After hundreds of unanswered calls, NASA mission engineers abandoned efforts to revive Opportunity, the space agency’s most durable Mars robot rover, which has been silent since a planetwide dust storm enveloped it in swirling grit this past June.
National Aeronautics and Space Administration officials announced an end to attempts to contact the $400 million Opportunity rover during a news briefing Wednesday at the Jet Propulsion Laboratory in California, which managed the 15-year mission. The gathering of agency managers,...