As with all great stories, the first round the world flight powered only by the Sun and without polluting emissions finished where it began.
When Solar Impulse 2 embarked on its improbable odyssey it was only meant to take five months. The damage inflicted on the aircraft during its crossing of the Pacific Ocean, however, stretched that to almost 18 months.
But for the mission control team in Monaco and the crowds who welcomed the aircraft back to Abu Dhabi, a year’s delay immediately became irrelevant as the plane touched down at Al Bateen Executive Airport.
The landing marked more than just a milestone in human ingenuity and adventure, no matter how remarkable.
It also represented the successful delivery of powerful messages about the power of renewable energy and technology, and about just what can be achieved with sufficient determination, courage and self-belief.
"Success isn't just measured by the fact that we got to the other side of the ocean or that we got back to where we started. It's about what we can bring to humanity," said Andre Borschberg, Solar Impulse 2's co-founder, co-pilot and chief executive after the flight's penultimate leg from Spain to Egypt.
“The most important thing is that this is a project that might inspire the younger generation.
“We hear so many times that things are impossible but if this project can show that the impossible really is possible, if this helps to change that mindset, then the project will have been a great success.”
If the effect of the flight is impossible to predict, the mission’s immediate outcomes are clearer.
By completing the world’s first solar-powered circumnavigation, the longest continuous flight by a single-person aircraft and the first crossings of both the Atlantic and the Pacific by a solar-powered plane, Mr Borschberg and partner Bertrand Piccard have secured themselves permanent entries in the annals of aviation.
They stand alongside the likes of Steve Fossett, Charles Lindbergh and Alcock and Brown.
After his successful, non-stop balloon journey around the world with Brian Jones in 1999, Mr Piccard was a record breaker even before Solar Impulse 2.
But in seeking out extremes of achievement and experience, the Swiss psychiatrist and adventurer has also continued his family’s tradition.
In 1960 Mr Betrand's father, the oceanographer and engineer Jacques Piccard, made history when he explored Challenger Deep, the deepest location on the Earth's surface, on board the bathyscaphe Trieste while his grandfather, the physicist and inventor Auguste Piccard, broke records in the early 1930s with a high-altitude balloon flights.
For solar technology historian John Perlin, Mr Borschberg and Mr Piccard’s latest achievements sit within a more recent history of solar-powered flight.
"Solar flight is slowly evolving into a real prospect for the future," said Perlin, author of Let it Shine: the 6,000-Year Story of Solar Energy.
“In 1980, Janice Brown opened the possibility of flying on sun power alone. She got off the ground and flew 3.2 kilometres at an altitude of almost two metres.
"Months later, in the same plane – the Gossamer Penguin – she flew more that 4,000 metres above the Earth.
"By 1981, Gossamer Penguin birthed the Solar Challenger, which became the first human flown solar-powered plane to cross the English Channel.
"Thirty-five years later the Solar Impulse 2 has taken solar flight to a new level by circumnavigating the globe. Who knows what's to come next?"
While some experts have discounted the possibility that Solar Impulse 2 will have any immediate effect on aviation, recent announcements by Nasa and Airbus suggest that electric and hybrid propulsion systems will soon play a key role in space exploration and small-scale commercial aviation.
In April, Nasa awarded a US$67 million, three-year contract to develop an advanced electric propulsion system that could be used by its deep space missions.
Meanwhile, the European plane maker Airbus and German industrial conglomerate Siemens announced they would be joining forces to develop aircraft that will be without conventional fuel, emissions and noise.
“We believe that by 2030, passenger aircraft below 100 seats could be propelled by hybrid propulsion systems,” Airbus chief executive Tom Enders said at the time.
Mr Borschberg, 63, an engineer and former fighter pilot, was delighted by the news.
“We are extremely happy to see that these technologies are finding their way into the road maps of big groups like Nasa and Airbus,” he said.
“By using the Sun as the sole source of energy, it gives us the possibility of flying almost forever and the next step would be to create an unmanned version of what we have and to let this fly in the stratosphere for six months.”
For social entrepreneur and energy activist Jeremy Leggett, Solar Impulse 2's circumnavigation has come at what he believes to be an "inflection point" in energy generation.
“We’re yet to see the real effect of the innovation that’s coming from all of these new technologies but people with the eyes to see agree that, for the energy incumbency, the writing is on the wall now,” says the founder of British company Solarcentury, a leading maker of photovoltaic, or PV, solar panels.
“It’s difficult not to feel sorry for the oil and gas industry. The average age of the employees, including all the graduates that they employ around the world, is 49 and the average retirement age is 55. This is an industry that is dying out.”
In part, the source of Mr Leggett’s optimism is the recent growth in the global market for solar power, which has doubled in size seven times in the past 14 years.
"I think the pace of change will only accelerate as people realise the manifest potential of renewables, and particularly the trio of solar, batteries and electric vehicles," said Mr Leggett, whose book The Winning of the Carbon War charts the progress made in renewable energy since 2013.
“In the utility industry there are now a clutch of major players who’ve said ‘OK, the game is up. Our business model doesn’t work any longer and we are changing 180 degrees’.”
He was referring to the 2014 decision by the world’s richest utility company, E.On, to focus on renewables.
The move, which was widely heralded at the time as the beginning of the end for traditional energy systems, was completed in January, when E.On’s new subsidiary, Uniper, assumed control of the energy giant’s fossil fuel assets.
This allowed E.On to focus exclusively on renewable energy, efficient grids and customer service.
For Mr Leggett, Abu Dhabi's support for projects such as Solar Impulse 2, Masdar City, the Zayed Future Energy Prize and the World Future Energy Summit shows its awareness of the broader shifts happening in the world energy market.
But UAE energy economist Mohammed Atif said the time for landmark projects was nearing an end.
“We’ve seen very positive signs of knowledge-building, around schools, around government and society about the viability of solar as a technology, which have highlighted the UAE’s strategy of being a clean-tech centre for the future,” said DNV GL’s regional manager.
“As well as providing education and research, the UAE is becoming a finance and project development crossroads and we’re also seeing manufacturers setting themselves up in the region.
“So if you look at the value chain in solar PV, the UAE has prepared itself all the way from research and development into manufacturing, advisory, finance and legal.”
Despite all of these preparations, Mr Atif believes further change is needed if the UAE is to move beyond a position of aspiration and fully embrace the disruptive potential of renewable energy.
“Given its economic cost, solar combined with energy storage technologies has the ability to disrupt the entire energy operation and planning model that we know today, but I think a lot of people haven’t quite grasped that,” he said.
“Here it still feels like the UAE is in trophy project mode. They have the biggest and they have the cheapest but we’d like to see an acceptance by the utilities that they have to change and transition their business model, and only then will we see a higher penetration of renewable energy into the system.”
Only posterity will be able to judge whether Solar Impulse 2's audacious landing will qualify as the UAE's historic E.On moment.
But one thing is certain – when it comes to the record books, Abu Dhabi’s place in the annals of aviation is now secure.
nleech@thenational.ae