Drag-Modulation Flight-Control System Options for Planetary Aerocapture

Abstract

Drag-modulation flight control may provide a simple method for controlling energy during aerocapture. Several drag-modulation flight-control system options are discussed and evaluated, including single-stage jettison, two-stage jettison, and continuously variable drag-modulation systems. Performance is assessed using numeric simulation with real-time guidance and targeting algorithms. Monte Carlo simulation is used to evaluate system robustness to expected day-of-flight uncertainties. Results indicate that drag-modulation flight control is an attractive option for aerocapture systems at Mars, where low peak heat rates enable the use of lightweight inflatable drag areas. Aerocapture using drag modulation at Titan is found to require large drag areas to limit peak heat rates to nonablative thermal-protection system limits or advanced lightweight ablators. The large gravity well and high peak heat rates experienced during aerocapture at Venus make drag-modulation flight control unattractive when combined with a nonablative thermal-protection system. Significantly larger drag areas or advances in fabric-based material thermal properties are required to improve feasibility at Venus.

Low-energy near Earth asteroid capture using Earth flybys and aerobraking

“…Considering the sensitivity of the transfer trajectory in the Sun-Earth CRTBP, especially the aerobraking phase, an accurate navigation and control strategy would be required to guarantee that the fly-by of the candidate NEA is at required altitude in order to obtain the required aerobraking manoeuvre. For example, the drag-modulation flight control method (Putnam and Braun, 2013) and the blended control, 27 predictor-corrector guidance algorithm (Jits and Walberg, 2004) may provide feasible solutions for the asteroid capture mission using aerobraking. Again, the carrier spacecraft is envisaged as remaining attached to, and shielded, by the NEA during the aerobraking manoeuvre to deliver active control.…”

Analytical Predictive Guidance Algorithm Based on Single Ballistic Coefficient Switching for Mars Aerocapture

“…This paper focuses on the drag switching control aerocapture guidance method. In order to control the terminal velocity, the probe may need to switch the ballistic coefficient between several constant values [7], as shown in Figure 1.…”

A Hybrid Aerocapture Guidance Algorithm

“…The basic idea of feedback linearization is to convert the original nonlinear system into a linear system by means of state feedback. Then mature linear control methods can be used to design the controller [6]. Let System output is defined as yD  .…”

“…In the HYPAS algorithm, the aerocapture process is divided into two phases: the first phase is capture phase which based on the quasi-equilibrium glide condition; the second phase is called exit phase in which the bank angle commend is generated according to the analytic predicted atmospheric exit altitude [4][5]. Compared with the analytic predictor-corrector approach, numerical predictive corrective guidance law (NPC) is more accurate, but the altitude of the trajectory is lower during the capture phase, which results in large overload [6,7]. Based on the NPC guidance law, Lu Ping proposed a series of energy-optimized guidance laws that focus on reducing the energy consumed to enhance perigee altitude [8].…”