Uncapped edges: spacecraft will be equipped with thermal "armor" for different planets

Software algorithms developed by Russian scientists will make it possible to quickly calculate the thermal protection of spacecraft during the preparation of interplanetary flights and landings on other planets. They take into account the specifics of each mission, including the density of the atmosphere of a celestial body, the speed and angle of entry of the device into it. In the future, the development may help to create spacecraft capable of visiting different planets in one flight. However, according to experts, this requires not only software solutions, but also suitable materials and structures.

How do spacecraft withstand thermal overload

Accounting for thermal loads is one of the most difficult tasks in the design of space technology, which requires the use of methods from aerodynamics, aerothermodynamics, heat distribution and other fields.

—The conditions for landing on different celestial bodies depend on gravity, the presence of the atmosphere, its composition, as well as the speed of the vehicle, the angle of entry into the atmosphere and many other factors," explained Alexander Bon, one of the developers, project manager of small spacecraft at the MAI Space Technology Center.

Photo: Global Look Press/NASA

For example, due to the thin atmosphere of Mars, the lander slows down less efficiently than on Earth, but it still experiences intense aerodynamic heating when entering the atmosphere. Therefore, materials capable of maintaining integrity at high temperatures are needed. They differ from ablative coatings, which protect the device by gradually destroying and removing the substance from the surface.

On Venus, the materials of the lander must withstand the effects of sulfuric acid droplets contained in the cloud layer. This requires taking into account their chemical resistance even at the design stage. Saturn's moon Titan has an atmosphere composed primarily of nitrogen, but it also contains methane and complex organic compounds. When designing the lander, it is necessary to take into account not only its interaction with the gas shell, but also the effects of ionizing radiation, the specialist explained.

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How to visit multiple planets in one flight

The ability to quickly assess the parameters of thermal protection is especially important at the early stages of design, when engineers are looking for the optimal design of the spacecraft, said Alexander Bon. Optimization methods are integrated into the software package to speed up calculations.

— For example, if an engineer changes the materials or flight path of the device during the design, the program uses the information already accumulated to obtain a quick approximate result, and then refines it using a complete physical model. This approach avoids repeated calculations and saves supercomputer resources," the developer said.

The algorithms were tested experimentally. The laboratory has produced samples of multilayer panels that simulate the thermal protection of a spacecraft wing. They were placed in a vacuum chamber, where they reproduced the conditions encountered by the returning vehicles upon entering the dense layers of the Earth's atmosphere.

The discrepancy between experimental and calculated data did not exceed 1.5%, which confirmed the accuracy of the method.

In the future, the team plans to expand the functionality of the software package. In particular, engineers will be able to calculate thermal protection schemes with active elements, for example, with forced heat removal systems or materials with variable properties, said Alexander Bon.

In the longer term, the development may be integrated into on-board computers of interplanetary ships. This will allow you to automatically select and prepare the appropriate type of thermal protective coating before landing on a particular celestial body.

Technologies for future spacecraft

— At the software level, this is a useful development, but for landings on several celestial bodies within the same flight, not only calculations are important. The materials and design of the ship must also meet this task and allow for parameter changes. These are difficult issues that have yet to be resolved. At the current technical level, multi—layer protection systems are used, individual layers of which can be dropped after each landing," astrophysicist and cosmonautics popularizer Vladimir Afanasyev explained to Izvestia.

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According to him, the development can also be useful when it is necessary to adjust the thermal protection parameters in a small range. For example, if the lander has to enter the dense layers of the atmosphere at a sharper angle than planned.

— On a conceptual level, I would separate the ship and the landers. The first one can deliver multiple modules to different targets. For each of them, the shield and the braking method will be designed for their own speed and atmospheric entry parameters. Fast algorithms will help you compare the spacecraft's approach trajectories with a celestial body in advance and choose the right thickness of protection," said Evgeny Vishnevsky, an expert at the National Technology Initiative for New Materials and Technologies.

However, special systems will be required to change the operating mode of the heat shield directly in flight, the expert noted. When developing them, you will have to find a compromise between the mass and reliability of the modules. For example, supplying cooling gas through a porous shield will require the installation of a tank, valves, and a supply control system, which will increase the weight of the structure.

Coatings with a fading outer layer have another feature: before reuse, it is necessary to evaluate the remaining protective material and, if necessary, restore it.

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— There are already precedents when one spacecraft visited several celestial bodies during one mission. For example, the Voyager 2 probe flew around four planets. However, landing on the surface of several celestial bodies during one mission and creating universal active thermal protection is an ambitious task, but it can be solved," said Dmitry Oliferovich, member of the Russian Cosmonautics Federation and head of educational programs at the National Center for Space Competencies.

The Voyager 2 probe

Photo: TASS/Zuma/ABACA

To do this, engineers will have to combine passive heat protection with active systems, the expert noted. Among the possible solutions are the modular architecture of spacecraft, redundancy of cooling circuits and built—in algorithms for rapid recalculation of protection parameters using artificial intelligence.