Today, at about 5:00 pm EST, this 750 pound probe from NASA's robot spacecraft Galileo will plummet into Jupiter becoming the first probe to fly through the atmosphere of a gas giant planet. Released by the Galileo orbiter in July of this year, it has been coasting toward its rendezvous with the Solar System's largest planet. The probe will smack Jupiter's atmosphere at over 100,000 mph slowing to less than 1,000 mph in a matter of minutes, experiencing a deceleration of about 230 times the Earth's surface gravity. If all goes well, it will then deploy a parachute and descend, using sophisticated instruments to profile Jupiter's dense outer layers of hydrogen and helium gas. Pictured here before launch, the probe descent module (top)is suspended above its deceleration module aeroshell (bottom) prior to being joined. The aeroshell should protect the descent module from the initial shock and heat of entry, which will initially create an intense fireball, over twice as hot as the surface of the Sun.