Weekly Online Lesson Online Lesson Archives Grade Level: 3-7 Subject: Science

A Close Call for Galileo

Scientists at NASA's Jet Propulsion Laboratory in Pasadena, California, had a scare on Thanksgiving day, 1999. Four hours before the Galileo spacecraft was scheduled to fly close to Io, one of Jupiter's 16 moons, intense radiation made the computer shut down. To fix the problem, engineers had to quickly send Galileo a new set of commands and reboot the computer.

The same problem happened during a flyby of Io (pronounced I-O, like saying the letters) on October 10. The engineers learned how to fix the problem then, so they were ready when it happened again on Thanksgiving. It was a close call, but Galileo was working in time for most of the Io flyby.

What is Galileo? How long has it been flying around Jupiter and its moons? Why do scientists want to learn more about Jupiter and its moons? And what does all this have to do with space volcanoes? You'll find out in this week's online lesson.

The Galileo Mission

Galileo is a spacecraft designed to take  measurements and photographs of Jupiter and transmit them back to earth. NASA launched Galileo in 1989 from the space shuttle Atlantis. On December 7, 1995, the spacecraft arrived at Jupiter and began its mission. Its first task was to drop a probe down into Jupiter's atmosphere. The probe radioed new information about Jupiter to Galileo, which relayed the data to eager scientists.

You can learn more about Galileo at Spacecraft Galileo at Jupiter Web site. Read about Galileo's Six-Year Journey to find out why it took the spacecraft so long to get to Jupiter, and what it did along the way. Read Galileo's Greatest Challenge to learn how engineers solved a big problem with Galileo early on. What was the solution? Now read Galileo Meets Jupiter and the Moons to learn what the spacecraft has been up to as it circles around Jupiter and its moons.

Ready to see some of the pictures Galileo has taken? Visit NASA's official Galileo Web site to see plenty of amazing images. Click any category to see more. There's even a page with cool animations.

The Galileo Probe

Galileo's first task was to drop a special probe down into Jupiter's atmosphere. The probe radioed new information about Jupiter to the Galileo spacecraft, which relayed the information to eager scientists on Earth.

You can learn more about the Galileo probe that dropped into Jupiter's atmosphere by visiting the Galileo Probe Web site. Start by clicking the Galileo Probe Spacecraft link a look at the probe itself, and look at the diagram that shows all the parts.

Go to the Galileo Probe Mission Events page to see the probe in action. See the picture of the probe separation from the orbiter. Look at a picture of Jupiter to see where the probe entered. Review a big chart showing the events as the probe descended into Jupiter's atmosphere. How many minutes did the probe last? What measurements did it take?

Jupiter

If scientists are so interested in learning more about Jupiter, it must be an important planet. Jupiter is the largest planet in our solar system, which makes it special. It's also a planet made up mostly of gas clouds. Learn more about this unique planet at Jupiter, Gas Giant.

After reading the introduction and Quick Facts, explore some of the other Jupiter links, like Why Explore Jupiter?, Atmosphere, Interior, and Discovery Summary.

How would you like to see Jupiter for yourself? You can by following these directions from Sky and Telescope. It's the brightest "star" in the evening sky.

IO and Europa

When Galileo suffered a computer shutdown on Thanksgiving, it was on its way to Io, the hottest spot in the solar system. What makes Io so hot are enormous active volcanoes dotting its surface. Learn more about the moon Io at the NASA Space Place Web site and the Io Flyby site. Read Io at a Glance for basic information about the volcanic moon, and read Volcanoes in Outer Space (or the younger kids version) to find out why Io would NOT be a nice place to visit. See for yourself by viewing these photos of erupting volcanoes on Io.

Before Galileo set its sights on Io, it had already explored the moon Europa — an ice world with an oxygen atmosphere. The ice looks solid on the surface, but it has many bergs and cracks that lead scientists to believe that a warmer liquid ocean may lie underneath. If that's true, Europa may have all the necessary ingredients for life. Read more about Europa at the Galileo site and at NASA's Solar System Web site.

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