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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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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Validation of Lithium-ion cell technology for JPL's 2003 Mars Exploration Rover Mission

n early 2004 JPL successfully landed two Rovers, named Spirit and Opportunity, on the surface of Mars after traveling >300 million miles over a 6-7 month period. In order to operate for extended duration on the surface of Mars, both Rovers are equipped with rechargeable Lithium-ion batteries, which were designed to aid in the launch, correct anomalies during cruise, and support surface operations in conjunction with a triple-junction deployable solar arrays. The requirements of the Lithium-ion battery include the ability to provide power at least 90 sols on the surface of Mars, operate over a wide temperature range (-20 C to +40 C), withstanding long storage periods (e.g., cruise period), operate in an inverted position, and support high currents (e.g., firing pyro events). In order to determine the viability of Lithium-ion technology to meet these stringent requirements, a comprehensive test program was implemented aimed at demonstrating the performance capability of prototype cells fabricated by Lithion, Inc. (Yardney Technical Products, Inc.). The testing performed includes, determining the (a) room temperature cycle life, (b) pulse capability as a function of temperature, (e) self-discharge and storage characteristics mission profile capability, (f) cycle life under mission simulation conditions, (g) impedance characteristics, (h) impact of cell orientation, and (i) performance in 8-cell engineering batteries. As will be discussed, the Lithium-ion prototype cells and batteries were demonstrated to meet, as well as, exceed the requirements defined by the mission.

2003 Mars Exploration Rover (MER)↗
NASA NTRS2004

Mars Exploration Rover Panoramic Camera Multidimensional Analyses and Surface Spectral Variability

The Mars Exploration Rover (MER) panoramic camera system (Pancam) has provided surface-based multispectral image data with unprecedented spatial and radiometric fidelity. The spectral coverage of the camera system allows for the discrimination of important Fe2+ and Fe3+ bearing minerals expected to occur on the Martian surface . This paper explores the spatially coherent and structurally consistent spectral variability present at both the Spirit and Opportunity landing sites using multidimensional analysis of representative Pancam multispectral scenes.

Seelos, F. P., IV↗
NASA NTRS2004

Pancam Imaging of the Mars Exploration Rover Landing Sites in Gusev Crater and Meridiani Planum

The Mars Exploration Rovers carry four Panoramic Camera (Pancam) instruments (two per rover) that have obtained high resolution multispectral and stereoscopic images for studies of the geology, mineralogy, and surface and atmospheric physical properties at both rover landing sites. The Pancams are also providing significant mission support measurements for the rovers, including Sun-finding for rover navigation, hazard identification and digital terrain modeling to help guide long-term rover traverse decisions, high resolution imaging to help guide the selection of in situ sampling targets, and acquisition of education and public outreach imaging products.

Bell, J. F., III↗
NASA NTRS2001

Optical designs for the Mars '03 Rover cameras

In 2003, NASA is planning to send two robotic rover vehicles to explore the surface of mars. The spacecraft will land on airbags in different, carefully chosen locations.

Optical design Mars Rover↗
NASA NTRS2007

Robust, Flexible Motion Control for the Mars Explorer Rovers

The Mobility Flight Software, running on computers aboard the Mars Explorer Rover (MER) robotic vehicles Spirit and Opportunity, affords the robustness and flexibility of control to enable safe and effective operation of these vehicles in traversing natural terrain. It can make the vehicles perform specific maneuvers commanded from Earth, and/or can autonomously administer multiple aspects of mobility, including choice of motion, measurement of actual motion, and even selection of targets to be approached. Motion of a vehicle can be commanded by use of multiple layers of control, ranging from motor control at a low level, direct drive operations (e.g., motion along a circular arc, motion along a straight line, or turn in place) at an intermediate level to goal-position driving (that is, driving to a specified location) at a high level. The software can also perform high-level assessment of terrain and selection of safe paths across the terrain: this involves processing of the digital equivalent of a local traversability map generated from images acquired by stereoscopic pairs of cameras aboard the vehicles. Other functions of the software include interacting with the rest of the MER flight software and performing safety checks.

Maimone, Mark↗
NASA NTRS2003

Mars Exploration Rover Landing Site Boulder Fields

As an aid in constraining the rock size-frequency distributions at the Mars Exploration Rover (MER) landing sites, Mars Orbiter Camera (MOC) images of all potential MER landing sites were systematically searched for boulder fields. Low-Sun angle MOC images can be used to identify boulders larger than 1.5 m diameter, which can be used to determine the shape of the rock size-frequency distributions. These distributions can be compared with the rock size-frequency distributions measured at the Viking and Mars Pathfinder landing sites to better quantify potentially hazardous rocks at the MER landing sites.

Schroeder, R. D.↗
NASA NTRS2003

The Mars Exploration Rovers Entry Descent and Landing and the Use of Aerodynamic Decelerators

The Mars Exploration Rovers (MER) project, the next United States mission to the surface of Mars, uses aerodynamic decelerators in during its entry, descent and landing (EDL) phase. These two identical missions (MER-A and MER-B), which deliver NASA s largest mobile science suite to date to the surface of Mars, employ hypersonic entry with an ablative energy dissipating aeroshell, a supersonic/subsonic disk-gap-band parachute and an airbag landing system within EDL. This paper gives an overview of the MER EDL system and speaks to some of the challenges faced by the various aerodynamic decelerators.

Steltzner, Adam↗
NASA NTRS2012

Interactive 3D Mars Visualization

The Interactive 3D Mars Visualization system provides high-performance, immersive visualization of satellite and surface vehicle imagery of Mars. The software can be used in mission operations to provide the most accurate position information for the Mars rovers to date. When integrated into the mission data pipeline, this system allows mission planners to view the location of the rover on Mars to 0.01-meter accuracy with respect to satellite imagery, with dynamic updates to incorporate the latest position information. Given this information so early in the planning process, rover drivers are able to plan more accurate drive activities for the rover than ever before, increasing the execution of science activities significantly. Scientifically, this 3D mapping information puts all of the science analyses to date into geologic context on a daily basis instead of weeks or months, as was the norm prior to this contribution. This allows the science planners to judge the efficacy of their previously executed science observations much more efficiently, and achieve greater science return as a result. The Interactive 3D Mars surface view is a Mars terrain browsing software interface that encompasses the entire region of exploration for a Mars surface exploration mission. The view is interactive, allowing the user to pan in any direction by clicking and dragging, or to zoom in or out by scrolling the mouse or touchpad. This set currently includes tools for selecting a point of interest, and a ruler tool for displaying the distance between and positions of two points of interest. The mapping information can be harvested and shared through ubiquitous online mapping tools like Google Mars, NASA WorldWind, and Worldwide Telescope.

Powell, Mark W.↗
NASA NTRS2005

Lifting Mechanism for the Mars Explorer Rover

A report discusses the design of a rover lift mechanism (RLM) -- a major subsystem of each of the Mars Exploration Rover vehicles, which were landed on Mars in January 2004. The RLM had to satisfy requirements to (1) be foldable as part of an extremely dense packing arrangement and (2) be capable of unfolding itself in a complex, multistep process for disengaging the rover from its restraints in the lander, lifting the main body of the rover off its landing platform, and placing the rover wheels on the platform in preparation for driving the rover off the platform. There was also an overriding requirement to minimize the overall mass of the rover and lander. To satisfy the combination of these and other requirements, it was necessary to formulate an extremely complex design that integrated components and functions of the RLM with those of a rocker-bogie suspension system, the aspects of which have been described in several prior NASA Tech Briefs articles. In this design, suspension components also serve as parts of a 4- bar linkage in the RLM.

Melko, Joseph↗
NASA NTRS2005

Mars Exploration Rover surface mission flight thermal performance

NASA launched two rovers in June and July of 2003 as a part of the Mars Exploration Rover (MER) project. MER-A (Spirit) landed on Mars in Gusev Crater at 15 degrees South latitude and 175 degree East longitude on January 4, 2004 (Squyres, et al., Dec. 2004)). MER-B (Opportunity) landed on Mars in Terra Meridiani at 2 degrees South latitude and 354 degrees East longitude on January 25, 2004 (Squyres, et al., August 2004) Both rovers have well exceeded their design lifetime (90 Sols) by more than a factor of 4. Spirit and Opportunity are still healthy and continue to execute their roving science missions at the time of this writing. This paper discusses rover flight thermal performance during the surface missions of both vehicles, covering roughly the time from the MER-A landing in late Southern Summer (Ls = 328, Sol 1A) through the Southern Winter solstice (Ls = 90, Sol 255A) to nearly Southern Vernal equinox (Ls = 160 , Sol 398A).

thermal design↗
NASA NTRS2002

Arc Jet Testing of the TIRS Cover Thermal Protection System for Mars Exploration Rover

This paper summarizes the arc jet test results of the Mars Exploration Rover (MER) Silicone Impregnated Reusable Ceramic Ablator (SIRCA) Transverse Impulse Rocket System (TIRS) Cover test series in the Panel Test Facility (PTF) at NASA Ames Research Center (ARC). NASA ARC performed aerothermal environment analyses, TPS sizing and thermal response analyses, and arc jet testing to evaluate the MER SIRCA TIRS Cover design and interface to the aeroshell structure. The primary objective of this arc jet test series was to evaluate specific design details of the SIRCA TIRS Cover interface to the MER aeroshell under simulated atmospheric entry heating conditions. Four test articles were tested in an arc jet environment with various sea] configurations. The test condition was designed to match the predicted peak flight heat load at the gap region between the SIRCA and the backshell TPS material, SLA-561S, and resulted in an over-test (with respect to heat flux and heat load) for the apex region of the SIRCA TIRS Cover. The resulting pressure differential was as much as twenty times that predicted for the flight case, depending on the location, and there was no post-test visual evidence of over-heating or damage to the seal, bracket, or backshell structure. The exposed titanium bolts were in good condition at post-test and showed only a small amount of oxidation at the leading edge locations. Repeatable thermocouple data were obtained and SIRCA thermal response analyses were compared to applicable thermocouple data. For the apex region of the SIRCA TIRS Cover, a one-dimensional thermal response prediction proved overly conservative, as there were strong multi-dimensional conduction effects evident from the thermocouple data. The one-dimensional thermal response prediction compared well with the thermocouple data for the leading edge "lip" region at the bolt location. In general, the test results yield confidence in the baseline seal design to prevent hot gas ingestion at the bracket and composite aeroshell structure interface.

Szalai, Christine E.↗
NASA NTRS2009

Autonomous Instrument Placement for Mars Exploration Rovers

Autonomous Instrument Placement (AutoPlace) is onboard software that enables a Mars Exploration Rover to act autonomously in using its manipulator to place scientific instruments on or near designated rock and soil targets. Prior to the development of AutoPlace, it was necessary for human operators on Earth to plan every motion of the manipulator arm in a time-consuming process that included downlinking of images from the rover, analysis of images and creation of commands, and uplinking of commands to the rover. AutoPlace incorporates image analysis and planning algorithms into the onboard rover software, eliminating the need for the downlink/uplink command cycle. Many of these algorithms are derived from the existing groundbased image analysis and planning algorithms, with modifications and augmentations for onboard use.

Leger, P. Chris↗
NASA NTRS2003

Gusev and Meridiani Will Look Different: Radar Scattering Properties of the Mars Exploration Rover Landing Sites

Analysis of all existing radar data for the two Mars Exploration Rover (MER) landing sites at Meridiani Planum and Gusev Crater suggest that their meter-scale morphological appearance will be noticeably different than previous Mars landing sites; their human-scale, decimeter-to meter-scale roughness is not the same as for previous Mars landing sites. We make this prediction based on a comparison of the MER landing sites.

A F C Haldemann↗
NASA NTRS2003

Gusev Meridiani will look different : radar scattering properties of the Mars Exploration Rover landing sites

Analysis of all existing radar data for the two Mars Exploration Rover (MER) landing sites at Meridiani Planum and Gusev Crater suggest that their meter-scale morphological appearance will be noticeably different than previous Mars landing sites; their "human-scale", decimeter- to meter-scal roughness is not the same as for previous Mars landing sites. We make this prediction based on the comparison of the MER landing sites.

Harmon, J. K.↗
NASA NTRS2006

A Strategy to Integrate Probabilistic Risk Assessment into Design and Development Processes for Aerospace Based pon Mars Exploration Rover Experiences

This paper will discuss the Probabilistic Risk Assessment (PRA) effort and its involvement with related activities during the development of the Mars Exploration Rover (MER). The Rovers were launched 2003.June.10 (Spirit) and 2003.July.7 (Opportunity), and both have proven very successful. Although designed for a 90-day mission, the Rovers have been operating for over two earth years. This paper will review aspects of how the MER project integrated PRA into the design and development process. A companion paper (Development of the Mars Exploration Rover PRA) will describe the MER PRA and design changes from those results.

Probabilistic Risk Assessment (PRA)↗