What are the hazards and resources in the solar system that will affect the extension of human presence in space?
Our home planet is continuously bombarded by energetic particles, cosmic rays, dust and - occasionally - larger objects, all of which can be hazardous to human life. This risks increase as robotic and human explorers venture farther beyond the protection of Earth's atmosphere and magnetic field.
While they were once a source of life-giving organics and water, comets and asteroids also have the potential to wreak widespread destruction. Evidence continues to mount that the so-called Cretaceous-Tertiary mass extinction event 65 million years ago was caused by the impact of an extraterrestrial body about 10 kilometers (about 6.2 miles) in diameter.
Efforts are currently underway to inventory the objects that might pose an impact hazard to Earth. Scientists believe they have catalogued about half of the potentially hazardous objects larger than 1 kilometer (.62 miles) in diameter. Future focus will zero in on objects with orbits that could bring them dangerously close to Earth.
Evidence of the effects of impacts is plentiful in our solar system - especially on Earth's Moon - but further study is needed. While NASA's Deep Impact spacecraft provided a unique change to witness a hypervelocity impact with a comet, there have been no direct observations of the formation of planetary impact craters.
One way to avoid the fate of the dinosaurs is to extend human life beyond Earth.
NASA is already working on plans to return humans to the Moon and begin inventorying resources throughout our solar system that humans will need to travel to Mars and beyond. Those resources include water, essential for drinking and creating fuel and air; rare metals for use on Earth and construction on space colonies; and other resources to protect and foster life beyond the protection of our home world.
NASA 2006 Solar System Exploration Roadmap