Zephalto: Pressurized Capsules and Stratospheric Balloons for Low-Carbon High-Altitude Flight

Zephalto: Pressurized Capsules and Stratospheric Balloons for Low-Carbon High-Altitude Flight

Between aviation and spaceflight lies the stratosphere, an operational layer that is increasingly attracting interest for both exploration and industrial use. Positioned above commercial air traffic yet below orbital regimes, this altitude range offers stable flight conditions, wide-area visibility, and repeated access without the complexity of rocket launches. While rockets provide access to orbit, they come with high cost and limited accessibility. Zephalto develops stratospheric balloon systems designed to carry passengers and payloads to altitudes of around 25 kilometers, above most of Earth’s atmosphere. The company combines aerospace engineering with balloon-based flight systems and pressurized capsules to enable controlled ascent and descent in near-space conditions. By positioning the stratosphere as a new operational domain, the approach aims to expand access to scientific research, observation, and human experience beyond conventional aviation.

Technology and Product

Operating in the stratosphere requires systems capable of maintaining pressure, thermal stability, and controlled flight at high altitudes. Zephalto develops reusable stratospheric balloons paired with pressurized capsules such as Céleste, designed to carry passengers and payloads in near-space conditions. The system uses lighter-than-air lift combined with controlled ascent and descent profiles, enabling flights of several hours with stable observation phases. The capsule integrates life-support systems, panoramic observation windows, and communication systems, while the balloon architecture leverages decades of research in high-altitude balloon flight. The overall platform is designed for both human flight experiences and scientific or industrial payload missions.

Stratospheric balloon systems enable controlled ascent to near-space altitudes of around 25 km. (© Zephalto)

Industrial Fit and Applications

Stratospheric platforms are particularly relevant in applications where high-altitude access, persistence, and lower operational cost are required. Zephalto positions its systems for space tourism, scientific research, atmospheric data collection, and technology testing. Use cases include environmental observation, and near-space experimentation. The platform is also used as a testbed for aerospace technologies and as an intermediate step between aviation and orbital missions. By enabling access to near-space without rocket launches, stratospheric flight can support new operational models across research, industry, and experiential applications.

The pressurized Céleste capsule is designed for passenger flights and scientific payload missions in the stratosphere. (© Zephalto)

Founding Team

Zephalto was founded in 2016 by aerospace engineer Vincent Farret d’Astiès, who established the company to develop low-carbon stratospheric flight systems. The company has since built a multidisciplinary team combining expertise in balloon engineering, aerospace systems, and high-altitude operations. Zephalto works in close collaboration with the French space agency CNES, integrating decades of balloon flight expertise into its platform development.