Technical Sessions

Session VII: Spacecraft Systems

Chair: Michael Sorrells, National Reconnaissance Office

Wednesday, August 12, 2009

8:30 a.m. Advanced System of Micro Satellite for Hyperspectral Remote Sensing Mission

Yoshihide Aoyanagi, Shin Satori, Ryuichi Mitsuhashi – Hokkaido Institute of Technology; Tsuyoshi Totani – Hokkaido University; Toshihiko Yasunaka – Uematsu Electric Co, Ltd.; Akihiro Nakamura– AIDMA, Inc.; Yusuke Takeuchi – Hokkaido Satellite, Inc.

ABSTRACT: The Space‐Science Industries Program has been performing investigations for the Micro‐satellite and Hyperspectral remote sensing missions. The Earth Observation Micro‐satellite “TAIKI” is a 50 kg satellite which has low‐cost and small bus‐subsystems for advanced remote sensing missions. This bus‐subsystem will be developed as manufactured products. The TAIKI is characterized by a small Hyperspectral sensor “HSC‐III” which is targeted at the performances of 30m of ground sampling distance and 61 spectral bands in VNIR (Visible and Near Infrared). The advanced remote sensing data such as Hyperspectral data are large volume, so the downlink uses the laser communication of 100Mbps. The terrestrial laser communication has already been successfully experimented. In addition, HSC‐III optics instrument which mainly consists of spectrometer, detector and on‐board calibration system has been developed in 2008. This paper reports the small bus‐subsystem including the laser communication system for the TAIKI and the Hyperspectral sensor instrument.

8:45 a.m. Autonomous Pose Estimations for In‐Orbit Self‐Assembly of Intelligent Self‐Powered Modules

Samia Smail, David Wokes, Craig Underwood and Phil Palmer – Surrey Satellite Technology Ltd./Surrey Space Centre

ABSTRACT: The ability to autonomously determine the position and attitude of a swarm of satellites is a promising way of assembling Intelligent Self‐powered Modules (ISMs) in orbit. This self assembly is guided through simple actuators and sensors and requires fewer resources. A vision based system is used to determine the pose of ISMs attempting docking, through two strategies: Spheroid modeling and feature detection methods. The former technique takes an image of the ISM to reconstruct its position. An additional set of reflectors are placed on each facet to then determine the attitude of the ISM. The attitude algorithms developed are validated for distances up to 30m, with the position determination tested for distances up to 50m. These methods are combined to autonomously estimate the pose of an ISM attempting to dock with a coupled structure of previously launched and connected ISMs.

9:00 a.m. Multi‐Mission Suitability of the NASA Ames Modular Common Bus

Sascha Tietz– Stinger Ghaffarian Technologies Inc.; James Bell, Butler Hine – NASA Ames Research Center

ABSTRACT: The obvious advantages of small spacecraft – their lower cost structure and the rapid development schedule – have enabled a large number of missions in the past. However, most of these missions have been focused on Earth observation from low Earth orbits. In 2006, the Small Spacecraft Division at the NASA Ames Research Center began the development of the Modular Common Bus, a spacecraft capable of delivering scientifically and technically useful payloads to a variety of destinations within 0.1 AU around the Earth. The core technologies used in the Common Bus design are a composite structure with body‐mounted solar cells, an integrated avionics unit, and a high performance bipropellant propulsion system. Due to its modular approach, the Common Bus can be adapted to fit specific mission needs while still using a standardized and qualified set of components. Additionally a number of low cost launch vehicles are supported, resulting in overall mission costs of around $150M including the launch vehicle but excluding the science payloads. This significant reduction in cost and the shorter development time would enable NASA to conduct more frequent exploration missions within its budget and timeframe constraints, compared to the status quo.

In this paper the suitability of the Common Spacecraft Bus for four different exploration scenarios is analyzed. These scenarios include a lunar orbiter, a lunar lander, a mission to a Sun‐Earth Libration Point, and a rendezvous mission to a Near Earth Object. For each scenario, a preliminary design reference mission is developed and key design parameters for the spacecraft are determined.

9:15 a.m. Advanced Middleware for Space Plug‐and‐Play Avionics (SPA) Architecture Standardization and Rapid Systems Integration

Grant Holcomb – ATK Launch Systems

ABSTRACT: The Space Plug‐and‐play Avionics (SPA) architecture is the foundation of the U.S. Department of Defense (DoD) Operationally Responsive Space (ORS) initiative. The ORS mission reflects the need to provide our warfighters, battlefield commanders, and first responders with reliable communications and real‐time situational awareness. Driven by operational requirements, the ability to rapidly and economically manufacture, assemble, and launch custom satellite configurations is essential. The most viable solution for delivering the software required to solve this problem is for all approved DoD vendors to have equal access to software middleware that possesses the characteristics to establish a standard for Plug‐and‐Play (PnP) for the broadest range of transducers (sensors and actuators) and third party algorithms (heritage and future flight systems software and mission control processes). This middleware must support all ORS goals to include fault tolerance, computing topology independence, common data understanding, network topology independence, operating system independence, autonomous processing, and automation of PnP processes for hardware and software sub‐components. A middleware candidate will be presented that has the potential to (1) establish industry wide standardization, (2) accelerate satellite system integration, (3) increase reliability and survivability of satellites, and (4) measurably support ORS goals in a cost effective fashion.

9:30 a.m. RISTRETTO: A French Space Agency Initiative for Student Satellite in Open Source and International Cooperation

M. Saleman, C. Lambert – CNES; D. Hernandez – Devil‐Hop

ABSTRACT: The EXPRESSO (EXpérimentations et PRojets Etudiants dans le domaine des SystèmeS Orbitaux) is a French acronym for a CNES (French Space Agency) initiative that aim at fostering networks of universities, laboratories and industries in the field of orbital systems. This program, started in 2006, strives to serve as an educational platform, promoting space and science and attempting to involve students in all aspects of a project from project management to “hands‐on” development. The first call of ideas EXPRESSO (2006) has permit to select three projects among which we have a cubesat for the validation of laboratory test methodologies for bipolar technologies, named ROBUSTA leaded by University of Montpellier (South of France). Today, ROBUSTA is on the way to be ready for launch and it is already a real success on pedagogic point on view (see article SSC09‐XII‐10). Its launch foreseen by VEGA launcher and the operational data collection are awaited to complete this success on scientific point of view. Therefore, CNES has decided to continue the experience with a future more ambitious initiative named RISTRETTO in the frame of EXPRESSO program. This paper presents the CNES internal studies on‐going on technical and programmatic feasibility of the RISTRETTO concept.

9:45 a.m. SatTherm: A Thermal Analysis and Design Tool for Small Spacecraft

Cassandra Allison – Universities Space Research Association/NASA Ames Research Center; Millan Diaz‐Aguado – ASRC Research and Technology Solutions/NASA Ames Research Center; Belgacem Jaroux – NASA Ames Research Center

ABSTRACT: Small spacecraft have become an attractive alternative for a significant class of space missions. They have the potential to provide valuable science data with shorter development times and at a reduced cost over traditional multi‐instrument spacecraft. However, many of the legacy tools used for spacecraft design and analysis have considerable cost and complexity that are not suited to small spacecraft and their associated short development cycles. SatTherm is an alternative thermal analysis tool specifically developed for small spacecraft as a collaborative effort between the Mission Design Center at NASA Ames and San Jose State University. It is intended to be available to the small spacecraft community. SatTherm consists of an easy to use, Microsoft Excel user‐interface coupled to a suite of Matlab routines that determine the time dependant temperature solution for spacecraft components. This paper presents a comparison that includes the accuracy of results and the ease of use between SatTherm and the commercially available Thermal Desktop software by Cullimore & Ring Technologies. A benchmark case of a model of the small spacecraft, PharmaSat, is presented. The time‐dependant temperatures predicted by the SatTherm model agree with those predicted by the Thermal Desktop model within 4 Degrees Celsius or less. Both models are also validated by the flight data, recorded after the spacecraft was launched in May 2009. This demonstrates that SatTherm can be a useful tool for the early design stage of a small spacecraft.

Alternate  Simulation‐Based Testing of Embedded Attitude Control Algorithms of an FPGA Based Micro Satellite

Muhammad Yasir, Toshinori Kuwahara, Claas Ziemke, Michael Fritz, Hans‐Peter Roeser – Institute of Space Systems

ABSTRACT: This paper focuses on the issues regarding the software based testing approach which mainly utilizes the software models for the satellite environment and the satellite itself. This approach facilitates the use of real on‐board software in a virtual satellite environment and hence gives an excellent means of system design qualification and performance verification. Use of FPGA as an on‐board computer leads to the requirement of implementing the attitude control algorithms in the hardware which emphasizes the need of its testing in the loop with the simulator. Two different type of simulation environments are used to increase the credibility of the results.