Engineering topics
Conway, Dylan
Publications and source records attributed to Conway, Dylan.
Deep-space Optical Communications Pointing Control Design
This paper provides an overview of pointing control design for NASA’s Deep Space Optical Communications (DSOC) system. DSOC is NASA’s first deep-space laser communications system and includes both a ground system and a space terminal. This paper focus on the pointing control system design and related issues for the Flight Laser Transceiver (FLT), including its key subsystems and components that support the space terminal pointing and control, its operational concept and sequence design, and its control systems design and related analyses. The paper also provides an overview of the achievable system pointing performance that meets the DSOC pointing control design requirements.
Vision-based Velocimetry over Unknown Terrain with a Low-Noise IMU
This paper presents a novel approach to terrain-relative navigation with a visual camera and Inertial Measurement Unit (IMU). The proposed algorithm uses an Extended Kalman Filter (EKF) to combine an IMU propagated state estimate with batch correction estimates computed over a sliding window of measurements. The batch correction algorithm follows the Maximum Likelihood Estimation (MLE) approach used in other Bundle Adjustment systems. Unlike other systems, the proposed system parameterizes the state over the entire window in terms of the state at a single epoch. By ignoring IMU error over the window duration, we obtain a state epoch MLE that jointly estimates the epoch state and terrain parameters with drastically reduced computationally cost. This paper presents the general architecture which can be adapted for various state parameterizations and measurement inputs. For space applications with high-accuracy IMUs, the reduction in computational cost comes with only a modest increase in estimation errors. The increase in error is quantified via a linear covariance analysis presented in this paper. Furthermore, we present simulation results which show the applicability of this algorithm to planetary landing problems.
BiBlade Sampling Tool Validation for Comet Surface Environments
The BiBlade sampling chain was developed for use in a potential Comet Surface Sample Return mission. Following prior versions of the sampling tool, a new tool was developed and validated to TRL 6. Sample acquisition testing was performed across a range of comet simulants and operational conditions. Tool operation was validated in a thermal-vacuum chamber. The end-to-end sampling chain was validated including sampling, sample measurement, and sample transfer. The sampling system is now ready for flight implementation.
The Intelligent Landing System for Safe and Precise Landing on Europa
Europa, the smallest of Jupiter’s Galilean moons, is thought to harbor a vast liquid water ocean beneath its icy crust, making it one of the most scientifically intriguing targets for a robotic surface sampling mission in our Solar System. However, autonomously landing a spacecraft safely and precisely on Europa poses unique challenges, such as very little existing high-resolution reconnaissance imagery, a surface expected to be very rough and hazardous over a wide range of scales, an extremely intense ionizing radiation environment, and very limited lander resources for mass and volume. To address these challenges, we propose a novel Intelligent Landing System (ILS) combining four Guidance, Navigation & Control (GN&C) sensing functions – velocimetry, altimetry, map-relative localization, and hazard detection – that would together enable safe and precise landing on Europa’s surface. The ILS is a smart sensor system, combining an inertial measurement unit (IMU), a monocular, passive-optical camera, and a light detection and ranging (Li-DAR) sensor with dedicated computing resources as well as an onboard 3D terrain map. The ILS leverages more than a decade of technology development from programs such as the Lander Vision System, currently baselined on the Mars 2020 mission. This paper provides a detailed description of the proposed ILS architecture and concept of operations, as well as select preliminary simulation results to assess performance and robustness.