A First Look at the Upcoming SISO Space Reference FOM

Spaceflight is difficult, dangerous and expensive; human spaceflight even more so. In order to mitigatesome of the danger and expense, professionals in the space domain have relied, and continue to rely, on computersimulation. Simulation is used at every level including concept, design, analysis, construction, testing, training andultimately flight. As space systems have grown more complex, new simulation technologies have been developed,adopted and applied. Distributed simulation is one of those technologies. Distributed simulation provides a basetechnology for segmenting these complex space systems into smaller, and usually simpler, component systems orsubsystems. This segmentation also supports the separation of responsibilities between participating organizations.This segmentation is particularly useful for complex space systems like the International Space Station (ISS), which iscomposed of many elements from many nations along with visiting vehicles from many nations. This is likely to be thecase for future human space exploration activities.Over the years, a number of distributed simulations have been built within the space domain. While many use the HighLevel Architecture (HLA) to provide the infrastructure for interoperability, HLA without a Federation Object Model(FOM) is insufficient by itself to insure interoperability. As a result, the Simulation Interoperability StandardsOrganization (SISO) is developing a Space Reference FOM. The Space Reference FOM Product Development Group iscomposed of members from several countries. They contribute experiences from projects within NASA, ESA and otherorganizations and represent government, academia and industry.The initial version of the Space Reference FOM is focusing on time and space and will provide the following: (i) aflexible positioning system using reference frames for arbitrary bodies in space, (ii) a naming convention for wellknownreference frames, (iii) definitions of common time scales, (iv) federation agreements for common types of timemanagement with focus on time stepped simulation, and (v) support for physical entities, such as space vehicles andastronauts. The Space Reference FOM is expected to make collaboration politically, contractually and technicallyeasier. It is also expected to make collaboration easier to manage and extend.