A Custom Launch System for Satellites Smaller than 1 kg

This paper presents the concept and design of a custom launch system for satellites with a mass equal or less than 1 kg. Current launch opportunities carry these satellites as secondary payloads to orbit. To date, no launch system has targeted a satellite of less than 1 kg as a primary payload. The case is made for an airborne, balloon based rocket launch. A four stage rocket using a hybrid propellant combination is proposed. With an assumed specific impulse of 235 seconds, four stages and a redundant structure to propellant mass ratio of 1/10, a burnout velocity of 9,200 m/sec can be achieved. Subtracting the velocity losses due to drag in the upper atmosphere, gravitation and earth rotation, a real burnout velocity of more than 7,600 m/sec can be achieved, which is sufficient to achieve Low Earth Orbit. The initial mass of the rocket and payload would be below 200 kg. For currently available zero-pressure balloons, this is an average payload which can be lifted up to 30 km in about an hour