Many in the science sector hope Sackett, who next month becomes Australia's full-time chief scientist, will use her talents to revitalise science in Australia and restore its influence on government policy, after more than a decade in which funding has fallen, the views of some scientists silenced and ignored, and projects with short-term commercial gain have often won out over fundamental research.

An astronomer may seem a surprising choice for a scientific adviser on politically contentious issues. But the most important first step with any problem is asking the right questions, says Sackett, and astronomers are used to asking some of the biggest questions possible.

Finding answers to the cosmos depends on international networks of collaborators. And the impact of their work can be profound.

"As human beings what makes astronomy important is the view it gives us of our place in the universe and the world around us," says Sackett.

The issues that will come across her desk as chief scientist will also be big and complex and have real impacts on people's lives. Often their solution will require international collaboration, says Sackett, who replaces the Howard government part-time appointee, Jim Peacock, a CSIRO plant biologist.

Sackett says climate change is the biggest issue facing Australia; but the list is long - water, clean energy, public health, food security, nanotechnology, and genetically modified crops, to name but a few. The dire shortage of young people taking up scientific careers is another challenge the country must address for its future prosperity, but the new chief scientist's aim is broader still: to make "everyone in society feel more comfortable talking about science".

And if any scientific topic is guaranteed to capture public imagination, it is her passion: the cosmos.

WHEN growing up in Lincoln, Nebraska, the young Sackett did not have a burning desire to be a scientist. "But I was curious. I liked puzzles," she says. It also helped that her mother was an accountant and her father a computer hardware technician. "Numbers didn't frighten them, and that's always a good start."

In high school, she was keen to study biology and thought about a career in medical technology, but to do this she had to take physics, a topic others warned her would be a boring diet of pulleys and levers.

As often seems the case with scientists, it was an inspiring science teacher who changed her life course. "Luckily I had a truly wonderful teacher who made us realise that physics really was about everything," says Sackett, who went on to study at the University of Nebraska before gaining a PhD in theoretical physics from the University of Pittsburgh.

She believes many children are born with the natural attributes of a scientist. "They certainly are curious, and they expect the world to behave in a logical way." Ensuring these childhood qualities are not stifled during the education process is vital.

At heart, Sackett considers herself an educator, and has certificates to teach science at primary and secondary school. Early in her career she spent two years as a university physics teacher at a liberal arts college, Amherst College, in Massachusetts. Being exposed to students and staff with a wide range of interests was a "very useful experience".

But she was drawn back to full-time research and contemplation of the nature of the universe with a fellowship at Princeton's Institute of Advanced Studies. Most people there were also postdoctoral researchers, and "it was an extraordinarily lively place to be as a young scientist - in an environment where new ideas were basically what you had for lunch every day".

Big ideas are needed to understand the universe because it is a truly strange place. Only about 4 per cent - the stars, planets and everything we see, including ourselves - is normal matter. About 22 per cent is thought to be dark matter, and the remaining 74 per cent is the even more mysterious dark energy.

More than 70 years after the existence of dark matter was first proposed, no one yet knows what it is. Sackett says a better name would be invisible matter, likening it to an invisible elephant in a china shop. "You would probably deduce fairly quickly something massive was in the room, even if you couldn't see it."

Sackett may not have discovered the identity of dark matter, as she had hoped, but she revealed its location. With colleagues, she showed that it forms large, flattened disc-like structures which are aligned in the same direction as the stars in a galaxy, a characteristic which will help pin down possible contenders. She says a remarkable thing about astronomy is its use of technologies developed on Earth to tackle questions about the cosmos. "It's amazing to realise that the universe is described by the same physical laws, regardless of whether you're here, on Pluto, or 10 billion light years away."

During her time at Princeton, one of the big and "somewhat crazy" ideas that surfaced was to try to find planets in other solar systems using micro-lensing - a technique first proposed by Einstein in 1936.

After moving to the Kapteyn Astronomical Institute in the Netherlands, Sackett established in 1995 a network of astronomers across 12 countries to use this technique, in which the distant planet is detectable from the gravitational effect that its planetary system has on the passing light of a distant background star. "Most people thought it was a long shot," she says.

But in 2006 her planet-hunting team made world news by discovering what was then the smallest known extra-solar planet in our galaxy, and showed these Earth-like planets were likely to be more common than massive ones such as Jupiter. The headlines lasted only a day or two, but the discovery had taken more than a decade of work by dedicated researchers to perfect sophisticated techniques since used by other scientists for different projects.

The lesson, says Sackett, is the value of "blue sky" research, exploring the unknown, and taking a long-term view. And as chief scientist she will be stressing the need to allow our best brains to tackle projects that do not necessarily bring just short-term commercial gain. "I think fundamental research can be strengthened in this country."

Astronomers have long had a global approach to research for one simple reason. "You can't see all the sky from one place," says Sackett, who sits on international boards governing a range of astronomical facilities, including the Hubble Space Telescope, the twin Gemini telescopes in Hawaii and Chile, and the Giant Magellan Telescope, which will be the world's biggest optical telescope.

Bradley Smith, the executive director of the Federation of Australian Scientific and Technological Societies, says Australian science policy and funding must rely more on global collaboration if issues such as climate change and the threats of emerging disease are to be tackled effectively.

"Professor Sackett brings a wealth of experience in managing complex, international science projects. That perspective will be invaluable," Smith says.

Sackett's advocacy for women in science is also welcome when one of the big problems is finding the scientists, mathematicians and engineers Australia will need, says Smith.

Sackett makes history as Australia's first female chief scientist. Megan Clark was recently appointed the CSIRO's first woman chief executive.

Sackett says encouraging women in science is not just a matter of equal opportunity but of maximising excellence. "Given the challenges and opportunities we face, we need to make sure we are drawing on all of our strengths as a nation, all of the expertise, and innovative ways of thinking."

In a career path with "many twists and turns" she also spent some time as a science reporter for Science News magazine, which fuelled her enthusiasm for improving science communication.

She also says scientists must be free to speak out in controversial debates, even when their views conflict with government policy, because only then can the rewards of research be maximised.

Sackett's decade-long search for extra-solar planets brought her to Australia for the first time, to enlist astronomers in Hobart and Perth to her worldwide network. After realising it was "a lovely place to live as well as work" she was keen to make it her home, and has become an Australian citizen.

Five years after the fire, a new kind of telescope, SkyMapper, has been built and will start operating at Siding Spring soon. It will make deep, digital maps of the southern sky, forming a cosmic encyclopaedia for the world's astronomers.

On Mount Stromlo, the university's precision instrument makers, with the help of local industry, have completed two multimillion-dollar instruments for the Gemini telescopes, and have other big projects planned. It is the kind of public and private collaboration called for in a recently released report by an expert committee on how to revitalise the nation's innovation sector. Venturous Australia also recommends a massive increase in funding to offset the decline in government support for science and innovation, which has fallen, as a share of GDP, by more than a quarter since 1993.

The Federal Government is expected to release before Christmas a white paper on innovation. Kim Carr, the Minister for Innovation, Industry, Science and Research, says that boosting to full-time the role of chief scientist demonstrates the Government values "high calibre, independent scientific advice".

Sackett is not yet willing to comment on any of the controversial scientific issues on which she will be providing advice. "I haven't formulated firm opinions as the chief scientist. I would think that would be as expected, for someone who wants to champion evidence-based scientific thought."