NASA rover nears rim of Martian crater ALICIA CHANG,AP Science Writer LOS ANGELES (AP) — Months after the death of the Mars rover Spirit, its surviving twin is poised to reach the rim of a vast crater to begin a fresh round of exploration. Driving commands sent up to Opportunity directed the six-wheel rover to make the final push toward Endeavour crater, a 14-mile-wide depression near the Martian equator that likely could be its final destination. At its current pace and barring any hiccups, Opportunity should roll up to the crater's edge on Tuesday.