ET Sep As the shuttle leaves Earth's atmosphere and enters low Earth orbit its huge External Tank or ET is jettisoned. Of all the components which make up the Space Transportation System or STS this is the one part which is not reusable. After jettison the tank will re-enter the Earth's atmosphere and come to a fiery end in the Pacific Ocean far below. The next task for the two man crew of the now Orbital Shuttle Atlantis is to take their craft into close proximity with the International Space Station so that the next phase of the mission can take place. To be continued. Author/Artists Notes I never realised how huge the External Tank of the Space Shuttle is until I got the chance to actually stand under one. You can see it in pictures, on film and on TV but until you stand next or under one you really have no idea what a monster it is. To try and give you an example, try to imagin two London double-decker buses side by side, and then put three of these in a row next to each other. These six buses would fit easily inside the External Tank with room to spare.