The Solar Impulse 2 crew said Wednesday the record-breaking aircraft was set to take flight early this morning.

Dependent on weather, the crew for the plane — attempting to travel around the world powered only by the sun — said the aircraft would depart from Kalaeloa Airport at 5 a.m. today. Solar Impulse 2 needs sunny weather, light wind and no risk of rain for a successful departure.

Solar Impulse 2 pilot and co-founder Bertrand Piccard will fly to Moffett Airfield in Mountain View, Calif., south of San Francisco. The flight from Hawaii to California will take approximately three days.

The public was invited to attend the takeoff at Kalaeloa Airport. Victoire Margairaz, spokesman for Solar Impulse 2, said Wednesday afternoon roughly 500 people had registered to attend.

The sun is the only source of energy for Solar Impulse 2. The plane’s wings were built using more than 17,000 solar cells, four electric motors and lithium batteries to replace the need for fuel. Its 236-foot wingspan matches that of a Boeing 747 jumbo jet and it weighs the same as a family car with the power of a small motorcycle. Solar Impulse 2 has a team of 80 engineers and technicians.

Solar Impulse 2 has been sitting in Kalaeloa Airport’s Hangar 111 since it arrived in July, when more than 250 residents gathered at the airport to watch the historic landing.

Swiss pilot Andre Borschberg touched down in Hawaii upon his arrival from Japan after five days and nights in the air, marking the longest solar flight both by time and distance.

The goal for the flight was to show the capability of clean energy, Borschberg said after landing.

Hawaii was the first of four U.S. destinations for the plane. After California, Solar Impulse 2 will make an as-yet-undetermined stop in the Midwest, followed by a landing in New York.

Since leaving Abu Dhabi, United Arab Emirates, in March 2015, the plane has traveled to Muscat, Oman; Ahmedabad and Varanasi, India; Mandalay, Myanmar; Chongqing and Nanjing, China; and Nagoya, Japan.

Together, Piccard and Borschberg will rack up about 500 flight hours during the around-the-world voyage in the plane’s 4-by-61⁄2-foot cockpit.