The Cassini-Huygens Mission

The Cassini spacecraft launched to Saturn in 1997 reached the planet in 2004. In January 2005, the spacecraft released the Huygens probe to explore Saturn’s moon, Titan. Parachutes slowed Huygens’s final descent, and its cameras began taking pictures of Titan’s surface from a height of 10 miles (16 kilome­ters). Finally, the probe landed on what looked like a shoreline-perhaps beside a lake of freezing liquid methane gas.

The Huygens probe continued to transmit data for 90 minutes, three times longer than scientists had hoped for. Signals from Huygens were transmitted to Cassini in orbit, and from Cassini back to Earth, where 45 minutes later they were picked up by large radio tele­scopes. The scientific instruments onboard the Huygens probe gave scien­tists much valuable data about Saturn’s large and distant moon.

Return to Mars

In 2004, NASA returned to Mars with twin robot rovers named Spirit and Opportunity. During the landing, each rover was protected inside a large airbag with a parachute attached. After impact, the ball bounced over the Martian sur­face until it came to a halt. Then the airbag deflated and opened to release the robot rover. The rovers landed at separate locations. One of the mission aims was to look for water-a discovery that would make future landings on Mars by astronauts a more realistic prospect. Landing during the Martian afternoon, with Earth in full view, meant that the landers could signal at once to the waiting scientists to let them know that the landing had been successful. The signals were sent to Earth by way of the Deep Space Network, a series of antennae in California, Spain, and Australia. Spirit and Opportunity were intended to work for about 90 days, but they were still busy two years after they landed. They found evidence that Mars was, in its past, apparently a watery planet.