What to do if you want to weigh yourself in space but always feel like you are floating? Astronauts have a "good helper"

A strong physique and abundant vitality are the "secret weapons" of astronauts to work and live in space for a long time. In a weightless environment, accurately measuring the weight of astronauts is crucial to tracking their health status and physiological changes. For astronauts on long-term missions, regular body mass monitoring can not only help adjust their diet and exercise plans and ensure a reasonable distribution of workload, but also make early predictions of potential space sickness and design effective safety protection measures to ensure that they can stay in the best condition even when they leave the earth.

Astronauts undergo medical examination

Weighing in space: a barometer of health

The environment of the space station is completely different from that of the earth. Astronauts not only have to deal with the physiological challenges brought by microgravity, but also have to overcome the psychological challenges that may be caused by enclosed space. When performing extravehicular activities, they must also face the potential damage to the body from cosmic rays. Being in the space environment for a long time may cause damage to organs such as bones, muscles, blood circulation and heart. Therefore, the space station must be equipped with advanced medical monitoring equipment to track the health of astronauts in real time. These devices can monitor key health indicators in a timely manner to ensure the safety of astronauts in space. In addition, after returning to Earth, astronauts will also need to undergo a long period of rehabilitation training to help them gradually adapt to the Earth's gravity environment and restore their body functions.

Astronauts' weight changes are often early signs of health abnormalities. In order to capture these subtle changes, astronauts will regularly use a special space "scale" to weigh themselves to see if they have "lost weight" or "gained weight." This monitoring not only helps to warn of potential health problems, but also provides important reference data for other health assessments.

A good helper for weight measurement——mass measuring instrument

The space station, like other satellites in Earth orbit, revolves around the Earth at a linear velocity between the first and second cosmic velocities. In this process, the space station and the astronauts in its cabin are actually affected by the Earth's gravity, but this gravity is completely converted into the centripetal force required to maintain rotation. Therefore, traditional lever-type or pressure-type weighing scales are like losing their magic in this environment and cannot measure the weight of objects or astronauts at all.

However, the Chinese space station is indeed equipped with a special "weighing scale" - a mass measuring instrument. This device can measure the weight of astronauts, but its working principle is completely different from that of traditional weighing scales.

The mass measuring instrument uses the principle of linear acceleration to determine the mass of astronauts based on Newton's second law. During operation, astronauts need to be fixed on the human body support and then pushed to a specific position. During the resetting process of the support, a constant force is applied by the constant force mechanism (composed of components such as cams, springs, fixed pulleys and wire ropes) to prompt the astronauts to perform uniformly accelerated linear motion. The grating ranging device is used to measure the displacement speed and time of the astronauts under the action of constant force, and then the acceleration is calculated. When the constant force is known, the mass of the astronaut is calculated by a formula. This method can accurately measure the mass of astronauts in a weightless environment, providing important data for health monitoring of the space station.

Quality measuring instrument upgrade

The first generation of mass measuring instruments successfully entered orbit with the Tiangong-1 target spacecraft. During the Shenzhou-9 mission, the three astronauts used this equipment to successfully complete the quality tests of human bodies, food packages, condensate tanks and other items. During the Shenzhou-10 mission, "space teacher" Wang Yaping explained and demonstrated the working principle and operation process of the instrument in detail to the global audience in her first space lecture.

During the demonstration, astronaut Nie Haisheng fixed himself on the bracket of the mass measuring instrument, and Wang Yaping was responsible for stretching the spring connected to the motion device to the preset position, and then releasing it, and the spring immediately rebounded to its original position. Through this process, the measuring instrument finally showed that Nie Haisheng weighed 74 kilograms. The force applied by Wang Yaping when stretching the spring to the preset position is constant. This value has been precisely tested and clearly marked during the manufacturing process of the equipment. A grating speed measurement system is also integrated into the measuring instrument, whose function is to monitor and record the changes in the speed of the body during movement in real time, and then calculate the acceleration. Once the constant force and acceleration are determined, according to Newton's second law, Nie Haisheng's weight can be accurately calculated.

Schematic diagram of the second generation mass measuring instrument

With the advent of the space station era, the mass measuring instrument has also ushered in its "upgrade". The second-generation mass measuring instrument has been improved in many key areas: improved measurement accuracy, enhanced measurement stability, optimized measurement and calibration algorithms, upgraded software systems, improved structural design, and incorporated ergonomic concepts. These improvements have significantly improved the accuracy of the second-generation mass measuring instrument, and the consistency of the measurement results has also been significantly improved compared to the previous generation. The second-generation mass measuring instrument was launched on the Tianhe core module and successfully completed the mass measurement mission of the Shenzhou XII to Shenzhou XVI crew during their in-orbit period.

In response to the medical monitoring needs during operation and the feedback from astronauts, the research team has carried out a new round of optimization and upgrades for the mass measuring instrument. This upgrade mainly focuses on improving the stability of measurement, the efficiency of operation and the comfort of use. Specific improvements include the optimization of the four-link and human body support structure, the enhancement of the strength and rigidity of the structure, the addition of anti-slip sleeves, and the improvement of the human body posture device. The improved four-link and human body support were successfully transported to the space station by the Tianzhou-7 cargo spacecraft. At present, the crews of Shenzhou-17 and Shenzhou-18 have completed the calibration of the equipment and the measurement of human body mass in orbit. According to their feedback, the improved equipment has not only significantly improved the measurement accuracy and stability, but also the operational efficiency and comfort of use, providing astronauts with a better user experience.

Astronauts of Shenzhou XIV successfully enter the Tianhe core module

Continuous technological innovation will drive the continuous optimization of mass measurement equipment, ensure its accuracy and reliability in space, and provide strong protection for astronauts' space missions and daily life.

The content is compiled from Beijing News Network, China Daily Network, China Manned Spaceflight, etc.

(Scientific reviewer: Zheng Yongchun, researcher at the National Astronomical Observatory of the Chinese Academy of Sciences)