The launch of the core module of the space station is imminent. Why do we go to space for experiments?

The "Tianhe" core module of the space station is ready!

According to the China Manned Space Engineering Office, the countdown to the launch of the core module has entered and will be launched at the end of April 2021. This means that the prelude to the construction of my country's space station is about to kick off, which will be another milestone in China's manned spaceflight.

China's Tiangong Space Station will officially complete its on-orbit construction mission around 2022, becoming a long-term, manned, national-level space laboratory to support large-scale, multidisciplinary space science experiments.

The special location of the space station will provide conditions for carrying out space experiments, such as a microgravity environment.

When it comes to space, everyone will see astronauts floating around in the space station, as if they are completely out of the constraints of gravity. In fact, astronauts are not in zero gravity but in microgravity in the space capsule.

According to the original meaning of the English "Microgravity" of the term "microgravity", it means that the level of gravity in the environment is one millionth of the gravity on the earth's surface. Or "low gravity"), the value of low gravity at this time is usually one ten thousandth of the ground gravity.

How did microgravity conditions develop?

In microgravity, common physical phenomena on Earth can undergo incredible changes.

These phenomena are the physical effects of space microgravity in physics.

The physical effects of space microgravity generally refer to the basic physical effects in the space microgravity environment that are different from the gravity environment, mainly including the basic elimination of natural convection caused by gravity in liquids and gases, the disappearance of buoyancy in liquids, and the ups and downs and separations caused by different material densities. The layer phenomenon also disappears and so on.

So, what kind of scientific research can be carried out in such a special microgravity environment?

Fluids in Microgravity

Microgravity fluid physics studies the laws and mechanisms of the flow, morphology, phase transition of fluids (liquids, gases and their multiphase mixtures) in microgravity. In microgravity, the effects of gravity-induced buoyancy convection, density stratification, subsidence, internal fluid static pressure and pressure gradient basically disappear, but some secondary effects are prominent, and the flow regime and heat and mass transport show new characteristics.

The contents of microgravity fluid physics research include interfacial phenomena, multiphase flows, complex fluids, etc. Research in this field plays a very important role in the development of advanced space fluid management, thermal management and other aerospace technologies, and its research results will make positive contributions to improving the production process of terrestrial petroleum, chemical, manufacturing and other industries.

The main research contents of space fluid physics include microgravity fluid dynamics, two-phase flow, phase change heat transfer and its application research, complex fluids, etc.

For example, the liquid bridge liquid capillary convection experiment carried by my country's Tiangong-2 is of great significance to the basic research on the flow and dissipation mechanism of space environment fluids, and is of great significance to human understanding and grasping the motion laws of space fluids.

Material preparation under microgravity conditions

More than just fluids, materials science has a lot to offer in space.

Under microgravity conditions, convection control, diffusion mechanism, solidification process, and defect formation based on ground material preparation are no longer applicable. Exploring the material preparation process under microgravity conditions can deeply understand the corresponding physical laws, discover new scientific problems, and develop new materials that are difficult to prepare on the ground.

Microgravity conditions also facilitate container-free processing of sample suspension, which provides favorable conditions for material research under extreme thermodynamic nonequilibrium conditions and accurate material thermophysical property measurements. Almost all materials such as metals, non-metals and composite materials can be studied in microgravity, including various functional materials such as crystals, semiconductors, superconductivity, magnetism, memory, thermoelectricity, metal alloys, foam porous and composite materials, as well as ceramics, glass, etc. Structural materials.

Materials are the cornerstone of the national economy, and new materials are the foundation of all high-tech and high-end manufacturing. Space material science is a unique way to carry out material science research in depth. It is possible to obtain advanced materials that are difficult to produce on the ground and important parameters that are difficult to accurately measure on the ground, develop materials science and technology, and contribute to the establishment of a new material industry system in my country.

The field of space materials science includes two main research directions: one is to study the law of the preparation process of materials and the changes in the structure and properties of materials under the exclusion of gravity; Service behavior in space environment such as low temperature alternating cycle.

The main research contents include growth (solidification) interface stability and defect control, supercooling, nucleation and crystal growth process, phase separation and aggregation behavior, space preparation and process research of high-performance materials, measurement and research of melt physical properties, material in Behavioral characteristics in space environment, etc.

Space microgravity resources are an extremely useful and scarce resource that is not available on Earth. After the launch of my country's space station, the use of microgravity conditions in the space environment to conduct various scientific researches will make a significant contribution to scientific research and applications in various fields in my country. contribute.

Facing the mysterious and fascinating space, Chinese space workers have never stopped exploring. Let us follow their steps and look forward to the future of China's space industry!