Chris D Karlgaard | Search NASA

NASA NTRS2020

InSight Entry, Descent and Landing Post-Flight Performance Assessment

On November 26, 2018, the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) lander successfully touched down on the surface of Mars. NASA Langley Research Center’s (LaRC) Program to Optimize Simulated Trajectories II (POST2) was used during both project development and flight operations to assess the Entry, Descent and Landing (EDL) vehicle performance against related requirements across the expected range of possible environmental and spacecraft conditions. During flight operations, these analyses were used to evaluate the need for updating flight software EDL parameters and the effects of executing a trajectory correction maneuver (TCM). Therefore, the NASA LaRC POST2 simulation had a critical role during the cruise, approach and ultimately EDL phases of the mission. This paper presents results of the final pre- and post- EDL flight performance assessments. A summary of the reconstructed “as-flown” trajectory with a comparison of key EDL metrics to the nominal and three-sigma bound pre-EDL predictions is also provided. Emphasis on the trajectory between entry interface and parachute deploy is provided as this is the period during which deviations from the pre-EDL prediction occurred. The post-flight assessment provides important verification of the POST2 models and analysis techniques used for InSight, providing critical feed-forward information to future lander missions.

Robert W Maddock↗

NASA NTRSDate not supplied

Mars Sample Return Earth Entry System Helicopter Drop Test Reconstruction

The Mars Sample Return campaign conducted four successful helicopter drop tests of the Earth Entry System at the Utah Test and Training Range on October, 2023. The tests acquired data for the 52.5 deg sphere cone geometry that can be used to develop models for the terminal descent aerodynamics and flight dynamics used to model ground impact conditions. The acquired test data included both sensor data outputs from an on-board inertial measurement unit, global positioning system, and video cameras as well as atmospheric measurements from weather balloons. This data was processed using a Kalman filter/smoother to reconstruct the capsule’s trajectory and aerodynamics. An equation-error method was used to reconcile the aerodynamics by solving for a set of dispersions in the aerodynamic database that form a best-fit to the reconstructed aerodynamics. The reconstructed trajectories were compared with flight simulations generated using Program to Optimize Simulated Trajectories II. The results indicate that the simulation underpredicted the vehicle oscillation amplitudes. The reconstruction exhibits a persistent low-amplitude oscillation that does not damp out as predicted.

Chris D Karlgaard↗

NASA NTRSDate not supplied

Mars Sample Return Earth Entry System Helicopter Drop Test Reconstruction

The Mars Sample Return campaign conducted four successful helicopter drop tests of the Earth Entry System at the Utah Test and Training Range on October, 2023. The tests acquired data for the 52.5 deg sphere cone geometry that can be used to develop models for the terminal descent aerodynamics and flight dynamics used to model ground impact conditions. The acquired test data included both sensor data outputs from an on-board inertial measurement unit, global positioning system, and video cameras as well as atmospheric measurements from weather balloons. This data was processed using a Kalman filter/smoother to reconstruct the capsule’s trajectory and aerodynamics. An equation-error method was used to reconcile the aerodynamics by solving for a set of dispersions in the aerodynamic database that form a best-fit to the reconstructed aerodynamics. The reconstructed trajectories were compared with flight simulations generated using Program to Optimize Simulated Trajectories II. The results indicate that the simulation underpredicted the vehicle oscillation amplitudes. The reconstruction exhibits a persistent low-amplitude oscillation that does not damp out as predicted.

Chris D Karlgaard↗

NASA NTRSDate not supplied

OSIRIS-REx Entry, Descent, and Landing Performance

The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) was the third mission in NASA’s New Frontiers program. OSIRIS-REx launched out of Cape Canaveral, Florida on September 8, 2016, with a science goal to return a minimum of 60 g of a primitive asteroid’s surface, specifically the near-Earth asteroid Bennu. The sample return capsule (SRC) successfully touched down at UTTR on the morning of September 24, 2023. The entry, descent, and landing (EDL) sequence had an off-nominal deployment of the parachute, but the spacecraft safely landed within the pre-flight prediction of the landing ellipse and the payload was safely recovered. This paper discusses the pre-flight EDL modeling and simulation and focus on predictions for EDL operations. Flight observations such as timeline are compared to the predicted timeline produced by the EDL simulation.

EDL↗