What Delayed China’s Moon Mission?

China’s Chang’e-7 lunar probe sitting atop its Long March-5 Y14 carrier rocket has been rolled back to the assembly and test building at the Wenchang Space Launch Site in Hainan. Chang’e-7 was ready to head for the Moon’s south pole on August 24 (Beijing Time) in a search for evidence of water ice. “China’s Chang’e-7 launch will not proceed in planned window this year” – that was the word from China Central Television (CCTV). Confluence of issues While not cancelled, the Moon mission was delayed due to an apparent confluence of issues. “Chang’e-7 will rely primarily on solar power, meaning it must arrive at the right time to take advantage of favorable lighting conditions. The spacecraft needs to reach and land in the target area before a high-quality period of continuous sunlight begins,” reports China Global Television Network (CGTN). “Preliminary estimates suggest that the total period each year offering particularly favorable lighting conditions for stable exploration may be only around 100 days,” CGTN reports. “These opportunities do not occur every month, and they cannot necessarily be recovered simply by launching a few days later.” Timing So the word posted on the China Manned Space Engineering Website explains: “Based on the principles of prudence, reliability, and absolute safety, and after comprehensive assessment, the Chang’e-7 mission does not meet the launch requirements and cannot be carried out within the scheduled launch window this year.” CGTN explains that is why official statements noted that Chang’e-7 could not be launched during its planned window this year, rather than simply saying that the launch has been delayed by a few days. “For a mission to one of the Moon’s most challenging environments, timing is not just about when the rocket leaves Earth. It is about making sure the spacecraft arrives at the Moon at exactly the right moment,” CGTN points out. Illuminating decision So it looks as if a tight launch window, a blossoming and troublesome Tropical Depression Narra, the need to have the lunar lander touch down precisely at an illuminated site near Shackleton Crater, as well as use of a Chinese lunar relay satellite to handle telecommunications between Earth and spacecraft – all have conspired to re-calibrate the sendoff of Chang’e-7. Indeed, typhoon Narra is forecast to land in China between late Tuesday night and Wednesday. Typhoon Saudel may hit the Chinese coast between late Thursday night and Friday morning, according to the National Meteorological Center (NMC). “It is my understanding that due to impending weather (tropical storm in the Gulf of Tonkin off Hainan Island), the launch of Chang’e-7 has been postponed beyond this week,” said James Head, a leading lunar expert at Brown University in Providence, Rhode Island. “Launch rescheduling is a complex algorithm for orbital study of the landing site with the optimal in-orbit time and also optimizing the landing illumination conditions,” Head told Inside Outer Space. For a detailed look at the challenging Chang’e-7 mission, go to this pre-delay story focused on this innovative mission by China at: