Space Logistics: The Ultimate Logistics Enterprise Challenge
Evans, William A
On January 14, 2004 President Bush announced a new vision for space exploration, and outlined a return to the moon and the further exploration of Mars and beyond. This vision also includes returning the Space Shuttle to flight, retiring it after completion of the International Space Station and eventual transition of the International Space Station. The vision will encompass generations, multiple administrations, and will necessitate the development of new technologies to support the human and robotic exploration of our solar system and beyond. The logistics support of this exploration takes our thinking into new dimensions and redefines the logistics enterprise.
In this new environment of exploration some things are going to change. The days of big rockets and bigger investments may be gone. What you may see is multiple launches to low Earth orbit (LEO), assembly of larger vehicles, possible integration of cargo and fueling of these vehicles on orbit, and launch from orbit to the moon, Lagrange points or planetary destinations. In order to do this our launch infrastructure on Earth must be robust and reliable, and our technology must be capable of routinely and autonomously mating the components for on-orbit launches. We may need space tugs to assist in gathering up the components, maintaining fueling operations, capturing spent, reusable stages, repositioning satellite orbits, and other support tasks. There may be human and robotic cooperative efforts, fast and slow flights designed to converge at a single location, different propulsion systems, common interfaces and a myriad of technology improvements over time.
The logistics enterprise will be based in the logistics chain and developed using a logistics architecture that takes into account the future supportability of the chain. There must be simultaneous life cycle management of established infrastructure, while building extended infrastructure in an evolving architecture. The development of this infrastructure must be planned in spirals, taking the next spiral development into account as the former is developed.
The logistics chain will be iterative. Exploration involves at least three separate operating environments:
– Low Earth Orbit (LEO)
– Lagrangian Station-Keeping
– Extraplanetary Orbit
– Surface Lunar
– Surface Martian
– Surface (n)
Design must look at supportability in the most challenging environment, and the challenges will change as the exploration evolves. For this reason, Spiral Development based on the needed capability will be necessary. Similarly, an environment of Evolutionary Acquisition will provide for technology development and integration, informed life cycle management and improvement of the supportability over time. The architecture (Figure 1) for support will similarly evolve over time, and continuous modeling will be needed to determine the optimal mix of push and pull support.
The complexity of operations in general, and support operations in particular, will evolve as human presence extends beyond the Earth. In situ resources will become part of the supply chain, driving the need for distribution capabilities. The support resources needed to sustain the production of oxygen, hydrogen, water, food and other essential resources will grow as the production bases develop. Maintenance planning, packaging, material handling, drilling, digging, health management, and mobility will all drive the development of technologies to live and operate in variable gravity and extreme environments.
How do we establish this everevolving chain in an atmosphere of tight budgets and control? The cost of launch to LEO has been monitored very closely, and the thrust requirements to escape the Earth’s gravity are substantially more. Sustained acceleration is required to embark on longer voyages. However, remember that the vision includes both human and robotic efforts, coordinated as a single effort. A regular launch rate for cargo is essential, as is design for commonality, modularity, reconfigurability and maintainability. The reduction of the logistics footprint demands these things. Additionally, element level reuse to extend transportability, the use of Lagrange points to decrease staging costs and propulsion needs, and the launch of in situ resources from planetary surfaces to Lagrangian, lunar, or orbital staging points or waypoints will all contribute to the lowering of costs. Self-healing or self-aware systems, redundant systems, and the reduction in size of replaceable units will all contribute to lowering costs and improving operations on long voyages. In situ manufacturing may also provide further benefits.
One of our oldest explorations, Voyager, provides some insight into our growing challenge. Voyager I was launched over 27 years ago. In November 2003 it was 90 Astronomical Units (AU);1 that’s 8.4 billion miles from home. Today it’s nearing the termination shock, followed by the heliopause at the edge of our galaxy. Voyager I still communicates results from six of seven instruments, but the distance is so great that the Deep Space Network on Earth struggles to keep in contact. In two to three years Voyager I will be sent into a pre-programmed routine because of return data power requirements. Power on Voyager will not be an issue for a long time, since it operates on Radioisotope Thermal Generators. If our communications and tracking capabilities improve, we may be able to gather data from Voyager I again. Voyager II is also nearing the edge of the galaxy on a different orbital plane. It’s 7.1 billion miles away and still transmitting daily. Both have entered an area of the galaxy that is different from any other. Their speeds have increased in a region of low dynamic pressure and very weak solar wind. The 1970’s technology must continue to integrate with today’s technology so we can learn more about the journey ahead. Voyager has been an invaluable source of information, but it has no environmental control, life support or continuous communication. Future explorations must evolve to fill in the blanks.
Future exploration will also provide the stepping-stones for humans to follow. By using robotic precursor missions to carry critical supplies and infrastructure to common points along the way, we may be able to establish waypoints in the supply chain more affordably and with less risk. The Cassini probe is a good example of this piggyback approach. The Huygens probe, a European Space Agency probe designed to enter the Titan atmosphere, is integrated into Cassini’s design. As Cassini explores Saturn’s environs, it can drop Huygens, communicate with it and provide pictures of a new world with no interruption of its scientific investigation.
Where do logisticians find themselves in this challenging environment? The reduction of the logistics footprint, influencing design for supportability, and architecting the supply chain all come to mind as exploration systems are designed and developed. Technology development will also be critical. The infrastructure on Earth must be improved over time to allow for better access to orbit. The emerging commercial use of space and concurrent use of performance-based logistics in making products like in-space refueling, maintenance and cargo integration that successfully drive down the costs of human space flight will also be critical to success. Over time, for example, as the moon is developed, new challenges will be met by logisticians taking lessons learned from earlier applications.
1. One AU = the distance from the Earth to the sun, approximately 93 million miles
Copyright Society of Logistics Engineers Jan-Mar 2005
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