Passengers aboard the stranded Russian ship Akademik Shokalskiy were getting ready to end their Antarctic adventure, now that the weather conditions have improved enough to attempt rescue-by-helicopter – but there’s another delay.

The Australian Maritime Safety Authority’s Rescue Co-ordination Centre said it was now unlikely the rescue will go ahead today.

Here’s why:  52 passengers – a mainly Australian group of scientists, journalists and tourists – were to be flown out in small groups, using a helicopter on board the Chinese icebreaker Xue Long, or “Snow Dragon”.  From there, they were supposed to be ferried by barge to the Australian Aurora Australis icebreaker.

But for that plan to work, both the Chinese and Aussie ships must be in open water, and the Xue Long got stuck in the ice.  The helicopter is too heavy to take the passengers directly onto the Aurora Australis, meaning the Xue Long is the only place it can land once it picks up passengers.

"This rescue is a complex operation involving a number of steps. Operations in Antarctica are all weather and ice dependent and conditions can change rapidly," said The Australian Maritime Safety Authority’s Rescue Co-ordination Centre.