Sampling begins on Mars as British scientist decides which rocks make it back to Earth

Perseverance abrading a rock target in preparation for sampling. CREDIT NASA/JPL-Caltech

Over seven months after its monumental arrival on the Red Planet, the NASA’s Mars 2020 Perseverance rover is preparing to collect rock samples for future return to Earth. 

Natural History Museum scientist and member of the NASA’s Mars 2020 Science Team, Dr Keyron Hickman-Lewis is one of 15 international Returned Sample Science Participating Scientists (RSS-PSs) on the mission who will lead the science team in its historic effort to determine which rocks the rover will collect to be returned home for future research.

The team are searching for rocks that offer a diverse representation of material found on Mars. They will be looking for interesting relationships between the rocks themselves, as well as potentially collecting multiple portions of a single rock in order to obtain the most scientifically compelling samples possible.

The two primary aims of the NASA Mars 2020 mission are to reconstruct the environment of Jezero crater 3.5 billion years ago and to look for signs of ancient life. At more than 3.5 billion years old, these rocks are some of the oldest in the Solar System. Martian rocks with primary sedimentary and igneous features will be prioritised for return to Earth, while those that hold signals of pervasive physical and chemical alteration that occurred long after the time of formation will be excluded from the sampling process.

It is hoped that by studying these rock samples in laboratories here on Earth in the years to come, scientists will be able to answer the question of whether there was ever life on Mars, and may eventually use Mars as a tool to better understand the early Earth.

Fossils of Martian life

Operating first in the “Green Zone” at Jezero crater, a region of the planet’s surface first studied from orbit, the rover has been taking images of its surroundings since its descent onto Mars earlier this year. The team has used orbital images as a guide for further exploration. Keyron explains:

“Images obtained from orbit are immensely useful and provide a good overview into what lies ahead. They are like Google Earth images of Mars – incredibly useful in giving the bigger picture, but we’ll only know exactly which samples we want to take once we get closer to the surface.”

Since landing back in February, Perseverance has successfully utilised its payload of scientific tools, using lasers to acquire chemical analysis of rocks, and cameras to capture more detailed images. Keyron and the other RSS-PSs will use these findings to guide and inform the wider science team on which samples best match the objectives of the mission. They will then act as custodians for documenting the pathway to sampling these rocks until they are safely locked away in the rover, carefully recording the decisions made until sampling, and recording detailed observations of the process – assets that will be called upon by scientists for generations to come.

Keyron says:

“As Perseverance begins its sampling campaign, it’s important to remember that that these materials will be called upon to answer the questions of a great number of scientists upon return to Earth over a number of years.

It is imperative that we carefully choose our sampling targets to be materials from which we can obtain the maximum geological and geochemical information”

At the end of the sampling campaign, the rover will house a total of more than 30 samples. Held in sealed containers, they will each be approx. 1 cm in diameter, several centimetres long and together will weigh approximately half a kilogram.

Plans are underway for these samples to be returned to Earth in approximately ten years’ time. This will mark the first time that specifically selected rocks from Mars will be studied in state-of-the-art labs here on Earth.

A huge international collaboration and a pioneering feat for space exploration, the UK is leading on production of the ‘Sample Fetch’ return rover.


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