Session
Poster Session 1
Abstract
Our objective is to design a small, semi-autonomous inspection satellite to observe the exterior of a "host" spacecraft, such as the International Space Station (ISS) or large space-based telescope, with minimal risk to the host vehicle and its crew. As NASA learned in the Columbia tragedy, the lack of external inspection capability can lead to catastrophic results. In less extreme cases, the ability to inspect any high-value spacecraft could provide early warning for impending failures or maintenance, and could reduce requirements for time-costly robot-arm operations and/or high-risk Extra Vehicular Activity (EVA).
In the extreme environment of space, two of the primary risks to vehicles are orbital-debris/micrometeorite impact and leakage of pressurized resources (gases and coolant). Although the value of spacecraft inspection is well-established, virtually no current spacecraft (including ISS) possess inspection capability. We believe that recent efforts in small-sat proximity operations, combined with advances in attitude control, propulsion, and navigation, sensors, and actuators on the cube-satellite scale now make it possible to create a safe and practical inspection satellite. The UC Davis team is currently defining the operations concept, mission objectives, safety requirements, and technology hurdles involved in the development of a disposable external inspection capability.
The first priority for the design of an inspection-sat is the minimization of added risk due to collision. For net risk-reduction, it is essential that the added risk of collision between inspector and host is smaller than the risk mitigated by inspection. To achieve this, in addition to redundant and fail-safe navigation and control strategies, inspector momentum must be kept small to the point of posing an insignificant risk of damage in the case of collision. Low mass enabled by current subsystem technologies, along with low-velocity inspection-paths are required to minimize inspector kinetic energy.
By making the design disposable, it does not return to the host. This ensures a safe distance can be maintained at all times during and after the inspection task. Furthermore, no docking or capture mechanisms are needed; therefore modifications to the host are not required.
Our design includes human-augmented control of trajectory, relative velocity, attitude, and inspection tasks via real-time video telemetry to onboard operators.
Efficiency will be increased by using a control scheme with predetermined optimized paths as well as adaptive navigation methods. Relative orbital motion will be used to minimize propellant usage. Automatic and manual abort commands will also be included so that a safe escape vector is available if a failure occurs.
Spatial navigation of the inspector relative to the host spacecraft will be based on computer vision techniques applied to the known external geometry of the host. Lidar/radar subsystems will enhance the relative state vector and provide backup separation sensing. Inspection-Sat control actuation will be achieved through a dynamically-optimized combination of reaction control wheels and cold gas thrusters.
A precursor to the computer navigation algorithm has already entered into testing phases.
The current UC Davis efforts shall lay out the mission objectives, concept of operations, high-level requirements, and system architecture.
Low-Risk Spacecraft-Inspection CubeSat
Our objective is to design a small, semi-autonomous inspection satellite to observe the exterior of a "host" spacecraft, such as the International Space Station (ISS) or large space-based telescope, with minimal risk to the host vehicle and its crew. As NASA learned in the Columbia tragedy, the lack of external inspection capability can lead to catastrophic results. In less extreme cases, the ability to inspect any high-value spacecraft could provide early warning for impending failures or maintenance, and could reduce requirements for time-costly robot-arm operations and/or high-risk Extra Vehicular Activity (EVA).
In the extreme environment of space, two of the primary risks to vehicles are orbital-debris/micrometeorite impact and leakage of pressurized resources (gases and coolant). Although the value of spacecraft inspection is well-established, virtually no current spacecraft (including ISS) possess inspection capability. We believe that recent efforts in small-sat proximity operations, combined with advances in attitude control, propulsion, and navigation, sensors, and actuators on the cube-satellite scale now make it possible to create a safe and practical inspection satellite. The UC Davis team is currently defining the operations concept, mission objectives, safety requirements, and technology hurdles involved in the development of a disposable external inspection capability.
The first priority for the design of an inspection-sat is the minimization of added risk due to collision. For net risk-reduction, it is essential that the added risk of collision between inspector and host is smaller than the risk mitigated by inspection. To achieve this, in addition to redundant and fail-safe navigation and control strategies, inspector momentum must be kept small to the point of posing an insignificant risk of damage in the case of collision. Low mass enabled by current subsystem technologies, along with low-velocity inspection-paths are required to minimize inspector kinetic energy.
By making the design disposable, it does not return to the host. This ensures a safe distance can be maintained at all times during and after the inspection task. Furthermore, no docking or capture mechanisms are needed; therefore modifications to the host are not required.
Our design includes human-augmented control of trajectory, relative velocity, attitude, and inspection tasks via real-time video telemetry to onboard operators.
Efficiency will be increased by using a control scheme with predetermined optimized paths as well as adaptive navigation methods. Relative orbital motion will be used to minimize propellant usage. Automatic and manual abort commands will also be included so that a safe escape vector is available if a failure occurs.
Spatial navigation of the inspector relative to the host spacecraft will be based on computer vision techniques applied to the known external geometry of the host. Lidar/radar subsystems will enhance the relative state vector and provide backup separation sensing. Inspection-Sat control actuation will be achieved through a dynamically-optimized combination of reaction control wheels and cold gas thrusters.
A precursor to the computer navigation algorithm has already entered into testing phases.
The current UC Davis efforts shall lay out the mission objectives, concept of operations, high-level requirements, and system architecture.
