Meet a model of NASA’s Perseverance rover and explore one of the biggest questions in science: is there, or was there ever, life on Mars? Discover how Raman spectroscopy uses light to identify materials without touching or damaging them, and how a mobile science laboratory searches the Martian surface for evidence of past habitability.
Have a go
Meet the model Mars rover: a scaled-down recreation of NASA’s Perseverance rover, built in-house using 3D-printed parts and custom electronics.
Explore how Raman spectroscopy can examine materials using light and reveal the chemical fingerprint of a sample. The activity introduces what the rover is looking for and why a mission like this requires scientists from many different fields.
Perseverance is exploring Jezero Crater, hunting for signs that Mars was once habitable. It carries an instrument that uses Raman spectroscopy to examine Martian rock without touching or damaging it.
What's going on
Raman spectroscopy
Every material is made of molecules, and every molecule is constantly vibrating in ways that are unique to its chemical structure. Raman spectroscopy is a technique that lets us ‘listen in’ on those vibrations using nothing but light.
Here is the basic idea: shine a laser onto a material and almost all of the light bounces straight back unchanged. But a tiny fraction, roughly one photon in every million, interacts with the material’s molecular vibrations and bounces back with a slightly different colour.
By carefully measuring that tiny shift in colour, scientists can build up a spectrum: a pattern of peaks that acts as a chemical fingerprint, revealing what a material is made of.
The technique is named after the Indian physicist Sir C. V. Raman, who discovered this effect in 1928 and won the Nobel Prize in Physics for it in 1930. Almost a century later, his discovery has found its way onto another planet.
What makes Raman spectroscopy so useful, on Mars and here on Earth, is that it is non-destructive. It needs no sample preparation, chemicals or physical contact. You simply shine a light on something and read what bounces back. That is an enormous advantage when the ‘something’ is an irreplaceable rock sample around 140 million miles from the nearest laboratory.
The Perseverance rover: a mobile science laboratory
Perseverance is roughly the size of a small car, about 3 metres long and just over 1,000kg. It touched down in Mars’ Jezero Crater in February 2021, at the site of an ancient river delta that scientists believe once fed a lake.
It is designed to search for chemical and structural evidence that microbial life could have existed there billions of years ago, and to collect rock samples for a future mission to bring back to Earth.
To do this, Perseverance carries a suite of seven scientific instruments, several of which use spectroscopy to study the chemistry of Mars in detail.
- SHERLOC: Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals is mounted on the rover’s robotic arm. It uses an ultraviolet laser and Raman spectroscopy to detect organic molecules and minerals altered by water. It works alongside a camera called WATSON, which takes close-up images to help pinpoint exactly where to aim.
- PIXL: Planetary Instrument for X-ray Lithochemistry is also mounted on the robotic arm. It uses X-rays to map the fine-scale chemical composition of rock surfaces, helping scientists understand the minerals present at a microscopic level.
- SuperCam: Mounted on the rover’s mast, SuperCam can fire a laser at rocks up to seven metres away and analyse the resulting flash of vaporised material. It also carries a microphone, capturing audio recordings from the surface of Mars.
- Mastcam-Z: Mastcam-Z provides high-resolution, zoomable, three-dimensional colour imaging, allowing scientists to study the landscape’s geology from a distance and plan where the rover travels.
- MOXIE, MEDA and RIMFAX: MOXIE is an experimental instrument that produced oxygen from the Martian atmosphere; MEDA is a weather station monitoring temperature, wind and dust; and RIMFAX is a ground-penetrating radar that reveals geological structures hidden beneath the surface.
Together, these instruments turn Perseverance into a fully mobile chemistry laboratory, built to survive a punishing environment. Mars’ surface temperature can plunge below −100°C and, with only a thin atmosphere for protection, instruments must also be shielded against intense radiation and fine, abrasive dust.