I'm nearing the end of the game at Launch Preparation. I have combined cartridges and pocket knife to make explosive powder for one of the retrorockets. I need more powder to fill the other rocket. The option is to open the barrel of powder which was taken early in the game for the moon landing but it isn't in inventory and I can't find it. thanks

Blackbird do you have more then one page of inventory? If so check out all the pages for powder.
Kay

Thanks. I have chkd all inventory pages and also items which I sold. I'll go back through the walkthrough again and check the colourful plant area in case I threw it out prior to moon landing and didn't pick it up. I'll come back if I still have a problem.
The barrel went from inventory after use early in the game. I did not notice the walkthrough said "make 2" when making explosive mixture earlier or I would have had one to use in the second retro rocket. So, I've had to go backwards to go forwards, all part of the fun.

You can use: explosive powder or Prulmis' explosive mixture.

I see you edited. Great - glad you found the solutiion.