“Relax! It’s not calculating longitude at sea.”

In the 18th century, before the advent of either rocket science or brain surgery, this is what folk would say to put the difficult and complicated problems of their peers in perspective. Described as the great scientific challenge of that century, the problem of knowing longitude at sea, and thus where your ship is, caused frequent shipwrecks and hampered the emerging global trade of goods. In 1714, the British government put a price on the problem—£20 000 for a method of determining longitude within 30 nautical miles. Half a century later, the Longitude Prize was won by Yorkshire watchmaker John Harrison and his H4, the marine chronometer.

Three hundred years later, the Longitude Prize is being reborn. Styled as the Longitude Prize 2014, with a reward of £10 million, it aims to find and tackle the greatest scientific challenge of our time. Exactly what that challenge is will be decided by a public vote.

The list of potential challenges have been shortlisted down to just six:

• Flight: How can we fly without damaging the environment?
• Food: How can we ensure everyone has nutritious sustainable food?
• Water: How can we help people with dementia live independently for longer?
• Antibiotics: How can we prevent the rise of resistance to antibiotics?
• Paralysis: How can we restore movement to those with paralysis?
• Dementia: How can we help people with dementia live independently for longer?

All very pertinent questions, provoking a Sophie’s choice for the voting public. They, and the Longitude Prize 2014, will be formally introduced to the public on the BBC Horizon programme airing tonight at 9pm. There is a strong emphasis that this is something the whole of the UK can have their say on—a democratic act of science. The conversation is being propagated online with the #LongitudePrize hashtag (something John Harrison never had to deal with).

The Longitude Prize 2014 was officially launched on Monday at New Broadcasting House by Astronomer Royal Lord Rees and a melange of BBC Horizon presenters. Standing next to Harrison’s historic H4, Lord Rees criticised awards like the Nobels for “rewarding geriatrics for work done decades earlier.” Instead, a challenge prize like this will reward innovation and boost young, fresh talent. Tony Hall, director general of the BBC described the aim of the prize to “ignite a spark to inspire curiosity in everyone.”

The challenges posed are all equally worthy, but which one will receive the £10 million bounty?

Saleyha Ahsan, A&E doctor and BBC Horizon presenter, described spinal cord paralysis as “the one thing that still confounds us as doctors.” In the UK, a person is paralysed every eight hours, and the effects—not just loss of mobility, but incontinence, sexual dysfunction, spasticity, and contractures—can be devastating. Rehabilation can be laborious but neural interfaces, nerve stimulation, and wearable devices all hold a lot of promise for the future. Ahsan offered a glimpse of what that future might look like. Her friend and volunteer, Sally Morgan, a young woman with a spinal cord injury, moved from her wheelchair to an industrial looking contraption. However, once strapped in to her robotic exoskeleton, Sally was able to stand up and walk around, albeit slowly and noisily. Personally, this feat of science fiction made scientific fact was mind blowing. Being able to stand and walk again has had a major positive effect on Sally’s state of mind but Rex—the exoskeleton has a name—is still expensive, slow, and cumbersome. Could the Longitude Prize 2014 be won by a similar device that could fit under someone’s clothes?

With the publication of a report by the WHO last month, it seems that the world may finally be waking up to the reality of antibiotic resistance. BBC Horizon presenter Liz Bonnin suggested that, based on our current drugs, we might reach the post antibiotic era in as little as 20 years time. I recalled my time with a paediatric infectious diseases consultant, who admitted that extensively drug resistant TB (XDR-TB) is the one thing that frightened him. This challenge would involve the race to develop a cheap, quick, point of care litmus test to distinguish between bacterial and viral infections. In my opinion, the genius who can convince people that they do not need antibiotics for their cold or sore throat equally deserves £10 million.

Equally universal is the oncoming tide of dementia that we can expect. Anaesthetist and BBC Horizon presenter Kevin Fong related that currently around two in three people with dementia live at home and live well. The challenge here is how to enable more people with dementia to live independently and well for longer. Fong was joined on stage by one possible solution: Linda the robot. Looking like the robot from Lost in Space, Linda passive aggressively reminded Kevin if he had tied his shoelaces that morning. An almost living aide-memoire is one response to the challenge of people staying safe in their own homes (although I couldn’t shake the feeling that Linda the robot would surely kill us all).

Michael Mosley tackled the challenge of food. The western diet, which many aspire to enjoy, as well as being full of fat and sugar, is rich in meat. A good source of protein, yes, but very inefficient. It takes more than 10kg of biomass input to get 1kg of meat as the output. On a crowded, resource starved planet this can’t continue. One solution is insects. Insects are rich in both protein and fibre, and are efficiently and ethically produced; the only downside is that they’re creepy crawlies. The gracious host Mosley shared around a platter of mealworms, locusts, and scorpions to those in the front rows. Fortunately, I was too far back for his hospitality. The solution to this image problem may be Waitrose stocking insects as the latest health food. Think of the Notting Hill dinner parties.

Air travel remains a significant source of CO2 emissions, cancelling out all the green work happening down on the ground. By 2050, it could account for 15% of all man made global warming. The problem is not carbon neutral flight. Helen Czerski, BBC Horizon presenter, showed footage of her in a solar-electric hybrid plane for two people—a slightly futuristic, slightly unsettling experience. The problem is carbon neutral flight for the masses. Electric batteries are too heavy to sufficiently power a 747-sized aircraft, and solar powered planes are too slow and their wingspans too great. With a focus on travel in a globalised world, this challenges recaptures the essence of the original longitude prize.

The last challenge is water. Although we live on the Blue Planet, 98% of our water is too salty for drinking. Forty four per cent of the world population and 28% of agriculture is in regions where water is scarce. Worse still, desalination plants are expensive and, unsurprisingly, not great for the environment. Creating a cheap, sustainable, and low carbon process of desalination is the most globally minded challenge. “The 21st century,” Kevin Fong added, “is going to be about water.”

Prepare to hear a lot more about these ideas as there’s £10 million at stake. The public vote opens after the BBC Horizon programme “The £10 Million Challenge,” which airs tonight, and concludes on 25 June. The fight against antibiotic resistance versus actuating people with dementia, with both scrapping against sci-fi exoskeletons. It’s a tough choice. As tough as calculating longitude at sea.

Rhys Davies is a final year medical student at Imperial College London. He is currently working as a Clegg Scholar in The BMJ offices.

Read The BMJ‘s News story on the 2014 Longitude Prize