MOSCOW (AP) -- Russia's space agency has adjusted its forecast for the crash of a failed spacecraft, saying it may shower its fragments into the south Atlantic.Roscosmos said the unmanned Phobos-Ground probe could plummet to Earth Sunday or Monday anywhere along a broad swath between 51.4 degrees north and 51.4 degrees south.It said Friday that the mid-point in the two-day window would have the craft crashing into the ocean about 400 kilometers (250 miles) east of the coast of Chubut province in southern Argentina. It said the precise time and place of the uncontrolled plunge can only be clarified later as the probe draws closer to Earth.At 13.2 metric tons (14.6 tons), the Phobos-Ground is one of the heaviest pieces of space junk ever to plummet to Earth, with highly toxic fuel accounting for the bulk of its weight.