Describe what you do in your current work situation. To explain what I do, assume for a minute that you have developed an instrument to do something at Mars...now you need to get it there. I am part of a large team at NASA that can do the job. Lets say your instrument is a camera and you want to use to take pictures of the planet. We design the satellites to hold your camera and we put them in orbit around other planets like Mars. Or say your instrument requires soil samples on Mars. We find out how many samples you would need and where you would like to take them and we design a rover (mobile) or a lander (immobile) that will go where you want and take the samples you want.