When explorer Bob Ballard says that he is taking on the greatest challenge of his career, it’s worth sitting up and paying attention.

Ballard is an underwater archaeologist and National Geographic’s Explorer-at-Large. He is the man who discovered the RMS Titanic in 1985, the Bismark in 1989 and the wreck of John F Kennedy’s PT-109 in 2002.

"Titanic was multiple expeditions. Bismark was multiple expeditions. We located President Kennedy’s PT-109 in the middle of the nowhere - now that was a needle in a haystack," reflects Ballard.

"But this is as daunting a challenge as we've faced."

Ballard latest deep-sea project is attempting to solve a mystery that many previously believed unsolvable – what really happened to Amelia Earhart on her final flight?

Amelia Earhart is a name synonymous with adventure, bravery and mystery. The famous aviator deftly traversed the world - and society - to pursue her passion for exploration. A passion that ultimately cost her her life.

Did she run out of gas and crash into the sea? Or did she make it to Nikumaroro and die on the island. Ballard and his team have used the most cutting edge technology across land and sea, autonomous vehicles and good old-fashioned digging to unearth the true final chapter of an aviation hero?

Expedition Amelia on NOW with a NOW Entertainment Membership hopes to finally bring closure to the incredible life of Earhart and discover and sort the fact from the myth.

Here are three reasons you need to watch this two-hour special.

1. It's an epic expedition on an unprecedented scale

National Geographic Channel
Expedition leader Allison Fundis and underwater archaeologist Bob Ballard

"The problem with this project was that it was a needle in a haystack," Ballard told BT TV.

"There are two main theories and they are hundreds of miles apart. One is that she crashed off the island of Howland and sank in 5,000 metres of water - which would take a particular approach to discover. Much like the Malasyian Airlines approach.

"The other theory is that she landed on Nikumaroro, died on the island and the plane washed off the island, tumbling down the side of a volcano."

Expedition leader, and chief operating officer of the Ocean Exploration Trust Allison, Fundis said: "We had some pretty cool technology on this project - we were prepared for any scenario we might find.

"We had to prepare for every terrain, we had vehicles on land and water. Remotely operated vehicles that meant we could go into places and get a quick look. We had scuba diver teams on standby.

"We were able to cover the entirety of the shore from the land to the depths of the ocean and we also had aerial drones to cover parts of the island that we couldn’t necessarily get to on foot."

Ballard added: "It was the most complicated expedition we’ve ever done and I’ve done a lot. This took us to new boundaries.

"I've really enjoyed conducting a symphony orchestra of talent and tools."

2. It's both a tribute and a celebration of Amelia

National Geographic Channel

Ballard and Fundis don’t want Expedition Amelia to only be a show about their project. They also want it to be a “celebration” of a feminist hero.

"Amelia, after her disappearance, continued to be such an inspiration for so many young people, especially young girls. She was a barrier breaker in the air and she was ahead of her time," said Fundis.

"She captured that spirit of being a pioneer and captured the attention of so many people - you can see that in the footage and ticker tape parades after she broke all the barriers.

"She lived her life on the ground in a way that made her an advocate for women and equality. She was a remarkable figure, who is still inspirational today. We really want to honour her legacy and tell her story in the best way possible."

Ballard has a more personal reason driving him on the quest for definitive answers.

"On a personal note, Amelia was born in Kansas and so was I. Not far away. And my mother was born in Kansas. And so was my grandmother," he said.

"They grew up, very intelligent women. My mum had to drop out of college to raise three children. Me, my brother and my disabled sister who she had to take care of. She was really inspired by Amelia. We wanted to celebrate Amelia’s life in this show and also find the closing chapter."

3. Conspiracies, adventure and missing skeletons - this story has it all

National Geographic Channel
Ballard is National Geographic’s Explorer-at-Large

"I felt like Sherlock Holmes trying to solve this mystery," chuckles Ballard.

And at times, this expedition does feel like it’s something out of a Conan Doyle novel.

Tiny clues scattered across islands – a compact and some freckle cream – could be vital evidence or red herrings.

There is discovery of a skeleton by British troops during the war, which was then transported and lost.

And then there are the many conspiracy theories about Amelia’s final days. One slightly more bold theory being that she was captured by the Japanese and kept as a prisoner of war. And what happened to her plane? Backers of her theory believe that her plane is hidden underneath an air strip.

"And I’m not into digging up air strips,” explains Ballard, who appears sceptical about that theory.

No matter how challenging and convoluted this investigation may be, Ballard is not showing any signs of flagging in getting answer.

"The hunt for Amelia is a really difficult hunt. And we love that," said.

“When I played tennis, I always liked to play someone who was better than me. You never want to play someone who was worse than you. It makes you play better.”

Watch this if you liked...

National Geographic Explorer, Save The Titanic: Treasures From The Deep, James Cameron's Expedition: Bismarck, Alien Deep with Bob Ballard, Drain the Oceans.

Watch Expedition Amelia on NOW with a NOW Entertainment Membership.

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