Mars once had rings like Saturn and a much bigger moon, a new study has revealed.
While Mars currently has two small moons, Phobos and Deimos, scientists from the SETI Institute and Purdue University believe that the red planet once had a much bigger moon.
Deimos, the smaller of the two moon, has an orbit that’s titled by two degrees, leading the researchers to question Mars’ past.
Matija Cuk, a researcher on the study, said: “The fact that Deimos’s orbit is not exactly in plane with Mars’s equator was considered unimportant, and nobody cared to try to explain it. But once we had a big new idea and we looked at it with new eyes, Deimos’s orbital tilt revealed its big secret.”
The researchers suggest that Mars used to have several moons, but these were destroyed over billions of years by the planet’s rings.
Each time, the ring would then give rise to a new, smaller moon, before the cycle repeated again.
According to the researchers, this could explain why Deimos orbits at a tilt – a newborn moon would move away from the ring and Mars.
Meanwhile, the team also suggests that Mars once had a moon 20 times the size of Phobos around three billion years ago.
This ‘grandparent’ moon was then followed by two more ring-moon cycles, with the latest moon being Phobos which was born around 200 million years ago, according to the scientists.
While the researchers are yet to verify the theory, they hope that an upcoming mission could help to prove the theory.
The Japanese space agency (JAXA) plans to send a spacecraft to Phobos in 2024, collecting samples from the moon and bringing them back to Earth.
Ms Cuk said: “I do theoretical calculations for a living, and they are good, but getting them tested against the real world now and then is even better.”