A report describes the Entry Descent Landing Data Analysis (EDA), which is a system of signal-processing software and computer hardware for acquiring status data conveyed by multiple-frequency-shiftkeying tone signals transmitted by a spacecraft during descent to the surface of a remote planet. The design of the EDA meets the challenge of processing weak, fluctuating signals that are Doppler-shifted by amounts that are only partly predictable. The software supports both realtime and post processing. The software performs fast-Fourier-transform integration, parallel frequency tracking with prediction, and mapping of detected tones to specific events. The use of backtrack and refinement parallel-processing threads helps to minimize data gaps. The design affords flexibility to enable division of a descent track into segments, within each of which the EDA is configured optimally for processing in the face of signal conditions and uncertainties. A dynamic-lockstate feature enables the detection of signals using minimum required computing power — less when signals are steadily detected, more when signals fluctuate. At present, the hardware comprises eight dual-processor personal-computer modules and a server. The hardware is modular, making it possible to increase computing power by adding computers.
This work was done by Timothy Pham, Christine Chang, Edgar Sartorius, Susan Finley, Leslie White, Polly Estabrook, and David Fort of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Electronics/Computers category.
The software used in this innovation is available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (818) 393-2827. Refer to NPO-41220.
This Brief includes a Technical Support Package (TSP).
Data-Analysis System for Entry, Descent, and Landing
(reference NPO-41220) is currently available for download from the TSP library.
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Overview
The document outlines the technical support package for the Data-Analysis System designed for the Entry, Descent, and Landing (EDL) phases of NASA's Mars Exploration Rovers, Spirit and Opportunity. It emphasizes the critical nature of the EDL process, which occurs over a brief six-minute window after a seven-month journey to Mars. This phase is often referred to as the "six minutes of terror" due to the complex and autonomous procedures required for a successful landing, including parachute deployment, radar signal acquisition, airbag inflation, and retrorocket ignition.
The document details the challenges faced during the EDL, particularly the extreme dynamics and uncertainties in predicting the spacecraft's motion as it enters the Martian atmosphere. The spacecraft experiences significant deceleration and temperature changes, which can affect communication signals. For instance, during the Mars Pathfinder mission, a communications blackout was noted due to plasma formation from hyper-deceleration, highlighting the importance of maintaining contact throughout the landing process.
To address these challenges, the EDL Data Analysis (EDA) equipment was developed, utilizing commercial-off-the-shelf hardware with sufficient computing power for real-time operations. The system included a UNIX workstation for high-level coordination and a cluster of dual-processor Linux PCs for computationally intensive tasks. This architecture allowed for significant improvements in processing power, enabling the system to handle the complex data analysis required during the EDL.
The EDA system processed open-loop recording samples from existing radio science receivers, extracting modulated tones and providing critical information about onboard events. The software supported both real-time and post-pass processing, allowing for flexibility in handling different signal conditions. The dynamic lock state concept enabled efficient signal detection, optimizing computing resources based on signal stability.
Overall, the document serves as a comprehensive overview of the technological advancements and methodologies employed in the EDL of the Mars Exploration Rovers. It highlights the importance of robust data analysis systems in ensuring successful mission operations and the ongoing efforts to enhance communication and tracking capabilities during critical phases of space exploration.
