[Illustration: The Voyager scan platform contains sophisticated instruments that gather data for Voyager’s remote sensing investigations. Five of the remote-sensing instruments—two TV cameras, the infrared spectrometer, the ultraviolet spectrometer, and the photopolarimeter—are mounted together on the scan platform, which can be pointed to almost any direction in space, allowing exact targeting of the observations. [373-7146BC]] CHAPTER 4 SCIENCE AND SCIENTISTS Introduction There are many reasons for sending spacecraft to the planets, but in the final analysis, we send our robot messengers across the vastness of space for the sake of scientific exploration. Science and exploration have always gone hand in hand, whether in the transcontinental journey of Lewis and Clark or the Pacific voyages of Captain James Cook. In this century, as exploration has become more and more dependent on advances in technology, the scientific element has attained increased prominence. The greatest legacy of the NASA Planetary Program is the knowledge it has provided of the other worlds that share our corner of the universe. Despite the central role of science in motivating missions to the planets, specific scientific considerations are not dominant during most of the development of a mission such as Voyager. The problem of building a spacecraft and getting it to the outer solar system is too demanding. Of the ton of mass in a Voyager spacecraft, the scientific instruments make up only 115 kilograms (about eleven percent). Similarly, the cost of these instruments amounts to only about 10 percent of the cost of the spacecraft and launch vehicle. Unless the launch and operation of the spacecraft are nearly perfect, there can be no scientific return in any case; even the most sophisticated package of scientific instruments will not tell much about Jupiter if, following launch, it rests at the bottom of the Atlantic Ocean. But it is equally true that the ultimate purpose of the mission is scientific discovery, and NASA makes every effort to ensure that the very best instruments are flown and that a broad scientific community is given the opportunity to participate in each mission.