A huge hunk of Russian space junk is set to crash to Earth in the next few days, but nobody knows exactly when or where it’s going to come down. According to the latest estimate of Roscosmos, Russia’s space agency the 14.5-ton Mars probe Phobos-Grunt, which got stuck in Earth orbit shortly after its November 8 launch, may re-enter the atmosphere at 11:22 a.m. EST (1622 GMT) on Sunday. If that projection is accurate, pieces of the failed spacecraft will splash into the Atlantic Ocean about 1,000 miles (1,600 kilometers) south of Buenos Aires. According to Roscosmos the predicted time and place of re-entry could change in the future. Indeed, the newest estimate is substantially different from two others the space agency issued earlier in
the week, which had the probe coming down earlier on Sunday and falling into the Indian Ocean off the coast of Java or near Madagascar. Further, other organizations and observers tracking Phobos-Grunt have their own estimates, some of which roughly agree with Roscosmos‘ predictions and some of which have the probe crashing later, perhaps early Monday morning. Most of Phobos-Grunt’s weight consists of toxic fuel, prompting some concern that its crash could spread dangerous chemicals over populated or environmentally sensitive areas. But Roscosmos officials have said that the fuel will burn up high in Earth’s atmosphere.