This paper contains results from ongoing ascent guidance studies being conducted at NASA's Marshall Space Flight Center. The studies include investigation of different open-loop and closed-loop guidance schemes for a variety of potential launch vehicles. The focus is on operations cost, satisfaction of load indicator constraints, and maximization of performance. Results show that open-loop designs as a function of altitude or velocity are preferable to designs that are functions of time. Optimized open-loop trajectories can increase performance while maintaining load indicators within limits. Closed-loop atmospheric schemes that involve linear tangent steering or that involve feedback of velocity terms for trajectory modification did not yield any improvement. Early release of vacuum closed-loop guidance, including use during solid rocket booster operation, yielded some improvements. A closed-loop optimization scheme for flying through the atmosphere shows promise, but work is incomplete. Dispersion study results for several potential guidance schemes and launch vehicles are included in the paper. The primary cost driver is mission operations philosophy (as opposed to choice of guidance scheme), although choice of more autonomous guidance schemes can help in movement towards a philosophy that would reduce operations costs.
展开▼
