Robert Twiggs

Orion - A low-cost demonstration of formation flying in space using GPS

This paper describes research on the design of a GPS based relative position and attitude sensing mission called Orion. The current Orion design consists of a eet of 6 micro-satellites launched simultaneously into low Earth orbit to demonstrate coordinated attitude control, relative navigation and control, and formation initialization techniques in space. This approach represents a new systems architecture that provides many performance and operations advantages, such as reduced operating cost, enhanced mission exibility, and improved science observations. A key objective of Orion is to demonstrate CarrierPhase Di erential GPS (CDGPS) techniques to autonomously track the relative position and attitude between several spacecraft. Based on a research program focused on low-cost spacecraft design, Orion represents a critical step towards the realization of formation ying and virtual platform capabilities. 1

CubeSats as Responsive Satellites

California Polytechnic State University, in coordination with Stanford University, has developed the CubeSat standard to provide inexpensive and timely access to space for small payloads. These picosatellites, built mostly by universities, are 10 centimeter cubes with a mass of 1 kilogram. Of the 40 or so participating universities and private firms, more than 60% of CubeSat developers reside in the United States. Our goal is to make launching these satellites easy and cost effective by coordinating launches and providing a reliable deployment system. This paper will discuss Cal Poly’s role in the CubeSat program, and the characteristics of the project which create practical, reliable, and cost-effective launch opportunities.

Development of an Off-the-Shelf Bus for Small Satellites

KySat1 is a 1 kilogram picoclass satellite being developed by college students across the state of Kentucky. To the best of our knowledge, the KySat effort is the first by a state to develop a satellite. The consortium assembled to fund and develop KySat includes public, private and educational partners throughout Kentucky. While the primary mission of KySat1 is educational outreach, the goals of the KySat program include (1) Educational experience for secondary and post secondary students (2) Cultivate an aerospace and satellite technology base in Kentucky (3) Develop a reliable reusable satellite bus that will form the basis for future education and commercial KySat missions. The timeline for KySat1 is aggressive and off-the-shelf technology is leveraged whenever possible. This paper overviews the KySat1 design and development.

Emerald: A low-cost spacecraft mission for validating formation flying technologies

Spacecraft formation flying is a proposed technology with vast performance implications ranging from enhanced mission capabilities to radical reductions in operations cost. To explore this concept and to enable its realization, Stanford University and Santa Clara University have initiated development of a simple, low cost, two-satellite mission known as Emerald. The Emerald mission has four primary goals. First, it will verify component-level technologies necessary for advanced formation flying missions. This will include the test of low-power Global Positioning System (GPS) receivers for position sensing, simple radio modems for inter-satellite communication, and experimental microthrusters for position control. Second, it will integrate the operation of these payloads in order to experiment with simple closed loop relative position control. Third, it will validate the formation flying concept by using coarse on-orbit relative position sensing and control to improve a scientific investigation of lightning-induced atmospheric phenomena. Fourth, it will extend low-cost satellite development techniques critical to fielding multi-spacecraft fleets. The bus design for the Emerald spacecraft will be based on Stanfords Satellite Quick Research Testbed (SQUIRT) microsatellite design. This consists of a 15 kilogram structure, a modular 12 inch tall by 18 inch diameter hexagonal configuration, a 68332-based flight processor, a single battery, solar panels, and simple attitude and thermal control. A Space Shuttle launch in 2001 has been tentatively selected for the launch of this mission. Emerald will be developed as part of the Defense Advanced Research Projects Agency (DARPA) and Air Force Office of Scientific Research (AFOSR) University Nanosatellite Program, an element of AFOSRs TechSat 21 Program. This paper discusses the Emerald mission objectives and approach, the conceptual design of the Emerald spacecraft, and the programmatic structure of this joint Stanford University-Santa Clara University project.

CubeSat Development in Education and into Industry

Cal Poly and Stanford students have worked together since 1999 to develop a picosatellite standard, called the CubeSat Standard. The CubeSat standard, with its small size (a 10-cm cube weighing up to 1 kg) and low launch cost, allows for an accelerated development schedule, which contributes greatly to educating current and future space scientists and engineers. The CubeSat Program provides students with opportunities to develop skills in teambuilding, systems integration, distributed engineering collaboration, complete product development lifecycle, and project management.

Experiments in distributed microsatellite space systems

Distributed space systems are often cited as a means of enabling vast performance increases ranging from enhanced mission capabilities to radical reductions in operations cost. To explore this concept, Stanford University and Santa Clara University have initiated development of a simple, low cost, two-satellite mission known as Emerald. Funded through the AFOSR/DARPA University Nanosatellite Program, the Emerald mission will involve several studies involving the design and operation of distributed space systems. First, “low-level” inter-satellite navigation techniques will be explored. Second, “high-level” multi-satellite health and payload operations will be demonstrated. Third, system validation will be attempted by assessing how these capabilities improve a baseline scientific investigation involving lightning-induced atmospheric phenomena. The Emerald bus design is based on a heritage Stanford University design, a 15-kilogram, modular hexagonal vehicle relying heavily on commercial off-the-shelf components. This paper will discuss the Emerald mission’s focus on distributed space system technologies as well as the design of the two spacecraft and the distributed ground segment.

Initial developments in the Stanford SQUIRT program

Stanford Universitys Department of Aeronautics and Astronautics has commenced full scale development of a new microsatellite initiative. Known as the satellite quick research testbed (SQUIRT) program, the projects goal is to produce student engineered satellites capable of servicing state-of-the-art research payloads on a yearly basis. This program is specifically designed to meet the education and research goals of the departments Satellite Systems Development Laboratory. SQUIRT vehicles are envisioned to consist of a 25 pound, 9 inch tall, 16 inch diameter hexagonal structure with complete processor, communications, power, thermal, and attitude subsystems. These spacecraft cater to low power, volume, and mass research experiments and student developed educational packages. Mission lifetimes of up to one year are considered. Through student participation, voluntary mentoring from the academic and industrial communities, and the extensive use of off-the-shelf components, the cash outlay target for SQUIRT class vehicles is

Space system developments at Stanford University: from launch experience of microsatellites to the proposed future use of picosatellites

50,000. This paper discusses the educational and research issues surrounding the development of Stanfords spacecraft design curriculum and the formulation of the SQUIRT program. A technical review of the first SQUIRT satellite, named SAPPHIRE, and an outline of the conceptual plans for other missions is also presented. Additionally, initiatives concerning partner academic institutions and public domain design information are featured.

Innovative methods for placing small payloads in space

The Space Systems Development Laboratory was established in 1994 at Stanford University to give graduate and undergraduate students project based learning experience in microsatellite design, fabrication, test, launch integration and space operations. These students have completed two satellites - one called OPAL was launched on January 26, 2000, and the second called SAPPHIRE is tentatively scheduled for launch in late 2002. There are three additional satellites now in developments. OPAL had a unique primary objective payload. This was to launch six small Klondike ice cream bar size picosatellites. It completed this mission to gain a record of orbiting the worlds smallest functional satellites. The next generation in picosats under developement that have a tentative late 2002 launch are called CubeSats. Launchers are under development to release multiple 4-inch cube CubeSats that can be used by amateur radio enthusiast, universities and government laboratories for inexpensive space testing.

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

There has been a significant increase in demand for testing, qualification and evaluation of satellite components in space by means of secondary rides on primary payloads and launch vehicle structures. A critical category of secondary payload developers exists that have needs for space launch services: the new/innovative developers of space components that do not have the knowledge, resources, or contacts necessary to successfully test their technologies in space. Schafer Corporation and Stanford Universitys Space Systems Development Laboratory (SSDL) have collaborated on the investigation of new, evolutionary and revolutionary approaches to low-cost space technology demonstrations. This paper describes potential approaches for implementing proactive rideshare brokering services that span all communities and potential customers. Proactive rideshare brokering is a new approach, but for the most part, adopting proven practices from the international marketplace will make advances. The paper draws conclusions by comparing what is working in the international space community versus what the current practices are in the U.S. The recommendations reflect a reduced timeline approach that acknowledges the close coupling between the technology base, the space systems industry, infrastructure and educational processes.