In a hidden area of the first long, vertical shaft in the Brinstar area, there is a Super Missile Tank under a low passage filled with charge blocks. Initially, it looks impossible to attain this item, but there is a way to get it, after you get the High Jump item. Roll into Morph Ball form through the low passage to the right. Note where you appear on the screen. At the same level on the right-hand side of the screen is another ledge. Get to this ledge and go right, bombing your way through the room with the two Rippers and coming back up to the surface in front of a door. Stand with your back against the wall, and wait until the bomb block returns, then shoot open the door and run to the right. Continue running until your Speed Booster activates, then immediately press Down to store the charge. Run back to the left, quickly shooting open the door, and in the 'dip' in the floor level before the door, roll into Morph Ball form and press A, then Left. If done correctly, you will blast to the left, crashing through some charge blocks in the next room, and destroying both Rippers on your way through the hidden room. After you leave the hidden room, as the screen is scrolling, you should hear the Speed Boost sound effect start again. Immediately hold Down until after you appear on the next screen to store your charge again. Roll out of the hidden passage, jump onto the lower platform, then press A, then Left again. If you have done everything correctly, you will blast through the hidden passage on the left side of the screen, crash through the charge blocks and collect the Super Missile Tank. Many items in this game can only be attained through creative uses of Samus' dashing attack like this; any time you see an item that is blocked by charge blocks, look for areas nearby where you can build up enough speed to activate the Speed Booster.