Dr. Rex said that, this week, two small Twin Otter planes had flown to the ship, where an ice runway has been constructed, and left about an hour later with seven expedition members. All had urgent family or professional commitments, he said. The planes, with limited range, stopped in northern Greenland to refuel before heading to Canada.

But the rest of the scientific team and crew, more than 90 people in all, will remain on board for about two months longer than planned.

Dr. Rex said about a dozen alternatives for the resupply mission had been considered, but most had insurmountable obstacles related to the global outbreak. “The challenges of the coronavirus crisis are huge,” he said. The plan they developed is complex, he added, “but it is certainly doable.”

The approach will make use of two other German research ships that recently returned from the Southern Hemisphere. The ships will sail from Bremerhaven through ice-free waters north to the edge of the ice near Svalbard in mid-May, and rendezvous with the Polarstern, which will have left its location about 200 to 300 miles (320 to 480 kilometers) north at about the same time. Reaching the rendezvous location is expected to take Polarstern about a week.

The ships will most likely meet in a fjord in Svalbard, where the water will be calm enough to allow safe transfer of supplies and people.

Scientists and crew members who are leaving for the Polarstern will be quarantined in Germany beginning in early May and will be tested frequently to ensure they are not infected. (The Polarstern has remained free of infection so far.)

Dr. Rex, who was on the ship for the first leg of the expedition and will return on this mission, said that, following the rendezvous, the Polarstern would either return to its original location in the ice, or travel farther north.