Space archaeology unlocking secrets of ancient planets - and their connection to Earth

Planetary unknowns from long, long ago could reshape understanding of our world's history

The polar ice cap on Mars. The image was taken by the UAE’s Hope probe and processed by graphic designer Jason Major. Photo: Emirates Mars Mission / Jason Major

Billions of dollars have been poured into exploring the far reaches of the solar system since exploration began more than six decades ago, with missions aimed at Mars, asteroids and icy moons to uncover their secrets.

Mars rovers such as the Perseverance, in a mission that cost about $2.4 billion, are scouring the Red Planet’s surface for evidence of ancient rivers and lakes, while spacecraft like Nasa’s $1.6 billion OSIRIS-REx and Japan’s $290 million Hayabusa2 have brought back samples from asteroids.

Researchers believe each mission provides a piece of a larger puzzle, shedding light on the processes that shaped the solar system and their connections to Earth’s history and climate.

Mars as a window into Earth’s past

Mars has been one of the most significant focus points in planetary science, offering a unique perspective on Earth’s early history. Unlike our own planet, which has been transformed by tectonic activity and weathering, Mars has preserved a geological record largely unchanged from billions of years ago.

Dr Dimitra Atri, an astrophysicist at New York University Abu Dhabi (NYUAD), told The National that studying ancient Martian environments can provide a window into Earth’s past.

"Mars shows evidence of ancient rivers and lakes, revealing past climates capable of sustaining liquid water," said Dr Atri, who is also group leader of the Mars Research Group at NYUAD's Centre for Astrophysics and Space Science. "The UAE’s Hope Probe and Nasa’s Maven mission help us study the atmospheric processes in great detail. By studying the surface features combined with atmospheric processes, we better understand planetary climate drivers, such as atmospheric loss and greenhouse gas dynamics."

But sending missions there is not enough to fully understand Mars's climate and geology. Analogous missions on Earth, in environments resembling Martian landscapes, are also crucial for testing instruments and interpreting Red Planet data.

"The UAE’s hyper-arid deserts, with their sedimentary structures, evaporite deposits and wind-driven erosion patterns closely resemble Martian landscapes," said Dr Atri. "These missions help us test instruments, refine exploration strategies and understand how water and climate shape planetary surfaces."

China’s Tianwen-1 mission has also joined the exploration of Mars, with its rover Zhurong that studied the planet’s surface and geology. Dr Gordon Osinski, principal investigator of the Canadian Lunar Rover Mission, told The National that all Mars rover missions have contributed to the understanding of the planet's geology.

"Perseverance is definitely one of the most exciting and important missions to date, as it is the first step in a series of missions to return samples back to Earth," Dr Osinski said, who is also a planetary geologist at the Western University in Ontario. "The site that it is exploring [the Jezero Crater] is also one of the oldest and most interesting sites visited so far and is helping us understand the first few hundred million years of Mars’ history.

"We think that Earth and Mars were very similar at this time, and so, by exploring Jezero Crater with the Perseverance rover, we’re also learning more about the early history of Earth, a record that is no longer preserved on our planet."

Impact craters: the solar system’s time capsules

Impact craters on celestial bodies also help scientists fill in the gaps of the solar system's history. These features, which are preserved on the Moon and Mars, act as time capsules that offer invaluable insights into planetary evolution. Unlike Earth, where geological activity has erased most craters, these celestial bodies retain billions of years of history in their landscapes.

"In recent years we have come to learn that the impact of asteroids and comets with the Earth have had a profound affect on the geological evolution of our planet," said Dr Osinski. "In addition to the better-known destructive effects of impact events, after they form, impact craters can provide protective niches for life and may even have been where life on Earth originated.

"Unfortunately, only a tiny percentage of the craters that have formed on Earth are preserved due to Earth being so geologically active. This is not the case on other planetary bodies, like the Moon and Mars, where there are literally tens of thousands of craters."

Nasa’s $504 million Lunar Reconnaissance Orbiter has mapped the Moon’s surface, revealing craters that are billions of years old, while China's Chang’e missions have collected samples from the lunar surface to study its composition.

Chang’e 5, for example, gathered and sent back 1.73kg of lunar soil, offering insights into the Moon’s volcanic history, and Chang'e 6 became the first mission to bring back samples from the dark side of the Moon. These efforts shed light on how asteroid impacts have influenced Earth’s geological history, including events such as the Chicxulub that led to the extinction of the dinosaurs.

Asteroids and comets: records of the early solar system

Asteroids and comets are remnants from the formation of the solar system, containing materials that have remained largely unchanged for billions of years. Missions targeting these bodies aim to uncover their role in shaping Earth’s environment and delivering key ingredients for life.

Nasa’s $1.16 billion OSIRIS-REx recently returned samples from the asteroid Bennu, which is rich in organic molecules and water-bearing minerals.

"Asteroids and comets, remnants of the solar system’s formation, contain pristine materials that likely delivered water and organics to Earth," said Dr Atri. "Analysing them helps reconstruct early Earth conditions and informs predictive climate models, including potential geoengineering solutions. Comparative planetology, supported by research, bridges Earth’s past and future climate systems."

Japan’s Hayabusa2, which brought back samples from the asteroid Ryugu, revealed similar findings, with organic compounds hinting at the building blocks of life. Meanwhile, Europe’s Rosetta mission studied comet 67P/Churyumov–Gerasimenko, providing detailed analysis of its composition and activity, deepening scientists' understanding of how comets might have seeded Earth with essential materials.

China is also contributing to this field with its planned Tianwen-2 mission, which will target a near-Earth asteroid to collect and return samples for study. Scientists hope the mission will reveal details about the asteroid's composition, including volatile elements such as hydrogen and carbon, which play a key role in shaping planetary atmospheres. Such findings could not only help researchers better understand the solar system's history but also provide practical data for defending Earth from further potential asteroid impacts.