A new report from the U.S. Government Accountability Office (GAO) recommends that NASA develop contingency plan for maintaining a U.S. presence on the International Space Station (ISS) in view of delays in the Agency’s Commercial Crew Programme.

The Commercial Crew Programme covers the development of a domestic transport capability, ending current U.S. reliance on Russia to transport astronauts to and from the ISS. Boeing and SpaceX are both developing crew transportation systems that meet NASA requirements and have contracts for initial missions to the ISS.

According to the report, the two contractors are facing aggressive development schedules that are increasingly under pressure. Both have determined that they will not be able to meet their original 2017 certification dates and both expect certification to be delayed until 2018. Schedule pressures, the GAO says, are amplified by NASA’s need to provide a viable crew transportation option to the ISS before its current contract with Russia’s space agency runs out in 2019.

The report warns that, if NASA needs to purchase additional seats from Russia, the contracting process typically takes three years. Without a viable contingency option for ensuring uninterrupted access to the ISS in the event of further Commercial Crew delays, NASA risks not being able to maximize the return on its multibillion dollar investment in the space station.

The GAO also notes that the programme is using a different model than every other manned spacecraft NASA has built, with NASA personnel less involved in the testing, launching, and operation of the crew transportation system. The level of visibility that the programme has required is taking more time than the programme or contractors anticipated. The report concludes that the programme office could face difficult choices about how to maintain the level of visibility it feels it needs without adding to schedule pressures.