China's Tianwen-2 to unlock secrets of solar system ’fossils’: professor

China's upcoming Tianwen-2 mission will confront unprecedented technical challenges to explore what scientists call a "living fossil" of the solar system, said Zhang Xiaotian, an associate professor at Beihang University, as the country is preparing for its first asteroid sample-return and comet exploration.

China is poised to take a major step forward in deep space exploration with the upcoming launch of Tianwen-2, a groundbreaking mission aimed at probing a near-Earth asteroid and a main-belt comet.

Scheduled for liftoff on May 29 from the Xichang Satellite Launch Center in Sichuan Province, Tianwen-2 will be the country's first mission to collect and return samples from an asteroid, an ambitious effort that could yield vital clues about the early solar system.

According to the China National Space Administration (CNSA), the spacecraft will conduct first rendezvous with asteroid 2016HO3, to perform close flybys, surface attachment, and sample collection. It will later continue its journey to investigate main-belt comet 311P, a small body with both asteroid-like and comet-like characteristics.

"We know that the Moon is Earth's natural satellite, located approximately 380,000 kilometers away. In contrast, even at its closest approach, asteroid 2016HO3 is about 40 times farther than the Earth-Moon distance, which makes its exploration significantly more challenging. Scientifically, this asteroid serves as a 'living fossil' for studying the formation and evolutionary history of the solar system, and thus holds immense research value," said Zhang.

"From a technical perspective, many may recall that China's lunar exploration program began in 2007 with the launch of Chang'e-1 and progressed through to Chang'e-5 in 2020, successfully completing the three-phase strategy of orbiting, landing, and returning from the Moon. In the case of the 2016HO3 mission, the Tianwen-2 probe will first conduct a flyalong with the asteroid, then approach and attach to its surface, perform surface sampling, and finally detach and return, essentially achieving the orbit, landing, and return phases in a single mission. This will be made possible by the solid technological foundation built through our earlier space endeavors. Furthermore, Tianwen-2 will achieve stable attachment to the asteroid's surface, providing a reliable condition for sampling. Various techniques such as robotic arms, drilling, and scooping will be employed to collect material samples," he said.

After the sample return capsule is released and begins its journey back to Earth, the main probe will continue its voyage to comet 311P, using a gravity assist from Earth to slingshot toward the second target, according to Zhang.

"After the return capsule is separated to deliver the samples back to Earth, Tianwen-2 will continue its mission by using Earth's gravity for a slingshot maneuver toward its second target, 311P. 311P is a small celestial body located in the asteroid belt between the orbits of Mars and Jupiter. It possesses the material composition typical of a comet, but follows an orbit more characteristic of an asteroid. Studying this object will help us better understand the composition and internal structure of small bodies in the solar system, as well as their evolutionary mechanisms," said Zhang.

CNSA confirmed that preparations are progressing smoothly. The Tianwen-2 probe has already completed assembly, testing, fueling, and integration with the Long March-3B Y110 rocket, which has been transferred to the launch pad. Final system checks, payload integration, and coordinated drills with ground control centers have all been successfully carried out.

The entire mission is expected to last around ten years. Approximately two and a half years will be dedicated to the encounter with 2016HO3, followed by the extended cruise to 311P.

Discovered in 2016 by the Pan-STARRS telescope in Hawaii, the asteroid 2016HO3 is a quasi-satellite of Earth, located millions to tens of millions of kilometers away from Earth.

The asteroid, which runs stably near the Earth's orbit, contains ancient materials from the early solar system, making it a "living fossil" that is useful for studying how the solar system formed and evolved.

The main-belt comet 311P, a celestial anomaly that orbits in the main asteroid belt between Mars and Jupiter, was discovered by American scientists in 2013. Regarded as a "rebel" of the main asteroid belt, it displays features of both comets and asteroids.

Studying it will provide researchers with valuable insights into the composition, structure and evolution of small space objects, helping to fill gaps in our understanding of the solar system.

China's Tianwen-2 to unlock secrets of solar system ’fossils’: professor

A video featuring a former member of Unit 731, a notorious Japanese germ-warfare unit during World War II (WWII), was released on Thursday in northeast China's Harbin, revealing details of how the unit used meteorological data to conduct horrific bacterial experiments on human beings.

The video was released by the Exhibition Hall of Evidence of Crimes Committed by Unit 731 of the Japanese Imperial Army, in which former Unit 731 member Tsuruo Nishijima detailed how the unit used meteorological data to carry out a bacterial dispersal experiment.

The video was recorded in 1997 by Japanese scholar Fuyuko Nishisato and donated to the exhibition hall in 2019, according to the hall, which was built on the former site of the headquarters of Unit 731 in Harbin, the capital city of Heilongjiang Province.

Jin Shicheng, director of the Department of Publicity, Education and Exhibition of the exhibition hall, said that Nishijima joined Unit 731 in October 1938 and served in the unit's meteorological squad. The squad was not a simple observation section but rather an auxiliary force supporting the unit's field human experiments by measuring wind direction, wind speed, and other conditions to ensure optimal experimental results, according to Jin.

Nishijima confirmed in the footage that "the meteorological squad had to be present at every field experiment." He testified to the "rainfall experiments" conducted by Unit 731, which involved aircraft releasing bacterial agents at extremely low altitudes.

At a field-testing site in Anda City, Heilongjiang, Unit 731 aircraft descended to about 50 meters above the ground. They sprayed bacterial culture liquids onto "maruta" -- human test subjects -- who were tied to wooden stakes. Each experiment involved about 30 people, spaced roughly 5 meters apart. After the experiments, the victims were loaded into sealed trucks and transported back to the unit, where their symptoms and disease progression were recorded over a period of several days.

"Unit 731's bacterial weapons were dropped by aircraft from a height of 50 meters in the open air. Therefore, the meteorological squad needed to observe wind direction and speed, which directly affected the precision and accuracy of the bacterial weapons deployment," said Jin.

Nishijima recounted the harrowing experience of the human test subjects.

"They were fully aware that inhaling the substances would certainly lead to death, so they closed their eyes and held their breath to avoid breathing them in. Their resistance prevented the experiment from proceeding. To compel them to comply, they were forced at gunpoint to open their mouths and lift their heads," said Nishijima.

These experiments, disguised as "scientific research," were in fact systematic tests of biological warfare weapons conducted by the Japanese military. The data generated from these inhumane activities became "research findings" shared among the Japanese army medical school, the medical community, and the military at large.

"At that time, the entire Japanese medical community tacitly approved, encouraged, and even participated in the criminal acts of Unit 731. The unit comprised members from Japan's medical and academic sectors who served the Japanese war of aggression against China. Thus, Unit 731 was not just a military unit but represented an organized and systematic criminal enterprise operating from the top down," said Jin.

Unit 731 was a top-secret biological and chemical warfare research base established in Harbin as the nerve center for Japanese biological warfare in China and Southeast Asia during WWII.

At least 3,000 people were used for human experiments by Unit 731, and Japan's biological weapons killed more than 300,000 people in China.

Video offers details of Japan's germ-warfare crimes in northeast China