Asteroids Challenge - Walkthrough

While inside the Entry Pod you will not take damage from lack of oxygen or from cold. Summon up your courage, and exit the Entry Pod.
If there are hostile mobs nearby, it's best not to take any items yet, just try to punch the mobs to death (alternatively, push them off the asteroid). Even if you die quite a few times, you will respawn next to the Entry Pod with full health so it doesn't matter.
At this point, Evolved Creepers are your friend - they mine Asteroid Rock for you.
Once there are no mobs nearby, right-click on the Entry Pod and move into the player inventory: Oxygen Mask, Oxygen Gear, 1 Heavy Oxygen Tank, the wood, the Thermal Cloth, and the Desh Ingots. Quickly switch to the Galacticraft inventory tab, and wear the Oxygen Mask, Oxygen Gear and oxygen tank.
Use 4 wood to craft a Crafting Table, 2 wood to craft sticks, and 2 Desh ingots to craft a Desh stick.
Craft the following: a full set of Thermal Padding (and wear it immediately). 1 wood pickaxe, 1 Desh Sword, 1 Desh Chestplate. Wear the Desh Chestplate. Return the rest of the wood, Desh ingots, and Thermal Cloth to the Entry Pod, it will be safe in there. (Pro tip: Thermal Helm, Leggings and Boots can be crafted quickly by laying out 16 Thermal Cloth in the crafting grid in the pattern made by the three recipes super-imposed, then Shift-Click three times.)
(There are other options for what you can craft out of the Desh Ingots - for example, 16 ingots could make either 2 pieces of Desh armor (Chestplate + Boots is best) and a sword, or it could be Helmet, Desh Pickaxe and a sword - or you could stay with a stone sword for now. The Desh Pickaxe has a higher harvest level than diamond, so it can mine any Ilmenite or Diamond Ore you find, which could be handy if you find those before you have diamond / iron tools. This might also allow you to skip the wooden and stone picks stage for a luxury start.)
Using the wooden pickaxe, mine a short way down inside the asteroid you are standing on, you are looking to have 2 different types of Asteroid Rock. Once you have a few blocks of 2 different types (which don't stack), craft them together to make Cobblestone, and make a Stone Pickaxe + a three or four spare Stone Pickaxes as well.
Mine 2 stacks of Asteroid Rock, you will use this to build bridges to other Asteroids.
You are now looking for two things, essential to make any progress: a Hollow Asteroid where you can start farming, and iron ore.
Look around to see if you can find any nearby large asteroids. (In the game Options / Video Options, increase your viewing distance if you need to.) Any large asteroid could contain Iron Ore or another valuable ore - the larger it is, the higher the chance. For a chance for a Hollow Asteroid you want one whose appearance is pure ice, not mixed rock and ice. Ice asteroids are easy to see because ice is brighter than rock.
Note down the exact co-ordinates of your current location where the Entry Pod is - it will be tough to find it again later if you don't.
Bring with you: sword, spare pickaxes, crafting table, spare wood (because you might need another pickaxe, and you will need to craft an axe when you find that Hollow Asteroid), all the food, 1 Canister of Liquid Oxygen, 1 Basic Wafer, and the Cryogenic Chamber.
Pick a nearby large asteroid, and build a bridge out towards it, or carefully jump towards it on small asteroids so that you don't need to build such a long bridge. If the large asteroid is somewhere below you, you may not even need a bridge, you could just 'fall with style' down to it.
Mine to the center of the large asteroid to see if it has anything useful in it. Even if it has no ores, stacks of Asteroid Rock are useful too at this stage of the game, you need plenty of rock for bridges and (later) for making cobblestone, sand, glass, flints, etc.
Mark asteroids you have explored / mined, so you can see your mark from some distance away. For example a cobblestone X, or a pillar of Asteroid Rock: later you can use Glowstone Torches.
Keep doing this until you find a Hollow Asteroid and also a good source of Iron Ore. You should not need to travel too far from your starting position, you are likely to find both within 150-200 blocks, though that could be in any direction and also 100 blocks above or below you.
Keep an eye on your oxygen levels. You can use your Liquid Oxygen Canister to top up your oxygen tank (you can do this quickly enough that you only lose half a heart).
Keep an eye on your food levels, the can of food restores around 2-2.5 hearts. Be careful eating the can of food, the Tin Canister will be thrown away afterwards somewhere nearby. That tin can is very precious, smelting it gives 3 Tin Ingots which you have no other way to obtain. So it's best to eat canned food only when you are inside an enclosed space so that you can't lose the can.
Fight any isolated mobs you find along the way, the mob drops are extremely valuable - at this stage of the game, you especially need the bones from Evolved Skeletons and the string from Evolved Spiders, but it's all good. But run from any large groups of mobs (especially multiple skeletons), those may be fights you can't win, and the items you are carrying are too valuable to take a chance. You do not need to fight Evolved Creepers yet.
When fighting mobs on Asteroids, the main problem is the knockback from their attacks, which knocks you up. Use this to your advantage: while in the air move so you are above the mob and score a critical strike as you come down. This is a great way to fight Evolved Skeletons (which are otherwise very challenging to fight...): if you are directly above their heads, they have a hard time targeting you. It doesn't work so well with Evolved Creepers, you need to attack and run back from them, the same as with vanilla creepers.
90% of Hollow Asteroids contain a tree. Break its leaves for saplings (and maybe an apple). Harvest its wood. Plant the sapling(s) and wait for more trees to grow.
A few Hollow Asteroids contain tall grass, but often not even enough to harvest any seeds. Use bonemeal on the grass to grow more tall grass (also flowers...). Gather seeds. Craft a stone hoe, make farmland and plant the seeds. You need to build up your wheat farm as quickly as possible, so that you have a food supply by the time your 16 starting cans of food are finished.
Craft one or more Furnaces from cobblestone. Use 1 wood to smelt 4 wood into charcoal. From now on, you will always use charcoal as your fuel source. (Pro tip: when you have too many saplings you can also use saplings as fuel. 2 saplings makes a nice fuel source for a furnace for when you only need to smelt 1 item, it saves you from wasting a whole charcoal on 1 item.)
If you have wood to spare, you can smelt cobblestone into plain stone, and craft half slabs - these are good for long bridges between asteroids, as you only need half the amount of stone.
As soon as you have iron, the priority is an Iron Pickaxe. And a full set of iron armor (+ 1 Desh item if you still have that from the start) gives reasonable protection so you can fight mobs properly.
Now that you have iron tools, you are looking for Aluminium Ore. If while looking for it you find other ores, make a note of where they are, although you probably do not yet have the tools to mine them.
By now, you should be fighting Evolved Zombies whenever you see them: you are hoping that one will drop a copper ingot when it dies (1 in 12 chance of that). Likewise, fight Evolved Spiders whenever you see them, you want the string they drop, so that you can make wool, so that you can craft Aluminium Wire.
When you have 6 Aluminium Ingots, 1 Copper Ingot, and 31 Iron Ingots, you are ready to craft your Compressor.
If iron and charcoal are plentiful, you should make a full set of Heavy Duty Armor and tools from Compressed Steel. This gives you strong protection (better than Diamond Armor) and strong tools which can mine everything.
A Grapple is also a pretty handy thing to have, note that you need spare string as well to use it properly.
Around now would be a good time to go all the way back to the original Entry Pod and fetch the rocket and items left in it and bring them safely to your base, if you didn't do that already. Any Liquid Oxygen Canister which is empty can be used to take the fuel out of the Entry Pod.
Using Once you have a Compressor, you could now fairly quickly craft only the items needed to build a Fuel Loader, a Solar Generator to power it, and a Launch Pad, so that you can leave the Asteroids dimension and return to the Overworld before your original oxygen tanks run out.
Alternatively you can create start to create other Galacticraft machines, starting with the Oxygen Collector, and build up a sustainable Asteroids base.
If you are lucky enough to get mob drops of netherwart and fermented spider eye, then you only need 1 blaze rod (from an Evolved Creeper, see above) and you can start brewing potions. A carrot (dropped rarely by Evolved Zombies, though this is even rare than cans of food) will be needed to start carrot farming for Night Vision potions.
If you have a pool of water in your Hollow Asteroid base, you can fish in it. (Yes, we know that the idea of wild fish spawning in space is weird...) If you don't have water, you should probably check out some other nearby Hollow Asteroids to find some.
For your power systems, you do not need an Energy Storage Unit (which is incredibly costly, requiring 15 tin ingots). The internal storage in your Solar Generator should be enough to power your first two machines (Oxygen Collector + Oxygen Compressor).
Once you have a Circuit Fabricator you should be looking to build Advanced Solar Generators if possible, that is the best way to gather enough energy to power a sealed base, and should reduce the amount of Aluminium Wire you need. Aluminium Wire is probably limited by how many spiders you can kill.
Unless you are totally desperate for food, do not use your chicken or cow eggs until you have a sealed base (or a bubble distributor: but a sealed base is better). Making a sustainable cow farm is your only way to get enough leather to make a book and start enchanting.
At some point you might want to build a mob spawner + grinder. Although plenty of mobs spawn naturally in the Asteroids, a more efficient system for harvesting mob resources will be nice to have. If you have a good design for a mob spawner + grinder which works in this dimension, please share it on the forum.