Jupiter Probe Electrifying Scientists Await Information On Lightning Storms

Like its namesake god, the planet Jupiter hurls thunderbolts.

But until this afternoon, when the Galileo spacecraft parachutes into Jupiter’s previously unexplored atmosphere, scientists have been able to only guess from afar how jovian lightning is formed.

The arrival of the spaceship will pose the toughest test yet to those theories, including one proposed by three University of Arizona researchers in today’s edition of the journal “Nature.”

The UA scientists assert that lightning indicates water droplets and ice particles are concentrated in a zone near the top of Jupiter’s thick atmosphere.

Their computer model suggests that there is water as abundant as in Earth’s tropical thunderstorms, at a layer where Jupiter’s atmospheric pressure is three to four times higher than sea-level air pressure on Earth.

But “if Galileo doesn’t find a significant abundance of water, it will raise new questions about how lightning is formed,” UA planetary scientist Eugene Levy said this week.

The 750-pound Galileo probe carries tools to detect lightning and to identify the substances in Jupiter’s atmosphere. It is scheduled to transmit readings from those and other instruments to the 2.5-ton Galileo orbiter, passing overhead, for up to 75 minutes after its parachute opens. In those minutes, the probe will descend about 100 miles, reaching a depth where it will likely succumb to heat of about 800 degrees and pressure of about 30 times Earth’s sea-level air pressure.

The orbiter will store information sent by the probe, then relay it slowly to Earth over the next two months.

Levy said the lightning that crackles in the storm clouds of the solar system’s biggest planet provides a chance to learn more about weather, atmospheres and the origin of life on Earth.

The first view of lightning flashes on Jupiter came from pictures that a fly-by spacecraft snapped of the planet’s dark side in 1979.

Lightning in Earth’s early atmosphere possibly sparked chemical reactions that produced molecular building blocks of life, Levy said. Jupiter’s lightning may also spark chemical reactions, but there is no evidence that they have produced those building blocks, he said.

Vertical movement of air carrying particles of water and ice is what causes the electric-charge buildups that throw lightning on Earth.

“The amount of water on Jupiter has remained a mystery,” said Andrew Ingersoll, a planetary scientist at the California Institute of Technology.

Water affects the stability of weather patterns, so learning about the abundance of water in different levels of Jupiter’s atmosphere “may help clarify an enduring jovian mystery - how storms like the Great Red Spot can last for hundreds of years whereas storms on the Earth last for days or weeks,” he said.