Resiliency, Reliability, and Sparing Approaches to Small Satellite Projects

Abstract

The design, manufacturing, testing, and sparing approaches that have been used in the space industry have been built up over the course of over 60 years of experience. That experience has come largely from two sources, namely, civil and military space agencies and the aerospace industry serving the operators of increasingly sophisticated space application systems primarily for telecommunications, remote sensing/Earth observation, and GNSS networks. These systems largely had in common that they were complex, big-budget programs that were expected to have a long life despite the harsh conditions of outer space and launch operations. This has led to a design and testing process based on the emphasis of high reliability. This included such concepts as in-orbit spares, providing for redundancy of components that represent a single point of failure and a very elaborate testing program to qualify all of the subsystems and fully integrated spacecraft against all types of possible flaws that could lead to failure. This approach has led to extensive quality assurance and lifetime testing for each spacecraft and key components. This testing program and the adding of redundancy for key components have extended the manufacturing time for spacecraft. It has also added significantly to the cost. This approach was believed to be necessary because there was no repair capability in space and of the high cost of launches, the expectation of quite long lifetime for spacecraft, plus the need to take this type of approach to obtain launch and operational insurance from underwriters.

The rise in recent years of the “NewSpace” industries, sometimes known as “Space 2.0,” has led to a revolution in how to design, manufacture, and operate spacecraft in Earth orbit. These new players in commercial space have questioned almost everything about commercial spacecraft design, manufacture, deployment, operations, and approach to reliability. They have asked basic questions about the long accepted “conventional approaches” as to how one should design, build, test, and launch spacecraft and even the orbits in which they should operate. Thus there are now a number of new ideas about the architecture of satellite systems and new concepts about how to design, manufacture, undertake quality and lifetime testing, launch, deploy, operate, and provide for operational spares in orbit. When there are hundreds or even thousands of operational spacecraft, the ratio of spares to operational satellites can be greatly reduced down to less than 10%.

The focus on this article is on how small satellites, and especially new small satellite constellations in LEO and MEO orbits, might be designed, built, tested, and deployed with new approaches to resiliency, reliability, and sparing. This approach started in a low-key way when much lower-cost satellites were using off-the-shelf components. This process began with the building of Amsat Oscar satellites and then the efforts of what is now known as Surrey Space Technology Limited. The next stage of thought came with the LEO systems designed by Iridium and Globalstar systems, but the most important breakthroughs came in the era of cubesats and the successful rise of small satellite projects such as those represented by Planet Labs, Spire, Skybox, and other small satellite projects born out of Silicon Valley-based entrepreneurs who have dared to think about satellite design and reliability in totally new ways.

This chapter examines these new ways of thinking and analyzes the pros and cons of these new ways of building and operating spacecraft and assesses how different approaches for different types of systems might still be appropriate. In short there may be more than one approach that can be used for different types of spacecraft that have different goals and aims.