A document describes the proposed addition of a radar function to the Autonomous Formation Flying Sensor, making possible coarse relative-position control to prevent collisions in the event of failure of one of the spacecraft. According to the proposal, in addition to tracking GPS-like one-way ranging signals transmitted by the other normally functioning spacecraft, each spacecraft could simultaneously track the reflection of its own ranging signal from a disabled, non-transmitting spacecraft. From the round-trip travel time, the approximate distance to the disabled spacecraft could be estimated. To prevent jamming of the receiver by the transmitter on the same spacecraft, the receiver would be switched off during transmission.
This work was done by Jeffrey Tien, George Purcell, and Lawrence Young of Caltech for NASA's Jet Propulsion Laboratory.
NPO-40417
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Pseudorandom Switching for Adding Radar to the AFF Sensor
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Overview
The document discusses a new technology innovation, identified as NTR Number 40417, titled "Pseudo-random Switching Technique for Simultaneous Dual One-Way Ranging and Radar Operation." This innovation is designed to enhance the capabilities of the Autonomous Formation Flying Sensor (AFF), which is crucial for multiple spacecraft formation flying in deep space or near-Earth missions.
The core of this innovation is a pseudorandom switching technique that allows the AFF sensor to utilize the same ranging signal for both dual one-way ranging and radar operations without requiring any hardware modifications. This capability is significant as it helps prevent potential collisions between spacecraft and enables coarse formation flying even in fault scenarios where one or more spacecraft may be out of service.
The AFF sensor itself is an integrated radio frequency (RF) based system developed from advancements in Global Positioning System (GPS) technology. It operates as a distributed system, with identical hardware and software installed on each spacecraft. Each spacecraft's transmitter sends out GPS-like signals, which are then tracked by the receivers on other spacecraft. The key measurements obtained from this system include pseudorange and carrier phase measurements, which are essential for accurate positioning and navigation.
The document emphasizes the importance of this technology in enhancing the safety and efficiency of spacecraft operations, particularly in complex formation flying scenarios. By allowing simultaneous radar and ranging operations, the AFF sensor can improve situational awareness and operational flexibility, which are critical for successful mission outcomes.
Additionally, the document is part of NASA's Commercial Technology Program, aimed at disseminating aerospace-related developments that have broader technological, scientific, or commercial applications. It encourages further exploration and collaboration through the NASA Innovative Partnerships Program and provides contact information for additional resources available through the NASA Scientific and Technical Information (STI) Program Office.
In summary, the Pseudo-random Switching Technique represents a significant advancement in spacecraft technology, enhancing the capabilities of the AFF sensor and contributing to safer and more efficient space missions. This innovation not only showcases NASA's commitment to technological advancement but also highlights the potential for broader applications in aerospace and beyond.
