Exploring Jupiter

Jupiter, taken by the Cassini satellite

With all the excitement the last few weeks of watching the new Mars Curiosity rover get packed up and on the first leg (JPL in California to Florida) of its long journey to Mars, it’s easy for me to forget that there is a lot of other space exploration stuff going on this summer. Juno, which I wrote a bit about last month, is another JPL-based NASA mission, heading out in August for the planet Jupiter. I realized in reading about Juno that I know very little about Jupiter so it’s time to remedy that deficit of knowledge. I knew Jupiter was the biggest planet in our solar system, and that it had some moons, but that’s really about it. So time to learn more about Jupiter.

First, why study Jupiter at all?  Because learning more about this huge planet can help us understand how our Sun and solar system formed over 4.5 billion years ago. From active volcanoes to icy moons, Jupiter and its moons are almost a solar system in themselves. Studying how these bodies interact, and the atmosphere and magnetic fields of Jupiter itself, will hopefully give us more information to understand our planet and our little corner of the universe.

Great Red Spot as seen by Voyager

Juno won’t be the first satellite to study Jupiter in detail. Voyager 1 and 2, Ulysses, Galileo and Cassini have all provided data information about this gas giant of a planet. In 1979, the separate visits of the Voyagers sent back detailed photos of the weather activity on Jupiter, discovering the Great Red Spot, as well as our first close-up views of its moons, including the first active volcano found outside of Earth on the moon Io.

In 1992, the Ulysses spacecraft, designed to explore our Sun, used Jupiter’s gravity to position itself to explore the Sun’s poles. During its fly-by, Ulysses identified changes in Jupiter’s gravity and recorded fewer active volcanos on Io than observed by the Voyagers 13 years earlier.

Galileo, the first spacecraft devoted to long-term exploration of Jupiter, was launched from the space shuttle Atlantis in October 1989 and reached Jupiter in December 1995, becoming the first satellite to orbit a planet in the outer solar system. Credited with a long list of discoveries, one of the most startling finds was evidence of subsurface salt water on three moons: Europa, Ganymede, and Callisto. Galileo’s mission ended in 2003 when it crashed into Jupiter’s atmosphere.

Cassini (artist's rendition, courtesy NASA)

Cassini did a fly-by in 2001 on its way to Saturn, sending back over 1,200 detailed photographs taken over 70 days that — strung together by JPL scientists into a time-lapse movie –showed how storms on Jupiter behave. The Cassini movie showed persistent storms moving across the planet’s surface by bands of latitude, with the storms lasting the entire 70 days covered by the photographs. In all, Cassini took over 26,000 photographs as it flew by Jupiter, and those photographs are being used to develop insights into the faint rings and the moons of Jupiter. Cassini’s single fly-by sent more than enough information to keep scientists busy for years.

Imagine, then, what Juno will do. Thirty-seven years after the Voyager spacecraft first sent back detailed images, Juno will observe Jupiter with cameras and instruments designed to capture information about the planet’s gravity, magnetic fields, and atmosphere. It is in studying these elements that scientists will work on determining the properties of Jupiter and how it evolved over billions of years.

I’ve saved the best for last. Go here to see a breathtaking video opening, then learn more about the Juno mission from a dedicated website:  The history of our planet lives on this planet. 


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