S99-04188 (1994) --- Laser power stations, perhaps drawing energy from the local environment, might one day propel spacecraft throughout the solar system. NASA studies of advanced planetary missions have ranged from small robotic probes to multiple-spacecraft human exploration missions. This image produced for NASA by Pat Rawlings, (SAIC). Note: NASA currently has no formal plans for a human expedition to Mars or the Moon. This image and others displayed may not reflect the hardware and overall concept of possible visits to either of those celestial bodies. However, the art work represented here serves as a comprehensive study of various concepts and ideas developed as possibilities over a period of years. The renderings were accomplished by NASA and/or NASA-commissioned artists.