Days after an Iranian tanker sank off the coast of China, succumbing to a deadly collision and several explosions, satellites are taking note of what the tanker left behind: several large oil slicks, stretching for miles in the East China Sea.The tanker Sanchi's entire crew — 30 Iranians and two Bangladeshis — are presumed dead, though only three bodies have been recovered from the wreck and surrounding waters. Chinese officials say they are preparing to probe the sunken vessel, which now rests beneath 377 feet of water, using a robot submarine. Later, human divers may inspect the wreck as well.Some effects of the deadly collision have already proved easy to observe from afar. However, citing China's State Oceanic Administration, Reuters reports that satellite imagery has revealed two slicks of a combined 42 square miles. The slicks contain natural gas condensate, described by the wire service as "an ultra-light, highly flammable crude oil."The Panama-registered tanker had been carrying nearly 150,000 tons of the substance when it collided with the freighter CF Crystal earlier this month. It burned for more than a week before it sank on Sunday. The sheer scale of the ship's contents threatens to make this the worst tanker spill since 1991, when some 285,000 tons of oil were lost off the coast of Angola.Chinese authorities hope to mitigate the environmental damage of the recent spill; The Associated Press notes they believe divers might be able to pump out much of the fuel tanks "before they leak and contaminate the seabed."Japanese officials have expressed some cautious optimism, as well."It is difficult to give an immediate assessment of what kind of environmental impact the oil leak may leave at this point. It depends on how much fuel the ship still had inside," a spokesman for the country's coast guard told AFP on Tuesday."We believe the situation is reasonably under control for now." Copyright 2018 NPR. To see more, visit http://www.npr.org/.