The Galileo spacecraft has settled into orbit around Jupiter, where it will conduct a two-year survey of the planet's moon. Thursday, a 746-pound probe released from the spacecraft in July slammed into the Jovian atmosphere. Dropping more than 125 miles through the clouds of the planet, the probe sent back the first-ever samples of the planet's dense air before being crushed by intense heat and pressure. "This will help clear up a lot of speculation about the composition of the Jovian atmosphere," says TIME's Leon Jaroff. "Scientists have been able to make a lot of inferences about the planet, but this would be the first time they've been able to sample the atmosphere. They expect to find a high water content, and some lightning, at the higher levels in the hour before the probe descends so far that Jupiter's extreme heat and pressure destroy it." Scientists at the Jet Propulsion Laboratory are expected to complete their analysis of data from the probe by mid-December.