Flight-like Hardware Research Articles

Kinematic Batch Estimator for Angular Velocity and Associated Uncertainty

Estimating the relative pose and angular velocity of an uncooperative space object is a critical component for many applications such as on-orbit assembly, inspection, and servicing. This paper presents new mathematical insights that permit a kinematic batch filter formulation for angular velocity estimation using quaternion measurements for relative orientation, thereby eliminating the need to know the moment of inertia of the target. In particular, a novel batch approach to computing the associated uncertainties for the angular velocity magnitude, spin-axis direction, and overall angular velocity vector estimates is presented and compared against previous recursive methodologies. Finally, a realistic use-case scenario is demonstrated in real-time on flightlike hardware.

The Mars Organic Molecule Analyzer (MOMA) Instrument: Characterization of Organic Material in Martian Sediments.

The Mars Organic Molecule Analyzer (MOMA) instrument onboard the ESA/Roscosmos ExoMars rover (to launch in July, 2020) will analyze volatile and refractory organic compounds in martian surface and subsurface sediments. In this study, we describe the design, current status of development, and analytical capabilities of the instrument. Data acquired on preliminary MOMA flight-like hardware and experimental setups are also presented, illustrating their contribution to the overall science return of the mission. Key Words: Mars—Mass spectrometry—Life detection—Planetary instrumentation. Astrobiology 17, 655–685.

Flight-Like Ground Demonstrations of Precision Maneuvers for Spacecraft Formations—Part II

As part of a multifaceted technology development program for the Terrestrial Planet Finder Interferometer (TPF-I) mission, system-level ground demonstrations of precision formation flying have been performed. These demonstrations were done in the Formation Control Testbed (FCT), a six degree-of-freedom, system-level testbed with flight-like hardware and software. The FCT is described in detail in a companion paper. The formation guidance, navigation/estimation, and control architecture and software used in these demonstrations are also discussed in the companion paper. The demonstrations consisted of synchronized rotations, which couple relative positions and attitudes. For TPF-I, this maneuver will require highest precision formation flying. This paper presents the experimental results for these demonstrations, which are the first major system-level demonstration of precision formation flying control for TPF-I. Multiple synchronized formation rotations were executed with real-time software and centimeterand arc minute-level relative position and attitude performance. The maneuvers occurred over two weeks to show a robust, repeatable capability. The FCT is subject to ongoing development. In particular, these demonstrations had five degrees of freedom: three rotational and two translational. The final translational degree of freedom has since been added. In addition, because terrestrial disturbances in the FCT are more severe than encountered on-orbit, the centimeterand arc minute-level performance of the FCT demonstrations is traced to the TPF-I flight requirements via a simulation-based error budget. We conclude with some directions for further development of formation flying technologies.

Flight-Like Ground Demonstrations of Precision Maneuvers for Spacecraft Formations—Part I

Formations of collaborating spacecraft enable orders-of-magnitude increases in Earth and space science. However, to realize robust, high-performance formations, the complex interactions of distributed guidance, estimation, control, sensing, actuation, and inter-spacecraft communication must be addressed. As in any technology development, such interactions are first dealt with through analysis and simulation. Then system-level, hardware-based demonstrations are needed to validate simulations and provide the technological maturity necessary to proceed with flight demonstrations and, eventually, a mission. This paper and its companion describe such a maturation process and system-level hardware demonstration results for the formation flying control system of NASA's Terrestrial Planet Finder Interferometer (TPF-I). In this paper, first technology and testbed needs are discussed for system-level validation of precision formation control systems. Then the Formation Control Testbed (FCT) is described in detail. The FCT is a ground-based, robotic environment for high-fidelity, six degree-of-freedom validation with flight-like hardware. Finally, the formation control architecture and synchronized rotation guidance algorithm used in the precision formation flying demonstrations are presented. The companion paper gives all the experimental results, traces the ground performance demonstrated to TPF-I flight performance through a simulation-based error budget, and highlights some technology areas for further development.

Qualification Testing of Engineering Camera and Platinum Resistance Thermometer (PRT) Sensors for MSL Project Under Extreme Temperatures to Assess Reliability and to Enhance Mission Assurance

Package qualification and verification (PQV) of advanced electronic packaging and interconnect technologies and various other types of qualification hardware for the Mars Exploration Rover/Mars Science Laboratory flight projects has been performed to enhance the mission assurance. The qualification of hardware (engineering camera and platinum resistance thermometer, PRT) under extreme cold temperatures has been performed with reference to various project requirements. The flight-like packages, sensors, and subassemblies have been selected for the study to survive three times (3×) the total number of expected temperature cycles resulting from all environmental and operational exposures occurring over the life of the flight hardware including all relevant manufacturing, ground operations, and mission phases. Qualification has been performed by subjecting above flight-like qual hardware to the environmental temperature extremes and assessing any structural failures or degradation in electrical performance due to either overstress or thermal cycle fatigue. Experiments of flight-like hardware qualification tests are described in this paper.

The Micro-Precision Interferometer Testbed Instrument Design

The Micro-Precision Interferometer Testbed is essentially a space-based Michelson interferometer suspended in a ground-based laboratory. The purpose of the testbed is to serve as a proving ground for technologies needed for future space-based missions requiring low-vibration environments. A layered control architecture, utilizing isolation, structural control, and active optical control technologies, allows the system to achieve its vibration attenuation goals.This paper focuses primarily on the interferometer instrument design for the testbed and the systems-level tradeoffs between the instrument and other systems due to the fact that the interferometer is on a large, lightly damped, flexible structure rather than on the ground. The testbed is designed to be a fully functioning interferometer spacecraft and makes use of flight-like hardware where possible, including an external star simulator, an attitude control system, fringe detection and tracking systems, delay lines, pointing control, laser metrology systems, and computers and electronic subsystems. The engineering decisions that led to the current instrument configuration are presented and explained.