More than a year ago, when the Chang'e 5 ascender successfully ignited from the lunar surface, Wu Yansheng, chairman of Space Science and Technology Group, lamented that this marked the first time China mastered the technology of taking off from an extraterrestrial body, and it would no longer be a dream for the Chinese to independently complete a manned lunar landing, establish a lunar space station, or even go to a more profound space.
Indeed, Chang'e 5 carries too many space dreams, this is a human fly to deep space, the largest unmanned probe, with a series of technical indicators many of them have reached the world's leading level, although the unmanned probe but for the future implementation of other more complex deep space missions, including manned missions to the moon, laid a solid foundation.
Chang'e 5 probe is composed of four modules: orbiter, returner, ascender and lander, with a launch mass of 8.2 tons, and has completed 11 stages: launch into orbit, Earth-Moon transfer, near-Moon braking, circumlunar flight, landing and descent, lunar surface work, lunar surface ascent, rendezvous and sample transfer, circumlunar waiting, lunar-earth transfer and re-entry recovery. The success of the mission marks the successful realization of the three-step plan of the Chang'e Lunar Exploration Project, which is the most complex deep space probe to date.
The 11 mission phases mentioned above are also the mission phases that a manned lunar landing mission will need to go through in the near future, so it is no exaggeration to say that Chang'e 5 laid the foundation for a manned lunar landing.
The orbiter is the service module of Chang'e-5 and also the general control module, which can be regarded as the space ferry of Chang'e-5. The orbiter takes the lead in the flight stages of the detector entering the circumlunar orbit, circumlunar orbit rendezvous and docking, circumlunar waiting section and lunar-earth transfer, etc. After completing the lunar-earth transfer section and separating the returner carrying 1731 grams of lunar soil samples, the orbiter's work is not over, and if measured in terms of time scale, its new phase of work has just begun.
The orbiter separated from the returner and then performed a maneuver to evade, at this time the orbiter's propellant balance is 200 kg, what concept is this?
One of the four modules of Chang'e-5, the orbiter, has a launch mass of 4.25 tons and carries 3 tons of propellant, which means that the dry weight of the module is 1.25 tons. A probe of this size carrying 200 kilograms of propellant is almost equivalent to a probe in a brand new state.
After completing the maneuver avoidance, the orbiter enters a large elliptical orbit around the Earth, creating favorable conditions for it to embark on a new journey.
After a few days, the orbiter entered the long-term operation management phase. After a long journey of about 88 days, the orbiter came to a new destination, which is the Lagrangian L1 point of the Sun and Earth, about 936,700 km away from the Earth, where the orbiter achieved the first solar-terrestrial L1 point orbit detection in China, verified a series of previously uncharted orbit control technology, obtained the solar-terrestrial L1 point measurement and control At the same time, a large number of components were tested in orbit in this complex space environment, which accumulated data for the development of subsequent deep space probes.
During its flight around the Sun-Earth L1 point, the orbiter used the surveillance camera to take photographs of the solar wing, Earth-Moon conjunction, and the Sun, unlocking new perspectives on space for humans.
After completing the expansion mission around the L1 point of the Sun for more than half a year, the orbiter set off again to return to the Earth-Moon system, which is another long journey, and finally flew the Moon to the elliptical high Earth orbit about 370,000 km from the Earth, and after running for more than a month, flew the Moon again to change the orbit to the orbit around the Sun.
That's not all, the tireless orbiter then changed orbit again to a substantially retrograde orbit around the Moon, an intriguing orbit with long-term stability and low entry energy, a free return orbit that could be applied to a manned mission to the Moon.
Manned spaceflight, human life is at stake. Half a century ago, NASA's 3rd manned lunar mission spacecraft Apollo 13 in the Earth-Moon transfer flight during the service module irreversible failure, the astronauts almost perished in space, for the flexible selection of the moon landing point mission considerations, when the spacecraft did not run in the Earth-Moon free return orbit, and finally is the lander engine into the Earth-Moon free return orbit successfully returned to Earth.
While manned spacecraft operating in near-Earth orbit can be evacuated by ship at any time in case of emergency, manned missions to the moon, which are part of the deep space domain, are different and are very sensitive to propellant consumption and the reliability of the orbit control power system.
The Chang'e-5 orbiter enters a significant retrograde orbit around the Moon with the feature that it can freely enter the Moon-Earth return orbit without orbital maneuvering in case of manned spacecraft orbital control engine failure. Obviously, the orbiter into the orbit or in the manned mission to the moon "to explore".
Compared to the Apollo manned lunar landing half a century ago, there is a new twist today, as the crew module of the manned lunar landing spacecraft will be launched separately from the lunar module, as the latter will be deployed in circumlunar orbit based on reuse requirements, which means that the manned spacecraft will not have a full backup available power system (Apollo 13's lunar module power system), and therefore the demand for free return orbit applications will be more robust.
As mentioned at the beginning of the article, we also have the need to build a lunar orbiting space station, and the low entry energy advantage of a large value retrograde orbit around the Moon will be further exploited, and the propellant consumption of cargo spacecraft entering this orbit can be minimized.
Chang'e 5 probe due to the implementation of the sample return to the main task is a short-cycle mission, so its design in orbit flight time margin is not long, is 3 months, and in fact the orbiter has been operating for more than a year so far, a launch mission to complete multiple areas of space exploration tasks, further reflecting the excellent tradition of China's low-cost and efficient space.
Another example of low-cost spaceflight in the world is Indian spaceflight, represented by Moonship II, which was claimed to be the lowest-cost lunar probe and eventually failed in its landing mission. Their low cost is a world away from our low cost. They are careful to save on development and testing costs, and as a result, the tests that should be done are not done, or not done properly.
India's Moon Ship II mission to the moon, seemingly low-cost, in exchange for the result is a failure, the next will have to redevelop the test Moon Ship III, the cost of failure into this is still low-cost?
On the contrary, our low-cost office space is not in the development and testing costs deducted from the search, but from ensuring high reliability, high success rate, as well as multi-task expansion efforts, a task multiple objectives to achieve, similar to the Chang'e 5 orbiter expansion mission, for us is not the first time, many years ago there was Chang'e 2 expansion mission is also the case.
In short, low-cost aerospace is not to spend less money, but to spend the money on the edge, the money we spend the same will not be less. For example, the service of deep space probe development of extraterrestrial objects landing test site a not enough to build two, large AIT center service capacity can meet not only the current types of large spacecraft, and even the next two decades of ultra-large spacecraft can also meet the demand.
It is because of our solid foundation that we have had a series of successes in space exploration missions, thus continuing to accelerate the pace of China's space development. There will be many more miracles that we can witness in the next eight years: Tiangong Space Station, Chang'e Lunar Exploration Phase IV, manned lunar landings, international lunar surface research stations, asteroid sample return, Mars sample return ......