Nasa's Goals for Solar System Exploration : Understand the nature and history of our Solar System, and what makes Earth similar to and different from its planetary neighbors; Understand the origin and evolution of life on Earth; Understand the external forces, including comet and asteroid impacts, that affect life and the habitability of Earth; Identify locales and resources for future human habitation within the solar system; Understand how life may originate and persist beyond Earth; and Make the solar system a part of the human experience in the same way that Earth is, and hence lay the groundwork for human expansion into the solar system in the coming century.

" Galileo Project Launched in 1989, the Galileo spacecraft arrived at Jupiter on December 7, 1995, when it fired its main engine for a successful orbit capture around Jupiter. On that day, Galileo's atmospheric probe plunged into Jupiter's atmosphere and relayed information on the structure and composition of the solar system's largest planet. The spacecraft's orbiter will spend the next two years orbiting the giant planet, studying Jupiter and its moons (encountering one moon during each orbit), and returning a steady stream of images and scientific data. After completing its primary mission, Galileo will then begin its two year extended mission called the Galileo Europa Mission..." more about the Galileo missions.

" In space exploration, the possibilities for discovery are without limits. Even with the vast amount of knowledge gained since exploration of our solar system began, there are still more questions than answers.
NASA's Discovery Program gives scientists the opportunity to dig deep into their imaginations and find innovative ways to unlock the mysteries of the solar system. It represents a breakthrough in the way NASA explores space, with lower-cost, highly focused planetary science investigations designed to enhance our understanding of the solar system. " more

" The mission objective of the Voyager Interstellar Mission (VIM) is to extend the NASA exploration of the solar system beyond the neighborhood of the outer planets to the outer limits of the Sun's sphere of influence, and possibly beyond. This extended mission is continuing to characterize the outer solar system environment and search for the heliopause boundary, the outer limits of the Sun's magnetic field and outward flow of the solar wind. Penetration of the heliopause boundary between the solar wind and the interstellar medium will allow measurements to be made of the interstellar fields, particles and waves unaffected by the solar wind.

" The Mars Exploration Program is a science-driven program that seeks to understand whether Mars was, is, or can be, a habitable world. To find out, we need to understand how geologic, climatic, and other processes have worked to shape Mars and its environment over time, as well as how they interact today.
Mars is similar to Earth in many ways, having many of the same "systems" that characterize our home world. Like Earth, Mars has an atmosphere, a hydrosphere, a cryosphere and a lithosphere. In other words, Mars has systems of air, water, ice, and geology that all interact to produce the Martian environment.
What we don't know yet is whether Mars ever developed or maintained a biosphere--an environment in which life could thrive." more

" Lunar Prospector was launched to the Moon, Jan 6th, 1998. Within a month it began returning answers to long-standing questions about the Moon, its resources, its structure and its origins. Prospector has accomplished these goals during its primary one-year polar orbiting mission. Using a complement of five instruments, the mission has yielded important science results at an unprecedented low cost. The first and most exciting data returned has answered the question first raised in the early seventies and underscored by the 1994 Clementine mission: Is there water in the form of ice in some polar craters? The significance of this information for further exploration of the Moon and future utilization of Moon resources is great. Prospector's final experiment consists of a series of events which begins on July 26, when, Lunar Prospector's orbit will be raised slightly to permit the spacecraft to stay in orbit for an additional 5 days to allow the moon's rotation to align the target crater with LP's orbit ground track. Before Prospector can go any further, however, it must first endure a long Earth eclipse period that will be the biggest challenge to its survival since it was launched a year and a half ago. In fact, the January launch date selected for LP was chosen in part to permit the spacecraft to complete its mission prior to July 1999, when the moon was predicted to pass behind the shadow of the Earth as it crosses the ecliptic plane in its monthly orbit. To economize on spacecraft costs, the LP battery was designed to handle maximum shadow periods of 47 minutes before being recharged by solar arrays mounted on the side the spacecraft..."

" The Marshall Space Flight Center in Huntsville, Ala., is one of NASA's largest and most diversified installations. The Marshall Center has been a key contributor to numerous significant NASA programs during the Agency's 45-plus-year history -- from the 1961 flight of the first U.S. astronaut into space, to the Apollo missions exploring the Moon, to development and operation of America's Space Shuttle fleet, and construction of and scientific discovery aboard the International Space Station.
Today, the Marshall Center is again contributing its collective expertise, ingenuity and energy as NASA and the nation begin carrying out the Vision for Space Exploration, which seeks to extend human presence across the Solar System -- starting with a human return to the Moon in preparation for human exploration of Mars and other destinations. " more