Without a clean room, there is no space travel! How does the space probe break through the last line of defense?

On September 16, Tesla boss Musk's private space exploration technology company, Space Exploration Technology Company, successfully launched the first commercial manned space mission Inspiration 4-"Dragon Spacecraft" with Falcon 9 rocket, sending four ordinary passengers into space and completing a three-day fantastic journey around the earth. Further verify that commercial aerospace enterprises have the full chain service capability from launch vehicles to manned spacecraft, and can open the market of commercial aerospace tourism at any time.

Not only the national space agencies of space powers such as Europe, America and China, but also private companies have made ambitious space plans for themselves. The success of emerging companies such as Space Exploration Technology Company first shows one thing: commercial space travel is full of optimism, and one industry will benefit from the huge growth of the aerospace market: clean rooms. In this article, CleanRoomTec will discuss how these clean room departments work together.

According to the management consultant's prediction, the global space technology market will increase by 10 times in the next 20 years, reaching 2.7 trillion euros in 2040. Many scientists, engineers, suppliers and service providers will make a fortune from this unprecedented growth. Of course, as the last line of defense against the spacecraft, clean room technicians will also benefit a lot. Because almost everyone involved in space travel will perform the same task: clean room and its cleaning technology.

Clean room technology is the last line of defense for aviation.

Maximize reliability and reduce failure rate.

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In space travel, mission failure is often due to details. When the European Space Agency (ESA) Ariane 4 was launched at 1990, it was a rag in the pipeline that caused the crash. 1994 had two wrong starts because dust paralyzed the turbopump. This happened not only in the European Space Agency, but also in the National Aeronautics and Space Administration (NASA) of the United States. They repaired the manufacturing defects of the Hubble telescope five times, because the main mirror was worn a few microns too flat, but it was found too late because it had been launched into space. When the satellite reaches the predetermined orbit, it must maintain the function of 100% in order to obtain the service task for decades. Once in space, repair and cleaning are usually impossible.

Through the error analysis after the accident, engineers realized the pain and high cost of the failed task. This enables engineers to accumulate experience and develop clean rooms and their technologies. After all, this fine chemical industry is closely related to the safety and reliability of space travel.

Aerospace manufacturing is the frontier field of precision manufacturing, and the parts must be kept strictly clean. Because even small particles can endanger the mission. Dirty optical components, dirty solder joints and dirty bearings are the weak points that must be prevented. Before launch, the rover and space telescope were placed in clean rooms to prevent damage to these valuable payloads. Satellites are produced along a long chain of clean rooms. This includes the production and integration of components, transportation, launch site and space closely related to clean room technology.

Between the manufacturing of all its space facilities, NASA has many clean rooms all over the country, including its academic and commercial partner facilities. These clean rooms help to prepare for the key flight component tasks, and are not affected by harmful pollutants such as dust, bacteria, hair and air pollution particles, because the existence of these pollutants will damage sensitive instruments on spacecraft worth millions of dollars.

With the control and monitoring functions of aircraft and rockets becoming more and more accurate, the requirements for accuracy in production are getting higher and higher. Therefore, the further development of clean room technology provides a strong guarantee for the aerospace industry-maximizing reliability, that is, reducing the failure rate of transmitter and payload, which is an important contribution of clean room to today's space travel.

Integration and coordination of clean room departments

Control pollutants to the lowest level.

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NASA and other agencies have strict regulations on the pollution level of space products. Environmental pollutants, such as dust, fingerprints, particles, steam, microorganisms and bacteria, are important considerations in the development of space instruments and components. These scattered dust particles or fingerprints may damage or damage scientific instruments.

The standard of clean room is stipulated by federal and international authorities, and designated by grade, which is an indication of allowable particle size and quantity per unit volume. International Organization for Standardization standards:

According to the class name of clean room, clean room has special system and function to control pollution. These include isolated air filtration, humidity and temperature systems; Lounge for employees to enter and leave the clean room; Special protective clothing for workers, including overalls, shoe covers, masks, gloves, hairnets and goggles. The equipment in the clean room is also controlled so as not to produce air or particle pollution.

One of the challenges in developing spacecraft is the space required for the control components during assembly. On-site high-shed clean room enables engineers to design large spacecraft flexibly. This 10,000-class clean room also has a large control room, an environmental test vacuum chamber, an antechamber where staff wear clean clothes and a clean room.

The quantitative design of clean room for space equipment has high requirements for the control of airborne suspended particles. The air modular filtration system (MFS) is composed of portable HEPA filtration device, which is designed to filter clean room air to eliminate work-level pollution. The design is universal, allowing the use of single or multiple units. MFS consists of HEPA air supply device, return air device (HEPA or non-HEPA) and full-side ESD wall. Because the device filters clean air in the clean room, the standard ISO 8 (100,000) area will be kept below ISO 7 (100,000). The main goal is to achieve a continuous laminar flow velocity of 90 +/- 30 ft/min. Keep the particles moving in the whole space, and the particle swarm moves below ISO 7( 10000). This design can achieve this goal by completely opening the ceiling passage, and allows modular design to adapt to changing requirements and equipment placement. Sidewall design depends on specific customer requirements or personnel entry points.

Detectors that land on other celestial bodies require the highest purity. They must be free of particles and bacteria. If spores or bacilli travel with the detector, it will affect the measurement results when looking for alien life. It will also violate a part of the Outer Space Treaty-States parties should avoid harmful pollution when they engage in research and exploration of outer space (including the moon and other celestial bodies). Therefore, during the work and rest of the spacecraft, the ultraviolet lamp can kill the bacteria in the air. The module is irradiated by radioactivity, filled with chlorine or heated to above140 C. Disinfection measures should be taken before reaching the lower limit of the number of bacteria. Complete aseptic integration is impossible. Therefore, it is inevitable to fully disinfect the landing troops.

All superior clean rooms are equipped with air conditioning. Their temperature is usually 22 degrees Celsius (+/-3 degrees Celsius) and their relative humidity is 55% (+/- 10%). Controlled humidity can protect electronic components, because dry air can lead to electrical breakdown. ESD (electrostatic discharge) floor can also prevent flashover. Anti-static equipment, including perishable clothes, shoes and gloves, is suitable for preventing voltages above 100 volts.

Steam during operation must be exhausted through the ventilation system. Vertical low turbulence displacement flow from ceiling to floor is an ideal way. Another possibility is horizontal flow-the discharge surface consists of a grid with many filtering fan devices with fans and terminal filters. The surface of the workbench is usually perforated to allow air to flow through without disturbing turbulence. Employees enter ISO 5 clean room through ISO 7/8 airlock system and adjust their clothes according to higher requirements.

Satellites with extremely sensitive optical systems, such as reconnaissance satellites, are all integrated in class 5 clean rooms. Particles on the optical surface will increase the scattered light component, while molecular impurities will cause spectral interference. Cleaning with a soft brush is time-consuming and scratches the coating. Stripes may remain after washing. Therefore, it is imperative to avoid all pollution as much as possible. Therefore, silica gel should not be used in clean rooms. Silicone will evaporate after more than 20 years, thus releasing molecules.

Other equipment functions include specially equipped cranes with sealed drives and coated belts. This is because the impeller will wear and the lubricated suspension rope will release gas.

Besides technology, the key factor is always people-the biggest pollution source of clean room, because he releases 1 30 million more than 0.3? M particle. (For related articles, please read "Maximum Pollution Source Control | Clean Room Personnel Accurate Management and Identification System Based on RFID Technology"). Therefore, people who move in clean areas will wear special protective clothing. These protect products, not people. Therefore, clean room robes or overalls, clean room shoes and headgear are mandatory, and beard bandages for beard wearers are also mandatory. Anyone who flies an airplane must wear gloves. Parts can only enter and leave the aircraft through the airlock.

Although it is a clean room, the room is not dust-free and must be cleaned according to the plan and regulations. Contaminants will deposit on the ground or in quiet areas on the surface. It is necessary to wipe the room with mop and distilled water once a day.

It is also necessary to re-certify and calibrate the clean room itself once a year.

It is very important for space telescope to observe the universe.

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When looking forward to the future clean room for space travel, higher requirements and costs are particularly prominent. A satellite about 5 meters long needs an area of about 300 square meters. The price per square meter is based on the usage fee of several hundred euros per day. This means that the cost of clean rooms alone has swallowed up millions of dollars.

When dealing with these costs, it can be seen in commercial projects that tenants tend to choose cheaper ones, that is, the clean room grade is too low or the service life is reduced. Automation has no way out, satellite integration is still manual.

In particular, the optical system has increased the requirements for clean rooms. For example, space telescopes can observe more and more distant space, or take more detailed pictures of the earth. At present, humans can only see a small part of the estimated 100000000 trillion stars, and more accurate technology is needed for deeper observation of space. An example of this is the ESA project Athena, an X-ray telescope whose mirror structure is made of millions of micron-sized silicon wafers. Microsatellites with a side length of only 10 cm also need higher clean room quality.

James Webb Space Telescope is the largest and most complex space telescope ever. NASA designed it to be folded like an origami flower, made it look like a rocket, and then launched it into space. Bearing is a part of the positioning structure, which can position the antenna, maintain the data link between the telescope and the earth, and let human beings witness Weber's amazing discovery. The cleanliness of bearings and their transmission system components requires seamless and flexible assembly in a higher clean room, so it is necessary to reject any dust as much as possible.

The smaller the system, the more sensitive it is to dust. In the future, such satellites will be integrated into clean rooms with ISO 5 or higher. This can be achieved by establishing a higher level only in a limited area to control or increase costs.

If employees even breathe into solar panels, their performance will drop significantly. This is permanent, and cleaning will not change this. Non-specific activated carbon filters for supplying and circulating air can filter out molecules. This standard will soon be applied to every ISO 5 clean room. More stringent standards must also be applied to measurement technology. Up to now, I have been in contact with the sampler for several days, so I can only carry out subsequent analysis. In order to eliminate the source immediately, real-time measurement is needed.

Space junk will become the biggest obstacle in front of people's homes on earth.

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Satellite integration requires a lot of transmission. The weakest link in the chain determines the final quality. Therefore, the conditions of transportation must be the same as those of integration. In principle, the transport container is a solid class 8 mobile clean room, including climate control. It is usually filled with dry nitrogen and pressurized under slight overpressure. Before the satellite fuselage enters from above or from the side, the roughly pre-cleaned transport container is carefully cleaned in the airlock.

The container only meets the satellite in the main airlock room. Large accessories such as solar collectors and antennas are transported separately. When transported by flatbed, the impact force can only be transmitted by damping. For this reason, the support structure of the container and the satellite is separated by a spring element.

Satellites are tested in test centers with large ISO and Class 8 cleanrooms, which are not available at every integration site. Enter the test facility from the central clean room to simulate the space conditions such as negative pressure, temperature scene and vibration.

On the "vibrator", the satellite vibrates in the same way as when it is launched. If the assembly breaks in this process, it can be reinforced or redesigned in time and its size can be determined. In order to avoid unnecessarily improving the quality requirements of the clean room, sensitive subsystems are included. After the test is successful, the satellite is usually sent directly to the launch site by cargo plane. Transport containers used for air transportation must meet the requirements of IATA (International Air Transport Association).

The launch site must also maintain the quality of the clean room. The satellite will be assembled in a clean room in an independent closed payload cabin. The advantages of separating the integrated module from the rocket space are purchased through additional adapters. Another possibility is to install the satellite directly on the carrier. In this case, the interface between the carrier and the payload extends horizontally to the clean room, where the satellite is placed and connected with the clamping ring. Before the enclosure (fairing) is closed, it will be checked whether the "stowaway" has quietly entered. When the shells are blown away at the height of 100 km, the atmosphere is very thin, and there is no longer the risk of being "smuggled" by atmospheric pollutants.

Although human beings try to send sky messengers in a clean state, they ignore the satellite at the other end of the life cycle-space junk. ESA model MASTER-2005 assumes that there are more than 600,000 objects in orbit around the earth with a diameter exceeding 10 mm.. Other simulations estimate that there are 654.38+0.5 billion objects of millimeter size. When they approach the spacecraft, they need to make evasive maneuvers, and the International Space Station is forced to make course corrections from time to time. Space countries have a lot of work to do if they want to clean up the garbage in the earth orbit.

If humans successfully clean up the space junk at home, it will prove their long-term efforts to settle in the solar system-in order to start from here, they may continue to conquer and colonize the new planetary world in the future.

Keywords: # CleanRoomTec Shanghai international clean technology exhibition # clean workshop/clean room # HEPA filter # air modular filtration system (MFS) # solar panel # rover # detector #