• Forum
• SITREP
• Military
• WMD
• Intelligence
• Homeland Security

• Space

• Introduction
• Systems
• Facilities
• Agencies
• Countries
• Hot Documents
• News
• Reports
• Policy
• Budget
• Congress
• Links

• Public Eye

Tianwen-2 Asteroid sample-return

Tianwen-2 asteroid probe had entered the initial sample development stage in 2022 and was expected to launch in 2025. Tianwen No. 2 was originally called Zheng He. "Tianwen" is the name of China's entire planetary exploration program, not specifically to detect Mars. After the Tianwen-1 mission, China will have a number of Tianwen series of planetary endeavors to explore the universe, according to a Chinese scientist. Wu Weiren, the chief designer of China's lunar exploration program, said 12 March 2022 the country's deep space exploration will continue and its Mars mission will be followed by the Tianwen-2, Tianwen-3, and Tianwen-4.

"Tianwen" originated from Qu Yuan's long poem "Tianwen " , which expresses the tenacity and perseverance of the Chinese nation in the pursuit of truth, embodies the cultural heritage of the exploration of nature and the universe, and implies that the search for scientific truth is a long journey, and the pursuit of scientific and technological innovation will never end.

By May 2022 the Tianwen-2 probe had entered the preliminary prototype development stage. In 2020, Wing-Huen Ip, Executive Director of the International Space Science Institute – Beijing, noted "It is possible that the driving force for the next step of in-depth Mars studies will come from the discoveries of “Tianwen-1” or “Tianwen-2” and other missions. What is of some concern at the present time is probably the long pause between two consecutive flagship-like missions, even though many comment on China’s rapid advancement in space exploration considering the lunar program and its additional space activities. It would actually be desirable to mount some small-scale planetary missions at lower costs (and hence lower risks), so that the scientific community will always be in the position of yielding and analyzing new data. Such strategy would also add flexibility and a high level of international cooperation to the fast-turning planning cycle, while maximizing scientific returns."

On April 23, Long Lehao, an expert in launch vehicle technology and academician of the Chinese Academy of Engineering, mentioned the news of "Tianwen-2" and "Tianwen-3" in a lecture on "Aerospace Moon" at BIT. Unexpectedly, the goal of "Tianwen-2" is not to fly to Mars, but an asteroid numbered 2016HO3.

The asteroid, numbered 2016 HO3, is highly suspected to be a lunar debris, that is, after the moon was hit by a meteorite, the debris that bounced and flew out, with a length of about 40 meters, oscillated in the same orbit with the earth, and was only discovered by humans in 2016, which astronomers call the "Oscillating Sky Star" and may also be called Earth's second "moon". At that time, "Tianwen No. 2" will reveal its secret.

"Tianwen-2" will be launched by the Long March-3 B/G2 rocket, and it is expected to attach and sample the asteroid 2016HO3 before 2025. The so-called attachment is landing, but it is more professional than the impact-style "landing" of the Japanese "Hyabusa No. 2". And because it is a certain distance from Earth, the launch time should be earlier than 2025, which is expected to be 2024. Interestingly, "Tianwen No. 2" was originally named "Zheng He", and it is estimated that there is a bigger plan to change its name.

According to the existing information, the "Tianwen No. 2" probe consists of two parts: the "main probe" and the "return cabin". The main probe is the main control module of the probe, similar to that of Tianwen No. 1. The orbital part of Mars is responsible for orbital transfer and control during flight, and is responsible for part of the scientific exploration mission when it reaches the asteroid. It is equipped with high photoelectric conversion efficiency solar wings, communication systems, sampling devices, sample transfer devices and other equipment.

Among them, the solar wing is a unique "circular flexible solar wing". This configuration is also selected to shorten the deployment size of the solar wing, reduce the touchdown risk of the traditional long-sized solar wing during the soft landing process, and improve the detection of the probe on asteroids. Reliability in the landing (attachment) mission, the diameter of a single solar wing is about 4.7 meters and the area has reached 17 square meters. The area of the two solar wings it is equipped with is 34 square meters. The reason why it carries such a huge solar wing is that Because after it completes the asteroid sampling and return mission, the main probe is likely to continue to fly out of the solar system to complete an expansion mission of comet detection. The tentative target should be the main belt comet 311P, in the process of flying out of the solar system. In the middle, the obtained sunlight energy will be lower and lower, so a large area of the solar wing is required.

However, the large area of the solar wing brings difficulties to the launch of the probe. Therefore, the researchers used a fan-shaped circular design. Before launching, the solar wing was folded and placed at a small angle fan, and then launched into space and then unfolded.

The detector is equipped with a number of advanced scientific detection and sampling, storage and operation equipment, and is also equipped with more than 20 thrusters, including ion electric thrusters, which are combined with chemical thrusters to form a dual-mode propulsion system, which can effectively save fuel and reduce launch weight.

The return capsule of Tianwen-2 is relatively small, with a maximum diameter of about 0.75 meters, which is much smaller than the return capsule of Chang'e-5 lunar sampling (about 1.5 meters in diameter). It is estimated that the amount of asteroid sampling will not be large.

The 2016HO3 asteroid to be detected by Tianwen-2 is also a very distinctive asteroid, because its orbit is very unique. In the next few hundred years, it will orbit both the sun and the earth, so It can also be said to be a quasi-satellite of the earth, with an average distance of about 20 million kilometers from the earth, which is about 53 times the distance from the earth to the moon.

Detecting this asteroid will test China's distant celestial object observation and detector telemetry and remote control technology very much, because its size is very small, with a diameter between 30 and 100 meters, which is only equivalent to the volume of a building. Think about it, from Detecting such a small celestial body at a distance of 20 million kilometers, and taking some samples from it, must be a considerable technical test.