Mars Smart Lander Parachute Simulation Model

A multi-body flight simulation for the Mars Smart Lan-der has been developed that includes six degree-of-freedom rigid-body models for both the supersonically-deployed and subsonically-deployed parachutes. Thissimulation is designed to be incorporated into a largersimulation of the entire entry, descent and landing(EDL) sequence. The complete end-to-end simulationwill provide attitude history predictions of all bodiesthroughout the flight as well as loads on each of theconnecting lines. Other issues such as recontact withjettisoned elements (heat shield, back shield, parachutemortar covers, etc.), design of parachute and attachmentpoints, and desirable line properties can also be ad-dressed readily using this simulation. Introduction A multi-body flight simulation for the MarsSmart Lander has been developed that includes highfidelity models for both the supersonically-deployedand subsonically-deployed parachutes. While parachutemodels are necessary for simulation of all MarsLanders, the Mars Smart Lander will have a capability,namely active, autonomous, on-board Hazard Detectionand Avoidance (HDA) that makes the inclusion of thesemodels even more imperative. None of the MarsLanders to date have had an active on-board HDA sys-tem. This HDA function for these earlier landers hasbeen served by a combination of restricting the landingto "safe" sites as judged by the Mars Project Office andby "robust" lander design. Restriction of landing siteplaces limitations on the scientific objectives that canbe achieved, while robust lander design commits a largeamount of mass to components which provide no addedvalue to the mission. The Mars Smart Lander will in-clude an active HDA designed to insure a safe touch-down even in hazardous terrain, thus allowing safelandings in areas that would be considered too danger-ous for missions to date. The hazards to be avoidedinclude rocks, craters, and large sloping terrain. TheHDA system is currently envisioned to be composed oflidar and radar elements that map the local terrain anddetermine the location of safe landing zones. The in-formation gathered from the sensors would be providedto the on-board guidance algorithm, which would mod-ify the target point to avoid the detected hazards. Toaccurately model this HDA capability requires an accu-rate end-to-end simulation of the entire entry, descentand landing (EDL) sequence. Flight simulation ofspacecraft with parachutes is mathematically compli-cated and not easily characterized with traditional ap-proaches. It involves multiple bodies, some of whichare very flexible, flying in close proximity with signifi-cant interaction effects. In previous Mars Lander mis-sions, a separate simulation was developed for the para-chute portion of flight, independent of the other por-tions of the EDL, because the dynamics are so differentfrom the rest of the entry. This was the approach fol-