The search for a missing Argentine submarine continued into a sixth day on Tuesday, and officials said if the vessel has been submerged all that time the crew may only have one day of air left.
"In the worst-case scenario, in the critical phase, where it could not come to the surface by its own means or renew its air and oxygen, we'd be in the sixth day of oxygen," Navy spokesman Enrique Balbi told reporters, according to the Associated Press.
Two possible developments in the search for the missing sub, the ARA San Juan, which has 44 crew members, turned out to be unrelated, according to the Argentine Navy: A raft sighted by an aircraft in the search area was determined not to be from the San Juan, and white flares spotted by a U.S. Navy plane were also determined to not be from the vessel.
The sub carries enough food, oxygen and fuel for the crew to survive about 90 days on the sea's surface, the Associated Press reported. But it only has enough oxygen to last seven days if submerged.
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Noises which had been detected in the search area were also analyzed and determined not to have come from the submarine, an Argentine Nay official said.
The San Juan lost contact with the Argentine Navy last Wednesday in the southern Atlantic Ocean. The U.S. Navy has sent resources, including sailors with Undersea Rescue Command, and aircraft, to help.
The San Juan was inaugurated in 1983, making it the newest of the three submarines in the Argentine naval fleet. Argentine military officials said an electrical outage on the diesel-electric-propelled vessel might have downed its communications.
An Argentine navy official said Monday that the submarine reported a battery failure Wednesday and was returning to base when it went missing, according to the AP.
Bad weather with waves of up to 20 feet had complicated the search, but Argentine Navy Capt. Gabriel Galeazzi said Tuesday that weather conditions were improving, allowing search efforts to intensify.
Meanwhile, the families of those aboard the missing sub were left with little to do but wait and hope. Leandro Fabian Cisneros a mechanical officer, is one of those aboard, his family said. He was married on May 19, they said.
"It's very hard, because we are trying to stay calm," Fabian’s sister, Noelli, said in a phone interview on Monday.
"We can't lose hope," his mother, Yolanda Susana Mendiola, said. "I'm certain they aren’t communicating because of the weather. They have to be OK because the submarine was well equipped.”
"Today is a critical day," said Maria Victoria Morales, the mother of Luis Garcia, an electrical technician aboard the vessel, according to Reuters. "We are holding up as well as we can."
Keir Simmons is a London-based foreign correspondent for NBC News.