The international space station (ISS) is the world’s largest international project. The huge investment made over the last two decades requires careful thought with regard to its ultimate disposition by its international partners in the post-2020 time period. The cumulative cost of designing, manufacturing, launching and deploying the ISS has been officially estimated to run to $140 billion. This project has been financed by 14 international partners — the United States, Canada, Japan, Russia and 10 member states of the European Space Agency (Belgium, Denmark, France, Germany, Italy, the Netherlands, Norway, Spain, Sweden and Switzerland).

These countries have joined to undertake this largest of all space-based projects. The space facility now represents an Earth-equivalent mass of 391,730 kilograms. This massive football-field-sized space station — the second-brightest object viewable in the night sky — represents 135 launches to low Earth orbit, including 37 space shuttle missions, 74 Russian launches and several European Automated Transfer Vehicle and Japanese H-2 Transfer Vehicle missions. The project has been in planning for over 20 years and it has taken 13 years — since November 1998 — to deploy all of the parts to low Earth orbit. The ISS now includes 388 cubic meters of habitable space, and its pressurized volume exceeds 916 cubic meters.

The ISS is currently being utilized by highly trained international crews to carry out a wide range of space-related scientific, engineering and medical experiments. It is now scheduled to sustain and support these experimental missions through 2020, when it is to be broken up and its parts returned to Earth via re-entry orbits. But to simply destroy this valuable space resource seems illogical and very bad fiscal policy when an investment that is likely less than 1 percent of the ISS deployment cost could redeploy the space station for an important new mission. In short, why bring it down when it could pay huge dividends by being moved up to the Moon? And if we could move the ISS to the Moon it could in theory — either in part or in whole — eventually go on to Mars using the same propulsion system.

The logic of extending the usable lifetime for this unique space resource beyond 2020 seems overwhelming — but is only true if one can identify a clear and vital mission after the ISS’s near-Earth experiments are complete. That quite obvious mission would be to add radiation shielding to this space habitat and then relocate it — in part or in whole — to a new location. This might be to geosynchronous orbit, where ion propulsion could be used to ferry astronauts back and forth to the Moon, or even more likely to a lunar orbit to serve as temporary space colony for astronauts until a permanent colony can be created on the Moon.

NASA’s record of researching and developing totally new technology is impressive, but its ability to carry out what might best be called “space operations” has not always been successful or cost effective. The project to reposition the ISS to lunar orbit might best be accomplished by one or more new international commercial entities modeled after Intelsat or Arianespace. This is not to say that NASA and other space agencies would have no role to play. Indeed, at the recent International Astronautical Federation Congress in Cape Town, South Africa, NASA officials began informal discussions with its ISS partners about whether components of the space station might be detached and sent to the Moon or Lagrange point L1 rather than de-orbiting the entire ISS and sending it back to Earth.

NASA certainly could play a key role in the development of a nuclear engine to attach to the ISS in order to allow the repositioning of the station or some of its components. This is not to say that such a project would not have major challenges. The greatest challenge might not turn out to be the propulsion system, but rather to accomplish the ISS repositioning in a safe way that avoids a major collision with orbital debris.

There is a longer-term perspective as well. If humans are to travel further afield, both within the solar system and one day beyond, there are many issues still to be addressed and researched in much greater depth. The issue of human travel to the farther reaches of the solar system and beyond needs to consider:

  • What levels of radiation can humans sustain for extended periods of time?
  • What are the longer term bio-psychological effects of humans living in space and in a low-gravity environment?
  • What propulsion systems can effectively power systems well away from the sun and perhaps into interstellar space?
  • Could a lunar-based observatory positioned above the Earth’s atmosphere and constructed with materials created from Moon-based material processing not only offer us new understanding of the distant universe but perhaps over time identify suitable targets for human space travel within a perimeter of five to seven light-years?
  • What are the challenges and technical requirements of creating a broadband communications, information technology, education and health care system to sustain a longer-term mission on the Moon, or ultimately a mission to the farthest reaches of the solar system and beyond?
  • Could the construction of a colony on the Moon using intensive robotic and human interactions better prepare us for extended human space travel to distant locations where humans might well be in suspended animation or as ovules to be grown to maturity and educated by robotic instruction in space?

In short, the redeployment and repurposing of the ISS could serve to help set the stage for many longer-term space exploration objectives that ultimately could support “star travel.”


Joseph N. Pelton is former dean of the International Space University and president of the International Space Safety Foundation (ISSF). This commentary is adapted from an ISSF and a Lifeboat Foundation study proposal.