A Small, Primary Solar-Electric Propulsion Demonstration Satellite

Interest in the application of primary solar-electric propulsion to high-energy Earth orbital and deep-space missions has increased in recent years because of its inherent propellant economy and the promise of greatly enhanced payload weight capacity for a given vehicle launch weight. This paper describes a small, low-cost electric propulsion demonstration satellite, capable of ascending from low altitude to geosynchronous orbit in ten months or less, using only about 1 kW of propulsive power. Based on available technology of ion thrusters and lightweight solar arrays, and using elements of current light satellite design, this mission is of timely interest as a step in the evolution of future operational electric propulsion transfer vehicles. Generic data on system and mission design for this demonstration vehicle are presented along with relevant literature references

Small Orbit Transfer Vehicle (OTV) for On-Orbit Satellite Servicing and Resupply

The field of on-orbit servicing of space systems has been studied extensively, and techniques for performing satellite resupply and repair functions have been developed in detail. They are covered extensively in the literature. Based on this background, Microcosm has performed design studies, partly under NASA/MSFC contract, of a small-size, 300 kg-class multi-function Orbital Transfer Vehicle (OTV) that can provide servicing and resupply functions for the International Space Station (ISS). It carries the required payload from a launch vehicle upper stage to the Station, and after berthing it supports servicing activities of the ISS crew members. The vehicle has a payload-carrying capability of 350 kg. The current design includes grappling fixtures specifically designed for ISS berthing which can be eliminated for servicing other satellites. The very strict safety requirements involving ISS access were taken into account in the servicing vehicle design. Repeated ISS servicing sorties to be performed by the OTV are of particular interest, to meet tight revisiting schedules. Extended reuse of the same OTV, once in orbit, allows substantial launch and operational cost savings. Propellant requirements for the servicing sorties are very modest, allowing an extended on-orbit life of this vehicle, with at least 3, but more likely 6 to 8 ISS revisits. The OTV discussed here can be utilized for low-cost servicing of other spacecraft as well. The paper discusses the vehicle’s maneuver sequences and propellant requirements, and describes its design features and its interactions with the ISS. The OTV’s total recurring cost is estimated at less than $35 Million. It would nominally be carried by a light-lift launcher, such as Microcosm’s planned Sprite vehicle, at a projected cost of the order of$2.5 Million

Low-Cost, Minimum-Size Satellites for Demonstration of Formation Flying Modes at Small, Kilometer-Size Distances

In-flight demonstration of close-range formation flying modes is discussed with emphasis on low cost, based on spacecraft design simplicity and minimum size, and hence minimum launch cost. Piggy-back launch of three identical demonstration spacecraft is the preferred option. This demonstration includes comprehensive collection and analysis, on the ground, of relative motion data derived from GPS signals that are received by the participating satellites. In addition to realistically reflecting the known Keplerian and non-Keplerian characteristics as part of the flight dynamics analysis, an important concern is to demonstrate the less well-known effects of differential drag perturbations. These can be deliberately induced by small aerodynamic cross section variations on the satellites. Results of the demonstration mission will benefit currently projected and other future missions that require close-formation flying, e.g., radar and visual observation missions, by proving feasibility, assisting detailed and comprehensive operations planning, and helping diminish their potential risks

Responsive, Low-Cost Access to Space with ELVIS — An Expendable Launch Vehicle with Integrated Spacecraft

The ELVIS (Expendable Launch Vehicle with Integrated Spacecraft) concept involves: (1) dropping off the upper stage of the launch vehicle as low as possible, with integral low-thrust propulsion taking the spacecraft to its final orbital destination; (2) using the spacecraft bus to provide the avionics functions needed to fly a launch vehicle to orbit so as to avoid the duplication of avionics hardware and software between the satellite bus and the launch vehicle. The result is a reduction in the parts count, weight, and cost of the launch vehicle. There are major benefits associated with early staging — the upper stage can reenter safely without a retro burn, and the mass-to-orbit available from small launch vehicles is significantly increased. The mass gain will depend on the hardware configuration and the orbit destination, but can be as much as a factor of two or more for some low Earth orbits. In addition, the spacecraft bus operates from the time of launch and can begin the mission essentially as soon as the spacecraft reaches its operational orbit or, in some cases, even before. The small spacecraft thus achieves a new level of responsiveness, allowing spacecraft to be launched in response to rapidly changing circumstances. This paper describes a representative ELVIS configuration and performance gains for typical mission destinations, and sample applications that are enabled or made more efficient by the use of this approach. Technical issues and tradeoffs associated with this design will be discussed

A selected bibliography on parameter optimization methods suitable for hybrid computation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68333/2/10.1177_003754976700800610.pd

Low-Cost Planetary Missions Utilizing Small Launch Vehicles and a Novel Launch Mode

The ability to substantially reduce the cost of planetary missions lies not only in the cost reductions to be found in spacecraft design but also in choice of launch vehicle. Smaller launch vehicles are cheaper but are also less capable at lofting sufficiently large masses to interplanetary velocities, while excessive miniaturization of spacecraft subsystems typically leads to higher cost. Microcosm has identified a new launch technique using traditional vehicles and technologies to circumvent these restrictions for many solar system exploration missions. For the purposes of this paper, we named it the Modified Launch Mode (MLM). This method can substantially increase the payload mass capabilities of all launch vehicles for high energy (high C3) missions. It is particularly advantageous in missions that require onboard propulsion at destination and therefore can make repeated use of that system. The technique has been described elsewhere and only a summary is presented here. This paper summarizes the newly available spectrum of low-cost planetary capability that this technique makes available to the small satellite community using smaller, cheaper vehicles to carry their spacecraft then have been commonly considered as necessary. A multi-faceted trade launch vehicle capability against spacecraft size will be appropriate to minimize overall mission cost or to enhance mission capabilities within specified cost constraints. Emphasis is placed on the matching of minimum-cost launch vehicles to small spacecraft now being considered for deep-space exploration