Re-injecting Innovation into the Space Test Process

The U.S. Space industry is losing market share to the International community, both in the launch vehicle and satellite fabrication marketplaces. Although many argue that this is due to restrictive export controls, this paper presents the concept that the erosion of innovation in the U.S. Space Industry has caused this downturn in U. S. market share. As U.S. space programs have grown in scope and cost, the capacity to accept risk as part of the development process has diminished. As a result, the U.S. Space industry is experiencing erosion in innovation, the foundation of our national security and space commerce leadership for the past four decades. To restore and regain lost market share, we must develop rapid access to space for testing of new ideas and must couple these efforts to hands-on university programs in space technologies that will train future U.S. space technologists. This paper summarizes findings on an innovative approach to using dedicated pico-satellite (CubeSat) space test capabilities for low-cost and regularly scheduled component testing. Schafer Corporation and Stanford University’s Space Systems Development Laboratory (SSDL) were awarded a contract in August, 2000 by the National Reconnaissance Office / Office of Space Launch (NRO/OSL) to investigate new, evolutionary and revolutionary approaches to facilitate low-cost space testing opportunities. The contract and study are entitled Proactive Rideshare Opportunity Brokering Services (PROBS) . This paper is based on the interim findings of the PROBS study

The Orion Microsatellite Mission: A Testbed for Command, Control, and Communications for Formation Fleets

The Orion microsatellite, under development at Stanford University, will fly along with two other Stanford satellites (“Emeralds”) as part of a NASA-funded project. The primary objective is to demonstrate, for the first time, the use of carrier-phase differential GPS (CDGPS) for the relative sensing, navigation and coordinated control of satellites to form a virtual spacecraft bus. Launch of this mission has been tentatively scheduled for late 2001. Formation flying offers an exciting new approach to conducting space science missions. Instead of employing a single, large satellite, a fleet of similar, smaller spacecraft is coordinated to perform mission-related tasks. While formation flying architectures have a significant amount of operational flexibility, the internal system complexity increases with the number of satellites in the fleet. In addition, constraints on satellite resources play a particularly key role. This paper is a summary of work conducted at Stanford to investigate the influence of resource constraints on mission and current-task planning. By making efficient use of knowledge associated with mission goals and operations, optimal strategies can be used to increase fleet life-cycle performance. In addition to discussing this topic, the role of the Orion mission as a testbed for these concepts is included

The Multi-Application Survivable Tether (MAST) Experiment

Tethers Unlimited, Inc (TUI) and Stanford University’s Space Systems Development Laboratory (SSDL) are collaboratively developing the Multi-Application Survivable Tether (MAST) experiment, which will obtain data on tether performance, survivability, and dynamics. This data is crucial to the development of operational tether systems for propellantless propulsion and deorbit, formation-flying, and momentum-exchange transportation applications. The first objective of the MAST experiment is to obtain detailed on-orbit data on the survivability of space tethers and other gossamer spacecraft structures in the micrometeorite/orbital (M/OD) debris environment. The MAST experiment will deploy three 1-kg Cube- Sats along a 1-km Hoytether that incorporates both conducting and nonconducting materials. The middle CubeSat will then slowly translate along the tether, inspecting the tether as it moves and returning data on the rate of damage to the tether by M/OD impacts. The second objective of the experiment will be to study the dynamics of tethered formations of spacecraft and rotating tether systems. This data is required to enable the validation of space tether simulation tools such as TetherSim and GTOSS. The third objective of the experiment will be to demonstrate momentum-exchange tether concepts. In this paper we will present results of initial design studies and analyses of MAST system dynamics and performance

Autonomous Satellite Command and Control through the World Wide Web: Phase 3

NASA's New Millenium Program (NMP) has identified a variety of revolutionary technologies that will support orders of magnitude improvements in the capabilities of spacecraft missions. This program's Autonomy team has focused on science and engineering automation technologies. In doing so, it has established a clear development roadmap specifying the experiments and demonstrations required to mature these technologies. The primary developmental thrusts of this roadmap are in the areas of remote agents, PI/operator interface, planning/scheduling fault management, and smart execution architectures. Phases 1 and 2 of the ASSET Project (previously known as the WebSat project) have focused on establishing World Wide Web-based commanding and telemetry services as an advanced means of interfacing a spacecraft system with the PI and operators. Current automated capabilities include Web-based command submission, limited contact scheduling, command list generation and transfer to the ground station, spacecraft support for demonstrations experiments, data transfer from the ground station back to the ASSET system, data archiving, and Web-based telemetry distribution. Phase 2 was finished in December 1996. During January-December 1997 work was commenced on Phase 3 of the ASSET Project. Phase 3 is the subject of this report. This phase permitted SSDL and its project partners to expand the ASSET system in a variety of ways. These added capabilities included the advancement of ground station capabilities, the adaptation of spacecraft on-board software, and the expansion of capabilities of the ASSET management algorithms. Specific goals of Phase 3 were: (1) Extend Web-based goal-level commanding for both the payload PI and the spacecraft engineer; (2) Support prioritized handling of multiple PIs as well as associated payload experimenters; (3) Expand the number and types of experiments supported by the ASSET system and its associated spacecraft; (4) Implement more advanced resource management, modeling and fault management capabilities that integrate the space and ground segments of the space system hardware; (5) Implement a beacon monitoring test; (6) Implement an experimental blackboard controller for space system management; (7) Further define typical ground station developments required for Internet-based remote control and for full system automation of the PI-to-spacecraft link. Each of those goals is examined in the next section. Significant sections of this report were also published as a conference paper

Single Injection Earth Return Trajectory Options for Small Spacecraft Missions to the Moon

There exist several classes of high energy trajectories that are injected from Earth centered orbits to deep space destinations and return to the vicinity of the Earth sometime later due to the direct influence of a third body perturbation. These trajectories can be designed to flyby the moon or near Earth asteroids and comets. The appealing characteristic of these trajectories is that they require a single injection maneuver at the Earth and no further translational control thereafter. A spacecraft on such a trajectory can take observations and measurements of the flyby body and download the data once it returns to the vicinity of the Earth. The return trajectory could place the spacecraft into a direct reentry path through the Earth\u27s atmosphere or an elliptical or hyperbolic Earth flyby that will be completely passive since no maneuvers are made. This type of trajectory is applicable to passive spacecraft missions such as student built micro satellites that have no on board propulsion for attitude or translational control. Issues addressed are the dispersions in the return trajectory due to errors in the injection maneuver and other orbit parameters. The characteristics of an Earth return lunar flyby mission for small satellites are discussed

A Single Geostationary Satellite for Mobile Terrestrial Transmitter Tracking

This paper will describe the Energetics Satellite Locating Service (ESLS) which is a unique, patented, proprietary satellite based geolocation system. This system called SAT/TRAC for Satellite Tracking, Ranging and Communications may be used to quickly determine the present location within 50 feet of any person, vehicle or object that is equipped with a ESLS low power transmitter. This technology represents a novel approach to radio tracking. The single point location system uses a single satellite with a 165 foot inflatable antenna

CubeSat: The Development and Launch Support Infrastructure for Eighteen Different Satellite Customers on One Launch

Stanford University and California Polytechnic State University have combined efforts to develop a means of launching small picosatellites called CubeSat. The CubeSat is a 10cm cube weighting 1 kg or less. The launching system developed will provide launches for three satellites in one launcher tube. The first mission for this launcher will be to fly six tubes to launch as many as 24 CubeSats in May 2002 on a Kosmotras, Dnepr ELV from Bikinour, Ukraine. Stanford and Cal Poly are providing active technical support for the CubeSat developers, which are mostly universities. Once the CubeSats have been developed by the universities and other customers, they will be sent to Cal Poly for final testing, insertion into the launcher then shipped to One Stop Satellite Solutions in Ogden, Utah where they will be mounted on the OSSS Multiple Payload Adapter, then sent to Russia and integrated onto the Dnepr

The Orion Microsatellite: A Demonstration of Formation Flying In Orbit

The Orion microsatellite project is funded by NASA Goddard Space Flight Center. The goals of the project are to demonstrate determination of position and attitude of spacecraft in a formation using carrier phase differential GPS, and closed loop autonomous control of the formation. The mission is designed so it can be performed with a constellation of three or more Orion spacecraft, or a constellation of one Orion spacecraft and the Emerald spacecraft. The spacecraft are designed and built by the Formation Flying Laboratory and the Space Systems Development Laboratory, both at Stanford. The Orion spacecraft will build on the heritage of prior Stanford satellites: Sapphire and Opal. The bus will be cube shaped, 0.5 meters on the side. The command and data handler is the SpaceQuest CPU, based on the NEC V-53 microprocessor. In addition there will be another StrongARM based CPU performing mission specific, CPU intensive calculations. This second CPU could be combined with the GPS computer. The Orion spacecraft will use a cold-gas propulsion system, using Nitrogen gas. The onboard propellant will provide 40 mls delta V. Kiraly, Engberg, Busse, Prof. Twiggs and How Magnetic torquer coils will be used for detumbling after deployment. The subsystems will be connected using an 12C serial data bus. The GPS receiver and computer is in development at Stanford. A single Orion spacecraft is slated to fly with the University Nanosatellite mission

CubeSat: A New Generation of Picosatellite for Education and Industry Low-Cost Space Experimentation

The launch and deployment of picosatellites from the Stanford University OPAL microsatellite in February 2000 demonstrate the feasibility and practicability of a new age of space experimentation. Two of the six picosatellites deployed from OPAL were built by The Aerospace Corporation in El Segundo, CA and demonstrated new space testing of MEMS RF switches and intersatellite and ground communication with low power wireless radios. These picosatellites weighting less than one kilogram with dimensions of 4x3x1 inch were built as test platforms for DARPA and were constructed and delivered for flight in less than nine months. From this experience, a new generation of picosats called CubeSat is being developed by a number of organizations and universities to accelerate opportunities with small, low construction cost, low launch cost space experiment platforms. California Polytechnic State University at San Luis Obispo, CA is developing launcher tubes that can be part of a satellite or attached to any orbiting platform to launch from 1-3 CubeSats per tube. These tubes will contain CubeSats of 1-2 kilograms weight and approximately 4-inch cube shape. This size as compared to the picosatellites launched on OPAL provide better surfaces for practical solar power generation, physical size for components and a shape that provides better space thermal stability. A consortium of potential CubeSat developers is now wide ranging with universities from Japan, New Zealand, the US, amateur radio clubs and industry participants. Potential launch opportunities exist with the Russian Dnepr (SS-18) about twice/year, with the OSP (Minotaur) every 18 months and possible 100 km altitude orbits from the second stage of Delta launches. This paper will review the OPAL picosatellite launch and performance, the launcher being built for the CubeSat, the development and payloads of CubeSat developers and cost and timing of launch opportunities

Design of a Pico-Satellite for the Monitoring of the Performance of a Thin Film Solar Array

This paper presents an overview of the design and mission of a pico-satellite designed to monitor the performance of a Thin Film Solar Array (TFSA) over a one-week period. TFSA is a solar array technology that allows solar cells to be deposited onto a thin, flexible substrate. This substrate can be easily folded, which allows large solar arrays to collapse into a small space. The Aerospace Corporation has developed a small deployable solar array based on this technology. During this mission, the pico-satellite will deploy the TFSA. Once deployed, the voltage and current generated by the array will be monitored. The majority of the pico-satellite’s subsystems are constructed from off-the-shelf components that have been modified for space flight. These are a Kenwood amateur radio communications system, a Basic-X micro-controller based computer system, and a power system. These components, along with the ability to be launched as a secondary payload help reduce costs. This mission is ideally suited for a pico-size satellite due to its short duration, low power requirements, and lack of pointing requirements. It is hoped that information gathered on this mission will allow larger TFSA’s to be built in the future, enabling them to act as primary power sources for future satellites