NASA plans to establish a long-term human presence on the moon by 2020, enabling settlement on an outpost to be built at the rim of the Shackleton crater near the lunar South Pole by 2024. The Vision for Space Exploration sets out other ambitious goals that involve both strategic and tactical objectives in addition to this one, including returning the Space Shuttle to flight and completing 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," noted Logistics Spectrum one year after the announcement.

Each of these goals has profound logistics implications, support for which redefines what we think of logistics and the supply chain.

For NASA's plan to be successful, a reliable stream of materials — fuel, food, spare parts, exploration equipment and, of course, oxygen — would have to make its way between Earth and the moon as dependably as any current Earth-based transportation-and-logistics system; probably more so. One missed shipment could have devastating consequences when you cannot easily replenish essential supplies.

Enter space logistics and the interplanetary supply chain.

According to the American Institute of Aeronautics and Astronautics, the abridged definition of space logistics might be "the science of planning and carrying out the movement of humans and material to, from and within space combined with the ability to maintain human and robotics operations within space." It is a specialty area dealing with supply chain management of human and robotic space missions for scientific and exploration purposes, says the Massachusetts Institute of Technology's Strategic Engineering Research Group.

"Increasingly, there is a realization that crewed space missions such as the International Space Station or the buildup of a lunar outpost should not be treated as isolated missions, but rather as an integrated supply chain," according to MIT's Olivier L. de Weck, associate professor of aeronautics and astronautics and engineering systems.

A well-designed interplanetary supply chain would operate on much the same principles as the typical supply chain that involves the flow of goods and materials between manufacturing facilities, distribution centers and stores — only with some slightly more complicated factors, according to de Weck.

Transportation, for one, would be a bit more elaborate. As opposed to a few days or weeks one might expect in today's supply chain process, delays in this interplanetary supply chain could be as much as six to nine months in the case of Mars.

Conceptual drawing of a lunar rover being unloaded from a cargo spacecraft. Credit: NASA

The successful completion of space shuttle Discovery's STS-114 mission to the International Space Station in summer 2005 demonstrated more cargo capacity (30 tons) and more passenger capacity (two crew, five passengers) than any other system flying at that time.

According to Aerospace America:

While the shuttle was grounded, logistics for the space station were supported by flights of Russian Soyuz-TMA spacecraft for crew transfer and escape, and by Progress-M spacecraft for supply transfer and for solid waste disposal.

Nonetheless, shipping capacities remain, for all intents and purposes, limited. Combine shipping capacities with delayed transport, and mission planners will be faced with some difficult decisions regarding trade-offs in supply and demand. Coordinating deliveries between bases on Earth, the moon and even Mars will be vital to future missions.

"Until now, planning has been largely ad-hoc, but it can't stay that way. If a manned colony doesn't get a shipment it could just disappear," Martin Barstow, a space expert at the University of Leicester, UK, recently told New Scientist.

Because such ambitious ideas will require drastic changes to the ways missions are planned, researchers at MIT's Space Logistics Project have created a software tool for modeling interplanetary supply chains. MIT's David Simchi-Levi, professor of engineering systems and civil and environmental engineering, along with de Weck created a software tool for modeling interplanetary supply chains.

SpaceNet works in a similar way to systems used by international courier firms to work out how to coordinate deliveries. It bases calculations on the needs of different bases, the capabilities of different vehicles, and changes in the relative position of bases and the gravitational pull of planets.

Its creators told New Scientist that SpaceNet can juggle supplies "to bases on the surface of planets, in orbit around them and at Lagrange points — where the gravity between different bodies cancels out."

According to MIT news office correspondent Deborah Halber:

The system is based on a network of nodes on planetary surfaces, in stable orbits around the Earth, the moon or Mars, or at well-defined points in space where the gravitational force between the two bodies (in this case, the Earth and the moon) cancel each other out. These nodes act as a source, point of consumption or transfer point for space exploration logistics.

Apollo 11 scenario visualization using SpaceNet. The latest version, SpaceNet 1.3, was released last month.

A reliable supply chain will "improve exploration capability and the quality of scientific results from the missions while minimizing transportation costs and reducing risks" to crew members, de Weck has said.

The future may hold 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.

While the moon base is thought of in terms of scientific challenges, noted Barstow, "working out how to keep it operating might be the bigger issue."

Resources

Engineers create SpaceNet — the supply chain
by Deborah Halber
MIT Tech Talk (via MIT News Office, March 19, 2007), March 21, 2007

Logistics program tests interplanetary supply chain
by Tom Simonite
New Scientist, March, 23, 2007

Space Logistics: The Ultimate Logistics Enterprise Challenge
by William A. Evans
Logistics Spectrum, January-March 2005

Logistics Lessons Learned in NASA Space Flight
by W. Evans W., O. de Weck, D. Laufer, S. Shull
MIT Space Logistics Project, May 2006

Interplanetary Space Logistics
MIT Strategic Engineering Research Group

President Bush Announces New Vision for Space Exploration Program
White House, House of the Press Secretary, Jan. 14, 2004

American Institute of Aeronautics and Astronautics

Photo via NASA