NASA's Earth Science Mission Portfolio, NASA OIG
"NASA's Earth science portfolio adequately reflects stakeholder input, ESD's approach to developing the Architecture Plan was reasonable, and the Plan includes missions that address all six of the Agency's Earth science focus areas. However, due primarily to budget issues and the availability and affordability of launch vehicles, NASA has not carried out the Architecture Plan as intended and is increasingly reliant on an aging Earth observation infrastructure to monitor the planet. Specifically, although the Architecture Plan envisioned launching 17 missions by 2020, including 11 by the end of 2016, as of September 2016 the Agency had launched only 7 missions, and it is unlikely the others will launch on the schedule outlined in the Plan. Consequently, as missions are delayed the Architecture Plan has become increasingly outdated and includes missions that may become a lower priority for the science community. While the delays have not prevented NASA from substantially meeting stakeholder needs for Earth observation data, more than half the Agency's 16 operating missions have surpassed their designed lifespan and are increasingly prone to failures that could result in critical data loss and gaps in long-term observation records."