Gary Crum

SpaceCube v2.0 space flight hybrid reconfigurable data processing system

This paper details the design architecture, design methodology, and the advantages of the SpaceCube v2.0 high performance data processing system for space applications. The purpose in building the SpaceCube v2.0 system is to create a superior high performance, reconfigurable, hybrid data processing system that can be used in a multitude of applications including those that require a radiation hardened and reliable solution. The SpaceCube v2.0 system leverages seven years of board design, avionics systems design, and space flight application experiences. This paper shows how SpaceCube v2.0 solves the increasing computing demands of space data processing applications that cannot be attained with a standalone processor approach. The main objective during the design stage is to find a good system balance between power, size, reliability, cost, and data processing capability. These design variables directly impact each other, and it is important to understand how to achieve a suitable balance. This paper will detail how these critical design factors were managed including the construction of an Engineering Model for an experiment on the International Space Station to test out design concepts. We will describe the designs for the processor card, power card, backplane, and a mission unique interface card. The mechanical design for the box will also be detailed since it is critical in meeting the stringent thermal and structural requirements imposed by the processing system. In addition, the mechanical design uses advanced thermal conduction techniques to solve the internal thermal challenges. The SpaceCube v2.0 processing system is based on an extended version of the 3U cPCI standard form factor where each card is 190mm × 100mm in size. The typical power draw of the processor card is 8 to 10W and scales with application complexity. The SpaceCube v2.0 data processing card features two Xilinx Virtex-5 QV Field Programmable Gate Arrays (FPGA), eight memory modules, a monitor FPGA with analog monitoring, Ethernet, configurable interconnect to the Xilinx FPGAs including gigabit transceivers, and the necessary voltage regulation. The processor board uses a back-to-back design methodology for common parts that maximizes the board real estate available. This paper will show how to meet the IPC 6012B Class 3/A standard with a 22-layer board that has two column grid array devices with 1.0mm pitch. All layout trades such as stack-up options, via selection, and FPGA signal breakout will be discussed with feature size results. The overall board design process will be discussed including parts selection, circuit design, proper signal termination, layout placement and route planning, signal integrity design and verification, and power integrity results. The radiation mitigation techniques will also be detailed including configuration scrubbing options, Xilinx circuit mitigation and FPGA functional monitoring, and memory protection. Finally, this paper will describe how this system is being used to solve the extreme challenges of a robotic satellite servicing mission where typical space-rated processors are not sufficient enough to meet the intensive data processing requirements. The SpaceCube v2.0 is the main payload control computer and is required to control critical subsystems such as autonomous rendezvous and docking using a suite of vision sensors and object avoidance when controlling two robotic arms. For this application three SpaceCube processing systems are required, each with two processor cards.

The Earth Photosynthesis Imaging Constellation: Measuring Photosynthesis with a cubesat platform

In response to NASAs Earth Venture Instrument-2 call, we proposed the Earth Photosynthesis Imaging Constellation (EPIC) mission. With EPIC, we will, for the first time, be able to provide the scientific community with global, spatially, and temporally explicit estimates of Photosynthesis, also known as Gross Primary Production (GPP) directly from satellite observations. Understanding the significance of terrestrial GPP for the global carbon, water, and energy balance, as well as its spatiotemporal dynamics is one of the key goals of Earth system science. Our proposed method is based on first principles of plant physiology and radiative transfer theory and has been demonstrated by the science team members in theoretical and experimental research. We expect EPIC to fundamentally change and improve our understanding of global photosynthesis and provide entirely new avenues for modeling and predicting Earth system behavior globally.The EPIC mission consists of four, 3-axis stabilized 6U CubeSats flown in pairs to enable multi-angle measurements. The two pairs may be launched on the same launch vehicle or on separate vehicles as necessitated by availability and destination orbits. If launched on the same vehicle, the two pairs can be spaced out via differential drag separation within a matter of months. To lower overall spacecraft costs, the CubeSats leverage existing off the shelf technologies as much as possible. Each EPIC spacecraft host an Integrated Vegetation Interferometer Spectrometer (IVIS) instrument. The highly compact IVIS consists of two primary sensors with separate, co-aligned optics: a spatial-heterodyne-spectrometer (IVIS/SHS) and hyperspectral imager (IVIS/HSI). The IVIS/HSI was specifically designed to implement a multi-angle measurement technique to determine the photosynthetic rate of vegetation (hereafter Hall-Hilker technique); the IVIS/SHS is designed to narrowly peer into a Fraunhofer line at high spectral resolution to obtain solar induced chlorophyll fluorescence (hereafter referred to as Joiner-Frankenberg technique). This paper will provide a description of the EPIC mission and science goals, details of the EPIC team, details of the science techniques to be implemented, and demonstrate how the design of the proposed EPIC CubeSat spacecraft and integrated IVIS instrument enable the proposed science at a fraction of the cost of larger systems.