Leon Alkalai

Micro APS based star tracker

JPL has conducted a study on how to design future miniaturized star trackers. The study proposes an ultra-low power (70 mW), ultra-low mass (42 grams) and very fast (50 Hz) Micro, APS-based Star Tracker (MAST). The accuracy of the MAST will be /spl sim/7.5 arcseconds at 50 Hz update rate. The MAST is indispensable to all low mass and power micro/nano spacecraft where mass and power is a concern. The MAST consists of only two chips-a breakthrough CMOS Active Pixel Sensor (APS) image detector optimized for star tracker applications and an ASIC chip including an I/sup 2/C interface, memory and an 8051 microcontroller. MAST has functionality so it outputs pixel data from small windows and the spacecraft computer performs the processing.

On-board preventive maintenance: a design-oriented analytic study for long-life applications

Abstract With respect to the long-life missions associated with NASA’s X2000 Advanced Deep-Space System Development Program, reliability implies a system’s continuous operation for many years in an unsurveyed radiation-intense environment. Further, the stringent constraints on the mass of a spacecraft and the power on-board create unprecedented challenges on the means for achieving the ultra-high mission reliability. In this paper, we present an approach to on-board preventive maintenance which rejuvenates a system by letting system components rotate between on-duty and off-duty shifts, slowing down a system’s aging process and thus enhancing mission reliability. By exploiting nondedicated system redundancy, hardware and software rejuvenation are realized simultaneously without significant performance penalty. Our design-oriented analysis confirms a potential for significant gains in mission reliability from on-board preventive maintenance and provides to us useful insights about the collective effect of age-dependent failure behavior, residual mission life, risk of unsuccessful maintenance and maintenance frequency on mission reliability.

On-board preventive maintenance for long-life deep-space missions: a model-based analysis

The long-life deep-space missions associated with NASAs X2000 Advanced Flight Systems Program creates many unprecedented challenges. In particular the stringent constraints on the mass of a spacecraft and the power on-board preclude traditional fault tolerance approaches which rely on extensive component/subsystem replication, calling for novel approaches to mission reliability enhancement. In this paper we present an approach to on-board preventive maintenance which rejuvenates a system via periodical duty switching between system components, slowing down a systems aging process and enhancing mission reliability. By exploiting the nondedicated system redundancy hardware and software rejuvenation are realized simultaneously without significant performance penalty. Our model-based evaluation confirms a potential for significant gains in mission reliability from on-board preventive maintenance and provides to us useful insights about the collective effect of age-dependent failure behavior residual mission life, risk of unsuccessful maintenance and maintenance frequency on mission reliability.

On low-cost error containment and recovery methods for guarded software upgrading

To assure dependable onboard evolution, we have developed a methodology called guarded software upgrading (GSU). We focus on a low-cost approach to error containment and recovery for GSU. To ensure low development cost, we exploit inherent system resource redundancies as the fault tolerance means. In order to mitigate the effect of residual software faults at low performance cost, we take a crucial step in devising error containment and recovery methods by introducing the confidence-driven notion. This notion complements the message-driven (or communication-induced) approach employed by a number of existing checkpointing protocols for tolerating hardware faults. In particular, we discriminate between the individual software components with respect to our confidence in their reliability and keep track of changes of our confidence (due to knowledge about potential process state contamination) in particular processes. This, in turn, enables the individual processes in the spaceborne distributed system to make decisions locally at run-time, on whether to establish a checkpoint upon message passing and whether to roll back or roll forward during error recovery. The resulting message-driven confidence-driven approach enables cost-effective checkpointing and cascading-rollback free recovery.

ADVANCED MICROELECTRONICS TECHNOLOGIES FOR FUTURE SMALL SATELLITE SYSTEMS

Abstract Future small satellite systems for both Earth observation as well as deep-space exploration are greatly enabled by the technological advances in deep sub-micron microelectronics technologies. Whereas these technological advances are being fueled by the commercial (non-space) industries, more recently there has been an exciting new synergism evolving between the two otherwise disjoint markets. In other words, both the commercial and space industries are enabled by advances in low-power, highly integrated, miniaturized (low-volume), lightweight, and reliable real-time embedded systems. Recent announcements by commercial semiconductor manufacturers to introduce Silicon On Insulator (SOI) technology into their commercial product lines is driven by the need for high-performance low-power integrated devices. Moreover, SOI has been the technology of choice for many space semiconductor manufacturers where radiation requirements are critical. This technology has inherent radiation latch-up immunity built into the process, which makes it very attractive to space applications. In this paper, we describe the advanced microelectronics and avionics technologies under development by NASAs Deep Space Systems Technology Program (also known as X2000). These technologies are of significant benefit to both the commercial satellite as well as the deep-space and Earth orbiting science missions. Such a synergistic technology roadmap may truly enable quick turn-around, low-cost, and highly capable small satellite systems for both Earth observation as well as deep-space missions.

Analysis of a multi-layer fault-tolerant COTS architecture for deep space missions

Fault-tolerant systems are traditionally divided into fault containment regions and custom logic is added to ensure the effects of a fault within a containment region would not propagate to the other regions. This technique may not be applicable in a commercial-off-the-shelf (COTS) based system. While COTS technology is attractive due to its low cost, they are not developed with the same level of rigorous fault tolerance in mind. Furthermore, COTS suppliers usually have no interest to add any overhead or sacrifice performance to implement fault tolerance for a narrow market of high reliability applications. To overcome this shortcoming, Jet Propulsion Laboratory (JPL) has developed a multi-layer fault protection methodology to achieve high reliability in COTS-based avionics systems. This methodology has been applied to the bus architecture that uses the COTS bus interface standards IEEE 1394 and I/sup 2/C. The paper first gives an overview of the multi-layer fault-protection design methodology for COTS based mission-critical systems. Then the effectiveness of the methodology is analyzed in terms of coverage and cost. The results are compared to the traditional custom designed system.

AN OVERVIEW OF FLIGHT COMPUTER TECHNOLOGIES FOR FUTURE NASA SPACE EXPLORATION MISSIONS

In this paper, we present an overview of current developments by several US Government Agencies and associated programs, towards high-performance single board computers for use in space. Three separate projects will be described; two that are based on the Power PC processor, and one based on the Pentium processor.

Pluto express: Advanced technologies enable lower cost missions to the outer Solar System and beyond

Missions to Pluto and the outer Solar System are typically driven by factors which tend to increase cost, such as: long life, high radiation exposure, a large power source, high ΔV requirements, difficult telecommunications links, low solar illumination at the destination, and demanding science measurements. Advanced technology is a central part of responding to such challenges in a manner which permits the cost of development and operations to be an order of magnitude less than for prior outer planet missions. Managing the process of technology planning and advanced development versus the associated cost and mission risk is a formidable challenge. Outer Solar System/Europa/Pluto/Solar Probe development activities are leveraging the latest products from the industry, government lab and academia technology pipeline in the areas of software, low power integrated microelectronics, low mass, high efficiency radioisotope power if used, and telecommunications. This paper summarizes the current technology develo...

Orion/MoonRise: A proposed human & robotic sample return mission from the Lunar South Pole-Aitken Basin

This paper describes a new mission concept called Orion/MoonRise that proposes to return samples from the Lunar far-side South Pole-Aitken Basin (SPAB) using a combination of a robotic Sample Return Vehicle (SRV) based on the MoonRise mission concept developed at National Aeronautics and Space Administrations (NASA) Jet Propulsion Laboratory, and the Orion Multi-Purpose Crew Vehicle currently under development by NASA at Lockheed Martin. The mission concept proposes significant challenges for both robotic and human parts of the mission. Whereas there are many ways to execute this mission concept, one approach is for the Orion and the SRV to launch separately. We assume that the Orion will be staged at the Earth-Moon Lagrange Point 2 (EM-L2) and the SRV at EM-L1. Once both are in place, the SRV descends to the SPAB while the Orion provides critical relay coverage with ground control on Earth. During surface operations, the Orion crew tele-operate the lander sampling system and possibly deploy a sample fetch rover. Once the samples are collected, the Lunar Ascent Vehicle (LAV) launches towards the EM-L2 to rendezvous with Orion. The samples are then brought back to Earth for detailed sample curation and analysis by the scientific community. The Orion/MoonRise mission concept has many strengths worth noting: it provides a very exciting mission to be performed in cis-Lunar space, as a precursor to future human exploration beyond the Earth-Moon System and as a technology demonstration for future sample return from Mars; it implements a mission that is of tremendous value to the planetary science community; it provides an exciting and challenging mission for astronauts to perform and demonstrate in deep-space including remote teleoperations and sample rendezvous and capture; and finally it provides an exciting opportunity for the broad engagement of the general public.

On-board guarded software upgrading for space missions

The authors describe an approach to guarded software upgrading through scenario-based descriptions. Their objectives are to avoid or minimize the unavailability and performance loss of spacecraft/science functions due to software upgrading activities and due to system failure caused by residual faults in an upgraded version. The approach emphasizes: 1) the utilization of nondedicated or inherent system resource redundancies such as an earlier software version and a processor that otherwise would be idle in the mission phase during which software upgrading activities are conducted, and 2) the low-cost efficient error containment and protection mechanisms based on adaptation/extension of the enabling technologies such as checkpointing and message logging.