Scientists read a sealed 4,000-year-old letter without ever opening it

A mobile X-ray scanner built by an international team of physicists and Assyriologists has read the contents of 4,000-year-old cuneiform letters without breaking open the clay envelopes that have sealed them since antiquity. The device, called ENCI, was tested on nearly fifty encased tablets at the Museum of Anatolian Civilisations in Ankara, and the results were published May 8, 2026, in the journal npj Heritage Science.

For decades, the only way to read a letter sealed inside a clay envelope was to break the envelope open, which destroyed the tiny seal impressions rolled into its surface identifying who had sent it. Museums and archaeologists stopped doing that years ago, leaving hundreds of sealed letters and contracts unread in collections around the world.

Cécile Michel and Christian Schroer’s mobile scanner

The scanner was designed and built over roughly four years at the DESY research center in Hamburg, Germany, by a team led by Assyriologist Cécile Michel and X-ray physicist Christian G. Schroer, as described in the published study. Named ENCI, for Extracting Non-destructively Cuneiform Inscriptions, the device uses computed tomography, the same underlying technology as a hospital CT scanner, but built small enough to disassemble into eight components, most weighing about 50 kilograms, so it can be carried up narrow museum staircases and reassembled on-site in about two hours.

The team’s engineering target was a spatial resolution better than 50 micrometers, fine enough to distinguish individual scribes’ handwriting and detect the razor-thin air gap between a tablet and the envelope wrapped around it. In practice, the completed scans achieved roughly 65 micrometers, plus or minus 10, across the tablets recorded during the project. ENCI was first tested on contract tablets at the Louvre Museum in Paris in February 2024, then shipped to Ankara in September and October 2024, where it produced 64 tomograms of 48 tablets and other objects over a three-week mission.

A merchant’s wife and her sealed letter from Kanesh

Among the tablets scanned was an envelope excavated in the house of a merchant family named Šalim-Aššur in the lower town of Kanesh, dating to the first half of the 19th century BCE. Its outer surface carries eight rolled impressions of a cylinder seal belonging to a woman named Anna-anna, wife of the merchant Ennum-Aššur, along with a short inscription naming him as recipient and identifying the seal as hers.

Once ENCI’s scan revealed the hidden tablet inside, researchers were able to transliterate and translate the full letter for the first time since it was written roughly 4,000 years ago. Anna-anna reports to her traveling husband that she repeatedly confronted a man named Kudātum over silver he owed the household, that Kudātum insisted he would only repay Ennum-Aššur directly rather than his wife, and that she was growing impatient with her husband’s continued absence, telling him plainly to return home within ten days.

Michel’s broader research on Old Assyrian merchant households treats letters like Anna-anna’s as evidence that women left behind for months while husbands traveled for trade actively managed contested debts and business affairs rather than simply waiting for their return.

48 tablets and an unexpected barley seed

Not every tablet ENCI examined was a letter. One envelope, cataloged as Kt 93/k 144 and excavated in the house of a merchant named Ali-ahum during a 1993 dig at Kültepe, preserved a contract-cancellation notice instructing a creditor to destroy a loan record of five minas of silver once the debt was repaid. A tomographic slice through that same tablet also revealed an unexpected inclusion in the clay, identified by Kültepe excavation archaeobotanist Andrew Fairbairn as a hulled barley seed, recognizable from its flattened shape and characteristic chisel-like ends without ever touching the object itself.

Another envelope, Kt 94/k 602, held a surprise of a different kind: a second, smaller oval tablet tucked inside alongside the main one. Letter-writers at Kanesh occasionally ran out of room on a single tablet’s five writing surfaces and shaped a second, palm-sized extension to finish their message, a practice attested only in the Assyrian archives at that site. Once opened digitally, the extra tablet showed faint traces of the main tablet’s text pressed into its reverse in mirror image, which had made separating the two nearly impossible before a non-destructive scan existed.

Beyond individual letters, the tomographic data let the team compare how tablets and envelopes were built. Sections through the clay showed that envelopes were made from multiple folded layers rather than a single sheet, a construction detail invisible from the outside and undetectable without opening, and therefore destroying, the artifact. In at least one case, cataloged as Kt 91/k 287, the clay used for the tablet turned out to be completely different from the clay used for its envelope, suggesting the tablet was written first and only wrapped and sealed later, likely at a different location entirely.

Between half a million and a million cuneiform artifacts have been unearthed across Iraq, Syria, Iran and Türkiye, spanning roughly 3,400 BCE to 200 CE, and a portion of that total remains locked inside unopened envelopes for exactly the reason ENCI was built to solve. ENCI has since been tested on other sealed or layered objects, including a ninth-century Georgian manuscript cover made of glued-together older pages, according to a University of Hamburg research summary, suggesting the same non-destructive approach could extend well beyond cuneiform tablets.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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