Solar Impulse 2 has successfully completed the first two legs of its historic round-the-world flight. The plane took off from its base in Abu Dhabi a few minutes before midnight on March 8th and touched down in Muscat, Oman 10 hours later. That’s a flight of 273 miles using only the sun for power. The craft has already taken off again and is on the ground in Ahmedabad, India — 910 miles with not a drop of fossil fuels. That’s impressive, but it’s only the beginning of Solar Impulse 2’s journey across the globe.

The crew reports Solar Impulse 2 is working extremely well. Engineers inspected the plane after its landing in Muscat to make sure nothing had gone wrong on the first leg, which was piloted by co-founder Andre Borschberg. With the batteries once again juiced up, the pilots swapped places and pilot Bertrand Piccard took off early Tuesday local time. Solar Impulse 2 will be inspected once again before taking off for the next flight to Varanasi, also in India.

Solar Impulse 2 is capable of speeds nearing 100 mph, but the maximum for this trip around the world will be about 60 mph. The crew decided to take the first leg a little slower at 45 kph (28 mph) to make sure everything was going as planned, but the second leg of the journey was flown at increased speed.

After a few more stops across Asia, Solar Impulse will begin the most challenging leg of the journey — a flight from Nanjing, China to Hawaii. This won’t just be an overnight trip as all previous legs, but is expected to take about five days, and only one person can fly in Solar Impulse at a time. To make this feat possible, the plane has a computer system that can sound the alarm if anything unusual happens, allowing the pilot to sneak in 20 minute cat naps throughout the trip. The pilot will wear a visor that flashes a series of lights if anything requires his attention and a special armband will vibrate if the plane pitches more than five degrees.

Solar Impulse 2 is a fantastic technical achievement completely independent of the round-the-world journey. Each square meter of the plane’s carbon-fiber body weighs only 25 grams. The wings of the craft are covered in more than 17,000 tiny solar panels, each one linked to the plane’s 1,400-pound lithium-ion battery array. It stores enough power for the plane to keep running all night, but no juice is wasted on luxuries like heating the cabin. It will also save power by climbing to higher altitudes during the day and descending slowly over the course of the night.

The full flight will take several months to complete when you account for the layovers and potential weather delays. Still, it’s amazing to know a machine exists that can get around the entire globe without any fuel. You can follow Solar Impulse’s progress on the official site.