The planet Mars has been of great interest to planetary scientists for as long as the discipline has existed. The planet has been extensively studied by telescope for centuries, and in recent decades by a series of robotic probes. These probes have taught us a great deal more about the planet than could be determined by remote sensing alone, but are only able to carry a limited amount of instrumentation, which cannot be changed, updated, or repaired once the probe has left Earth. To this end the planned Mars Sample Return program aims to bring samples from the red planet back to Earth, where they can be studied with a full range of laboratory techniques. However, this program is still in its very early stages, with no fixed target on Mars or spaceship design settled upon, and it is by no means settled that the mission will go ahead at all.
Until such time as samples are returned from Mars to Earth, the only way in which terrestrial scientists can gain direct access to material from Mars is by the examination of Martian meteorites, pieces of rock from the surface of the planet Mars which have been ejected into space, usually as a consequence of other large bodies impacting the planet. These can be confirmed as having come from Mars by a distinct mineralogy and the presence of isotope ratios detected on the planet by remote probes and not found elsewhere in the Solar System (this is not peculiar to Mars, each large body in the Solar System has its own unique isotope signature). To date, the Meteoritical Society has confirmed 402 meteorites as being of Martian origin.
The majority of Martian Meteorites have been discovered in desert environments, with 343 (85.3%) coming from the Saharan region (61 from Algeria, 1 from 'Algeria or Mali', 1 from 'Algeria or Mauritania', 4 from 'Algeria or Morocco', 1 from 'Algeria or Western Sahara', 1 from Egypt, 15 from Libya, 13 from Mali, 1 from 'Mali or Mauritania', 1 from 'Mali or Niger', 19 from Mauritania, 184 from Morocco, 1 from Niger, 1 from Nigeria, 1 from Tunisia, 15 from Western Sahara, and 23 from unknown 'Northwest African' countries).
Of the 343 known Martian Meteorites from the Sahara, 184 (53.4%) come from Morocco, with a further 15 (4.4%) from the Western Sahara, a disputed territory occupied by Morocco since 1976. This is not because Morocco is more prone to Martian Meteorite falls than other countries, but rather to a difference in the law. While most countries in the region ban the trade in, and export of, meteorites, Morocco allows a trade by licensed dealers, as long as all meteorites are registered with the Moroccan Geological Survey, and a sample of the material is deposited with them.
This has led to the development of a successful meteorite market in Morocco (which also has a similar trade in fossils). However, there is also a suspicion that many of the meteorites traded through Morocco might originate in other countries (although, given the willingness of the international meteorite community to trade in meteorites either with no known point of origin, or known to have been smuggled out of countries where their trade is forbidden, this scarcely seems worth the effort).
The unregulated way in which meteorites (including Martian Meteorites) are traded also means that many are held in private collections, rather than by public bodies where they can be accessed by scientists (some private collectors do allow scientists to examine their material, but this is of limited value unless it can be guaranteed that all scientists in the field have, and will continue to have, access).
The largest Martian Meteorite discovered to date is NWA 16788 (North West Africa 16788), with a mass of 24.665 kg. This is not just important because bigger meteorites are more impressive; the body from which this was derived is likely to have been significantly larger, which means that the event which caused it to be ejected from Mars must also have been particularly large, giving scientists a reasonable hope of connecting this meteorite to a specific geographic location on Mars.
NWA 16778 was (allegedly) discovered on 16 July 2023 near Kefkaf in Niger. It was confirmed as being a Martian Meteorite on the basis of samples sent to the Shanghai Astronomy Museum, with the Meteoritical Society being informed that the meteorite was being held in the collection of the Purple Mountain Observatory in China. However, in 2024 the meteorite appeared in a private collection in Arezzo, Italy. Two small samples of the meteorite were donated to the University of Firenze, and it was loaned to the Italian Space Agency during the 2024 European Researchers’ Night, on 27 September, an event intended to boost public engagement with science.
On 8 July 2025 NWA 16788 was placed on display at the auction house Sotherby's in New York, ahead of a planned auction on 16 July, at which it was predicted to fetch US$2-4 million; it was eventually sold to an anonymous buyer for US$4.3, which is likely to amount to a final cost to the buyer of about US$5.3 million once fees and taxes are taken into account.
This sale has prompted a protest by the Government of Niger, which pointed out that since 1997 Nigerien law has prohibited the unlicensed export of a range of heritage items including 'mineralogical specimens', and that the meteorite appeared to have been illegally trafficked out of the country. Sotherby's has denied any wrong-doing, noting that the legislation in question does not specifically mention meteorites.
Since the meteorite was placed on sale, a number of prominent international scientists have come forward to support the Nigerian Government's position, including palaeontologist's Steve Brusatte of the University of Edinburgh, who has raised concerns about the loss of valuable scientific specimens into the private vaults of oligarchs, and Paul Sereno of the University of Chicago, who believes that the term 'mineralogical specimens' clearly covers meteorites, and that the sale represents a clear breach of international law. Sereno, who has led expeditions to fossil sites in Niger for many years, and who founded the organisation Niger Heritage with the intention of building a museum in the country's capital, Niamey, further went on to point out that the removal of heritage items, cultural or natural, from a country without that country's consent is reflective of a colonial attitude which the world should have moved on from.
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