When mining with a Heavy-Duty pickaxe(or Diamond), there is a chance to recover raw meteoric iron. The ingot can be made by smelting the items you get from mining meteors in a furnace. Meteors randomly hit on the surface of the moon and you will likely run into one while exploring the surface of the moon. They can be used to make airlock
They can be crafted into airlock frames (and heavy duty tools)
They also play the important part when combining Tier one Heavy Duty Plate to a Tier 2 Plate to have the Ability to go onwards to Mars.
All Items Craftable with Meteoric Iron:
Cable Facade (Applied Energistics 2)
Molten Meteoric Iron Can (Forestry)
Solid Meteoric Iron (Galacticraft Core)
Compressed Meteoric Iron (Galacticraft Core)
Meteoric Iron Gear (JAOPCA)
Meteroic Iron Seeds (Mystical Agriculture)
And a few more items within the Mods.
If you are Curious on what you can use this for, Open your Crafting Bench and Type in "Meteoric Iron" and you should see the results