A report proposes the development of a system for launching payloads into orbit at about one-fifth the cost per unit payload weight of current systems. The system would be based on the formerly secret PILOT micro-satellite-launching system developed in response to the Soviet launch of Sputnik-1. The PILOT system was a solid-fuel, aerodynamically spun and spin-stabilized, five-stage rocket with onboard controls including little more than an optoelectronic horizon sensor and a timer for triggering the second and fifth stages, respectively. The proposal calls for four improvements over the PILOT system to enable control of orbital parameters:
- the aerodynamic tipover of the rocket at the top of the atmosphere could be modeled as a nonuniform gyroscopic precession and could be controlled by selection of the initial rocket configuration and launch conditions;
- the attitude of the rocket at the top of the first-stage trajectory could be measured by use of radar tracking or differential Global Positioning System receivers to determine when to trigger the second stage;
- the final-stage engines could be configured around the payload to enhance spin stabilization during a half-orbit coast up to apoapsis where the final stage would be triggered; and
- the final payload stage could be equipped with a "beltline" of small thrusters for correcting small errors in the trajectory as measured by an off-board tracking subsystem.
This work was done by Brian Wilcox of Caltech for NASA's Jet Propulsion Laboratory.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to: Refer to NPO-20908. (reference NPO-20908) is currently available for download from the TSP library. Don't have an account? The document from NASA's Jet Propulsion Laboratory discusses innovative methods for launching payloads into orbit at relatively low cost, focusing on the use of spin-stabilized solid-propellant multi-stage rockets. This approach aims to reduce complexity and expenses associated with traditional liquid-fueled rockets, which often require advanced systems like cryogenic tanks and pumps. One of the key innovations highlighted is the use of precise information, such as off-board tracking and delta-GPS measurements, to determine the optimal timing for firing the upper stage assembly during the ballistic trajectory of the rocket. The document describes the PILOT system, which utilized a horizon sensor to estimate the vehicle's elevation angle. This sensor, mounted to spin with the vehicle, would eventually detect the horizon and trigger the orbit insertion stage. The document also emphasizes the importance of accurately timing the firing of trim thrusters, which are used to correct any errors in the vehicle's flight path. By measuring the phase of rotation through optical signatures, commands can be precisely timed to ensure that the thrusters exert forces symmetrically, maintaining the vehicle's mass distribution and maximizing delta-V. Another significant innovation discussed is the configuration of the final stage assembly around the payload to be oblate, which enhances stability and allows for symmetric thrust distribution. This design minimizes the mass penalty associated with the circularization burn required for low orbit insertion, as the thrust timing and distribution can be managed effectively. The document outlines the advantages of using small trim thrusters placed along the "equator" of the spinning final assembly. These thrusters can be triggered by a small radio or optical receiver linked to an off-board tracking system, allowing for real-time corrections based on the vehicle's trajectory and spin state. Overall, the document presents a comprehensive overview of the strategies employed to achieve cost-effective and reliable payload launches into orbit. By leveraging innovations in tracking, thrust management, and vehicle design, NASA aims to enhance the efficiency and accuracy of space missions while minimizing the complexity and mass of the systems involved. Innovative Technology Assets Management
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This Brief includes a Technical Support Package (TSP).
Launching Payloads Into Orbit at Relatively Low Cost
Overview
