Staging in Low Earth Orbit
Because the number of launches which are required to deliver the equipment for just one satellite is so high, some assembly of the satellite will have to take place in space. Each launch rocket will deliver its payload into low earth orbit, where an assembly crew of both humans and robots will check that the equipment has arrived intact to the assembly site. Once several payloads have been delivered to the assembly site, the modular components will be connected, the operation of the SSP satellite will be tested, and finally the satellite will be sent into GEO (Figure 1).
Figure 1. Process Flow for Satellite Assembly
As is evident from the process flow diagram, several of these steps can occur concurrently. This parallel processing will make the most efficient use of assembly time and space resources.
Use of Existing Space Infrastructure
The International Space Station (ISS) is a third generation space station, featuring a modular design which allows the mission of the station to be changed over time. Crucially, modules can be added to the existing LEO structure, which is why the ISS (Figure 2) will be the assembly site of the first SSP satellite. An ISS module will be built with all of the tools and supplies necessary to assemble the first SSP satellite at that location.
Figure 2. The International Space Station
Currently the ISS can accommodate 7 astronauts, and the station is rarely full. Using the ISS for the assembly of the first satellite provides a relatively low-risk and low-cost method for testing the technology and implementation of the SSP design before ramping up production and building full-scale assembly sites.
Dedicated Assembly and Service Stations
The ISS would be able to handle the assembly of the prototype SSP satellite, and perhaps all of the Phase 1 satellites, in order to get the system functioning and to prove its viability. However, the only way to achieve the desired scale of operation is to construct additional assembly stations in LEO, thereby increasing the speed at which SSP satellites can come online.
Four dedicated LEO facilities are proposed, launched serially until the cost of launch is reduced enough to construct the stations in parallel. Once operational, each assembly station would be able to handle up to four SSP satellites concurrently. In addition to the initial SSP satellite assembly and testing, these stations would be responsible for any maintenance and service that aging SSP satellites would require, such as replacement of derated solar arrays or additional technological upgrades. These four stations would be placed near the orbit of the ISS (Figure 3) and at roughly equal distances from each other so that availability of launch windows would be optimized.
Figure 3. Orbit of the ISS
References
http://www.nasa.gov/mission_pages/station/main/onthestation/facts_and_figures.html
http://www.nasa.gov/mission_pages/station/multimedia/exp22_130undock.html
http://www.spaceprojects.com/iss/
http://www.scientificamerican.com/blog/post.cfm?id=international-space-station-still-u-2009-07-13
http://www.challenger.org/programs/iss/iss.cfm
http://historical.whatitcosts.com/facts-space-station-pg2.htm
