Ready for an intergalactic adventure? Take this virtual flight over Mariner Valley, Mars's version of the Grand Canyon, a geological feature as deep as Mt. Everest and as wide as the distance from New York to Los Angeles. Kind of makes Earth's biggest dry river bed seem a bit less "Grand," doesn't it?

Exploring the intricacies of Martian geology requires a steady climber, nimble enough to scale cliffs and dexterous enough to sample the strata. A climbing primate would be a good candidate, if only there were air to breathe and the temperature were warmer than -140

This short animation is made up from a sequence of images taken by the Descent Imager/Spectral Radiometer (DISR) instrument on board ESA's Huygens probe, during its successful descent to Titan on Jan. 14, 2005.

The year opened with a presidential commitment to space unrivaled since John F. Kennedy's vow to put a man on the moon: In January, George W. Bush promised not only to return astronauts to the moon by 2020 but also to use it as a testing ground for possible "human missions to Mars and to worlds beyond." His directive came less than a year after the Columbia disaster grounded NASA's human-spaceflight program.

Seven years ago, the largest and most expensive interplanetary probe ever built blasted off from Cape Canaveral. It was loaded with 12 advanced scientific instruments, 72 pounds of plutonium to power them, and a capsule destined to be jettisoned toward the only other object in our solar system protected by a nitrogen-based atmosphere. After launch, the spacecraft began its voyage through the void of space and was promptly forgotten by all but a few scientists and space enthusiasts.

Galileo, the interplanetary spacecraft that has changed the way we understand Jupiter and its 61 known moons, will perish on the 21st of this month as it plunges into the Jovian atmosphere. NASA engineers have put Galileo on a collision course with the planet so that the spacecraft, which is running low on propellant, can study the Jovian magnetosphere as a final task. The suicide mission will also ensure the craft won't end up crashing intoand possibly contaminatingthe ocean of Europa, one of Jupiter's moons.

In 1999, Yoseph Bar-Cohen of NASA's Jet Propulsion Laboratory challenged the engineering world to an arm-wrestling contest. Sort of, anyway. He doesn't plan on participating himself, and the arm, which will face off against a human opponent of middling strength, has to be robotic. The catch is, he's not asking for your standard metallic appendagethis robotic arm must be built with electroactive polymers (EAPs).

It's the fourth day of a scientific conference in Denverfour busy February days in a huge rabbit-warren convention center with long hallways and fluorescent lighting and serious scientists giving serious PowerPoint presentations in darkened auditoriums; four days of breakthroughs and advancesnanotech to biotech, anthropology to zoology, the whole mind-spinning stew. Four days, for the assembled journalists, of making sense of it all and banging out stories on the fly-and now comes word of what could be a light interlude: Keep an eye out for the guy carrying the head. Say what? The robotic human head.

In 1966, Mrs. Weddle's first grade class at Las Lomitas Elementary School got its first homework assignment: We were to find out what our fathers did for a living, then come back and tell the class. The next day, as my well-scrubbed classmates boasted about their fathers, I was nervous. For one thing, I was afraid of Mrs. Weddle: I realize now that she was probably harmless, but to a shy, elf-size, nervous little guy she looked like a monstrous, talking baked potato. On top of that, I had a surprise in store, and I wasn't sure how it would be received.