24 Hours from Jupiter . ... Credit Copyright: NASA , R. Beebe, NMSU Explanation: NASA's robot spacecraft Galileo began its long voyage to Jupiter more than six years and 2.3 billion miles ago. About 24 hours from now it will reach its destination. On arrival (December 7th, 1995) , Galileo should become the first spacecraft to orbit around a gas giant planet and the first to drop a probe into a giant planet's dense atmosphere. ... NASA Web Site Statements, Warnings, and Disclaimers . ...