After four days trapped in Antarctic sea ice, the 74 people aboard an expedition vessel could soon be freed. Two ice-breaking ships are expected to reach them on Friday.

The Chinese icebreaker Xue Long ("Snow Dragon") was about 15 miles (24 kilometers) from the vessel as of Friday morning, the icebreaker's captain said. China's State Oceanic Administration said the ship sailed through an intense cyclone to try to reach the stranded vessel as soon as possible.

But the Chinese ship is moving slowly because the ice is very thick, Capt. Wang Jianzhong told CNN by phone. He said he expects to reach the stranded vessel late Friday local time.

Meanwhile, the French icebreaker Astrolabe was within 17 nautical miles of the stuck ship and is expected to reach the trapped researchers and tourists a few hours later. And the Australian ship Aurora Australis is expected to follow.

"Between the three of them, we're hoping to get out relatively quickly," said Chris Turney, the expedition leader aboard the trapped ship and a professor of climate change at University of New South Wales in Australia.

Jianzhong said he's worried the extreme weather could cause the Chinese ship to get stuck itself. But even in that case, the French ship could help rescue the Chinese ship, Jianzhong said. If the French vessel also gets trapped, they would call for more help.

The Chinese crew is hoping to break the ice around the trapped Russian-flagged ship, so it can leave on its own. If an emergency arises, the Chinese team is willing to help those on board the Russian boat onto the Chinese one, Jianzhong said.

Sea ice locked up the MV Akademik Shokalskiy on Monday night. The crew members, researchers and tourists on board spent the next 12 hours hoping that high winds would subside.

They didn't.

A British rescue coordination center received a satellite distress signal Wednesday morning from the ship and contacted the Australian Maritime Safety Authority, which handles the Southern Ocean region where the vessel was stuck, a safety authority statement said.

But the passengers had to spend Christmas at a frozen standstill 100 nautical miles east of the French base Dumont D'Urville, about 1,500 nautical miles south of Hobart, Tasmania.

"We had a great Christmas," Turney told CNN via Skype, even though everyone was frustrated about not being able to venture out into the open ocean.

Despite the conditions, Turney said morale was "remarkably high."

"We just want to assure family and friends everyone is fine," he said. "The vessel is safe, and we're looking forward to getting home and having a decent cup of coffee soon."

The setback gave scientists more time to conduct research and study life under the sea ice.

"This is an area of enormous change. We're in an area of a big driver of global climate," Turney said. "We wanted to come here to see how much change has taken place."

Turney said everyone aboard the expedition vessel is scheduled to return to southern New Zealand by January 4.

Expeditions Online, a polar booking agent for the MV Akademik Shokalskiy, said on its website that the ship got stuck partway through her Australasian Antarctic Expedition towards Mawson's Hut at Cape Denison.

The Expeditions Online website described the ship as "a fully ice-strengthened expedition vessel" for working in polar regions.

"This class of vessel is world-renowned for polar exploration, because of its strength, maneuverability and small passenger numbers," the company's website said.