After more than 33 years, NASA’s Astrophysics Data System will close its virtual doors in November 2026 and be replaced by its much-expanded successor, Science Explorer. While the core functionality and astrophysics database will remain the same, SciX will extend its relevance to a broader range of scientists.
There was a time, before the Internet, when, to read the latest research in your field, you had to go to a library, locate the shelves bearing reams of leather-bound tomes (they were usually at the back, or in the basement), find the volume you required, and scan through pages of tables of contents until you found the paper you wanted. To preserve the relevant information, you might take notes — on paper! — or, for the fortunate, make a photocopy of the most useful content, such as tables or graphs, and retreat to your office after re-shelving the volume in the approximate location you found it. It was a time-consuming and sometimes frustrating experience. The arrival of computer networking and, later, the Internet, led scientific journals to migrate from the printed page to the computer screen, making research available at our fingertips. It is probably a substantial understatement to say that this breakthrough in availability of scientific research and data has considerably changed the way we do science.
The NASA Astrophysics Data System (ADS) was there at the start of this revolution in accessibility, serving up abstracts, initially, and a year or so later, full texts of papers — essentially providing an indexing service for the burgeoning wealth of astronomical information. ADS existed before the Internet as a 160,000-paper database of abstracts on a custom-built network in the USA, and from the inception of the World Wide Web in 1994, it became one of the most utilized resources for research in the world. Through various incarnations (Classic, Labs, Bumblebee), it has persisted for more than 30 years. The 16 November handover to ADS’s successor, SciX, will mark the end of an era for astronomy and a new beginning for interdisciplinary science.
As its name would suggest, ADS started as a service to provide links between papers and data on astronomical objects, through a partnership with the Centre de Données Astronomiques (CDS) in Strasbourg (données meaning ‘data’ in French). It was developed concurrently with databases like the High Energy Astrophysics Science Archive Research Center archive (HEASARC; 1990), the NASA/IPAC Extragalactic Database (NED; 1990), INSPIRE-High Energy Physics library (formerly SPIRES; 1969) and the arXiv (1991), in a wave of digitization and a growing demand for access to siloed institutional data. Through sustained funding from NASA and development from a dedicated team, over time ADS has shifted away from its initial data-centricity to quickly become an essential bibliographic resource for astronomers, with most visiting its website on a daily or weekly basis. While astrophysics has always been the focus of ADS, NASA has long recognized the utility of the platform, recommending similar resources be developed by the US National Science Foundation and Department of Energy in 2007 and encouraging the expansion of ADS further into heliophysics and planetary science in 2021. Shortly after that, NASA approved its expansion into Earth science and the biological and physical sciences, so that all the disciplines included in its Science Mission Directorate were covered. In April 2023 it was announced that this comprehensive database would be known as Science Explorer, or SciX for short.
ADS has died before. The initial manifestation, so-called ‘ADS Classic’, was laid to rest in 2019 after many years of service, which caused a great agitation amongst astronomers at the time. Such was the affinity of the community for ADS Classic that its dated search interface (consisting of individual search boxes for author, title, astronomical object, and so on) had to be preserved in its progeny, ADS Bumblebee, despite the introduction of a more modern, multifunctional search box. The more versatile capabilities and stability of Bumblebee gradually worked to overcome the community’s early misgivings.
In a Comment in this issue, the NASA ADS team explain what to expect from the new SciX; the key takeaway being that although the look of the interface will change somewhat, the underlying functionality and interactivity will not. Visitors will be able to select ‘Astrophysics’ as the primary domain and continue to use the new system as they did ADS, even via the decades-old ‘Classic’ form. Researchers whose work spans multiple fields — astrobiologists, for example — will be able to experience the joy of using ADS with substantially expanded search results, covering their entire discipline. And as has been the case in recent versions of ADS, the database will also cover data repositories that are mentioned in papers (such as those on Zenodo, GitHub or Figshare) and software.
As astronomers, we have been very privileged to have had NASA ADS serving our community for the past third of a century. As scientists, we will continue to enjoy the fortune of having a carefully curated, highly functional and comprehensive bibliographic database — SciX — at our disposal for as long as NASA funding persists. We should not take this blessing for granted. Imagine how long it would take to search 36.5 million scholarly articles (SciX’s current capacity) by hand, looking for all instances of ‘voorwerp’ (and how much library dust we would inhale). SciX finds 240 full-text instances, including 9 in the Earth sciences, one of which appears on page 447 of an article in Conservation Biology, a journal that is probably not on many astronomers’ reading lists. Thank you, NASA ADS team, for your service towards research efficiency and accessibility. The astronomy community owes you a debt of gratitude.