The ALMA antenna is transported to the Chajnantor plateau.

The largest astronomical project in existence is getting under way in the high plains of northern Chile. The Atacama Large Millimeter Array, or ALMA, will be comprised of 66 giant 40-foot and 23-foot antennas, spread over 11.5 miles, operating as a single, giant radio telescope. ALMA will help astronomers answer questions about our cosmic origins and will observe some of coldest and most distant objects in the cosmos.

• The ALMA antenna is transported to the Chajnantor plateau.
• ALMA news release.
• ALMA Web site.

One of the first new images from the repaired Hubble.

In September, NASA declared the Hubble Space Telescope back in full working order. All the instruments are in excellent shape after being checked out and calibrated. The new instruments are the Wide Field Camera 3 (WFC3), which can see wavelengths ranging from the optical into the infrared, and the Cosmic Origins Spectrograph (COS), which studies the ultraviolet. The Advanced Camera for Surveys (ACS), which had partially stopped working, has new circuitry and functioning as well as ever. The Space Telescope Imaging Spectrograph (STIS), which was also in need of repairs, is now back on the job.

• HubbleSite news release featuring the new images.

Image acquired during September 2009 flyby.

The three Mercury flybys of the Messenger spacecraft are complete. Despite a glitch during the third pass, most of the surface of Mercury has been imaged. The Messenger team is examining the craters, bright and dark spots, and other surface features in the hopes of understanding the geologic history of Mercury.

• Messenger's main Web site.
• The Third Flyby Web page.
• Graphic of the Messenger orbital tracks.
• A collection of additional Messenger images.

The shadows of a pair of Saturn moons pass over the planet's rings in this Cassini image.

Saturn’s rings have fascinated us ever since Galileo first spotted them in his telescope in 1610 — almost 400 years ago. But how these icy rings came into being remains a mystery. Saturn’s rings are thought to consist of roughly 35 trillion trillion tons of ice, dust and rock. Cassini and Voyager spacecraft have revealed many new details of the rings, but many mysteries still remain.

• Space.com on Saturn's rings.
• NASA's Solar System Exploration on Saturn's rings.
• The Cassini Web site.

LCROSS will impact the Cabeus A crater on the Moon.

The Lunar Crater Observation and Sensing Satellite (LCROSS) mission is designed to determine whether water ice is present on the Moon. Water is always an issue for future lunar exploration. LCROSS has two components — a rocket that will impact a shadowy Moon crater and excavate it, and a satellite that will sample the plume produced by the impact. If ancient ice lies buried on the Moon, it may be ejected and then detected by specialized instruments.

• Video of the LCROSS launch.
• The LCROSS Web site.

Meteor Crater in Arizona, caused by an 80-foot meteor 20,000 to 50,000 years ago.

NASA says that without more funding, it will not meet the asteroid tracking goals mandated by Congress. NASA hopes to spot 90% of potentially dangerous objects by 2020. Large asteroids could cause global catastrophe if they strike Earth, and the U.S. is the only country with an asteroid-detection program.

• The Planetary Society on Near-Earth Objects.
• Near Earth Asteroid Tracking Web site.

A map of debris in a low-Earth orbit, the most concentrated area of debris.

Leftover pieces of satellites orbit the earth as debris. Some of this debris has been hazardous for the International Space Station and the Space Shuttle, as well as orbiting satellites. The debris re-enters Earth’s atmosphere at the rate of about one piece per day. One of the most famous pieces of orbital debris, a tool box dropped by an astronaut while performing a space walk, re-entered the atmosphere on August 3, 2009.

• NASA's Debris Web Site.
• Space debris in Google Earth.
• Video of the lost tool bag, recorded by an amateur astronomer.

Canyons on Titan

Saturn’s moon Titan is far from Earth, but both worlds have some things in common — wind, rain, volcanoes and tectonics. These forces sculpt features on Titan, as on Earth, but in an environment more frigid than Antarctica. Titan looks more like Earth than any other body in the solar system, despite the huge differences in temperature and environment.

• Space.com on the Titan-Earth similarities.
• The Cassini Mission studies Titan.