Saharan meteorite suggests Mars had water 4.1 billion years ago

A meteorite* found in 2022 in the Sahara Desert formed in the Martian crust at least 4.1 billion years ago, according to scientists. Its estimated age makes the reddish igneous* rock possibly the oldest of the 435 meteorites from Mars known on Earth.

The researchers said the composition of the meteorite, called Teghaza 001, is providing insight into the environment early in the history of Earth’s planetary neighbour, with fresh evidence of liquid water on the surface supporting the theory of microbial* life on primordial* Mars.

Planetary scientist Dr Yang Liu of NASA’s Jet Propulsion* Laboratory in California called the meteorite, “a witness to a time when Mars was likely warmer and wetter than it has been for most of its history.”

The chemistry of the meteorite, a type of coarse-grained rock called gabbro, shows that it experienced interactions with water when it was slowly cooling and crystallising in the Martian subsurface. It was part of the Martian crust, the planet’s outermost layer, but formed from magma* from greater depths in the planet’s mantle.

Mars is now cold, dry and desolate*, but extensive evidence indicates it had water flowing on its surface in the form of rivers, lakes and an ocean in the northern hemisphere billions of years ago.

Teghaza 001 was discovered in eight pieces, with the largest chunk about the size of a fist, in the desert roughly 21 miles (34 km) from the Malian village of Bir Chali. Its main minerals are feldspar* and pyroxene*, and it contains zircon crystals containing the element uranium. The researchers determined its age using a technique based on the decay of uranium into lead over time.

“Martian meteorites are our only samples from Mars, forming our basis for understanding the formation and differentiation of early Mars and allowing us to evaluate in laboratories whether ancient Mars could have supported habitable conditions,” said Dr Liu, lead author of a study on the meteorite published in the journal Science.

“The detailed information we can extract from these meteorite samples complements and validates our exploration of Mars using satellites, landers and rovers,” she said.

This information provides clues about how the evolution of Mars diverged from Earth’s when they were in their infancy and life was beginning to take hold on our planet, Dr Liu said. Earth, Mars and the solar system’s other planets formed roughly 4.5 billion years ago.

Only three Martian meteorites, including Teghaza 001, date to the planet’s early history. One of them, discovered in Antarctica in 1984, was initially assessed as being about 4.5 billion years old but more recently was determined to have a similar age to Teghaza 001. Teghaza 001 likely is the older of the two, according to the new study.

WATER WAS PERCOLATING
Isotopes*, or forms, of the elements oxygen and hydrogen present in the meteorite show that water was percolating* down into the planet’s deeper crust, as occurs on Earth, and mixing with molten rock from the mantle.

“Multiple lines of evidence in Teghaza 001 suggest Mars’ surface had water at more than 4.1 billion years ago. This is reflected by hydrogen isotopes in phosphate and oxygen isotopes in minerals and bulk samples,” Dr Liu said.

Water is considered a key ingredient for life.

“The findings lend support to the idea that early Mars had the necessary ingredients and conditions to harbour life, but do not directly answer the question of whether there was life on Mars,” said planetary scientist and study co-author Dr Lee Saper of NASA’s Ames Research Center and the BAER Institute in California.

“The rock is a snapshot in time that shows how a wetter early Mars with a thick atmosphere could have supported habitable* conditions but that these conditions were waning* rapidly over the first billion years or so of Mars’ existence, trending towards its currently dry and inhospitable environment,” Dr Saper said.

Teghaza 001’s chemistry shows it is distinct from the other known Martian meteorites. It may have originated in the southern highlands, possibly from near Hellas Basin, one of the largest Martian impact craters, Dr Liu said.

The meteorite has a dramatic backstory.

“It was blasted by an impact from the surface of Mars and was flying through space until its path crossed that of Earth. It then entered the atmosphere as a meteor and survived as a meteorite by landing in the Sahara,” Dr Liu said. “We do not know when the sample landed on Earth.”

Minor edits have been made to this story for Kids News. Reuters reporting by Will Dunham, editing by Rosalba O’Brien.

POLL

GLOSSARY

• meteorite: a piece of rock or other matter from space that has landed on Earth
• igneous: refers to rocks formed from magma, or very hot liquid rock that has cooled
• microbial: relating to microbes, which are very small living things
• propulsion: a force that pushes something forward
• magma: hot liquid rock found just below the surface of the earth
• desolate: empty, lifeless
• feldspar: a common type of mineral found especially in igneous rocks such as granite
• pyroxene: any of a group of silicate minerals having the general formula ABSi2O6, where A is usually calcium, sodium, magnesium, or iron, and B is usually magnesium, iron, chromium, manganese, or aluminium
• isotopes: one of two or more types of atoms of a chemical element with the same number of protons but with different numbers of neutrons
• percolating: when a liquid percolates, it moves slowly through another substance
• habitable: providing conditions that are good enough to live in or on
• waning: to become weaker in strength or influence

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QUICK QUIZ

1. How many Martian meteorites are known to have landed on Earth?
2. What has the Saharan meteorite been called?
3. What are its two main minerals?
4. What suggests that water was percolating down into Mars’ deeper crust?
5. What was the water mixing with once it got there?

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CLASSROOM ACTIVITIES
1. Then and now
Create a side-by-side illustration comparing what Mars may have looked like 4.1 billion years ago with what it looks like today.

Write a paragraph to accompany each illustration, describing what scientists believe Mars was like in the past and explaining how the planet’s environment has changed over billions of years. Include details about its atmosphere, temperature and the presence (or absence) of liquid water.

Time: allow 20 minutes to complete this activity
Curriculum Links: English, Science

2. Extension
Some people are fascinated by the possibility that life may have once existed on Mars, while others might wonder, Why does it matter?

Which point of view do you agree with? Write a persuasive text explaining your thoughts about the possibility of life on Mars and whether you believe scientists should continue researching this topic.

Use reasons, examples and persuasive language to convince your reader to agree with your point of view.

Time: allow 40 minutes to complete this activity
Curriculum Links: English, Science

VCOP ACTIVITY
Wow word recycle
There are plenty of wow words (ambitious pieces of vocabulary) being used in the article. Some are in the glossary, but there might be extra ones from the article that you think are exceptional as well.

Identify all the words in the article that you think are not common words, and particularly good choices for the writer to have chosen.

Select three words you have highlighted to recycle into your own sentences.

If any of the words you identified are not in the glossary, write up your own glossary for them.

Extension
Find a bland sentence from the article to up-level. Can you add more detail and description? Can you replace any base words with more specific synonyms?

Down-level for a younger audience. Find a sentence in the article that is high level. Now rewrite it for a younger audience so they can understand the words without using the glossary.