Longitude Prize 2014: The challenges
To commemorate the 300th Anniversary of the original Longitude Prize (for the invention of a clock that could keep time at sea), a new prize has been launched to encourage inventors and scientists to find solutions to six key problems facing the world.
These themes are being put to a public vote to determine which of the six will become the winning prize challenge.
More people are developing dementia with a great personal and financial cost to society. With no existing cure for dementia, the organisers of the prize say there is a need to find ways to support a person's dignity, physical and emotional wellbeing and extend their ability to live independently.
Alzheimer's Research UK says that 820,000 people in this country suffer from dementia and 25 million have a close friend or family member with the condition. The annual financial cost of dementia to the UK is estimated to be about £23bn.
"We might live well in our old age, if properly cared for and properly looked after," said BBC Horizon presenter Kevin Fong.
"So technology that allows us to live our lives as long and as fully as possible is all important."
If dementia wins the vote, the challenge will be to develop intelligent, yet affordable technologies that revolutionise care for sufferers, enabling them to live independent lives.
Dr Fong added that the number of people with dementia would grow to a million within the next decade.
"This is an essential challenge: it is something we face going into the future in quite horrendous proportions," he said.
The rapid growth of air travel needs to be managed to help tackle the threat of climate change. The organisers say the potential of zero-carbon flight has been demonstrated but it has had little impact on the carbon footprint of the aviation industry, which still relies on fossil fuels.
So far, green flights have been achieved with small aircraft running on solar or battery power, but these have either been over short distances or on flights carrying only a few people.
For example, in 2013, a plane flew across the US on solar power alone, but the 63m-wingspan aircraft built by Solar Impulse was designed to carry only a pilot.
Another innovative aircraft is the Pipistrel Taurus electrical aircraft, which won a Nasa green aviation prize in 2011. The aircraft had to fly 200 miles (322km) in less than two hours and use less than one gallon of fuel per occupant, or the equivalent in electricity.
If flight wins the vote, the challenge will be to design and build a zero-carbon aeroplane that is capable of flying from London to Edinburgh, at comparable speed to today's aircraft.
By 2050 there will be an estimated 9.1 billion people on the planet and there will be increased demand for resource-hungry foods such as meat and milk. Yet even now, many people do not get enough nutrients to live healthy lives.
BBC science presenter Dr Michael Mosley commented: "Worldwide, malnourishment is a huge issue.
"One of the biggest deficiencies is in protein. The other problem is that the way we produce protein is incredibly inefficient."
The meat-rich western diet that many aspire to enjoy incurs huge environmental costs. Increasing demand for meat may raise grain and land prices and commercial fishing practices can deplete stocks relied on by subsistence fishing communities.
If food wins the vote, the challenge will be to invent the next big food innovation, to help ensure a future where there is enough nutritious, affordable and environmentally sustainable food that people want to eat.
Dr Mosley said encouraging people to eat insects has been proposed as one solution. "They are incredibly rich in fibre and protein. They don't mind being farmed and there are very few ethical issues around farming insects. They are incredibly efficient," he explained.
A report in 2013 by the UN Food and Agriculture Organization said insects "underutilised" as food for people and livestock. But it said consumer disgust continues to be a barrier.
Paralysis can emerge from a number of different injuries, conditions and disorders and the effects can be devastating for those affected.
But in recent years, major advances have been made in wearable devices such as robotic exoskeletons, in brain-computer interfaces that can be used to control assistive technology, and in regenerative medicine. These areas have the potential to significantly boost the quality of life of those with paralysis.
At the launch of the Longitude Prize in London on 19 May, Sophie Morgan, who has a spinal cord injury, tested an exoskeleton called Rex. She said: "I've been psychologically affected by talking to people at eye level and there are health benefits. Already, I'm sleeping better, feeling better, my body is getting better and the pain is gone."
A leading scientist in the field, Miguel Nicolelis of Duke University is planning to demonstrate a mind-controlled exoskeleton at the opening ceremony of the World Cup this summer.
If paralysis wins the vote, the challenge will be to come up with a solution that gives paralysed people close to the same freedom of movement that most of us enjoy.
Some 98% of our planet's water is too salty for either drinking or agriculture. In addition, 44% of the world population and 28% of the world's agriculture are in areas where fresh water is scarce.
Dr Kevin Fong said: "It is something that's very much about health, but will also have massive economic and massive political impacts."
When drought his agricultural regions, for example, food prices rise.
As water demand grows and reserves shrink, many are turning to desalination - but current technologies are too expensive - requiring significant upfront investment - and inefficient.
In addition, desalination plants also produce contaminants, usually in the form of a concentrated brine.
If water wins the vote, the challenge will be to alleviate the growing pressure on Earth's fresh water by creating cheap, environmentally sustainable desalination technology.
The World Health Organization (WHO) estimates that antibiotics add an average of 20 years to all of our lives. But since the discovery of penicillin in the early 20th Century, overuse of these drugs has led bacteria to evolve resistance, leading to the emergence of untreatable superbugs that threaten the basis of modern medicine.
Broad spectrum antibiotics are often prescribed to patients because doctors have to act quickly on imperfect information.
There is also widespread use of antibiotics in agriculture, to treat infection in livestock.
These practices are contributing to the growing global threat from antibiotic resistance. The WHO has warned of a "post-antibiotic era", where key antibiotic drugs no longer work, and people die from simple infections that were previously treatable.
If antibiotics wins the vote, the challenge will be to create a cheap, accurate, rapid, and simple test for infection that will allow medical professionals to better target their treatments - administering the right antibiotics at the right time.
Horizon presenter Alice Roberts said: "One of the things we need to do is come up with new drugs. The other is to tackle over-prescription. Perhaps one idea is to very quickly and rapidly diagnose somebody to tell the difference between a bacterial infection and a viral infection. We're treating viral infections with antibiotics which are useless."