Group 1 - The Tianwen-2 mission marks China's first interplanetary sample return mission, targeting asteroid 2016HO3 and comet 311P for scientific exploration and sample collection [1][2] - The mission aims to enhance understanding of the origins and evolution of small celestial bodies, with 2016HO3 potentially holding primordial information from the early solar system [2][3] - The Tianwen-2 spacecraft is equipped with 11 scientific payloads to study the morphology, composition, internal structure, and potential ejection materials of the targeted celestial bodies [2][3] Group 2 - The mission involves significant technical challenges, including long distances (2016HO3 is 18 to 46 million kilometers away, and 311P is 150 to 500 million kilometers away), which complicates communication and requires advanced orbital design and energy management [3] - The spacecraft must operate under weak gravitational conditions, making sample collection difficult, as the average diameter of 2016HO3 is approximately 41 meters and it is in a high-speed rotation [3][4] - The launch of the Long March 3B rocket required precise trajectory calculations, with a separation speed exceeding 11.2 kilometers per second and a deviation tolerance of less than 1 meter to ensure accurate orbital insertion [5]

央视网消息：5月29日1时31分，我国在西昌卫星发射中心用长征三号乙运载火箭，成功将行星探测工程天问二号探测器发射升空，我国首 次小行星探测与采样返回之旅正式开启，深空探测任务迈出新的一步。 5月29日凌晨1点31分，长征三号乙运载火箭点火起飞，飞行约18分钟后，将天问二号探测器送入地球至小行星2016HO3转移轨道。 天问二号主要任务目标是对小行星2016HO3进行探测、取样并返回地球，预计于2027年底着陆地球并完成回收。此后再对主带彗星311P开 展科学探测。天问二号任务周期约10年。 探月与航天工程中心副主任 天问二号任务新闻发言人 韩思远：天问二号任务是我国首次开展的行星际取样返回，这次任务实施难度大， 周期长、风险高，发射任务取得了圆满成功，但这只是我们万里长征的第一步。我们一共搭载了11台科学载荷，希望能够为我们相关小天体的 认知起源和演化带来更多的突破和发现。 主带彗星311P，是运行在火星和木星轨道之间小行星带中的一个小天体，对它进行探测，有助于了解小天体的物质组成、结构和演化机 制。 探测目标如何选定？ 天问二号探测的目标小行星有两个，分别是小行星2016HO3 和主带彗星311P，浩瀚宇 ...