Rank 79 documents Mars Odyssey — the 2001 Mars Exploration orbiter that became the longest-operating spacecraft at Mars and the communications backbone for Spirit, Opportunity, and Curiosity surface operations. Launched 7 April 2001 aboard Delta II 7925, Odyssey entered Mars orbit 24 October 2001 and completed aerobraking by January 2002 into a 400 km sun-synchronous path. George Pace's project team and Philip Christensen's THEMIS instrument lead mapped minerals across the surface in nine infrared bands while the Gamma Ray Spectrometer discovered vast subsurface water ice at the poles — reshaping where rovers could hunt for habitability. Odyssey has relayed more than 85 percent of rover data to Earth across two decades of extended missions. Wallimilist renders the Odyssey bus with THEMIS barrel and high-gain dish over Mars with polar ice cap, red MARS ODYSSEY title, and italic still-active kicker exactly as the master PNG dictates — 2001 launch line, orbit insertion footer, and curator copy on relay duty and polar ice discovery.