China has embarked on an ambitious space mission called Tianwen-2, aiming to explore two unique celestial bodies in our solar system that have yet to be visited by spacecraft. The mission commenced with a launch from the Xichang Satellite Launch Centre via a Long March 3B rocket at 1:31 am local time, marking yet another significant step in China’s expanding space programme.
Similar to the earlier Tianwen-1 mission, which successfully placed two instruments on Mars, Tianwen-2 has dual objectives. Its primary goal is to conduct a flyby of Kamoʻoalewa, also known as asteroid 2016 HO3, a near-Earth object believed to be a fragment of the Moon. Over the next two years, the spacecraft will travel to and orbit around the asteroid for extensive analysis before returning samples to Earth in approximately 2½ years.
Following this, the mission will venture to conduct a flyby of main belt comet 311P/Pan-STARRS, an intriguing object located between Mars and Jupiter, known for its comet-like tails. These targets represent a new frontier for scientists, as recent discoveries have revealed little about objects like Kamoʻoalewa and 311P/Pan-STARRS until now.
The KamoÊ»oalewa asteroid has a diameter estimated between 46 and 58 metres, making it the smallest asteroid to be explored by a spacecraft. Initially identified in 2016, this quasi-satellite’s reflective properties raised questions about its origins—whether it is indeed a piece of the Moon or just visually similar. The mission quells the curiosity of astronomers eager to uncover more about the origins and compositions of such celestial bodies.
In addition to scientific exploration, the mission holds practical implications for understanding potential asteroid threats to Earth, especially as Kamoʻoalewa is comparable in size to an object that caused significant devastation in Siberia in 1908. Observing these asteroids can enhance our awareness of their trajectories and compositions, potentially informing future planetary defence strategies.
The challenges of orbiting and landing on such small bodies are notable. As Dr. Patrick Michel indicated, the mission’s success relies on precise manoeuvres given the low gravity and rapid rotation of Kamoʻoalewa. Additionally, the complexity of sample collection zones means decisions will need to be judiciously made.
This mission opens doors to revolutionise our understanding of both Kamoʻoalewa and 311P/Pan-STARRS, offering insights into their nature and formation processes. As scientists anticipate unexpected discoveries, Tianwen-2 promises to be a milestone in our exploration of the solar system, potentially unveiling surprises that could reshape our current understanding of these intriguing objects.