The National Space Society (NSS) is the preeminent citizen’s voice on space exploration, development, and settlement. The NSS Vision is “People living and working in thriving communities beyond the Earth, and the use of the vast resources of space for the dramatic betterment of humanity.”

The NSS artificial-gravity Orbital Space Settlement Design (OSSD) Project is a 5-year effort to produce a complete engineering design for the first rotating space settlement in cislunar space. The nominal population target is 1,000, with the expectation that populations from 100 to 10,000 will be considered as part of the work. The design is to be based on terms of reference adopted by NSS in March 2026. This Terms of Reference (TOR) document formally defines the mandate, scope, responsibilities, boundaries, and working methods of the project and are available at:

https://nss.org/wp-content/uploads/NSS-OSSDP-Terms-of-Reference-v12.pdf

The OSSD Complete Engineering Design specification as per the TOR:

• Provided as a series of question-focused Recommendations that contain all the technical information needed to construct a working system. However, this is not a “screw and bolt hole” level-design but is similar to the level of technical information provided in international technical standards. Such standards typically, as is the case with patents, contain drawings, flow charts, tables, charts, etc. that are needed to understand the implementation. The Recommendations will be capable of implemention by those skilled in the relevant art, with the phrase “those skilled in the art” having the same meaning as within the U.S. patent system.

• In some cases, Recommendations will suggest multiple options, i.e. varying sizes with sensitivity analysis and associated assumptions.

• In some cases, Recommendations do not contain a description of a buildable item, but a specific answer to a technical question such as “Where should the first orbital space settlement be constructed?

• Recommendations should be written at the standard of professional technical papers with sufficient references to allow any background material needed to be found by the reader/implementer who is skilled in the art.

• Covers all major subsystems of an orbital space settlement (structures, attitude and spin control, power, thermal, radiation protection, life support, habitability, logistics, operations, and safety) to conceptual/preliminary engineering design level, with quantified performance, margins, and mass/power budgets.

• Be “buildable” under an explicitly stated technology and industrial baseline without requiring speculative science or undefined technologies. Specifically, the technology used in the design must be:

  • Currently available, or

  • Agreed by working group participants to be under development, and achievable in operational practice within 5 years with 80% probability.

• Be “buildable” under a plausible set of economic and legal assumptions which are documented as part of the project and appear in Recommendations addressing economic and legal matters. These Recommendations must be internally consistent and grounded in existing legal frameworks and economic mechanisms.

• All source code and designs will be publicly available, but the project will include a patent pool for proprietary technology as is common practice for international standards

• No classified information or trade secrets will be used in the engineering design