Hosted Payload Packages as a Form of Small Satellite System

Abstract

In recent years there has been an enormous amount of attention that has been given to small satellites. Much of the focus of that publicity has related to very large constellations of small satellites such those proposed by OneWeb, SpaceX, Boeing, Thales Alenia, Planet, Spire, and others. Many of these constellations involve the launch of hundreds or even thousands of satellites. The rapid buildup of these small satellite constellations has to some extent overshadowed another important concept that has been effectively used in recent years as an alternative to free-flying small satellite projects.

This important alternative is known as a “hosted payload.” The concept is simply to place a smaller “payload” on board of a satellite platform. This allows a small and typically quite efficient payload to carry out its intended function not as a free-flying small satellite but as an adjunct to a larger space platform. In this type of configuration, a hosted payload derives its power, stabilization and orientation, and tracking, telemetry, and command services from its larger host platform. In some cases there might be only one hosted payload on another satellite. In other cases there might even be a number of hosted payloads all flying on a single satellite platform, rather than as free flyers.

Such a hosted payload arrangement can provide a number of advantages that can be derived from such an arrangement. These advantages can include (a) improved launch arrangements and associated improvement in launch costs, reduced regulatory requirements related to frequency coordination, registration of satellite launching notification to the United Nations, etc.; (b) economies of scale and cost reductions associated with the ability to share the power system, thermal controls, TT&C system, and stabilization, pointing, and orientation system of the larger spacecraft platform; (c) reduced operational cost associated with maintaining a small satellite in order or in some cases maintaining a large network of satellites in orbit (Note: this advantage includes not having to be concerned about avoidance of conjunctions with other satellites since this function is carried out by the larger satellite operator); and (d) not having to be concerned with the end-of-life disposal of the hosted payload(s), since these functions will also be carried out by the spacecraft operator that manages the larger satellite or in some cases an entire satellite constellation.

This does not mean that there are only positive benefits derived from carrying out a mission or even providing an ongoing space service by means of a hosted payload approach. If there is a failure (i.e., partial or total) of the host satellite or even a system failure that applies throughout an entire network of the host platform satellites, this is clearly a problem for the hosted payload. This failure of the host satellite or the constellation of host satellites would clearly be a very serious nature. There can be more complex types of problems beyond a host satellite not achieving orbit or total failure. There could be problems such as partial loss of a capability. This might be a problem with the solar arrays that require a cut back or even total loss of power supply to the hosted payload. In the case of a hosted payload mission, it is prudent to anticipate potential problems and seek to spell out in a contractual document an equitable solutions to possible problems before they occur.

The following article seeks to present examples of the various types of ways that hosted payload systems have been used to carry out missions that might have otherwise been undertaken by small satellites. It explains the types of organizations that operate in this area, including the Hosted Payload Alliance, that promotes this approach to governmental and military organizations that have been a frequent adopter of this approach over the past decade. It provides information about the possibility of use of hosted payloads on an entire constellation such is now the case with the Aireon hosted payloads that are currently operational on all 66 of the satellites in the Iridium Next small satellite constellation.