Immortality is a fairly easy problem to solve once you get enough levels. Instead, I've been looking for easy ways to help out ESA (or NASA if you're American) at low/mid levels, while still following the "no custom items" rule. Obviously at high levels you can just Greater Teleport an astronaut to Mars to gather samples or whatever, and eventually build a Stronghold space that can bring passengers from planet to planet. But in the meantime, here's what I've come up with:
  1. Weeping Flask seems very very easy to make, and creates 8 ounces of water a day. If all you want is personal consumption, you could do worse than this.
  2. Everful Basin promises an endless supply of water, and requires only Craft Wondrous Item and Create Water. Of course it stops working if it's even turned upside down and emptied, but that's what covers are for. This item immensely facilitates logistics and weight issues.
  3. Similarly, once you get third-level Cleric spells you can give them infinite food fairly easily (Everlasting Rations, Travel Cloak, etc)
  4. If you want motive force, then good ship design + "solar" sails are now the optimal way to move through space. Everfull Sails from Stormwrack are very easy to craft (my Sha'ir 3 could make them right now!) and creates enough motive force to drive the ship forward "at its full normal speed". Simply design a spaceship so that its "normal speed" is spaceworthy, and you have now created a cheap way to travel through space that doesn't rely on Teleportation or high-level spellcasters! Of course you'll want a real space agency to actually design the ship. This isn't the kind of space exploration one PC can do from his backyard (you'll want to wait a few more levels for that).
  5. Obviously there's the Necklace of Adaptation (craftable at level 7) that I'm sure every astronaut would love to have. Theoretically, you could even use it to fly in something that isn't very spaceworthy (that doesn't bother with air supply, for example). This again potentially massively decreases logistical constraints on safety, range, etc.
  6. I'm not listing Decanter of Endless Water, because at the level where you can craft this you can already Plane Shift or whatever.