A Norwegian team is set to embark on an expedition to find the submerged wreck of a plane which carried Norway's great polar explorer Roald Amundsen.
Amundsen was aboard a Latham 47 sea plane when the aircraft disappeared over the sea on its way to the Arctic island of Spitsbergen in 1928.
Two ships will set sail from the Norwegian city of Tromso on Monday to begin the two-week expedition.
The team will use an underwater robot to scan for the plane using sonar.
Between 1910 and 1912, Amundsen led the first expedition to reach the South Pole, reaching the target some five weeks before his British rival Robert Scott.
On 18 June 1928, Amundsen joined a rescue operation to save another rival: Umberto Nobile.
The Italian aviator had crashed his airship Italia on a return voyage from the North Pole. Nobile and his surviving crew members found themselves drifting helplessly on pack ice.
Amundsen boarded a Latham 47 sea plane along with a team of French Air Force pilots to try to reach them.
According to experts involved in the 2009 expedition, the Latham 47 should have been about 19 nautical miles south of Bear Island when the plane's last radio message was picked up at 1845 on 18 June.
The 2009 search will be headed by New Zealander Rob McCallum, a veteran expedition leader and project co-ordinator. He will be joined on the team by Nicolay Jacobsen, a great-nephew of Amundsen.
Mr Jacobsen said: "If we were to find something, it would be really amazing... I feel really excited and the rest of the family are too."
He added: "If we can find some leads to strengthen some theories, or can help in some way to find out what actually happened, then it will be even more interesting."
Two ships will work together on the search: the Royal Norwegian Navy vessel KNM Tyr and its larger supply vessel, the Norwegian Coast Guard ship KV Harstadt.
Together, they will scour some 117 sq km (45 sq miles) of sea floor for the downed plane. State-of-the-art technology will be crucial to the search.
The expedition will use an autonomous underwater vehicle (AUV) called Hugin 1000, capable of making high-resolution maps of the sea bed.
The sonar-equipped AUV can function independently for about 12 hours. After this, it will need to be brought aboard the Tyr for the data to be downloaded.
The Tyr will also deploy a tethered underwater robot called Scorpion 21. This remotely operated vehicle (ROV) is equipped with an HDTV camera and receives power from the ship.
This means it can be used in the water for as long as necessary.
KNM Tyr will set sail at 0800 on Monday from Tromso; the KV Harstadt will follow at 1600.
A camera crew from German production company Context TV will be filming the search efforts for a documentary about Amundsen.
Several items belonging and purporting to belong to the plane have been found over the years. In August 1928, during the original rescue operation for Amundsen and the French crew, the left wing pontoon of the Latham 47 plane was recovered from the sea.
A piece of the fuel tank was found a couple of months later near Trondheim in Norway.
A trawler may have recovered one of the Latham's engines in 1933. Unfortunately, it disappeared into the sea again. Then, in 1964, a double sheet of plywood which may have belonged to the aircraft was found near Svalbard.
© 2009 - BBC NEWS