Record-breaking Solar Impulse 2 starts riskiest leg of longest ever solo flight

Record-breaking Solar Impulse 2 starts riskiest leg of longest ever solo flight
The Solar Impulse 2 solar-powered plane is starting its second bid to fly solo across the Pacific Ocean, and is set to land in Hawaii in about five days. The plane’s pilot has “passed the point of no return,” the mission’s website says.

The eighth leg of the journey was scheduled to begin from Nanjing in China, but bad weather diverted the flight to Japan, where it was delayed for a month.

However, once the weather cleared, Solar Impulse 2 – the second generation of this revolutionary solar-powered craft – took off from Nagoya Airfield in Japan at 6:03pm local time on Sunday (9am GMT).

"Andre Borschberg has passed the point of no return and must now see this 5 days 5 nights flight through to the end," Solar Impulse said on its website, meaning the pilot has no option to turn around and return to Japan.

If the pilot succeeds, he will have completed the longest solo flight in aviation history, plus the furthest distance covered by a solar-powered craft.

“We really are in the moment of truth now. It’s the moment of truth technically and in human terms as well. Can the plane manage it?” Conor Lennon, a member of the Solar Impulse team told the Guardian from the project’s headquarters in Lausanne, Switzerland.

The 62-year-old pilot will spend the flight strapped in his seat in a cockpit about the size of a telephone booth, and will have to endure temperatures of up to 55 degrees Celsius.

Borschberg will only be able to take 20-minute cat-naps, and says he will use yoga and meditation to get him through the ordeal.

Over the ocean, the plane should be able to take in enough energy to get through the night.

The pilot is prepared for all eventualities. If the plane fails, he has a dinghy and supplies for a few days while the team traces his location.

If Borschberg manages to complete this perilous Pacific leg, project co-founder Bertrand Piccard will take over for the crossing from Hawaii to the US mainland.

André Borschberg and his wife Yasemin at the takeoff from Nagoya. A very emotional moment!

A photo posted by Solar Impulse (@solarimpulse) on Jun 28, 2015 at 11:55pm PDT

The experimental aircraft has a 72-meter (236-foot) wingspan – larger than a Boeing 747 – and is bristling with 17,248 solar cells that power four electric motors. The plane weighs 2,300 kilos, about as much as an SUV.

Solar Impulse 2’s speed is comparable to that of a car’s, ranging from 36 km/h to 140 km/h.

This is the plane’s first flight over an ocean and it’s vulnerable to wind and precipitation.

READ MORE: Solar plane takes off on 1st ever round-the-world trip without fuel (VIDEO)

The trip is being sponsored by the Abu Dhabi government, Masdar, Omega, Google, and Moet Hennessey among others.

Solar Impulse 2 started its record-breaking journey on March 9, and the 35,000-kilometer route is split into 12 stretches, with a total flight time of some 500 hours.

The plane took off in Abu Dhabi, from where it flew to Oman, India, China and Myanmar.

Bertrand Piccard, psychiatrist and aeronaut, who made the first non-stop round-the-world balloon flight, and André Borschberg, an engineer and professional airplane and helicopter pilot, are the project’s fly guys.