French Guiana, Guyana: The location of Papillon and a space program

Even from the mainland I can see that they're beautiful. The Isles du Salut, the Salvation Islands, lie less than 20 kilometres from the shore of French Guiana and as I approach on Pro Marine's catamaran, their beauty only becomes more obvious. All three are fringed by palm trees, each dip their toes into the beautiful cyan waters of the equatorial Atlantic. Between them, dozens of sea turtles swim. The islands' obvious beauty, however, does not entirely protect them from rocket fire.

Of the many odd things about French Guiana (including the fact that France never really let it go), perhaps the oddest is that the semi-nation's biggest industry lies in outer space. The town of Kourou is home to the Guiana Space Centre, which shoots satellites into orbit at a near-monthly rate, right over the islands. Each time there's a launch they must be evacuated.

Despite the threat of annihilation, however, the islands are famous in their own right. The colonial French ran part of their infamous "bagne" programme here. The idea was to build a successful colony on the backs of convicts, inflating charges and handing out insane sentences in order to justify shipping them out here for hard labour. As Australia was to the British Empire, so Guiana was to the French.

In total about 70,000 men and 900 women were sent to Guiana over the years. Of this unhappy number, the most famous prisoner was probably Henri Charriere, a convict-turned-author who went by the nickname Papillon. His eponymous 1969 novel will turn 50 next year, and before that a remake of the 1973 film of the same name will be released with Charlie Hunnam taking over from Steve McQueen in the titular role.

Theoretically, then, the islands will be back in the limelight, but as I step off onto Isle Royale, the largest of the trio, it doesn't seem entirely ready for tourists. About 20 passengers go ashore, but no one is there to greet us. There isn't even a sign to explain where to go, and it soon becomes clear there's no guide, for French or English-speaking visitors.

Thankfully, in the centre of the island there's a small but excellent museum in one of the old officers' buildings. With detailed signage in English and French, it explains the cruel logic behind the bagne system, while also documenting some of the "famous" prisoners who were sent here. Charriere's write-up is not flattering: "Papillon never was an outstanding figure … he had bad relationships with the other convicts with whom he frequently quarrelled."

This seems surprising, given the amiable way he presents himself in the book, but it's perhaps easier to understand when you realise that Papillon's story wasn't his own, as he claimed, but rather a compilation of tales from prisoners over the years. Charriere died shortly before the release of the first Papillon film without acknowledging this perfidy. As Pascal Ufferte, manager of the Auberge Des Isles in the heart of Isles Royale, later tells me: "Papillon is mostly a true story – it's just not his story."