Mars Rover Trapped in Sand, But What Can End a Mission?

摘要

Times are tough for the Spirit rover. Last week, in its 5th year of exploration, Spirit became mired in a dry martian version of quicksand. Mission engineers are studying how it might extricate itself, but the crisis raises a perennial question: When, if ever, should a mission in its declining years be put out of its misery? When does the diminishing science output no longer justify the millions of dollars it costs?rn"NASA always has a hard time cutting off any operating mission," says planetary geologist Harry McSween of the University of Tennessee, Knoxville, who is on the Spirit science team. "If it turns out that Spirit can't move anymore, perhaps that decision will be easier."