An Argentine submarine with 44 crew members on board has been missing since Wednesday, according to reports from the nation’s Navy.  Search and rescue efforts are ongoing, and have now been bolstered by both U.S. Navy and NASA aircraft.

Argentinian navy spokesman Enrique Balbi told reporters on Saturday that the ARA San Juan submarine was last seen in the San Jorge Gulf, not far from the coast of southern Argentina’s Patagonia region.  The vessel was underway from Argentina’s Tierra del Fuego archipelago, en route to its home base in Mar del Plata.  The Navy has had no communication with the ARA San Juan since, and has no further information as to its whereabouts or condition.  Had the submarine not gone missing, it would have been due to arrive on Sunday.

“Detection has been difficult despite the quantity of boats and aircraft [in the search],” Balbi told reporters. “Obviously, the number of hours that have passed — two days in which there has been no communication — is of note.”

The Argentinian government search efforts have seen participation from both ships and aircraft, and the U.S. Navy recently began aiding the effort.  It is possible that if the submarine went down, members of the crew may still be alive.  Officials hope that the submarine’s crew may still have the capability to bring the vessel back to the surface even if otherwise disabled, as it would dramatically increase their chances of finding it before it’s too late.

“The submarine knows that if it does not have communication with land for this long, it has to surface,” Balbi said.

Aside from the physical effort, the Argentine government has called on “all terrestrial communication stations along the Argentine coast to carry out a preliminary and extended search of communications and to listen into all the possible frequencies of the submarine.”

According to a statement made by the U.S. Navy’s Southern Command, a P8-A Poseidon has been deployed to the region to assist in the search effort on Saturday morning.  The same aircraft, as well as its 21-person crew, has recently seen action supporting “counter-illicit trafficking patrol operations,” as well as search and rescue efforts in April for a missing South Korean ship in the South Atlantic.  It was also called into service in support of recovery operations following Hurricane Maria. The statement read,

The aircraft and its 21-person crew will depart El Salvador’s Comalapa Air Base, where it was supporting counter-illicit trafficking maritime patrol operations. Once in Bahia Blanca, they will join the ongoing international search for the Argentinean Navy vessel and its crew, as requested by the government of Argentina.”