A small rock has been hitching a ride on NASA‘s Perseverance rover on the surface of Mars for four months without falling off.
The rock attached itself on the Perseverance’s wheel in February and has since been transported more than 5.3 miles (8.5 km) aboard the rover, NASA has said.
Photos show the Martian fragment tucked into the front left wheel of the Perseverance rover, which landed on the surface of Mars in February last year.
The photos of the rock were taken by the rover’s front cameras used to navigate hazards, called ‘Hazcams’.
NASA said the ‘unexpected traveling companion’ isn’t doing any damage to the wheel, although it could drop off at any time.
Perseverance can only go up to 0.07 miles per hour (0.12 km per hour), which may just be slow enough to stop it from falling off.
Prior to being caught on Perseverance’s wheels, the rock could have been in the same spot for millions of years.
The Mars rock can be seen on the front left wheel of Perseverance on May 26, 2022 (sol 449) beside track marks in the Martian surface
Image taken using the front left Haz Avoidance Camera (Hazcam), acquired on April 19, 2022 (sol 413)
Perseverance touched down on Mars’ Jezero Crater on February 18, 2021 after a nearly seven-month journey through space.
The car-sized Mars rover is tasked with seeking traces of fossilised microbial life from Mars’ ancient past and to gather rock specimens for return to Earth.
Last month, it reached a key phase of its mission – climbing up an ancient delta known as ‘Three Forks’.
NASA said the ‘pet rock’ attached itself to the wheel on the 341th ‘sol’ or Martian day – over 100 sols ago, in early February 2022.
One sol lasts 24 hours, 39 minutes and 35 seconds – slightly longer than an Earth day. As of Wednesday (June 8), Perseverance has been on Mars for 462 sols.
On sol 341, Perseverance was still working on its first science campaign focused on picking up samples from the Jezero crater floor.
‘We examined rocks that are part of the Máaz formation, which we believe is made up of lava flows,’ NASA said in a statement.
Martian rocks are so variable on the red planet’s surface that if this pet rock were to fall off the wheel so far from its original location, it could stick out if a ‘Martian geologist from the future’ were to encounter it.
‘It’s possible that the rock may fall out at some point along our future ascent of the crater rim,’ NASA said.
‘If it does so, it will land amongst rocks that we expect to be very different from itself.’
The public can track the route taken throughout Perseverance’s 462-sol journey using an online interactive map on NASA’s website, which uses dots to denote where the rover stopped.
‘Engineers created this experience with software used by the mission team who decide where Perseverance will explore, and how to get there,’ NASA said.
‘Each dot represents the end point of a drive and is labelled with the day, or sol, on Mars, that the rover stopped.’
The same rock is seen in an image acquired on February 6, 2022 (sol 343). Photos were taken by the rover’s front cameras used to navigate hazards, called ‘Hazcams’
The rover has turret-mounted scientific instruments that are able to determine chemical and mineral composition and look for organic matter, as well as better characterise the planet’s geological processes.
It uses a drill and a hollow coring bit at the end of its 7-foot-long (2-meter-long) robotic arm to extract samples slightly thicker than a pencil, which it stores under its belly.
However, Perseverance is not bringing the samples back to Earth – the rover is stashing in certain locations on Mars them to be collected by a future retrieval mission, which is currently being developed.
It was in February last year that Perseverance touched down on Mars’ Jezero crater, which scientists believe was once home to an ancient river delta
One option involves NASA and ESA launching two more spacecraft that would leave Earth in 2026 and reach Mars in 2028.
The first will deploy a small rover, which will make its way to Perseverance, pick up the filled sampling tubes and transfer them to a ‘Mars ascent vehicle’ – a small rocket.
This rocket will blast off – in the process becoming the first object launched from the surface of Mars – and place the container into Martian orbit, meaning it will essentially be floating in space.
At this point, the third and final spacecraft involved in the tricky operation will manoeuvre itself next to the sample container, pick it up and fly it back to Earth.
A multi-billion dollar project to bring back a piece of Mars to Earth will involve three separate launches and would only be successful as soon as 2031
Providing its re-entry into the Earth’s atmosphere is successful, it will plummet to the ground at a military training ground in Utah in 2031, meaning the Martian samples likely won’t be studied for about another decade.
Perseverance also made the journey to Mars equipped with a detachable 4-pound (1.8-kilogram) robotic helicopter called Ingenuity.
The copter has performed a series of nearly 30 flights of increasing complexity on the red planet, the most recent in April this year.
Ingenuity, which is just 18-inches tall, made its first flight on April 19, 2021, making history as the first powered controlled flight on another planet.