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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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8 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Multimission high speed spacecraft simulation for the Galileo and Cassini missions

A simulation system has been developed which is capable of bit level simulation of spacecraft data systems. Object oriented techniques and an embedded interpreted language have been employed to produce a highly configurable tool for control and viewing of spacecraft states. Parallel processing computers have been used for running simulations to achieve execution performance of up to ten times real time, which allows for effective utilization of the simulator in testing spacecraft command sequences before they are committed to operation. Elements of simulations can be reused as-is in the construction of new simulators.

Morrissett, Alan↗
NASA NTRS2002

System engineering challenges of real-time simulation for Mars SmartLander entry, descent, and landing

The Jet Propulsion Laboratory (JPL) is developing a high-fidelity, real-time 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 the JPL Darts/Dshell multi-mission spacecraft dynamics and devices simulation toolkit which is in use by missions such as Cassini, Galileo, SIM, and Starlight.

Dshell EDL simulator↗
NASA NTRS2018

The Europa Lander Mission: A Space Exploration Challenge for Autonomous Operations

NASA has proposed a Europa Lander Mission, with a notional launch date in the 2024-2025 timeframe. Key features of the mission are: Take 5 samples from 10 cm under the Europa surface; Mission duration is expected to be 20 (Earth) days; Data will be telemetered data back to Earth via a dedicated Carrier Relay Orbiter (CRO) spacecraft. Some information about the Europa surface is available from Cassini, indicating the presence of mountains, ridges, and other complex features, and simulations of planet-wide lighting can be performed, but this information is available only at 6m per pixel resolution (Galileo imagery). While surface temperatures are exceedingly cold (average of 114 degrees Kelvin, or minus 160 degrees Centigrade at the equator), this need not translate to solid (and hard) ice. The possible presence of small grain features (snow-like), penitentes (inverse-icicles), plumes, and other complex terrain features, will complicate operations. The time delay for such a mission is 30-60 minutes. The CRO is in view of the Lander for roughly 8 hours, and is in view of Earth for roughly 10 hours, meaning significant autonomy will be needed. A compelling case can be made for the use of aggressive autonomous operations of the *entire* mission. In this talk we will describe the Europa mission and its objectives, as well as similar Icy Worlds missions of the future. We will then describe the autonomy challenges of such a mission, using examples of similar missions and specific autonomy technologies that have been used in the past to address these challenges. We will make the case that despite some technologies that may be suitable, Europa lander presents a unique, and unaddressed, challenge for autonomy.

Plan Execution↗
DOE OSTI2020

Magnetics Testing on Radioisotope Power Systems at the Idaho National Laboratory

National Aeronautics and Space Administration (NASA) uses Radioisotope Power Systems (RPS) to power deep-space and planetary explorations such as Cassini-Huygens, Galileo, New Horizons, Mars Science Laboratory—Curiosity, and most recently Mars 2020--Perseverance. The Space Nuclear Power and Isotope Technologies (SNPIT) division, at Idaho National Laboratory (INL), fuels, tests, and delivers the RPS to ensure it can provide the electrical power needed to complete mission objectives. Some space crafts have instrumentation specifically designed to study the subject’s magnetic field or may have instruments that can be affected by magnetic fields produced by the RPS. Analyzing and measuring the RPS’s magnetic fields ensures the required thresholds are not exceeded and accurate data can be collected for the mission. Magnetics testing provides numerical values of the RPS’s magnetic field. During Magnetics testing at INL, the RPS is placed on a resistive load to simulate actual spacecraft load characteristics (voltage and current). During this simulation, magnetometers are used to measure the magnetic field of the RPS. Raw data is collected and then analyzed to ensure the field created by the RPS is below NASA thresholds or that the magnitude of the field is accounted for to ensure mission success.

42 ENGINEERING↗
DOE OSTI2012

Emissivity Tuned Emitter for RTPV Power Sources

Every mission launched by NASA to the outer planets has produced unexpected results. The Voyager I and II, Galileo, and Cassini missions produced images and collected scientific data that totally revolutionized our understanding of the solar system and the formation of the planetary systems. These missions were enabled by the use of nuclear power. Because of the distances from the Sun, electrical power was produced using the radioactive decay of a plutonium isotope. Radioisotopic Thermoelectric Generators (RTGs) used in the past and currently used Multi-Mission RTGs (MMRTGs) provide power for space missions. Unfortunately, RTGs rely on thermocouples to convert heat to electricity and are inherently inefficient ({approx} 3-7% thermal to electric efficiency). A Radioisotope Thermal Photovoltaic (RTPV) power source has the potential to reduce the specific mass of the onboard power supply by increasing the efficiency of thermal to electric conversion. In an RTPV, a radioisotope heats an emitter, which emits light to a photovoltaic (PV) cell, which converts the light into electricity. Developing an emitter tuned to the desired wavelength of the photovoltaic is a key part in increasing overall performance. Researchers at the NASA Glenn Research Center (GRC) have built a Thermal Photovoltaic (TPV) system, that utilizes a simulated General Purpose Heat Source (GPHS) from a MMRTG to heat a tantalum emitter. The GPHS is a block of graphite roughly 10 cm by 10 cm by 5 cm. A fully loaded GPHS produces 250 w of thermal power and weighs 1.6 kgs. The GRC system relies on the GPHS unit radiating at 1200 K to a tantalum emitter that, in turn, radiates light to a GaInAs photo-voltaic cell. The GRC claims system efficiency of conversion of 15%. The specific mass is around 167 kg/kWe. A RTPV power source that utilized a ceramic or ceramic-metal (cermet) matrix would allow for the combination of the heat source, canister, and emitter into one compact unit, and allow variation in size and shape to optimize temperature and emission spectra.

08 HYDROGEN↗