Orientale basin
The Moon's largest impact basin, first seen with unaided human eyes by the Artemis II crew.
Last refreshed: 5 April 2026 · Appears in 1 active topic
Why did NASA's Artemis II crew prioritise photographing Orientale basin?
Latest on Orientale basin
- What is Orientale basin on the Moon?
- A 965-kilometre multi-ring impact crater on the Moon's far western limb, formed ~3.8 billion years ago. It is the best-preserved basin of its type and was first seen by human eyes during the Artemis II flyby in April 2026.Source: background
- Did the Artemis II crew see Orientale basin?
- Yes. Christina Koch and the three other crew members became the first humans to observe the complete basin with unaided eyes during closest lunar approach on 6 April 2026.Source: background
- Why is Orientale basin scientifically important?
- Its three concentric mountain rings are so well preserved that geologists use it as the reference model for how large impacts reshape planetary crusts. No spacecraft has landed there, making Artemis II imagery particularly valuable.Source: background
- Where exactly is Orientale basin on the Moon?
- On the far western limb, straddling the boundary between the near and far sides. From Earth it appears as a foreshortened arc near the lunar edge.Source: background
Background
Orientale basin sits on the Moon's far western limb, straddling the boundary between the near and far sides. On 6 April 2026, Christina Koch and the three other Artemis II crew members became the first humans to observe the complete 965-kilometre-wide crater with their own eyes, looking down from the Orion capsule at closest lunar approach.
Formed roughly 3.8 billion years ago during the Late Heavy Bombardment, Orientale is a textbook multi-ring impact basin: three concentric mountain rings surround a dark basaltic mare at the centre. The outermost Cordillera Mountains span 930 km. Its geometry is so well-preserved that geologists use it as the reference model for how large impacts reshape planetary crusts. The Lunar Reconnaissance Orbiter has mapped it in detail, but no spacecraft has ever landed there.
Artemis II made Orientale a target of opportunity. The crew rehearsed a six-hour photography choreography ahead of the flyby, working through NASA's prioritised surface-feature list. The imagery gathered will inform landing-site analysis for future Artemis missions and deepen understanding of a basin that, from Earth, appears only as a foreshortened arc near the lunar limb.
