Zephalto is making reaching the stratosphere more accessible than ever. The French Agency introduced its Celeste, a low-carbon space balloon designed to take passengers through the Earth's atmosphere. Up to six guests will board the 215-square-foot balloon and ascend nearly 100,000 feet off the ground for three hours. They can then take in panoramic views of Earth and dark space through the largest window on the market. The final part of the journey is a 90-minute descent back down to Earth. Flights are expected to launch in 2025.