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ponents of the robotic vchicle mechanical subsystem, senson, on-board control software, as well as the environment This paper describes recent developments in the ROAMS and terraidvehicle interactions. ROAMS provides interfaces physics-based simulator for planetary surface exploration to close many different rover control loops ranging from rover vehicles. ROAMS includes models for various subsys-IOW level motor control, locomotion estimation and control, tems and components of the vehicle including its mechani-to navigation and .,ision control loops shown in Figure 1. cal subsystem, sensors. on-board resources, on-board control The ROAMS 'simulator is being used for stand-alone simsoftware, the terrain environment and terraidvehicle interactions. The ROAMS simulator can be used in stand-alone mode, for closed-loop simulation with on-board software or for operator-in-the-loop simulations. 0-7803-8155-6/04/$17.00 @ZW4 IEEE 0-7803-8155-6/04/$17.00 02004 IEEE

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This paper provides a system overview of a new Mars rover prototype, Rocky 7 1. We describe all system aspects: mechanical and electrical design, computer and software infrastructure, algorithms for navigation and manipulation, science data acquisition, and outdoor rover testing. In each area, the improved or added functionality is explained in a context of its path to ight, and within the constraints of desired science missions.

Two primary simulations have been developed and are being updated for the Mars Science Laboratory entry, descent, and landing. The high-fidelity engineering end-to-end entry, descent, and landing simulation is based on NASA Langley Research Center's Program to Optimize Simulated Trajectories II and the end-to-end realtime, hardware-in-the-loop simulation test bed, which is based on NASA Jet Propulsion Laboratory's Dynamics Simulator for Entry, Descent, and Surface landing. The status of these Mars Science Laboratory entry, descent, and landing end-to-end simulations at this time is presented. Various models, capabilities, as well as validation and verification for these simulations, are discussed. Nomenclature decln star = angle between the spacecraft subplanet radius vector and equatorial plane gcrad = geocentric radius to spacecraft hgtagl = height above ground level rcalc = calculated radius to surface α = spacecraft-center-surface angle (angle between gcrad and rcalc) β = center-spacecraft-subsurface angle (angle between gcrad and hgtagl) θ = center-surface-spacecraft angle (angle between rcalc and hgtagl)

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Before the Perseverance rover landing, the acoustic environment of Mars was unknown. Models predicted that: (1) atmospheric turbulence changes at centimetre scales or smaller at the point where molecular viscosity converts kinetic energy into heat1, (2) the speed of sound varies at the surface with frequency2,3 and (3) high-frequency waves are strongly attenuated with distance in CO2 (refs. 2–4). However, theoretical models were uncertain because of a lack of experimental data at low pressure and the difficulty to characterize turbulence or attenuation in a closed environment. Here, using Perseverance microphone recordings, we present the first characterization of the acoustic environment on Mars and pressure fluctuations in the audible range and beyond, from 20 Hz to 50 kHz. We find that atmospheric sounds extend measurements of pressure variations down to 1,000 times smaller scales than ever observed before, showing a dissipative regime extending over five orders of magnitude in energy. Using point sources of sound (Ingenuity rotorcraft, laser-induced sparks), we highlight two distinct values for the speed of sound that are about 10 m s−1 apart below and above 240 Hz, a unique characteristic of low-pressure CO2-dominated atmosphere. We also provide the acoustic attenuation with distance above 2 kHz, allowing us to explain the large contribution of the CO2 vibrational relaxation in the audible range. These results establish a ground truth for the modelling of acoustic processes, which is critical for studies in atmospheres such as those of Mars and Venus.