UWMS toilets are expensive to build.
On October 2, 2020, the American “Cygnus” cargo spacecraft was launched in Virginia, USA, sending about 3.6 tons of materials and equipment into space, and arriving at the International Space Station on October 5. Among them, the most eye-catching is undoubtedly a titanium alloy toilet designed by NASA (NASA), its official name is “Universal Waste Management System” (UWMS). In 2014, this “most expensive toilet in history” was officially approved. After 6 years of research and development by engineers and technicians, it cost 23 million US dollars (over 150 million yuan) and finally succeeded. The biggest difference from the previous ISS system It is compact and completely independent. The old ISS system is usually hidden behind the bulkhead, which is difficult to repair, while the UWMS toilet is placed in a compartment next to the old toilet of the space station and will undergo a 3 to 4 year inspection. It will not only be used inside the space station, but will also be used in the US manned moon landing program in the future.
The design of the UWMS toilet is relatively simple. It weighs about 45 kilograms and is 71 cm high. It is 40% lighter and 65% smaller than the toilets currently used in space stations. It is about half of the 2 toilets in use on the space station. This means that the workload of maintaining and dredging the pipeline is reduced, and astronauts have more time to focus on the scientific tasks they are going to complete. The old toilet is more suitable for men, while the UWMS toilet is unisex. Therefore, the urine funnel and gasket are designed to make it more convenient and comfortable for women to use the toilet. The shape of the UWMS toilet is a bit weird. It looks like a mechanical drain as a whole. It also designs footholds and handles, and abandons the thigh straps that help astronauts fix positions in a zero gravity environment.
The old toilet only allowed astronauts to either urinate or defecate, not at the same time. The design difficulty of the space toilet is how to deal with the zero gravity environment. In order to ensure that the excrement does not float around, the UWMS toilet uses a 3D printed titanium alloy fan separator, which can generate strong suction to suck urine and feces into the toilet. It can also separate dry and wet, recover urine, and properly preserve feces. After testing, the urine recovery efficiency of UWMS toilets has been significantly improved, and the proportion of recovered urine that can be converted into drinking water after treatment has increased. Although it sounds bad, astronauts have become accustomed to using refined urine as drinking water. American astronaut Pettit has a subtle analogy-“Yesterday’s coffee becomes tomorrow’s coffee”.
According to Melissa McKinley, NASA’s Advanced Exploration System project manager, they spent a lot of time communicating and cooperating with astronauts in order to improve all aspects of the space toilet. The core design concept of the UWMS toilet is that it can be easily configured into various spacecraft and life support systems, and the urine purification process is improved to recover more urine. When performing shorter tasks, the UWMS toilet cooperates with another system, and the excrement can be stored without chemical pretreatment.
Even so, disposing of excrement in space about 390 kilometers from the surface is still a complicated process, and challenges remain. “What we want to do on the space station is to imitate the principle of natural water circulation on the earth, recovering water from the air for recycling.” American astronaut Jessica Meyer wrote on NASA’s blog, “90% of the water on the space station based liquid will be recycled, including urine and sweat. ”
space toilet is not easy
, many people envy astronauts can experience the feeling of weightlessness in space, not knowing the long-term living in weightlessness we have a lot of trouble, difficulty going to the toilet is one of the One. American astronaut Peggy Whitson has spent 665 days in space. She said that she likes to complete various space station tasks, from installing battery components on the space station’s solar panels to sampling space microorganisms, which is difficult Miss. Only going to the toilet is the part of life in space that I don’t miss. Everyone calls it a “camping trip.” British astronaut Tim Peak sighed after returning to Earth from the space station: “When you just return to Earth, the process of re-feeling gravity is particularly bad, but there are a few exceptions… For example, when you go to the toilet, gravity becomes yours. My friend, this is what we astronauts all look forward to.”
In the state of weightlessness, the intestines in the human body are floating, and the internal organs cannot work as calmly as on the earth, and the motivation for defecation is insufficient, making excretion a very challenging Sexual activity. The engineers came up with some better solutions. Unlike toilets on Earth, designing space toilets can be much more complicated. Since there is no gravity on the space station, the design of the toilet must use directional airflow instead of gravity.
The first astronauts to enter space have no toilets at all. On April 12, 1961, the “first man in space”-Soviet Yuri Gagarin took a car to the launch pad. Due to the long distance, he burst into urine before boarding the launch pad, and finally had to pass through the spacesuit’s pipeline. Urine on car tires. A month later, Alan Shepard, the first American astronaut, was also troubled by excretion. On May 5, 1961, he entered the space capsule, when there was no need to urinate. After the launch was delayed due to technical reasons, he was forced to wait in the cabin. At this time, he realized that his bladder was full, and hurriedly asked the headquarters for instructions. After a fierce debate among senior leaders, he was asked to stay where he was. Shepard later recalled: “The cotton underwear I wore was immediately soaked, but it was completely dry at the time of launch.”
More than 50 years ago, NASA’s Apollo program brought human space exploration to a new level. It has successively carried out many pioneering flights and successfully manned the moon. However, the astronauts aboard the “Apollo” did not have toilets to use. They can only drain the urine into a container like a rubber tube, then store the urine in a bag and bring it back to the earth for testing. But it is even more embarrassing if you want to go to the “large”. Astronauts have to use plastic bags with sticky loops on the edges to attach them behind them. In order to prevent the spread of odors and bacteria, the bag mouth adopts a stickable design to ensure complete isolation from the outside world. NASA’s first space station, Skylab, was put into operation, marking the first time a space toilet was installed in a NASA spacecraft. The space toilet consists of a hole in the wall that can suck urine and feces and store them in a bag for analysis.
Later, NASA’s space toilet facilities have developed to a certain extent, and the space toilet on the space shuttle is also called the “waste collection system.” The system uses rotating fan blades to disperse the solid waste in the container, and then exposes the container to a vacuum environment to dry it. The liquid waste is discharged into space. NASA’s Lunar Toilet Challenge Project Manager Mike Intel Batllo once said that the design of the space toilet in the past was too messy to effectively control the smell, which made the astronauts disgusted. Moreover, without the help of a partner, it is difficult to ensure the tightness of the toilet.
Currently, there are two Russian-made space toilets available on the International Space Station, about the same size as a small wardrobe. Among them, one is located in the service module “Star” in the Russian section, and the other is located in the node module “Secure” in the US section. The fan suction system of the toilet is similar to that of a vacuum cleaner. The solid waste is stored in the bag of the aluminum container, and the liquid waste is stored in the 20-liter container. Compared with the diapers and urine bags used in the Apollo mission to the moon, the space toilet on the space station is much more comfortable, but it still brings a lot of embarrassment. For example, astronauts often complain about bad smell and inconvenience when going to the toilet.
The area of the space station is equivalent to a football field. The bathroom is separated from other areas by a curtain, and the astronauts do not have much personal space and privacy. Frequent failures make toileting problems one of the most embarrassing problems in their space life. On July 19, 2009, the main toilet of the space station malfunctioned, causing a total of 13 astronauts on the space station and the U.S. space shuttle Endeavour to face difficulty in toileting. They were forced to use a backup that resembled a pocket and was connected to the toilet drainage pipe. The dirt collection device solves the problem. On November 27, 2019, the space station toilet failed again, leaving the astronauts with no toilets available and could only use “space diapers.”
Brainstorming for the public
On June 25, 2020, NASA and the HeroX platform announced a competition called “Moon Toilet Challenge”. A prize of 35,000 US dollars was set up to collect a toilet that can be used on the moon. The highest prize is 2 Ten thousand dollars, the second and third place will receive 10,000 dollars and 5,000 dollars respectively. NASA is soliciting ideas for everyone and even minors (there is a junior category for teams under 18). The “Moon Toilet” will be part of NASA’s “Artemis Moon Landing Program”, which aims to allow the United States to return to the moon before 2024. At that time, the 13th male and first female astronaut will land on the moon. Will be the first female astronaut to land on the moon in human history. In addition, NASA also plans to establish a permanent residence on the moon.
According to the design guidelines issued by NASA, the design of the “lunar toilet” must meet a number of requirements: it needs to operate normally under both microgravity and lunar gravity. Microgravity is usually called “zero gravity”, which is almost weightless, while lunar gravity Equivalent to 1/6 of the earth’s gravity. The weight of the toilet must be less than 15 kilograms under the earth’s gravity, and the volume must be less than 0.12 cubic meters, which can be compatible with men and women. The height of the user is usually 1.47 to 1.96 meters and the weight is 48.5 to 131.5 kg. The toilet should contain the excretion of 2 astronauts for 14 days, enough to hold 1 liter of urine each time, and 500 grams of feces per excretion, allowing the collected waste to be transferred to storage or processed outside the spacecraft.
NASA emphasized that the lunar toilet should be easy to clean and maintain, and the interval between two uses should not exceed 5 minutes. The power of the toilet should be less than 70 watts, and the noise during operation should not exceed 60 decibels (lower noise than ordinary bathroom fans). The resources on the moon are limited, and it is necessary to save water and complete water recycling. Keep the original environment inside the lander free of odors and other pollutants. The toilet also needs to ensure that when the toilet fails, feces or urine will not be scattered throughout the cabin and cause pollution. If astronauts can deal with vomit without having to put their heads in the toilet, then such a design will get extra points.
NASA does not lack experience in designing space toilets. They are currently studying how to update the existing space toilet design. However, space experts still hope that the public can provide new and different ways to meet human needs for toileting on other planets, which will pave the way for innovative lunar systems. Mike Intel Batlló said: “We recognize that there are many innovations from free flush toilets to dry toilets to excrement management. We hope to learn more advanced ideas and experiences through this’lunar toilet challenge’ competition. So as to expand our knowledge base and find the unknown factors that may exist.”