The Advent of the PnP Cube Satellite Craig J. Kief and Brian Zufelt COSMIAC 2350 Alamo Avenue SE, Suite 100 Albuquerque, NM 87106 Scott R. Cannon Utah State University Space Dynamics Laboratory Logan, UT 84341 James Lyke and Jesse K. Mee AFRL/RVSE Kirtland AFB, NM 87117 Abstract— In terms of time and budget, integration is a sig- nificant time-consuming component of spacecraft development. While many useful COTS spacecraft components are available, interfacing and controlling these components in an integrated satellite system remains a complex engineering task. The Stan- ford/Cal Poly CubeSat and Poly-Picosatellite Orbital Dispenser (PPOD) standards have begun to standardize small satellite mechanical systems and revolutionize the way small satellites are deployed. NASA has recognized this as evident by their Educational Launch of Nanosatellites (ELaNa) program which recently selected 17 CubeSats for the ELaNa-4 launch in 2012 (including one high school). To capitalize on this momentum, the Air Force Research Lab (AFRL) has organized and supported a team of commercial and academic laboratories to develop and test an over-arching Space Plug-and-play Architecture (SPA) set of standards to support the rapid integration of independently developed satellite modular systems. SPA represents not only an electrical inter-connection and communication scheme, but a complete model for a self-organizing and self-configuring system to support the rapid assembly of mission-specific small satellites. Rather than forcing existing modules to be re-developed to a common messaging standard, SPA utilizes an XTEDS (eXtended Transducer Electronic Data Sheet) model. Each satellite module contains an electronic document describing its interface, capa- bilities, messages, data formats, etc. By reading a components XTEDS, other systems can quickly integrate and utilize a new module. While designed to initially take advantage of nanosatel- lites, everything developed can easily scale to larger spacecraft, UAVs or other aerospace and defense systems. This paper discusses our experience in developing the CubeSat Trailblazer, a 1U SPA-only spacecraft – launching in 2012 as a testbed for SPA technology. The mechanisms of self-organization for independent modules as a cooperating communications system are discussed. The simplifications associated with software development of a Command and Data Handler (CDH) is also presented. 1. BACKGROUND:CUBES ATS , ELANA AND REVOLUTIONARY CHANGE Several programs are now creating revolutionary changes in the space industry. The first is the CubeSat model [1]. The CubeSat is a nanosatellite class structure defined in Units. A 1U stands for a satellite that is one unit in size (4” x 4” x 4”). A 2U doubles the length. The 3U spacecraft is the largest satellite that will fit in the Poly Picosatellite Orbital Deployer (PPoD) launcher. Currently, the PPoD is the accepted standard for CubeSat development. It was announced at the CubeSat Workshop in Logan, Utah in August, 2011 that there are currently 26 countries building CubeSats. CubeSats have allowed countries like Columbia and Spain that could never afford a space program to begin to design, build and launch a space mission. Although CubeSats are the tools, the real catalyst has been the NASA Educational Launch of Nanosatellites (ELaNa) program [2]. ELaNa has made it affordable for academic institutions to have their spacecraft placed into orbit. Before this program, few opportunities existed for CubeSat launch with average 978-1-4577-0557-1/12/$26.00 c 2012 IEEE. 1 IEEEAC Paper #1, Version 1, Updated 3/11/2011. launch cost of approximately 10,000 dollars a pound. ELaNa has changed everything. It is now possible for academia to easily get to space while at the same time building an entirely new generation of students excited about space activities. The Trailblazer spacecraft [3] described in this document is being launched as part of the ELaNa program. There has always been a struggle to determine if the CubeSat model is capable more complex missions than have previously been demonstrated. The ELaNa Program is opening the door again and changing the potential missions for CubeSats thus increasing the missions these spacecraft are capable of performing. The new ELaNa solicitation is allowing for submissions of 6U satellites [2]. These spacecraft will be 4” x 8” x 12”. The larger spacecraft are beginning to create opportunities for real missions such as imaging, communications and space weather. A 6U spacecraft has sufficient room for large enough optics to begin to do high resolution imaging of Earth from space. There are several serious issues that need to be addressed as this paradigm moves forward. The first is the level of complexity. A 1U CubeSat generally has a very limited mission and as such, the level of complexity of design was greatly reduced. This meant that the average developer could write all the required code to support the hardware in a few weeks. Most of the hardware has standard interface, connectors and software. As the size of the spacecraft grows, this paradigm begins to break down. There is not a linear curve when comparing time of completion of a software project to the number of lines of code written. As the complexity of the Command and Data Handling system increases, the time required to design, code, integrate, and test the system exponentially increases. The amount of time required to write the control system for a 3U spacecraft is not three times the amount of time required for a 1U. There are more modules and interface issues to be addressed. This significantly increases development time and costs for a larger Nanosatellite spacecraft. Secondly, to be truly responsive, there must be a way to easily reuse hardware from one system to another. Traditional spacecraft development has often failed here. Without a standard bus interface, there is often no easy way to move parts from one CubeSat (or larger spacecraft) to another. The way to truly advance small satellite development is to find a method to break the one-of-a-kind mentality in our current satellite build paradigm. One of the competing standards in this area is AFRLs open source SPA bus and the Satellite Data Model software architecture. [4]. Several spacecraft are currently being built to this standard including the Quadsat [5] and the Trailblazer [6] missions. The power of this methodology is that components from one satellite can easily be integrated into a different satellite in a truly PnP fashion. Parts and software can be developed with- out a specific mission in mind and then be automatically configured and used in a variety of satellite missions in a rapid fashion. This strategy significantly reduces the size and complexity of the Interface Control Document (ICD). The ICD for many spacecraft is where failure occurs. Often, this has been the reason for CubeSat success. The ability to utilize kits to assemble systems reduces the possibility of 1