MARS was once crisscrossed with rivers twice as wide as any on Earth – and some were filled with water “recently”.
Satellite images of the red planet show that water flowed on its surface for far longer than was previously believed.
A preserved ancient river channel on Mars, taken by an orbiting satellite, with colour overlaid to show different elevations (blue is low, yellow is high)[/caption]
In total, space boffins looked at more than 200 long-dead riverbeds on the Martian surface.
Their findings suggest that the planet’s rivers flowed with water as recently as a billion years ago – at least a billion years later than previous estimates.
This shakes up our understanding of Mars’ history, and makes life tricky for scientists hoping to map the ancient Martian climate.
“It’s already hard to explain rivers or lakes based on the information we have,” said scientist Dr Edwin Kite, from the University of Chicago.
The research shakes up our understanding of Mars’ ancient history[/caption]
“This makes a difficult problem even more difficult.”
Scientists have long known of the ancient riverbeds that line the surface of Mars, but how it had water at its surface has long been a mystery.
The planet has had a very think atmosphere throughout its history, and only received a third of the sunlight of present-day Earth, which shouldn’t be enough heat to hold liquid water.
To understand how Martian rivers even existed, scientists analysed satellite snaps of more than 200 ancient Martian riverbeds spanning over a billion years.
They then worked out the amount of water running through them using multiple methods, including an analysis of the size of the river channels.
How long does it take to get to Mars?
It's not that short of a trip…
- There’s an immense distance between Earth and Mars, which means any trip to the red planet will take a very long time
- It’s also made more complicated by the fact that the distance is constantly changing as the two planets rotate around the sun
- The closest that the Earth and Mars would ever be is a distance of 33.9million miles – that’s 9,800 times the distance between London and New York
- That’s really rare though: the more useful distance is the average, which is 140million miles
- Scientists on Earth have already launched a whole bunch of spacecraft to (or near) Mars, so we have a rough idea of how long it takes with current technology
- Historically, the trip has taken anywhere from 128 to 333 days – admittedly a huge length of time for humans to be on board a cramped spacecraft.
Between 3.6 and 1billion years ago, and likely after 1 billion years ago, there was intense runoff in these channels, scientists found.
In total, three to 20 kilograms of water flowed through per meter squared each day, making the rivers bigger than anything on Earth.
Scientists previously thought that the Martian atmosphere thinned out about 4billion years ago, triggering a gradual drying out of the planet.
The new study suggests this potentially happened billions of years later than these estimates.
It’s also possible the climate had a sort of “on/off” switch, which tipped back and forth between dry and wet cycles, Dr Kite speculated.
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Mars had ‘raging rivers’ twice as wide as any on Earth – as scientists explore more than 200 ancient Martian riverbeds ‘recently filled with water’