月面可能熔岩洞

[peter]

http://www.universetoday.com/128208/buried-lave-tubes/


Marius Hills pit



Artist concept of the GRAIL mission, twin spacecraft that fly in tandem around the Moon to measure its gravity field. Credit: NASA/JPL



Artist’s impression of a lava tube measuring several kms wide, with the city of Philadelphia shown inside for scale: Purdue University/David Blair
科學家認為 直接蓋在洞內比較快
還能抗宇宙射線



月面重力圖

地球上的  
https://en.wikipedia.org/wiki/Lava_tube

[peter]

eva 中  第三東京市


不知道 地球有沒夠大洞 ??