Rapley joined the Science Museum as its director in September 2007 after a decade as the director of the British Antarctic Survey (BAS), which oversees the UK's scientific activities in the region. It was here that he gained a worldwide reputation as a climate change expert and his views will feed into the museum's new £6.5m gallery, which will open in 2010.
"The first part of the gallery will present evidence that climate change is real, driven by humans and is serious," Rapley says. "Then the main thrust will be to address the question of what we can do about it."
Climate change is a contentious subject and the Science Museum has already come under fire for its Does Flying Cost the Earth? exhibition. The show runs until October and is part of a series of temporary exhibitions in the Antenna Space looking at sustainability. Rapley feels that being criticised by both the environmentalists and the pro-flying lobby means the museum is getting it about right.
"We're trying different ways of presenting complicated and often controversial information, helping people find their own way through it and come to their own conclusions, and then giving them some options in terms of actions they might take.
"We are moving into unknown territory for museums, so sometimes we will make mistakes. If you are working on the edge, you will probably make mistakes; if you are not making mistakes, you are probably not working on the edge."
Does Flying Cost the Earth? is sponsored by the aerospace and defence firm EADS, while energy company Shell gave £2m to the recently revamped Launchpad gallery. Rapley is comfortable with such corporate backers, arguing that the museum "retains editorial control of content". Anyone expecting him to cast big businesses as the bad boys in the climate change debate will be disappointed.
Rapley says: "It seems to me, if you take the triangle of government, people and business, government has a role in setting the regulatory framework, people have a role because we control how we use carbon-intensive energy, but the big technological solutions will come from the corporate sector.
"They are the only ones who have the financial and intellectual capital and the wherewithal to change the world; the way things are built, transported and so on."
Rapley arrived at South Kensington with a strong scientific record, but no experience of working in museums, although he seems unfazed by this.
"You have to work quite hard at first, but you quickly spot the things that are the same and the things that are different. I may not have worked in a museum but all my career I have taken a special and active interest in what is called science and society, explaining to people what science is about and what science is being done."
Rapley was widely credited with revitalising the BAS and giving it a new direction and a clear purpose, something that would not go amiss at the Science Museum, which has been through a tricky few years.
Finding a middle way
Rapley was appointed by Martin Earwicker, the director of the National Museum of Science and Industry (NMSI), the umbrella body that comprises the Science Museum, National Media Museum, National Railway Museum and a storage facility in Wroughton.
Earwicker, who joined in May 2006 from the government agency, the Defence Science and Technology Laboratory, has had to steer the NMSI through ongoing disputes with staff over pay, a complex restructuring of the group and last year's knock-back by the Big Lottery Fund of a £50m plan to redevelop Wroughton.
More broadly, it is having to address the issue that all science-led museums face: the challenge of being both a scientific institution and a visitor attraction.
"Clearly all museums are struggling to find the right balance between drawing people through the door and fulfilling what you might call their higher purpose, which in our case is making people aware of and interested in science," Rapley says.
"I don't think we should become this techno-Disneyland of west London, but on the other hand there is no point existing at all if no one comes through the door."
One of the tools that Rapley believes will help the museum attract new audiences is technology. Its current Dan Dare and the Birth of Hi-Tech Britain exhibition is piloting the downloading of information to iPods and other portable media players, including mobile phones. Visitors can also contribute their thoughts about the objects to a wiki site.
But there is very different area that Rapley is also keen to pursue: "I think one of the biggest revelations I have had since I've been here is the extent to which a knowledgeable human is pretty much unbeatable in terms of giving somebody an insight into what they are looking at. I am keen to increase the number of curators on the beat, and the number of volunteers we have taking people on tours."
Duty to inform
Rapley's role means he does not have to worry about managing front-of-house work, human resources or finance. These are overseen by Jon Tucker, the former head of the museum who is now head of corporate services. This leaves Rapley free to concentrate on his aim of making the museum "the most admired in the world".
An important part of this will be making sure it becomes more relevant and addresses contemporary issues such as climate change. "We don't want to be seen as place where exhibits from the past gradually gather dust. We want to use our collection to illuminate how we got where we are and help us to figure how we might progress in the best possible way in the future."
His chances of success look better now the museum's finances seem to be improving, although it still has the threat of strike action hanging over it in the latest pay dispute. Rapley says he has an extra £1m a year to play with following a good settlement from the department of culture last year, combined with savings made by Earwicker's restructuring of the whole NMSI group.
On a practical level this means that, combined with sponsorship money and grants, the museum should be able to do more. As well as the climate change gallery, the museum has just heard that the Wellcome Trust has given £2.5m to revamp the Who Am I? gallery.
There is also a new plan for Wroughton following last year's lottery rejection. Plan B will cost about £11m and will involve joining together the two existing hangars that are in a reasonable condition.
Part of the scheme for Wroughton involves using it as a shop window for low-carbon technologies, which will be broadcast live to the climate change gallery in South Kensington. On top of that, next year is the centenary of the museum opening, which will be marked by a number of projects, including a reworked entrance area.
All this will be supported by Rapley's conviction that science deserves to be better understood. "I feel a huge responsibility as this is such an important institution. When I speak to scientists, they nearly always say the Science Museum had a significant influence on them when they were kids, and was part of the process that caused them to become professional scientists.
"As there has been a withdrawal from science, we have a big role in persuading children and their parents that science, technology, design and engineering are fun, exciting and hugely satisfying to be involved in."
Chris Rapley became the director of the Science Museum in September 2007. Before that, he spent 10 years as the director of the British Antarctic Survey.
His first degree was in physics from the University of Oxford. He then took an MSc in radioastronomy at Manchester University, where he spent time at the Jodrell Bank Observatory in Cheshire, home to the Lovell telescope.
After this he did a PhD in x-ray astronomy at University College London (UCL), a period that included a spell in the US as part of his work on an instrument that was accepted on a Nasa mission.
This was followed by 12 years as professor of remote sensing science at UCL and then time as the executive director of the International Geosphere-Biosphere Programme at the Royal Swedish Academy of Sciences in Stockholm.
In January 2008 he was awarded the Edinburgh Medal for his work on climate change.
He was born in 1947 and is married with two daughters.
The Museums Association is currently conducting a consultation on museums and sustainability. For more information, click here.