JPL, Attn: D. Quinlan, Mail Stop 190-220, 4800 Oak Grove Dr., Pasadena, CA 91109-8099

A -- LOW-THRUST ACCELEROMETER SOL 95/7 DUE 122995. The Jet Propulsion Laboratory/California Institute of Technology (JPL/Caltech), operating under a prime contract with the National Aeronautics and Space Administration (NASA), is currently investigating a Low-Thrust Accelerometer for inertial guidance of electrically propelled spacecraft. An abstract describing the technical features and requirements is provided as Attachment 1 as follows: Attachment 1 - Overview - The goal of this work is to significantly lower the cost of space missions by fully automating the guidance, navigation and control (GN&C) functions. An electrically propelled spacecraft with fully autonomous GN&C would make its way to its destination without ground control intervention. During its cruise phase, the spacecraft would periodically (e.g., once every few days or weeks) determine its position by processing optical observations of relatively nearby known objects against the background of stars. Using this information, plus knowledge of the destination coordinates, the spacecraft would recompute an optimal (e.g., time optimal) trajectory to go. Until the next position fix, the spacecraft would track this trajectory through a combination of thrust vector control, using accelerometers, and attitude control, using a star tracker. When the target is sufficiently nearby, the spacecraft would enter a terminal guidance mode in which it uses optical observations of the target to complete its approach. Periodic calibrations of the accelerometers, performed autonomously on board, would limit spacecraft drift between position fixes. Among the potential beneficiaries of this work are the New Millennium Program (NMP) and various outer planet exploration missions currently being investigated. NASA's NMP is chartered to demonstrate, in representative space missions, the technology that will be required in the missions of the next century. NMP's first mission, designated Deep Space 1 (DS1), is scheduled to fly by a set of small bodies (i.e., asteroids and comets), demonstrating NASA's NSTAR ion (i.e., xenon) thruster, on-board optical navigation (i.e., position estimation and trajectory planning) and an intelligent real time executive. Launch is scheduled for January 28, 1998. Currently, no accelerometer is planned as part of the baseline system. However, the program is very interested in assessing the state of the art for potential follow on missions, or given suitable cost and delivery requirements, as a possible add-on experiment payload in DS1. The outer planet exploration system study, which is currently under way, is focusing on a Neptune orbiter mission, envisioned for launch in 2005. That mission is planning to fly a fully autonomous, electrically propelled, spacecraft, which will be inserted into orbit around Neptune by autonomously controlled aerocapture. The mission design team is currently identifying technology needed to enable the mission. Accelerometer requirements: (1) maximum sensible acceleration - 100 micro g; (2) minimum sensible acceleration1 (i.e., resolution): 10 nano g. 1. Useful minimum sensible acceleration (i.e., useful sensitivity): 100 nano g (dynamic range of 1,000). (a) dynamic range: 10,000; (b) bias instability: 10 nano g over 3 weeks; (c) survivable steady-state acceleration: 10 g(launch); (d) bandwidth: 0.01 Hz2; 2. Useful bandwidth: 0.001 Hz (consistent with hour scale thruster changes). (e) survivable vibration spectrum: depends on isolator. If your organization wishes to be considered a potential source for the anticipated procurement action, you are requested to submit the following information to JPL no later than December 29, 1995: (1) A written request for placement on the source list. Provide the full name and address of your organization and the designated contact person, including phone and facsimile numbers; (2) A summary description of the device you recommend, addressing the following: (a) Compare the expected performance parameters of the device you recommend with the parameters provided in Attachment 1, including any areas of margin or shortfalls; (b) Discuss why your device is suitable for JPL's application and describe the underlying technology of your device (e.g., force rebalanced pendulous proof mass vibrating beam, pendulous gyro accelerometer, actively suspended free mass, etc.); (c) Discuss the compatibility of your device with impulsive propulsion (e.g., chemical delta-v maneuvers); (d) If the recommended design is traceable to a device that has already been used in another space program, please provide the name of the program and a list of the requirements; (e) Provide estimates of the mass, power, and volume of the Accelerometer device you recommend. (3) A Rough Order of Magnitude (ROM) recurring cost and delivery estimate for the accelerometer you describe under paragraph. (2) Do not include costs associated with any further development, modifications, or integration with a spacecraft or operations. Provide the ROM cost estimate in FY96 dollars and state the accuracy of the estimate; (4) Describe the calibration method and any special equipment required for your device to establish and maintain the bias to the level described in Attachment 1, and any special equipment required for your device to survive the launch loads described in Attachment 1. Provide estimates of the mass, power, and volume of any equipment that must fly with the Accelerometer you recommend. Provide a ROM cost estimate in FY96 dollars for all such equipment and state the accuracy of the estimate; (5) Describe what further development work you would anticipate to meet the requirements of JPL's application and provide a ROM nonrecurring cost and schedule estimate for such work. Provide the ROM cost estimate in FY96 dollars and state the accuracy of the estimate. Cost data provided will remain proprietary and will be used only for planning purposes. If other proprietary information is provided, it should be clearly marked along with any restrictions on its use. This is a Request for Information (RFI) only and will be used for planning purposes. It does not constitute a commitment, implied or otherwise, that JPL will take procurement action in this particular matter. Neither JPL nor the Government will be responsible for any costs incurred in furnishing this information. Telephone inquiries will not be honored. This is not a solicitation or Request for Proposal (RFP). (332)

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