda galaxy has had a much more violent history than our own Milky Way has had (163: 291 *).

Holey mass Astronomers measured the mass of the most-distant black hole known (163: 317).

Farewell, Galileo Out of fuel, the Galileo spacecraft followed NASA's plan and ended an 8-year tour of Jupiter and its moons on Sept. 21, when it dove into the planet's dense atmosphere (164: 196).

Splish splash Using radar-based observations, planetary scientists obtained the best evidence yet that Saturn's smog-shrouded moon Titan has lakes or oceans of hydrocarbons (164: 213).

Neptune summer Belying its location in the deep freeze of the outer solar system, Neptune may undergo a change of seasons (163: 325).

Lost and found Astronomers reported that they had finally found the whereabouts of most of the ordinary matter in the universe (163: 174). Other researchers rediscovered an asteroid that had been missing since 1937 (164: 277 *).

Infrared debut Astronomers unveiled the first images and spectra recorded by an orbiting infrared observatory, the newly named Spitzer Space Telescope (164: 387 *).

Warmer, fluffier Pluto Although Pluto has been receding from the sun for more than a decade, its atmosphere recently doubled in size and its temperature increased by about 1[degrees]C (164: 126).

Explosive data Gamma ray bursts may be even more energetic than scientists had estimated (163: 180). Astronomers uncovered direct evidence that gamma ray bursts are linked to the creation of supernovas (163: 317).

Cosmic blowout Supermassive black holes at the cores of galaxies can blow out as much material as they swallow, creating high-speed winds that seed the universe with elements essential for life (163: 214 *).

Sound from a hole Astronomers for the first time detected sound waves generated by a black hole (164: 163 *).

Using a gravitational zoom lens, scientists found the hottest, brightest, and most crowded star-forming region yet observed (164: 291).

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The sharpest images of the sun ever taken showed surprising details of our star's turbulent surface (163: 404 *).

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ALL ABOUT MARS

Planetary scientists discovered ice near the edge of Mars' south polar cap (163: 45). Melting snow may have sculpted the recently formed gullies on Mars (163: 116 *). The presence of large amounts of the mineral olivine argued against ancient oceans or lakes on Mars (164: 301). Scientists deduced that the Red Planet's core is at least partially liquid (163: 221). Mars came closer to Earth than it had in nearly 60,000 years (154: 148).

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