Planetary Society study says small NASA missions cannot match larger missions’ output

The Planetary Society released its Science Mission Impact study, concluding that low-cost NASA science missions cannot match the scientific output of larger missions.

The research reviewed every NASA-led science spacecraft launched from 1980 through 2024 across all five science divisions, converting life-cycle costs to 2025 dollars. Life-cycle costs cover the full expense of developing, launching, and operating a mission. For every mission, the study collected peer-reviewed articles discussing the mission and its data, then tallied how frequently other scientists cited them. Researchers gathered the publication and citation figures through NASA’s SciX Digital Library, which gathers publication references across the agency’s main scientific fields.

Users can browse all 143 missions on the accompanying dashboard by cost, failure rate, and time to first result, with separate pages for each of NASA’s five science divisions. The complete methodology is documented. The full dataset can be downloaded. A peer-reviewed article with the full analysis is forthcoming.

Of missions below $150 million, 30% failed, while 8% of all more expensive missions failed. To equal the efficiency of bigger missions, surviving small missions would need roughly one-third higher output on average, yet they fall short. Surviving small missions would need to outproduce larger ones to match their efficiency, but they do not.

Missions priced from $150 million to $1 billion matched or outperformed cheaper and costlier projects in science per dollar across three of the four divisions with sufficient missions for comparison. Science per dollar measures how much research output a mission delivers for each dollar spent. The most productive mid-cost missions were usually proposed by independent scientists through an open NASA competition instead of being directed inside the agency.

Building large flagships takes years, yet many low-cost missions deliver no significant science. Those that do can take as long as mid-cost missions to get there. Cheaper missions therefore do not automatically mean faster science, even though flagships require lengthy construction periods. A flagship is a large, expensive science mission designed to achieve major discoveries.

NASA’s fiscal year 2026 and 2027 budget requests each proposed cutting the Science Mission Directorate by nearly 50%. The Science Mission Directorate oversees NASA’s science missions. More than 50 science missions are facing termination under these proposals. The Planetary Society describes the situation as historic budgetary threats to the agency’s science portfolio.

Mars Sample Return, missions to Venus, and the Geospace Dynamics Constellation have been canceled or delayed because of budgetary constraints. These events accompany strong criticism about cost growth and schedule delays. The agency is deciding which science efforts to support as budget pressure mounts.

NASA is shifting toward cheaper, tightly controlled projects aimed at returning scientific discoveries faster and for less money. Tightly controlled projects are managed directly by the agency rather than selected through open competition. The clearest example is the Commercial Lunar Payload Services program, launched in 2018, which purchases transportation for NASA instruments on privately built lunar landers.

The Commercial Lunar Payload Services program, started in 2018, buys rides for NASA instruments aboard commercially built lunar landers. Each of the four flown CLPS missions has generated fewer papers than equivalent NASA-led science missions counting from the beginning of operations.

Over the past two years, NASA has started internally directed science missions selected without competition, including SkyFall helicopters and Aeolus instruments headed to Mars and the PROMISE rover bound for the Moon. These directed missions contrast with competitive programs that have produced celebrated missions but have recently stalled. Competitive programs have produced missions such as New Horizons and Juno. Directed missions are chosen inside the agency instead of through an open call for proposals.

Discovery was meant to launch every two years, yet the span from Psyche’s 2023 launch to DAVINCI’s expected 2030 launch leaves a seven-year gap. New Frontiers, which produced New Horizons at Pluto and Juno at Jupiter, was supposed to hold competitions twice per decade but now faces at least a ten-year gap following Dragonfly’s 2019 selection.

An untested premise behind NASA’s choices is that smaller and cheaper missions can substitute for the science of larger ones at reduced cost. A premise is an assumption that underlies a decision. The Society argues that major multibillion-dollar choices need evidence that until now existed only in scattered budget documents and uneven publication archives. The premise has guided agency decisions without a comprehensive data foundation.

Nine years ago, the National Academies directed NASA to create an open database tracking mission costs and effects on science and society. Such a database would show the varying value of different mission types. It would also help NASA choose which ones to fund for transformative discoveries per dollar or faster science results.

Because NASA has not created this database, the Planetary Society is releasing its own version based on key National Academies recommendations. The Society compiled the data as a first step to track and compare science output across missions. The effort fills a gap left by the uncompleted National Academies directive.

The report does not call for ending small or large missions entirely, though top-down small missions have not historically delivered high-impact science faster. When the aim is rapid high-impact science, past top-down small missions have not delivered that result. The findings leave both mission sizes available to NASA planners.

Small missions still matter because they prepare people for space industry careers, demonstrate new technology, and some produce excellent science. Flagships remain valuable because they achieve discoveries previously viewed as impossible and support whole scientific communities over decades. Flagship missions sustain research communities across many years.

Flagships achieve discoveries previously considered impossible and support whole scientific communities for decades, while both ends of the mission spectrum rely on each other. Small missions, flagships, and all missions in between are interdependent according to the study’s conclusions. One end of the mission spectrum cannot replace the other.

A much-cited NEOWISE paper on near-Earth asteroid measurement shapes part of how the United States measures progress toward its congressional mandate to characterize impact threats. NEOWISE studies near-Earth asteroids. This example shows how mission-derived publications trace the development and application of technologies with broader societal use.

Compact, low-power cameras developed for spacecraft now underpin more than 7 billion sensors built annually in a $25 billion market. Publications across Earth Science, Planetary Science, Heliophysics, and Astrophysics missions trace the development and application of these digital cameras.

The report connects to current choices in NASA’s budget request and appropriations bills concerning which mission lines begin and which wait another year for competition. NASA is choosing among mission lines while competitive programs stall. Budget pressure mounts on the Science Mission Directorate as these decisions are made. The study arrives as the agency weighs which science efforts to fund.

The Planetary Society summarized the trend in a statement accompanying the study. “NASA is turning to cheaper and more tightly controlled projects in an effort to return scientific discoveries more quickly and at a lower cost,” the Planetary Society said.