China is studying how to build a very large spacecraft that is 0.6 miles (1 km) long. But what is the feasibility of this idea, and what is the use of such a huge spacecraft?
The project is part of the extensive solicitation of research proposals by the National Natural Science Foundation of China (a funding agency managed by the Ministry of Science and Technology of China).A sort of Research outline An article published on the foundation’s website described such a huge spacecraft as “the main strategic aerospace equipment that uses space resources in the future, explores the mysteries of the universe, and lives in orbit for a long time.”
The foundation hopes that scientists will study new lightweight design methods to limit the amount of building materials that must be sent into orbit, as well as new technologies for safely assembling such large structures in space. If funded, the feasibility study will last for five years with a budget of 15 million yuan (2.3 million US dollars).
The project may sound like science fiction, but former NASA chief technologist Mason Peck said that this idea is not completely divorced from reality, and the challenge is more about engineering issues than basic science.
“I think it’s totally feasible,” Peck, who is now a professor of aerospace engineering at Cornell University, told Live Science. “I will not describe the problem here as an insurmountable obstacle, but a problem of scale.”
Peck pointed out that by far the biggest challenge is the price tag, because it takes a huge cost to launch objects and materials into space.International Space Station (ISS), only 361 feet (110 meters) wide at its widest point According to NASA, The construction cost is about 100 billion U.S. dollars, Peck said, so even the most generous national space budget will be tight to build something 10 times the size.
However, much depends on what kind of structure China plans to build. The International Space Station is full of equipment designed to accommodate humans, which significantly increases its mass. “If we are talking about something that is long and not heavy, that’s another matter,” Peck said.
Construction technology can also reduce the cost of sending giant spacecraft into space. Peck said that the traditional method is to build components on the earth and then assemble them in orbit like Lego bricks, but 3D printing technology has the potential to turn compact raw materials into larger structural components in space.
A more attractive option is from moonPeikko said that compared to the Earth, its gravity is lower, which means it will be much easier to launch materials from its surface into space. Nevertheless, this first requires launching infrastructure on the moon, so it is not an option in the short term.
Big ship, big problem
Such a large-scale structure will also face unique problems. Peck explained that whenever a spacecraft receives force, whether it is maneuvering in orbit or docking with another vehicle, this movement transfers energy to the spacecraft’s structure, causing it to vibrate and bend. He said that for such a large structure, these vibrations take a long time to subside, so the spacecraft may need shock absorbers or active controls to counteract these vibrations.
Peck said that designers must also carefully weigh when deciding what altitude the spacecraft should operate at. At lower altitudes, drag from the outer atmosphere will slow down the aircraft, requiring them to continuously push themselves back to a stable orbit. Peck pointed out that this is already a problem for the International Space Station, but for a larger structure, it has more resistance and requires more fuel to return to its original position, which will be a major problem.
On the other hand, launching to higher altitudes is much more expensive, and radiation The farther the object is from the earth’s atmosphere, the level will increase rapidly. This will be a problem if the spacecraft accommodates humans.
Michael Lembeck, a professor of aerospace engineering at the University of Illinois at Urbana-Champaign, said that although building such a structure may be technically feasible, it is not feasible in any practical sense. He has participated in government and commercial space. plan.
“It’s a bit like we are talking about building Starship Enterprise,” he told Live Science. “Considering the cost, considering the cost, this is incredible, it is not feasible, and it is very interesting to think about, but it is not realistic for our technical level,” he said.
Lembeck said that given the small budget of the research project, it may be just a small academic study used to draw the earliest outlines of such projects and identify technological gaps. In comparison, the budget for building a space capsule to send astronauts to the International Space Station is $3 billion. “Therefore, the level of effort here is very small compared to the desired result,” he added.
Some people also questioned what such a large spacecraft will be used for. Lembeck said the possibilities include using microgravity and abundant solar energy to build space manufacturing facilities for high-value products such as semiconductors and optical equipment, or long-term habitats for extraterrestrial life. But both require huge maintenance costs.
“The space station is a $3 billion a year enterprise,” Lembeck added. “Multiply it by a larger facility, and it will soon become a sizable, expensive enterprise.”
China also expressed interest Build huge solar arrays on the track And the energy is transmitted back to the earth through the microwave beam, but Peck said that such a project is not economical. Peck made some rough calculations and estimated that the cost per watt is about $1,000, while the energy produced by solar panels on the earth is only $2 per watt.
Peck said that perhaps the most promising application of this large space structure will be scientific. A space telescope of this size may see features on the surface of other planets in the solar system. “This may be transformative in our understanding of the planets outside the solar system and the potential life in the universe,” he added.
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