Session IV: New Systems Concepts

Chair: Peter Mendham – University of Dundee

Tuesday, August 12, 2008

10:45 a.m.Innovative Design Concepts for the Low Cost Remote Sensing Satellites: Jer Ling, Bo Chen, Cynthia Liu, Eden Hsueh – National Space Organization (NSPO); ABSTRACT: This paper presents some innovative design concepts for the low-cost remote sensing satellites, including: designing the special low-altitude orbit; implementing the in-flight fine refocusing to increase image quality; applying the radiation-hard FPGA (field-programmable gate array) for advanced data compression processors; using the time delay integration (TDI) sensor concept for reducing the camera aperture size. By implementing the calculated perturbation, the selected low-altitude orbit is capable to achieve daily revisit of Taiwan area and near-global coverage. By using commercial FPGA and technologies such as TDI and the refocusing, the smaller telescope aperture and the smaller satellite and thus cheaper cost can be met. The key advantages associated with these design concepts are introduced. The simulations of the mission performance for different approaches are demonstrated. The limitations of those concepts have also been discussed.

11:00 a.m. Geostationary Small Satellite for Operationally Responsive Space (ORS) Communications Missions

Frank Taylor Bryce Carpenter, Hannes Hacker, John Hibbs, Zach Thicksten, Jason Hinkle – SpaceDev, Inc.

ABSTRACT: Existing military communication systems use large, very expensive, heavily tasked national asset communications satellites located in geostationary orbits, often supplemented by leased capabilities on commercial satellites. As data and voice communication needs have increased with the adoption of network-centric warfare operations, these assets may becoming increasingly oversubscribed and unavailable when needed by tactical warfighters. The Air Force has established an office of Operational Responsive Space (ORS) to address these and other challenges.

The Geo Small Sat (GSS) concept is less complex than a LEO constellation system, employing only a single small UHF/L Band communications satellite launched by a small responsive vehicle and self-boosted to a geostationary orbit over a region of interest. The small, highly capable satellite will be reconfigurable to support all UHF and L-band communication networks. Making this novel solution a reality will require the use of several key mission technologies: • Compatibility with existing small responsive launch vehicles. • A propulsion system capable of LEO-to-GEO transfer. • A small satellite bus capable of supporting a communications payload adaptable for existing ground systems. • A deployable antenna (18 meters in diameter), that can be packaged within the available launch vehicles volume.

11:15 a.m. The Implementation of a Plug–and–Play Satellite Bus: Maurice Martin, Don Fronterhouse, James Lyke – Air Force Research Laboratory/Space Vehicles Directorate; ABSTRACT: Several years ago, the Air Force Research Laboratory (AFRL) began a research program to understand the complexity of aerospace systems and how, through technology, it would be possible create them much faster. To underscore the ambitions of this work, we referred to this research as the pursuit of the “six-day” spacecraft. The six-day interval is marked starting with identification of a mission need and ending with a fieldable spacecraft ready to integrate onto a launch vehicle. This body of work culminated in the creation of a plug-and-play satellite bus (PnPSat) as a “clean-sheet” approach to spacecraft architecture. With PnPSat, we demonstrate how a complete spacecraft can be developed, integrated, and tested based on plug-and-play components and supporting software, design, and simulation technologies. This paper reviews the architecture and current status of the PnPSat project.

11:30 a.m.Micro–GEOs: An Emerging Small Satellite Bus Class

Andy Lewin, Victoria Davis – Orbital Sciences Corporation

ABSTRACT: Over the last few years, Orbital has witnessed the emergence of a new spacecraft bus market class we call Micro-GEO. Micro-GEO spacecraft operate in high-altitude orbits such as Geosynchronous Earth Orbit (GEO) and typically weigh an order of magnitude less than traditional GEO communications satellites. Initial demand has primarily been driven by defense needs, but NASA is expected to have an interest in this capability as well. This paper describes the market class and some of the bus design drivers. The obvious challenge to this class bus is access to space. Two basic means are available, direct injection into GEO and launch into geosynchronous transfer orbit (GTO), with the spacecraft responsible for boosting itself to GEO. The launch approach has a substantial impact on both the availability of launch opportunities as well as the complexity of the spacecraft bus design.

Operation of spacecraft in high-altitude orbits such as GEO has many similarities to their low-Earth orbit (LEO) counterparts, but there are important differences as well. The paper addresses technical similarities and differences between the two orbital regimes and the resulting design implications.

11:45 a.m. Reading the Fine Print from Orbit: It's Not Just About the Resolution

Adam Baker, Andrew Cawthorne, Mike Cutter, Alex da Silva Curiel – Surrey Satellite Technology Ltd.

ABSTRACT: Is it possible to offer sub metre imaging from a small satellite, in this case defined as having a total mass under 500 kg, while still staying within the boundaries of a low cost space mission? If so, can a constellation of such spacecraft offer an operationally unbeatable combination of imaging resolution, area coverage and timeliness for less than the cost of a single, large, high resolution spacecraft?

Government and a growing number of commercial customers have recognised the utility and price-performance benefits of small spacecraft. Sub-1m imaging opens up a huge range of applications to the user of Earth Observation (EO) data, however targeting improved imaging payload resolution does not make a system more useful, unless a number of other parameters are improved. The paper firstly summarises the options for building a sub-metre resolution camera in a low cost, small satellite mission context, since this is currently the metric used to compare small satellites against the state-of-the-art. An analysis is then presented of the complex trade-offs between orbit height, image resolution & quality, lifetime, and spacecraft configuration. This initial trade-off is required to identify the most appropriate operational altitudes associated with different orbit maintenance strategies. A comparison is made with other high resolution commercial EO missions.

The paper will cover the engineering challenges of flying a sophisticated optical bench into orbit, considering in particular the propulsion, structure, thermal and Attitude control; and the modes of operation that can be supported with a spacecraft designed to deliver very high resolution from orbit. Some of the trade-offs associated with detector design will also be addressed, including the potential need for active attitude control during imaging to control the read-out rate required from the sensor. The paper concludes with a short section on the estimated performance of a constellation of small, low cost very high resolution imaging spacecraft, which has the potential to offer an operationally unbeatable combination of imaging resolution, area coverage and timeliness for less than the cost of a single, large, high resolution spacecraft.

12:00 p.m. Launch and Deployment of the High–Latitude Dynamic E–Field (HiDEF) Explorer Satellite Constellation: Stephen Whitmore – Utah State University; Brian Bingham, Quinn Young – Space Dynamics Laboratory; ABSTRACT: A consortium of organizations has proposed an experiment to map Earths high-latitude electric field. The High-latitude Dynamic E-Field (HiDEF) Explorer will observe poorly understood magnetosphere, ionosphere, and thermosphere phenomena. Utah State University Space Dynamics Laboratory is responsible for systems engineering and mission planning for achieving science objectives. A constellation of 90 pico-satellites is deployed at high latitudes over a range of inclinations and altitudes increments that evolve from a densely-packed cluster to a fully global high-latitude coverage over a period of approximately 18 months. Planned constellation “fold-out” allows measurements of high latitude electric fields over wide spatial and temporal scales. Launch and deployment analysis including operational constraints, constellation foldout, and orbit lifetime predictions are described. The deployment analysis recommends a lowest-risk option using Orbital Sciences Corporation Pegasus XL launch vehicle with the Hydrazine Auxiliary Propulsion System (HAPS) system as an upper stage. Pegasus deploys the payload into an initial orbit, and the HAPS delivers the constellation elements to desired initial orbits using a series of 10 burns including an initial trim burn, on-orbit maneuvers, and de-orbit. The paper concludes that using the Pegasus/HAPS option, the required orbits can be achieved with reasonable weight-growth margins but little ΔV margin.

12:15 p.m. Low Cost Rapid Response Spacecraft, (LCRRS) — A Research Project in Low Cost Spacecraft Design and Fabrication in a Rapid Prototyping Environment

Stevan Sprem, Jesse Bregman, Christopher Dallara, Shakib Ghassemieh, James Hanratty, Evan Jackson, Chris Kitts, Pete Klupar, Michael Lindsay, Ignacio Mas, David Mayer, Emmett Quigley, Mike Rasay, Aaron Swank, Jeroen Vandersteen – NASA Ames Research Center

ABSTRACT: The Low Cost Rapid Response Spacecraft (LCRRS) is an on going research development project at NASA Ames Research Center (ARC), Mofett Field, California. The proto type spacecraft, called Cost Optimized Test for Spacecraft Avionics and Technologies (COTSAT) is the first of what could potentially be a series of rapidly produced low-cost satellites. COTSAT has a target launch date of March 2009 on a Space X Falcon 9 launch vehicle. The LCRRS research system design incorporates use of COTS (Commercial Off The Shelf), MOTS (Modified Off The Shelf), and GOTS (Government Off The Shelf) hardware for are remote sensing satellite. The design concept was base lined to support a 0.5 meter Ritchey-Chretien telescope payload. This telescope and camera system is expected to achieve 1.5 meter/pixel resolution. The COTSAT team is investigating the possibility of building a fully functional spacecraft for $500,000 parts and $2,000,000 labor. Cost is dramatically reduced by using a sealed container, housing the bus and payload subsystems. Some electrical and RF designs were improved/upgraded from GeneSat-1 heritage systems. The project began in January 2007 and has yielded two functional test platforms. It is expected that a flight-qualified unit will be finished in December 2008. Flight quality controls are in place on the parts and materials used in this development with the aim of using them to finish a proto-flight satellite. For LEO missions the team is targeting a mission class requiring a minimum of six months life time or more. The system architecture incorporates several design features required by high reliability missions. This allows for a true skunk works environment to rapidly progress toward a flight design. Engineering and fabrication is primarily done in-house at NASA Ames with flight certifications on materials.

The team currently employs seven Full Time Equivalent employees. The success of COTSATs small team in this effort can be attributed to a highly cross-trained engineering team. The engineers on the team are capable of functioning in two to three engineering disciplines which allows highly efficient interdisciplinary engineering collaboration. NASA Ames is actively proposing mission concepts to use the COTSAT platform to accomplish science. If the COTSAT team validates this approach, it will allow the possibility for remote sensing missions to produce a high science yield for minimal cost and reduced schedule. Another aim of this approach is to yield an accelerated pathway from a Phase A study to mission launch. Leaders in the aerospace industry have shown interest in this methodology. Several visits and tours have been given in the lab. Although the concept to flow-cost development is initially met with skepticism from some with in the prohibitive aerospace industry, the projects efforts have been highly praised for the accomplishments met within a limited time and budget. Overall the development has progressed tremendously well and the team is answering critical questions for current and future low-cost small satellite developments. COTSAT subsystems are not limited to a specific weight class and could be adapted to produce smaller platforms and to fit various launch vehicles.

12:30 p.m. Cellular–Satellite, a Different Kind of Final Frontier: James Lyke – Air Force Research Laboratory/Space Vehicles Directorate; Robert Pugh – Think Strategically!; ABSTRACT: Extending the ideas of reconfigurable components and self-organizing, plug-and-play systems offer some very intriguing prospects for rapid satellites of the future. In this talk, we describe the “cellular satellite” as a paradigm for the ultimately modular and rapidly formed system. In this vision, all systems are formed as a vast ensemble of black-box cells, each of which is individually customizable to collectively form an integral system. Locally (with in a given cell), all significant functions and properties (e.g., electrical, thermal, and mechanical) are software-definable, similar in principle to the approaches used in ordinary field programmable gate arrays but extended far beyond digital building blocks. Systems are “merely” ensembles of cells whose arrangements are also soft-defined, leading to a DNA-like analogy in which a very long Boolean string, in effect, forms a unique specification of a constructible spacecraft. Initial attempts at cellular satellites would proceed with cells that are physically large (in some sense, the panels of our plug-and-play satellite could be viewed as very large cells), but would evolve through a Moore’s Law-like principle to become eventually tiny smart particles. We believe these ideas provide the ultimate solution for responsive space, in which containers of such “programmable matter” could be rapidly configured with powerful computer-automated design tools to form complex shapes, structures, and systems.