Galileo's Gone

The Planetary Society has a good summary of the Galileo mission, culminating with a lovely account of its last minutes this past Sunday as it descended into Jupiter's atmosphere. Some of the niftier facts:

• The launch was seven years late, which added another four years to the length of the trip there.
• The large thunderstorms on Jupiter sport lightning strikes up to 1,000 times more powerful than on Earth.
• Jupiter's ring system is formed by dust kicked up as interplanetary meteoroids smash into the planet's four small inner moons and the planet's outermost ring is actually two rings, one embedded within the other.
• Europa appears to have a salty ocean up to 100 kilometers (62 miles) deep underneath its frozen surface, about twice as much water as all the Earth's oceans. Callisto and Ganymede may also have saltwater layers, and Ganymede has an iron core, like Earth.
• Galileo has been orbiting around in the jovian system for the last 8 years, traversing nearly 3 billion miles, powered by two long-lasting radioisotope thermoelectric generators.
• It took 49 minutes for the spacecraft's final message to make it across the half-billion mile distance to Earth.

Next up, Cassini will fly by Saturn's furthest moon, Phoebe, in mid-June, before settling into orbit around Saturn on July 1st. If all goes according to plan, it will land a probe on the surface of Titan, a moon nearly the size of Mars, in January 2005. Already, Cassini turned upside down one longstanding assumption about Jupiter during its flyby in the spring, as well as sending back some beautiful pictures. We are about to be swimming in new information about the saturnian system.

Seven spacecraft will be poking at Mars next year once the four currently in transit arrive, and NASA plans to return to Jupiter's moons with the Jupiter Icy Moons Orbiter (JIMO), which aims to launch in 2011 toward Europa, Callisto, and Ganymede. Space.com has an interesting discussion about the propulsion systems being designed to get them there.

Heady times to have an interest in this stuff.