Daniel Politi

BUENOS AIRES, Argentina — Argentina’s Defense Ministry said Saturday night that it had detected seven communication attempts throughout the day from an Argentine navy submarine — with 44 crew members aboard — that has been missing since Wednesday.

“We received seven signals from satellite calls that originated from the San Juan submarine,” Defense Minister Oscar Aguad wrote on Twitter. “We are working hard to locate it and we are transmitting hope to the families of the 44 crew members: that they’ll soon be able to have them in their homes.”

The Defense Ministry said it is working with a U.S. company that specialises in satellite communication to determine the exact location of the signals.

“This changes everything,” said Fernando Morales, a navy expert and vice president of the Argentine Navy League. “It’s a very hopeful sign because it suggests at least several crew members are alive.”

To carry out the communications attempt, the submarine had to be close enough to the surface of the water to take out its antenna, Morales explained.

“It should move along relatively quickly now,” Morales said, characterising the signals as the first optimistic news since reports of the missing submarine began transfixing Argentina on Friday morning.

A U.S. Navy aircraft, a NASA airplane and a British Royal Navy ice patrol ship on Saturday joined the search for the missing submarine, the ARA San Juan.

The search was hindered by strong winds in waters off Argentina’s Patagonia, where the submarine was believed to be stranded, officials said. A day after playing down the severity of the situation, Argentine officials on Saturday signalled growing concern as they welcomed all international assistance.

“Detection has proved to be difficult despite the number of boats and aircraft,” Capt. Enrique Balbi, a spokesman for the Argentine navy, said in a televised interview Saturday. “Waves are of approximately 6 meters” — about 20 feet — “which makes it much more difficult.”

The Argentine navy is “accepting all possible or necessary help” in order to “not discard any hypothesis,” Balbi said, noting that search teams had scoured about half the area where they believed the submarine could be.

President Mauricio Macri went on Twitter on Friday night to say that his administration was “committed to using all the national and international resources necessary to find the submarine ARA San Juan as soon as possible.”

Macri also said his government was in touch with the family members of the crew. “We share their concern and that of all Argentines,” he wrote.

Pope Francis, who is Argentine, added his “fervent prayers” in a telegram Saturday.

The British navy’s assistance was notable given the war Britain and Argentina fought in 1982 over the Falkland Islands, which Argentina has long claimed as its sovereign territory. Both navies lost vessels, and nearly 1,000 military personnel died in the 10-week conflict.

The Protector, a British ice patrol ship, was expected to arrive at the search area from the Falkland Islands on Saturday afternoon, according to the British Embassy in Buenos Aires. In February, the ship was denied permission to dock in Buenos Aires, Argentine news media reported.

British officials have also put a C-130 Hercules aircraft stationed in the islands on standby.

A U.S. Navy P-8A Poseidon plane was expected to arrive in Argentina on Saturday night after being diverted from a counternarcotics mission in El Salvador.

In a statement, the U.S. military said the plane, the Navy’s newest maritime patrol and reconnaissance aircraft, has “state-of-the-art sensors and communication equipment, allowing it to support a wide range of missions over large bodies of water, including subsurface search-and-rescue operations.”

A NASA research plane had been dispatched late Thursday to assist in the search, the U.S. Embassy in Buenos Aires said.

Chile has dispatched an aircraft to assist with the rescue mission, and Brazil, Uruguay, Peru and South Africa have also offered help.

The missing submarine was 240 nautical miles from the coast when it was last tracked. It was traveling from the Patagonian city of Ushuaia to Mar del Plata, in Buenos Aires province, conducting a routine security patrol. Argentina’s three submarines are usually deployed to combat illegal fishing.

The submarine left Ushuaia on Nov. 8 and was scheduled to arrive in Mar del Plata on Sunday, according to the navy.