A Brazilian probe, launched from the state of Bahia, reached an altitude of about 32 kilometers and was able to take pictures of the Earth from the stratosphere. This equipment, which was lifted by a hot air balloon, passed through clouds made of ice crystals and reached an area where the horizon and the planet's curvature can be observed more clearly.
These images are part of the Naos Project—an initiative that uses stratospheric balloons for launches and recording what happens during the ascent. During the Olhar Espacial program last Friday (the 4th), science popularizer Marcelo Zuri explained the project's principle of operation and that the probe is capable of observing at high altitudes.
The second version of the project used a more complex probe equipped with new cameras and systems. The goal was to reach an altitude between 28 and 32 kilometers and record images of the so-called 'edge of space.' During the ascent, the equipment passes through clouds composed of ice crystals.
Altitude also affects the behavior of the balloon. As it rises, the density and atmospheric pressure decrease, allowing the gas inside the equipment to expand. Marcelo explained: 'When the pressure decreases, the balloon inflates.'
This process leads to the balloon increasing in size until it reaches the material's strength limit. Balloons used in these projects can reach approximately 35 kilometers in height, depending on the probe's mass, the balloon's size, and the amount of gas. Marcelo stated: 'These homemade balloons we use here for these projects can reach a maximum height of 35 km.'
The project balloon starts from a ground diameter of about 2 meters and can reach approximately 10 meters during ascent. Therefore, the team does not fill it completely before launch. The science popularizer explained: 'We never fill it completely. We always leave a good reserve so that it can fill up as it ascends.'
At an altitude of about 25 kilometers, the probe is already significantly higher than passenger airplanes. The view of the horizon also expands, providing a line of sight of approximately 700 kilometers in all directions. Marcelo noted: 'The view from above is so incredibly good that we can get an incredible line of sight, about 700 km in all possible directions.'
The altitude allows observation of the ocean even at a distance of about 170 kilometers from the coastline. The images also demonstrate the curvature of the horizon, although wide-angle cameras can cause spherical distortions. When the horizon passes through the center of the camera, Marcelo explains that the curvature corresponding to the perspective of that observation point can be seen.
Starting at approximately 20 kilometers in altitude, the curvature begins to be perceived more clearly and becomes increasingly obvious as the probe ascends. Marcelo said during the program: 'This is the curvature that this probe sees from above. It is roughly what you would see if you were there.'
