NASA NTRS2013
Before there is a funded space mission, there must be a present need for the mission. Space science and exploration are expensive, and without a well-defined and justifiable need, no one is going to commit significant funding for any space endeavor. However, as discussed in Chapter 1, applications of space technology and many and broad, hence there are many ways to determine and establish a mission need. Robotic science missions are justified by their science return. To be selected for flight, questions like these must be addressed: What is the science question that needs answering, and will the proposed mission be the most cost-effective way to answer it? Why does answering the question require an expensive space flight, instead of some ground-based alternative? If the question can only be answered by flying in space, then why is this approach better than other potential approaches? How much will it cost? And is the technology required to answer the question in hand and ready to use? If not, then how much will it cost and how long will it take to mature the technology to a usable level? There are also many ways to justify human exploration missions, including science return, technology advancement, as well as intangible reasons, such as national pride. Nonetheless, many of the questions that need answering, are similar to those for robotic science missions: Where are the people going, why, and will the proposed mission be the most cost-effective way to get there? What is the safest method to achieve the goal? How much will it cost? And is the technology required to get there and keep the crew alive in hand and ready to use? If not, then how much will it cost and how long will it take to mature the technology to a usable level? Another reason for some groups sending spacecraft into space is for profit. Telecommunications, geospatial imaging, and tourism are examples of proven, market-driven space missions and applications. For this specific set of users, the outstanding questions include: What is the product or service? Who will buy it? How can it be profitable? What is the most cost-effective solution to fielding the product or service? And, of course, is the technology in-hand or is there advanced development required? In order to answer these questions, the responsibility falls to a specially-skilled set of engineers and scientists who understand how to assess the readiness of new technologies.