English: Designing spacecraft involves prioritizing criteria and making trade-offs based on environmental and resource constraints faced by engineers. NASA has been exploring Mars since the early 1960s and developing those missions is easy small task, taking many years and thousands of people working together to complete. Dr. Sarah Milkovich, a science system engineer, says, “One important aspect of system engineering is to think about what do you really need your system do to before you figure out how it’s going to do that.”