Mary Anning 3

In October 2020, Curiosity drilled three holes near the base of Mount Sharp at Gale crater. The site was a clay-rich sandstone in a bed called the Knockfarrill Hill member, deposited about 3.5 billion years ago by lakes and the rivers that fed them. The team named the drill targets Mary Anning, Mary Anning 3, and Groken — the third for the cliffs of Shetland; the first two for the Lyme Regis fossil collector. A pinch of powder from Mary Anning 3 was tipped into a small sealed cup of tetramethylammonium hydroxide. It took five years to publish the result.¹

Tetramethylammonium hydroxide is a strong alkali that does two things at once. It hydrolyses large carbon molecules — the kinds that hide in clay because they are too heavy to have evaporated over geological time — and it methylates the broken pieces, sticking a small methyl group onto certain reactive handles so the fragment becomes light enough to enter a gas chromatograph. The technique is standard in earth-bound organic geochemistry. SAM, the instrument suite that carried it to Mars, has only two cups of TMAH onboard, reserved for the highest-value samples. Mary Anning 3 was the first to be opened — the first time the technique has run on another planet.

The chromatograph, with the mass spectrometer downstream, read off twenty-one carbon-containing molecules, of which seven had never been observed on Mars: benzothiophene, methyl benzoate, a couple of methylated benzenes, naphthalene and two of its near relatives, and one molecule the team and the press have been careful to describe as a nitrogen-bearing heterocycle — a ring of carbon atoms with a nitrogen interrupting it. That ring is the structural form of every nucleobase that builds DNA and RNA. The team does not call it a biosignature. The molecules can be made by ordinary chemistry without anything alive. They say only that nitrogen heterocycles have not been confirmed before in Martian rock. The molecules were always there. They were not visible until a cup of liquid put a label on them.

Mary Anning, the Lyme Regis fossil collector for whom the rock is named, was twelve years old when her brother Joseph found the skull of an Ichthyosaurus in the cliffs at Black Ven in 1811. She excavated the body of it over the following winter. Sir Everard Home wrote six papers describing the specimen for the Royal Society starting in 1814; none of them mention the Annings. In December 1823 she found the first complete skeleton of a Plesiosaurus; William Conybeare announced the find at the Geological Society of London on 20 February 1824 and named the genus. She was not in the room. She could not have been. Women were not admitted as Fellows of that society until 21 May 1919 — by coincidence, what would have been her hundred-and-twentieth birthday.² She was buried in 1847.

The naming of the rock is a sample-numbering scheme. NASA's mission planners pick fossilist names for fossiliferous formations. The parallel worth holding is smaller and more specific than restoration. Wet-chemistry derivatization is, mechanically, a way of putting a label on a molecule so that an instrument can see it. Fossil collection, in Anning's century, was, mechanically, a way of pulling a specimen out of a cliff so that a paper-writer could see it. The labour disappears into the result it makes possible. Both are kinds of preparation that the seeing-instrument cannot do without and does not record.

The mudstone of Mount Sharp was laid down about 3.5 billion years ago, which is roughly fifteen million times the span between Anning's birth and now. The molecules were waiting for an instrument that could not yet exist. The fossils, in their cliffs, were waiting too. So were the names of who had pulled them out. The waiting is the same.

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1. Williams et al., Diverse organic molecules on Mars revealed by the first SAM TMAH experiment, Nature Communications, 21 April 2026 (10.1038/s41467-026-70656-0). Lead institution: the University of Florida. SAM (Sample Analysis at Mars) is a NASA Goddard instrument suite. NASA JPL's accompanying release: "NASA's Curiosity Finds Organic Molecules Never Seen Before on Mars," 24 April 2026. The three drill targets — Mary Anning, Mary Anning 3, and Groken — appear in the famous October 2020 selfie at the Mary Anning location, sol 2,922 of Curiosity's mission. ↩

2. Anning was born 21 May 1799; she died 9 March 1847. The Geological Society of London was founded on 13 November 1807; the first female Fellows were elected on 21 May 1919, seventy-two years after her death. See the Society's online exhibition on women and geology. Everard Home's six Ichthyosaurus papers ran in Philosophical Transactions of the Royal Society from 1814 to 1819. Anning's Plesiosaurus dolichodeirus — found 10 December 1823 — was announced by William Conybeare at the GSL on 20 February 1824. In 1838, on Buckland's petition, the British government granted Anning a £25 annual pension. ↩