DSENDS - A high-fidelity dynamics and spacecraft simulator for entry, descent and surface landing

Abstract

The Jet Propulsion Laboratory (JPL) is developing a high-fidelity spacecraft simulator for Entry, Descent and Landing (EDL) on planetary and small-bodies. This simulator, DSENDS (Dynamics Simulator for Entry, Descent and Surface landing), is an EDL-specific extension of a JPL multi-mission simulation toolkit (Darts/Dshell) which is capable of modeling spacecraft dynamics, devices, and subsystems, and is in use by interplanetary and science-craft missions such as Cassini, Galileo, SIM, and Starlight. DSENDS is currently in use by the JPL Smart Lander project [1] to provide a high-fidelity testbed for the test of precision landing and hazard avoidance functions for future Mars missions. We first briefly describe the core tool capabilities in dynamics, instrument/actuator device models, and real-time simulation engineering. These allow the modeling of the flight-train elements during various phases of EDL and all of the spacecraft responses. We then address the various EDL-specific aspects of the simulator. These include the high-fidelity entry-body and parachute aerodynamic models and supporting atmospheric models. In addition the simulator provides real-time terrain and instrument simulations for terrain imaging lidars and radars. The simulator hosts guidance/navigation simulation modules for hypersonic steering and powered descent. Models for landing kinematics and dynamics are being incorporated to determine contact and impact forces. We also discuss the automated state-machine driven model switching used to handle spacecraft separations and re-configurations, as well as specific visualization tools developed to support EDL execution interpretation. The DSENDS system is capable of supporting the entire mission lifecycle use of simulators. This includes the facility to embed the simulator into a Matlab/Simulink environment where control analysts can use the same high-fidelity simulation used in real-time operations within a familiar analysis environment. DSENDS also provides stand-alone simulations to provide mission visualization and support for Monte-Carlo analysis. Using the real-time features of the underlying Darts/Dshell toolkit, DSENDS can be made to operate in a VxWorks/VxSim real-time testbed.

Wheel-Terrain Contact Modeling in the ROAMS Planetary Rover Simulation

“…Likewise this has had the effect of making available these extensions to other simulators sharing the same simulation infrastructure. A case in point here is the DSENDS entry, descent and landing simulation tool [5] that uses the same DARTS & Dshell simulation framework and shares several modules with ROAMS including those for dynamics simulation and terrain environment modeling. …”

A Lunar Surface Operations Simulator

“…The software infrastructure to enable this was developed for the ROAMS [15] simulator to vary terrain and soil parameters and DSENDS [7] simulator to vary atmospheric conditions in entry, descent and landing simulations. This parametric analysis infrastructure was adapted for LSOS to orchestrate batch runs of lunar habitat simulations.…”

“…Subsequent development around DARTS has led to supporting packages and simulators for a variety of space applications. These include Dshell [4], SimScape [8], ROAMS [5,6], and DSENDS [7]. This paper gives an overview of LSOS.…”

Large Terrain Modeling and Visualization for Planets

“…These missions require the development and use of closedloop simulations for the space platforms and the planetary environments. These simulations can involve entry, descent, landing (EDL) [1] and rover traverses over rough terrain scenarios [2]. The simulations are used for, among other things, landing site selection, science planning, and outreach.…”