| Popis: |
A NASA Innovative Advanced Concepts (NIAC) study aims to develop a technique for interrogating the molecular composition of asteroids from an orbiting spacecraft. The measurement concept relies on a high-power laser aboard the spacecraft whose objective is to melt and evaporate a spot on the surface of the target; the heated spot is then viewed by a spectrometer through the plume of ejected material. A CubeSat mission is envisioned as a test of the concept in the space environment, with a laser and spectrometer aboard a main craft, and a target craft flying in formation. A systems analysis is presented to define operational and mechanical characteristics of a laser and optical subsystem for the envisioned CubeSat experiment. Target materials drive the target flux requirement; common compounds found in celestial bodies were evaluated for spectral absorption and thermal properties. Suitable lasers are identified to provide the required flux, taking into account their technical specifications of size, power, intensity, wavelength, laser aperture angle, and analysis of Gaussian beam propagation. Respecting the technical specifications that should be taken into consideration in order to obtain the desired outcome (from the action of the laser), optical components suitable for use in a CubeSat were considered. An optical analysis is presented, based on models of the energy dissipation of the laser beam through optical components and along its path and through the space environment. Results of simulations are presented, including selected scenarios for distance between the laser source and the target. |
