 Good morning, I'm Sasha Pfeiffer. When Neil Armstrong took his giant leap for mankind in 1969, he did so on the moon's Sea of Tranquility. Now, not too far from there, researchers have discovered a cave on the moon for the first time. It's more than 300 feet deep, and it could be connected to hundreds of other caves, which scientists say could be perfect for a future lunar base, protecting moon residents from radiation and cosmic rays. It's Morning Edition.