David Bowie might have asked whether there was life on Mars, but scientists now think that life may have started on a very different red world.
Experts in France and the US say a snowman-shaped space rock called Arrokoth, in the outskirts of our solar system beyond Pluto, is covered in sugars.
These include glucose and ribose – sugars that are ‘fundamental building blocks’ of RNA, the molecule found in cells of humans and most of Earth’s lifeforms.
At 4 billion miles away from the sun, Arrokoth is ‘too cold to support life as we know it’, NASA says.
But the new findings suggest smaller comets could have transported sugar molecules required for the origin of life from Arrokoth to early Earth, about 4.5 billion years ago.
Arrokoth is a bizarre ‘snowman-shaped’ red rock in our solar system, around 4 billion miles away from the sun. Pictured, Arrokoth in a 2019 snap by NASA’s New Horizons spacecraft
Researchers say Arrokoth is rich in glucose and ribose, which are fundamental building block of RNA (a nucleic acid present in all living cells)
The team of experts, led by Dr Cornelia Meinert of CNRS-University Côte d’Azur in France, think methanol ices are transformed into sugars on Arrokoth by cosmic rays, giving it its red colour.
Arrokoth is not a planet but a ‘planetesimal’, meaning it is a very early remnant of the solar system left over from the formation of the planets.
It consists of two bodies, 13 and nine miles in diameter, that were likely orbiting each other before coming together billions of years ago.
Orbiting in the distant Kuiper Belt and 3.93 billion miles (6.33 billion km) from Earth, it is the most distant object ever visited by a spacecraft.
In 2019, the spacecraft New Horizons completed a flyby of Arrokoth revealing its unusual shape and staggeringly red hue.
But just why Arrokoth – which means ‘sky’ in the Native American Powhatan or Algonquian language – became so red has remained something of a mystery.
Arrokoth’s surface is coated by a layer of frozen methanol, the kind of alcohol that makes humans go blind, as well as organic compounds responsible for its red colour.
One theory proposed that at very low temperatures, methanol might be converted into these red compounds under the radiation of ‘galactic cosmic rays’ – high-energy particles that bombard the solar system.
In 2019, Arrokoth became the furthest object to be visited by a spacecraft when New Horizons passed by this distant object
To test this theory, the researchers cooled samples of frozen methanol to -233 °C (40 Kelvin) with electrons to simulate 1.8 billion years of Arrokoth being exposed to galactic cosmic rays.
They not only discovered that this process produced a red colour extremely similar to that of Arrokoth, but that this also produced a ‘complex suite’ of ‘biologically significant’ sugars.
However, Dr Meinert told the MailOnline that this doesn’t mean Arrokoth would have been transformed into a delicious treat.
Dr Meinert says: ‘We detected glucose and galactose in those samples that are known to trigger the sweet taste.
‘Given the low abundances of these individual sugars and especially other organic molecules in these ices that are considered to be toxic, I would definitely not lick such ices.’
Setting aside the gastronomical significance, this discovery could be vital for understanding how life could emerge in the solar system.
The sugars found on Arrokoth are the same simple organic compounds that make up RNA, a molecule similar to DNA found in all living cells.
Although these are organic compounds, it doesn’t mean that Arrokoth, or rocks like it, would be home to any form of life.
Instead, billions of years ago sugars on Arrokoth could have been transferred via comets to the inner solar system, acting as one of the many ingredients needed for life to form.
The researchers suggest that a ‘sugar world’ like Arrokoth might have been pulled out of the Kuiper Belt and collided with our planet billions of years ago.
This discovery makes an object like Arrokoth a strong contender for the origins of the molecules which kickstarted life on Earth
Although Arrokoth (pictured) is rich in organic molecules and is believed to contain ice at its core it is not likely that it harbours any forms of life
However, Dr Meinert explains: ‘Simple building blocks of life do not automatically lead to living cells.
‘Evolution is required to assemble simple molecules into functional polymers.’
Although studies suggest that the planetesimal might contain ancient ice at its core, it is far too cold for the formation of liquid water.
Arrokoth and other planetesimals are left over from the formation of the planets 4.5 billion years ago and are found in the Kuiper Belt which harbours comets.
In their paper, published in Proceedings of the National Academy of Sciences, the researchers write that this could have ‘delivered biologically important molecules such as carbohydrates to the early Earth.’
Studies have even shown that comets which are slowed down by the gravity of other planets could keep biological molecules safe during a fiery collision with Earth.
That could mean that the origins of life as we know it could have started with a sugary red rock in the frozen reaches of space.
WHAT IS ARROKOTH?
Ultima Thule, now known as Arrakoth, was originally thought to be two separate objects
The Kuiper Belt object was discovered by the Hubble Space Telescope in 2014. Officially known as 2014 MU69, it got the nickname Ultima Thule in an online vote.
In classic and medieval literature, Thule was the most distant, northernmost place beyond the known world.
It was formally renamed in November 2019 to Arrakoth to avoid unwanted connections to the Nazi regime.
Arrokoth means ‘sky’ in the Powhatan and Algonquian languages.
The Nazi party used the phrase ‘Ultima thule’ to refer to the mythical homeland of the Aryan people.
When New Horizons first glimpsed the rocky iceball in August it was just a dot.
NASA’s New Horizons flew past the object on January 1 2019, 4.1 billion miles from Earth.
In 2019, ongoing research into data sent back from new Horizons revealed it was not two items, but a single, snowman-like object
In 2019, ongoing research into data sent back from new Horizons revealed it was not two items, but a single connected item.
High resolution images revealed it had a ‘snowman-like’ appearance.
It is now the most distant, most primitive and most pristine object ever explored by spacecraft.
t is now known to be roughly the size of Seattle at 22 miles long and 12 miles wide.
It also boasts a uniformly reddish surface that is smooth and undulating with few craters.
It has now been officially classified as a planetesimal, objects that were among the solar system’s original building blocks.
