Asteroids Challenge - Tips

Here are some ways to get various items.

Thermal Padding - you start with enough Thermal Cloth to craft a full set of thermal padding, with 8 spare so that you can replace 1 item if you lose it. If you need more after that, you will have to obtain Wool.

Iron Ingot - from Asteroid Iron Ore. Some large asteroids have a solid core of Iron Ore, making Iron in plentiful supply. It can also be obtained from mining Ilmenite Ore with a suitable pick. In Galacticraft 4 there are also a small number of iron ingots hidden in Abandoned Base. Note that Asteroid Iron Ore itself requires an iron tool to mine it, which gives you a problem near the start. An Evolved Creeper explosion near ores might give you a few ore blocks even if you don't have tools.

Copper Ingot - this is an occasional drop from an Evolved Zombie. Note it is a similar colour to rotten flesh and is only dropped if the player kills the zombie. Killing 50 Evolved Zombies should give you around 4 copper ingots, more if you have a Looting enchantment.

Tin Ingot - tin is in very limited supply: smelting a Tin Canister produces 3 Tin Ingots. (This is in contrast to the Moon and Mars where tin is abundant.) The only way to replenish your supply is that Evolved Skeletons and Evolved Zombies make rare drops of Tin Canister and Canned Food.

Meteoric Iron Ingot - meteors occasionally collide with asteroids. Also some large asteroids have a solid core of Meteoric Iron (rare, but a very rich supply if you find one).

Desh Ingot - you start out with 16 ingots. In Galacticraft 3 these cannot be replaced unless you travel to Mars. In Galacticraft 4 you might be able to find some more Desh supplies on an Abandoned Base.

Titanium Ingot - Some large asteroids have Ilmenite Ore, note you will need a diamond pickaxe or better, to mine it.

Wood - there are small or medium trees (oak mainly, sometimes birch) inside most Hollow Asteroids. If a Hollow Asteroid has no trees, or you don't succeed in collecting any saplings from the trees, then you will need to search out a different Hollow Asteroid.

Coal - this can be manufactured in the Compressor out of Charcoal, so it is unlimited if you have a tree farm.

Sand - this can be manufactured from Gravel, see Compressor Recipes.

Ice - it is a rare drop from Evolved Creepers, alternatively if you need a lot of it, you would need to mine Dense Ice with a tool with the Silk Touch enchantment, and compress that in the Compressor.

Water - either make this from Ice, or search for a Hollow Asteroid which contains a pool of water - around 1 in 5 will contain a pool.

Lava - lava pools can also, rarely, be found in Hollow Asteroids - though never at the same time as water.

Redstone - dropped by Evolved Creeper on death.

Lapis Lazuli - this is an occasional drop from Evolved Skeletons, you should not need much of it except to fabricate extra Solar Panels or (in Minecraft 1.8.9+) for enchanting.

Silicon - some large asteroids have solid cores of silicon ore (rare, but a good supply if you can find one - worth getting a Fortune enchantment for)

Diamond - some large asteroids have solid cores of diamond ore (rare, but an incredibly rich supply if you can find it - worth getting a Fortune enchantment for)

Wool - can be crafted from string, this is a vanilla recipe. String is dropped by Evolved Spiders.

Glowstone Dust - glowstone blocks are plentiful inside Hollow Asteroids.

Blaze Rod - if an Evolved Creeper is burning when it is killed by the player, it will drop a Blaze Rod. This is difficult to achieve in an airless dimension but not completely impossible.

Slimeball - can be crafted from Cheese Curd (which is a rare drop from an Evolved Spider), sugar cane and green dye. Without cactus, green due can be made from combining blue dye (Lapis) and yellow dye (from flowers). If you need a large amount of slimeballs - without travelling to the Overworld - you would need to visit the Moon and mine Cheese Ore. Or visit Mars and slaughter Slimelings, but that is not a very kind way to behave.

Ender Pearl - Endermen (or in Galacticraft 4, Evolved Enderman) spawn in the Asteroids dimension in this game mode - they are about as rare as they are on the Overworld.