On 22 March, a House Science Space Subcommittee hearing looked at options and impacts of extending U.S. support for the International Space Station (ISS) beyond 2024. At issue was whether resources required to maintain the space station platform would adversely affect the planning for a Mission to Mars and other NASA strategic priorities.
At the time Congress set the 2024 target date for phase-out of ISS operations, NASA estimated that sustaining ISS operations would cost $3-4 billion dollars annually through 2024, roughly half of NASA’s total human spaceflight budget, an estimate which the NASA Inspector General (IG) dubbed optimistic in a 2014 report. The IG report also highlighted several emerging hardware concerns, including degradation of the station’s solar power arrays.
In its 2014 report, Pathways to Exploration, the National Academies warned that “continuation of flat budgets for human spaceflight is insufficient for NASA to execute any pathway to Mars and limits human spaceflight to low earth orbit (LEO) until after the end of the ISS program.” A subsequent report by the Planetary Society, Humans Orbit Mars, concluded that a Mars exploration could be funded on a flat budget, although ISS transition in 2024 would free up resources to enhance the Mars mission.
At the same time, the ISS platform is being used by an increasing number of private sector stakeholders, raising the question whether commercial uses of the station could generate sufficient revenues by 2024 to cover the full cost of continued U.S. participation.
Further complicating the picture, geopolitical issues and the changing priorities of the U.S. partners in ISS are also adding complexity. The European Space Agency has shifted its focus from ISS support to collaboration on the Orion Crew Vehicle. China is also planning to launch its own space station in the same time frame as ISS would be decommissioned.
William Gerstenmaier, NASA’s Associate Administrator for Human Exploration and Operations, testified that “the ISS continues to be a healthy system that is operating well within prudent technical margins while consistently demonstrating outstanding steady-state performance that meets or exceeds prior engineering estimates” and the lifetime extension data that NASA and the ISS Partnership have reviewed to date indicates that extension to 2028 is technically feasible.”
He also cautioned that any decision-making about the future of ISS post 2024 may be premature in that “the ISS has now entered its intensive research and technology demonstration phase and is enabling a maturing commercial market ” While the future of ISS will require both careful consideration and advance planning, we have a few years yet to allow the program to continue to produce results, and for potential markets for commercial facilities in LEO ” which will take time to develop ” to evolve before committing to a specific course of action, in consultation with the ISS partners.”
Mary Lynne Dittmar, Executive Director of the Coalition for Deep Space Exploration, emphasized the importance of ISS’s ongoing research, its role in supporting commercial development of low Earth orbit, and its role as a “critical asset for development of systems needed for human deep space exploration.”
She concluded that “prior to making a decision about the ISS, additional time is needed to better define the nature of international collaboration in deep space, to seed economic development and broaden both the range of actors and the nature of research and technology development with the goal of stimulating economic demand in LEO, and to ensure that a human spaceflight program to cislunar space is well underway, avoiding any “gap” in human activities in space as the United States charts a course into the future of human space exploration.”
Eric Stallmer, president of the Commercial Spaceflight Federation, recommended that “the ISS should be sustained beyond 2024 to the extent that the space station is technically capable and safe to remain in orbit. In addition, rather than abruptly ending such a major program without a functional successor, any ISS transition plan should prepare an evolutionary path in order to avoid disrupting science and operations on orbit, and unnecessary economic upheaval to local economies.” According to Stallmer, the key to such a plan would be expanded use of public-private partnerships with American commercial space companies.
Robert J Ferl, Ph.D., director of the Interdisciplinary Center for Biotechnology Research at the University of Florida, addressed the question from the viewpoint of fundamental research conducted on the ISS. While endorsing the directions outlined by previous witnesses, he cautioned that whereas “the potential transition of LEO to the private sector is a compelling notion” the notion is complex and nuanced when considering the spectrum of microgravity science under discussion. Without careful consideration of this notion, we risk assurance that the nation’s exploration goals could be met.” Among the unknowns, Ferl noted the question of what crew time would be available for research in a commercialized ISS, and whether the advance of commercial spaceflight outside NASA sponsorship would provide other opportunities for research affecting the potential pace of microgravity science.