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STLS Concept

   The Space Track Launch System (STLS) is a two stage system. The first stage is a tall tower 100-150 km high. An electrically driven rotating truss at the top of the tower is attached to two sets of ribbons made of high strength fiber composites. Counterweights (CW) are attached to the end of each ribbon. The second stage is a reusable liquid fueled launch vehicle (LV) designed to launch form the STLS.

   The system is unique for several reasons. First, the first stage is all electric and can be used up to three times a day. The electric motors restore rotational kinetic energy to the ribbons in approximately 8 hours. Second, the launch vehicle launches from a point along the ribbon as opposed to being released from the end of the ribbon. For a 30 ton launch vehicle, launching from the end of the ribbon produces a compressive shock wave that will destroy the ribbon and damage the tower. When launched from the middle of the ribbon, the additional force on the ribbon is several orders of magnitude less than the tension in the ribbon. As such, the impulse from launch is absorded by the ribbon and counterweights and the stress on the tower is greatly reduced. Finally, the materials are presently available to build a first generation system capable of placing 400 kg of payload into a low earth orbit up to three times a day.

   A torque is produced when the electric motors restore rotational kinetic energy to the system. Precession of the tower occurs due to an unbalanced lateral load at the top. Both torque and precession are controlled by a 100 m section of inlflated cylinders called a torque buffer. The torque buffer bleeds off the torque produced by the electric motors during restoration of rotational kinetic energy. The STLS is essentially a very large gyroscope. The angular momentum due to rotation of the ribbons and counterweights set up a restoring force which stabilizes the tower and reduces tip displacement. Pressure variation in the inflated clylinders is used to keep the lateral force from setting up uncontrollable oscillations and keep tip displacemnt to a minimum.

   A 25 km proof of concept system is proposed. The proof of concept system will demonstrate the launch of a second stage suborbital launch vehicle with separation from an overcarriage on a rotating ribbon. Also, it will demonstrate the mitigation of the shock wave produced during launch. The proof of concept system will demonstrate torque buffering while restoring rotational kinetic energy and, it will demonstrate gyroscopic and pressure stabilization of the unbalanced force. Finally, the proof of concept system will demonstrate the viability of using inflated mult-beams for the all electric first stage of the STLS.

Fisher Space Systems LLC

Space Track Launch System

   A more detailed review of the Space Track Launch System can be found in the updated STLS concept paper. Also, the updated paper discusses in more detail torque buffering and pressure stabilization. A more detailed review of the proof of concept system is found in the Proof of Concept paper. Use the comment form on the contact page if you wish to comment on the STLS concept. Be sure to review the creative commons licenses. All comments and suggestions will be shared equally throughout the space access community.  
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Updated Aug 2012