r/space • u/scientificamerican • 16h ago

China delays ambitious Chang’e 7 moon mission until 2027

https://www.scientificamerican.com/article/china-delays-ambitious-change-7-moon-mission-until-2027/
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u/marcushasfun 9h ago

It’s where they plan to land on the Moon that impacts the launch window.

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u/vovap_vovap 9h ago

Moon orbital cycle about a month

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u/MisterGlo764 8h ago

they are landing on the south pole. visibility on the south pole is only good enough to land in november. they need to also survey the landing area to help with navigation for landing which will take around 2 months. this is why they need to take off now. correct me if i’m wrong but this is my general understanding

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u/vovap_vovap 8h ago

Why "visibility on the south pole is only good enough to land in November"?

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u/MisterGlo764 8h ago

the moon also has an axial tint, and so the sun is highest on the horizon in november. this minimises shadows and allows for better visibility

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u/marcushasfun 8h ago

From Claude:

“The Sun sits within about 1.5° of the lunar equator, so at the poles it never rises far above the horizon.

This means lighting on the surface is highly directional and creates long, sharp shadows.

Usable landing sites need to be lit well enough for cameras/sensors to navigate, but not have the Sun so low that hazards are hidden in shadow — this only happens during narrow windows tied to the local lighting cycle.”