Nostalgia for the Light begins with what appears to be black-and-white close-ups of bullet holes on rugged skin, like photographs drawn from coroners' files of gunned-down people. But the images, it turns out, are of craters on the moon, formed millions of years ago.
The ambiguous scene is intentional. Chilean documentary maker Patricio Guzman's film brings together two groups of people - sky-gazing astronomers on the one hand, earth-turning women scouring a vast desert for the remains of their murdered husbands and sons on the other - and highlights the passion that links them together: a dogged pursuit of the past, whether it's through the light of celestial bodies reaching earth after travelling thousands of light years through space, or bodies exhumed from mass graves that testify to the atrocities committed by US-backed Chilean dictator Augusto Pinochet against his own people.
'The present doesn't exist,' Guzman said when we met at the Cannes Film Festival last year, where his film was shown as an out-of-competition entry. 'We're just made up of memories, and with these memories we construct the future.'
Remembrance and forgetting have been at the forefront of the 69-year-old director's work, as he has fought valiantly to remind his compatriots and the world of how the Pinochet regime tortured and murdered tens of thousands of dissidents during its 18-year rule.
His first film, The Battle of Chile, is an epic documentary that chronicles the rise of Salvador Allende's democratically elected socialist administration and its downfall in 1973 in a bloody CIA-backed coup d'etat. In 1997, he made Obstinate Memory, which reveals a growing collective amnesia in Chile about those dark days. And in the beginning of The Pinochet Case (2001), a group of people are seen combing through heaps of dust to look for the remains of their loved ones in what has just been revealed as a dumping ground for the bodies of regime victims.
Nostalgia for the Light, which is part the programme for the Hong Kong International Film Festival this year, shared similarities with The Pinochet Case by following a group of women who have been digging in the vast Atacama desert for the past 29 years with the hope of unearthing the remains of their relatives. They did find some, mostly small bones, but archaeologists believe most bodies had already been removed by the culprits, Guzman says.
'They know some of them were [exhumed and] thrown into the sea from helicopters ... because once a body washed up to the shore with wire wrapped around it,' he says.
The 'women of Calama', as they are known, worked not far from the astronomers' desert observatory where perennial clear skies offer ideal conditions for telescope observations. The studies of faraway galaxies, black holes and vanquished stars mirror the women's search for the truth, the dark past and what remains of the many young men and women whose lives were cut short before they could shine.
Guzman knows well of their pain: while shooting what would become of The Battle of Chile, most of Guzman and his crew were arrested by mutinous army units during and after the coup. His cameraman, Jose Silva Muller, was never seen again - until his remains were found several years ago. Guzman was subjected to mock executions before being released after two weeks. He fled first to Cuba, then Spain and France. He did not return to Chile until the late 1980s.
Guzman worked on The Battle of Chile until 1979, when the finished trilogy premiered to widespread critical acclaim at the Berlin International Film Festival. But the project took a personal toll - he suffered a breakdown soon after and didn't work for two years.
Guzman has since returned to helm a string of documentaries about Chilean history - he also made In the Name of God (about the Chilean Catholic clergy's resistance against the junta), Barriers of Solitude (about historical memory in a Mexican village) and Salvador Allende (a portrait of the deposed Chilean president).
It's a thankless task, he says - he spent five years working on Nostalgia because of the challenges in securing financial backing for the project (the film was completed with funds from Germany, Chile, France and Spain).
'Today documentaries could reach more people than 30 years ago,' he says. 'We are at a point when we have fatigue towards fiction films - it's always a repetition of action [scenes]. We need reflexive, contemplative cinema with more silence in it. We have to return to slowness, because life is like this.' Nostalgia for the Light could serve as an exemplar of such ethos.
Nostalgia for the Light, Mar 30, 9.30pm, Science Museum, Apr 3, 3.40pm, Space Museum