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From ADS to SciX

How a service built for astronomers grew to serve the Earth and space sciences

SciX grew out of the Astrophysics Data System, a NASA-funded service. ADS has served astronomers since the early 1990s and is credited with raising the research efficiency of the field by at least six percent, which is roughly the entire annual astronomy output of a G7 country.

  1. 1988

    Proof of concept

    A prototype containing forty papers was built at the CfA, putting into practice an idea discussed at a conference in Garching the year before.

  2. 1993

    Moved online

    ADS joined with SIMBAD, the astronomical object database, in the summer of 1993, and moved onto the World Wide Web in early 1994.

  3. 2001

  4. 2002

  5. 2011

    A modern stack

    ADS begins to experiment with a more modern technical stack, including a new user interface, a more flexible search engine, a microservice-based API, and a cloud platform.

  6. 2019

    ADS Classic retires

    After more than twenty-five years in service, the original interface is switched off and its successor becomes the only one.

  7. 2021

    Expanding beyond astrophysics

    At NASA’s request, ADS expanded to include heliophysics and planetary science, with the same depth of coverage as astrophysics.

  8. 2023

    Expanding into Earth science

    Following the successful expansion into heliophysics and planetary science, NASA asked ADS to expand into Earth science, bringing its coverage to all of NASA’s Science Mission Directorate disciplines. The Earth science collection launched at the AGU Fall Meeting in San Francisco.

  9. 2025

    SciX launches

    SciX officially launched in September, with existing ADS accounts, libraries, and alerts carried over to the new service.

  10. 2026

    ADS moves to SciX

    On 16 November, the ADS interface was redirected to the astrophysics view of SciX, completing the transition to the new service.

Growing our collections

SciX has grown from a small collection of astronomy abstracts into a multidisciplinary literature database spanning the Earth and space sciences and related fields. Today, it contains more than 37 million records—and continues to grow.

Records added to the collection each year, by discipline From 1995 to 2022 the collection takes in between fifty thousand and a million records a year. In 2023 that rises to 2.4 million, in 2024 to 5.5 million, and in 2025 and 2026 to about 7.5 million. Earth science accounts for most of the increase. 0M 2M 4M 6M 8M 1995 2000 2005 2010 2015 2020 2025 2026 Earth science 5M 2.5M 0 1995 2026 Physics 2.5M 1.2M 0 1995 2026 General science 2M 1M 0 1995 2026 Astronomy 100k 50k 0 1995 2026 Planetary 150k 75k 0 1995 2026 Heliophysics 60k 30k 0 1995 2026

Each subject on its own scale, so the smaller ones can be seen. Note the different y axes: compare the shapes, not the heights.

  • Earth science
  • Physics
  • General science
  • Astronomy
  • Planetary
  • Heliophysics
  • Earth science that is also physics
Records are counted by the year they joined the collection, not the year they were published. Hatching marks papers that are both Earth science and physics.

From ADS to SciX

SciX builds on more than thirty years of ADS: its collections, its connections to data and archives, and the tools researchers have come to rely on. As the service has expanded into new disciplines, preserving that continuity has been a priority. Existing ADS accounts, libraries, and alerts moved with users to SciX.

SciX remains free to use and open to build on. Our code, models and datasets, and much of the infrastructure behind the service are openly available, and our records follow the FAIR principles.

SciX is also still built and maintained by a team of people. If you find a problem or have a question, get in touch.