Chinese Voyager-type missions could be launched in 2024, making planetary flights before focusing on the science of the heliosphere.
HELSINKI – China is developing a mission to send a pair of spacecraft to study the limits of the solar system and reach interstellar space by the middle of the century.
The project aims to send separate spacecraft on the nose and tail of the heliosphere, a region of space dominated by the solar wind created by our Sun, to study distinct areas of this bubble and how it interacts with the interstellar environment.
Wu Weiren, a leading figure in China’s monthly exploration project, said China’s official China Space News newspaper on Friday that scientists are working on a plan to implement the mission.
Wu says the mission aims to reach 100 astronomical units – one AU is equivalent to a Sun-Earth distance, or 150 million kilometers – from Earth by 2049, when the People’s Republic of China celebrates its centenary.
Wu did not provide any release date. However, an overview of the proposed mission present at the 2019 European Congress of Planetary Science indicates that the probes of the Chinese heliosphere will be launched in 2024. The first would make a flyby of Jupiter in 2029 before heading to the nose of the heliosphere.
The second probe would make a Jupiter flyby in 2033 before an ice giant Neptune flyby in 2038. The spacecraft could also release a small impact probe shortly before arrival, the main probe observing the interaction with the Neptune atmosphere.
The project echoes somewhat from NASA Voyager missions, but the intermediate objectives of the probes are constrained by the current relative positions of the planets. Voyagers used a rare planetary alignment to visit all four outer planets. Voyager 1 and 2 are now 22.7 and 18.9 billion kilometers (152 and 126 AU) away from Earth.
Therefore, for Chinese probes, more science is focused on the heliosphere and interstellar environment, including the study of phenomena such as abnormal cosmic rays and the “hydrogen wall” at the boundary of the solar system and interstellar space.
Chinese heliosphere probes will benefit from advances in China’s space propulsion and space station and deep space communications industry. Such progress has recently facilitated missions to Mars, the return of a lunar sample, and a planned mission to Jupiter.
“Interstellar Express” from China
The profile of the above mission was understood to be still under development. A workshop hosted by the International Institute of Space Sciences in Beijing in late 2019 explored the mission’s commercial space and presented possibilities, including a flight of the Kuiper belt object Quaoar and her little moon Weywot. The workshop also used the name “Interstellar Express” for the proposed Chinese mission.
A 2019 paper on “Exploring the Border of the Solar System” published in Scientia Sinica by Wu and other high-quality Chinese scientists in space exploration provides information on the likely launch and design of spacecraft.
The ship will be powered by radioisotope thermoelectric generators (RTG) with a scientific payload of more than 50 kilograms. Long rockets from March 3B and higher are considered for launching long rockets from March 5, depending on the propulsion systems – dual chemical propulsion systems or monopropellant and ion-electric propulsion – are selected.
Another mission proposal mentioned in the paper would move away from the Sun perpendicular to the ecliptic plane. This mission will be launched in 2030 and will be powered by a nuclear thermal reactor.
Reaching speeds of about 6 AU per year, the spacecraft could target extreme Kuiper belt objects on its extremely sloping trajectory. The level of technological maturity for the mission is noted as low, thus requiring discoveries and verifications.
The two Chinese missions in 2024 will become the sixth and seventh spacecraft to reach the speed of the solar system’s evacuation, following NASA’s Pioneer 10 and 11, Voyager 1 and 2, and New horizons.
The Pioneer 10 is the only spacecraft heading for the tail of the heliosphere. Communication with the spacecraft was lost in 2003 at a distance of 12 billion kilometers (80 AU) from Earth.
Scientists at Johns Hopkins University Laboratory of Applied Physics study meanwhile Interstellar probe mission that could be launched before 2030.
China recently approved a 14th five-year plan for 2021-2026. Wu noted that the missions to the fourth phase of the Chinese lunar exploration, including a base international monthly research station, would be carried out or developed during that period.
Wu added that the 2010 lunar orbit Chang’e-2, which later performed a flyby of the asteroid Toutatis, is expected to return to Earth’s vicinity around 2027.