Since its discovery in 1610, Europa-one of Jupiter's four large moons-has been an object of interest to astronomers and planetary scientists. Much of this interest stems from observations made by NASA's Voyager and Galileo spacecraft and from Earth-based telescopes indicating that Europa's surface is quite young, with very little evidence of cratering, and made principally of water ice. More recently, theoretical models of the jovian system and Europa have suggested that tidal heating may have resulted in the existence of liquid water, and perhaps an ocean, beneath Europa's surface. NASA's ongoing Galileo mission has profoundly expanded our understanding of Europa and the dynamics of the jovian system, and may allow us to constrain theoretical models of Europa's subsurface structure. Meanwhile, since the time of the Voyagers, there has been a revolution in our understanding of the limits of life on Earth. Life has been detected thriving in environments previously thought to be untenable-around hydrothermal vent systems on the seafloor, deep underground in basaltic rocks, and within polar ice. Elsewhere in the solar system, including on Europa, environments thought to be compatible with life as we know it on Earth are now considered possible, or even probable. Spacecraft missions are being planned that may be capable of proving their existence. Against this background, the Space Studies Board charged its Committee on Planetary and Lunar Exploration (COMPLEX) to perform a comprehensive study to assess current knowledge about Europa, outline a strategy for future spacecraft missions to Europa, and identify opportunities for complementary Earth-based studies of Europa. (See the preface for a full statement of the charge.)

Few worlds are as tantalizing and enigmatic as Europa, whose complex icy surface intimates the presence of an ocean below. Europa beckons for our understanding and future exploration, enticing us with the possibilities of a water-rich environment and the potential for life beyond Earth. This volume in the Space Science Series, with more than 80 contributing authors, reveals the discovery and current understanding of Europa’s icy shell, subsurface ocean, presumably active interior, and myriad inherent interactions within the Jupiter environment. Europa is the foundation upon which the coming decades of scientific advancement and exploration of this world will be built, making it indispensable for researchers, students, and all who hold a passion for exploration.

Recent spacecraft and robotic probes to Mars have yielded data that are changing our understanding significantly about the possibility of existing or past life on that planet. Coupled with advances in biology and life-detection techniques, these developments place increasing importance on the need to protect Mars from contamination by Earth-borne organisms. To help with this effort, NASA requested that the NRC examine existing planetary protection measures for Mars and recommend changes and further research to improve such measures. This report discusses policies, requirements, and techniques to protect Mars from organisms originating on Earth that could interfere with scientific investigations. It provides recommendations on cleanliness and biological burden levels of Mars-bound spacecraft, methods to reach those levels, and research to reduce uncertainties in preventing forward contamination of Mars.

NASA's exploration of planets and satellites during the past 50 years has led to the discovery of traces of water ice throughout the solar system and prospects for large liquid water reservoirs beneath the frozen ICE shells of multiple satellites of the giant planets of the outer solar system. During the coming decades, NASA and other space agencies will send flybys, orbiters, subsurface probes, and, possibly, landers to these distant worlds in order to explore their geologic and chemical context. Because of their potential to harbor alien life, NASA will select missions that target the most habitable outer solar system objects. This strategy poses formidable challenges for mission planners who must balance the opportunity for exploration with the risk of contamination by Earth's microbes, which could confuse the interpretation of data obtained from these objects. The 2000 NRC report Preventing the Forward Contamination of Europa provided a criterion that was adopted with prior recommendations from the Committee on Space Research of the International Council for Science. This current NRC report revisits and extends the findings and recommendations of the 2000 Europa report in light of recent advances in planetary and life sciences and, among other tasks, assesses the risk of contamination of icy bodies in the solar system.

A true story from one of the Women of NASA! Margaret Hamilton loved numbers as a young girl. She knew how many miles it was to the moon (and how many back). She loved studying algebra and geometry and calculus and using math to solve problems in the outside world. Soon math led her to MIT and then to helping NASA put a man on the moon! She handwrote code that would allow the spacecraft’s computer to solve any problems it might encounter. Apollo 8. Apollo 9. Apollo 10. Apollo 11. Without her code, none of those missions could have been completed. Dean Robbins and Lucy Knisley deliver a lovely portrayal of a pioneer in her field who never stopped reaching for the stars.

What comes next for the human race after all the natural resources are consumed, and global warming has run it "s course? This was the all-consuming question in 2032. Mars exploration fails. Humans are just too fragile for deep space exploration. Scientist Tom Casey has the answers, and found himself at the right place at the right time to act on them.

In 2003, NASA began an R&D effort to develop nuclear power and propulsion systems for solar system exploration. This activity, renamed Project Prometheus in 2004, was initiated because of the inherent limitations in photovoltaic and chemical propulsion systems in reaching many solar system objectives. To help determine appropriate missions for a nuclear power and propulsion capability, NASA asked the NRC for an independent assessment of potentially highly meritorious missions that may be enabled if space nuclear systems became operational. This report provides a series of space science objectives and missions that could be so enabled in the period beyond 2015 in the areas of astronomy and astrophysics, solar system exploration, and solar and space physics. It is based on but does not reprioritize the findings of previous NRC decadal surveys in those three areas.