Laser Propulsion for Ground to Orbit Launch

Ground to orbit launch using laser propulsion requires a thermal system. Physically allowed thermal concepts are discussed and compared. It is argued that the laser supported detonation (LSD) mechanism presents a number of advantages over the alternatives. Numerical simulations of ascent trajectories for a system based on the LSD mechanism were performed to gain insight into the mechanics of laser propulsion and the influence of the most relevant mission parameters. Comparison with the Lightcraft flight data was made and it is shown that the 70 meter height limit is due to excessive laser diffraction. A hypothetical 10 km Lightcraft simulation employing existing technology is presented.Astrodynamics & Space Mission

Long-distance electron transport in individual, living cable bacteria

Electron transport within living cells is essential for energy conservation in all respiring and photosynthetic organisms. While a few bacteria transport electrons over micrometer distances to their surroundings, filaments of cable bacteria are hypothesized to conduct electric currents over centimeter distances. We used resonance Raman microscopy to analyze cytochrome redox states in living cable bacteria. Cable-bacteria filaments were placed in microscope chambers with sulfide as electron source and oxygen as electron sink at opposite ends. Along individual filaments a gradient in cytochrome redox potential was detected, which immediately broke down upon removal of oxygen or laser cutting of the filaments. Without access to oxygen, a rapid shift toward more reduced cytochromes was observed, as electrons were no longer drained from the filament but accumulated in the cellular cytochromes. These results provide direct evidence for long-distance electron transport in living multicellular bacteria.BT/Environmental Biotechnolog