Dr. Roger Wiens
Leader of the SuperCam Team

Wiens earned a B.Sc from Wheaton College in Physics and received a NASA Graduate Student Research Fellowship to study Mars meteorites at the University of Minnesota. After obtaining his PhD, he worked as a Scientist at Caltech where he remained for seven years. In 1997, Wiens made the move to New Mexico to work at Los Alamos National Laboratory. He started as a developer and flight payload lead of NASA’s Genesis mission, which was the first spacecraft to have returned to Earth from deep space beyond the Moon. Despite its crash landing on return, samples of the sun were successfully brought back and analyzed. The solar-wind particles showed evidence that Earth may have formed from different solar nebular materials than those that created the sun. Their findings were published in Science in 2011.1

Wiens went on to become the Principal Investigator (PI) of ChemCam on the Curiosity rover and the PI of SuperCam on the Perseverance rover, both of which were developed in conjunction with Centre National d’Études Spatiales (CNES) in France. The more advanced SuperCam2,3 is equipped with a telescope, a camera (remote micro imager), a microphone and four spectrometers: infrared (IR) spectrometer at the top, and in the body, two reflection spectrometers for laser-induced breakdown spectroscopy (LIBS), and a remote transmission spectrometer with an intensifier capable of Raman spectroscopy, LIBS and time-resolved fluorescence (TRF) spectroscopy. The LIBS spectrometers also have the ability to perform passive visible spectroscopy. The spectrometers inside the body of the rover obtain their light from a long optical fiber originating at the mast. “These spectrometers get light all the way from 240 nanometers in the ultraviolet (UV) to 850 nm in the near infrared (IR) region,” says Wiens. In addition, the infrared spectrometer on the mast operates from 1.3 to 2.6 µm.

The microphone on SuperCam has picked up sounds of wind, zaps from LIBS focused laser creating supersonic plasma and blade slaps from the helicopter, Ingenuity, which give information about how sound propagates in a different atmospheric environment. The red planet consists of 95% CO2, which absorbs sound waves, and its atmosphere is 1% as thick as Earth’s and does not propagate sound very well; these effects are more significant at higher frequencies. Thus sounds from helicopter blade rotation and its first resonance have been detected, but the higher pitches present on Earth have not been heard on Mars. Wiens and his team also use sound to learn about the hardness of the rocks and whether a coating is present.

The remote micro imager on SuperCam was originally designed to have the same optics and resolution as its predecessor, ChemCam. However, in the final stages of assembling SuperCam, a major accident destroyed almost all the unit optics. Rather than calling it a disaster, Wiens refers to what happened as a miracle. They found a defect in the mirror—a slight deformation occurred at colder temperatures—and the accident provided time for the design and construction of a new mirror while the rest of the instrument was being rebuilt. The new mirror enabled the camera to capture higher resolution images as compared to ChemCam.

With advanced instrumentation aboard Perseverance and new terrains to explore on Jezero Crater, a place Wiens describes as a geologist’s playground full of big crystals and igneous rocks, the possibilities for discovery are endless. Orbital images of Jezero crater had shown a fan-shaped body believed to have once been a river delta, possibly rich in organic materials, deeming it a hot spot for finding evidence of ancient life. New images taken from SuperCam’s high resolution camera found the fan to have outcrop faces with inclined strata, which confirmed the existence of deltas that advanced into a lake. Furthermore, the upper fan strata showed boulder conglomerates with sedimentary succession, which indicated transition from a persistent lake environment to episodic high-energy flows. These results have recently been published in Science and the article was featured on the coveted cover.4

Wiens is also a co-investigator of SHERLOC on Perseverance, which uses Raman spectroscopy but in a different way than SuperCam. SHERLOC employs a deep UV laser beam at 248 nm in the continuous wave mode to get enhanced Raman signals in situ whereas SuperCam uses a pulsed laser at 532 nm to perform remote Raman spectroscopy. Both Raman systems use fluorescence signals to search for organic and other luminescing materials but have the ability to avoid interference with Raman signals. SuperCam’s laser uses a frequency doubler to convert 1064 nm light from its Nd:YAG laser to its green beam for Raman spectroscopy. To prevent the infrared and green laser beams from being emitted at the same time, a small beam stop has been integrated. A fault protection also ensures that the rover itself is not shot by the lasers.

In addition, automation assists with sample selection. Scientists at NASA’s jet propulsion laboratory have developed a software algorithm called AEGIS, which stands for Autonomous Exploration Gathering Increased Science. The rover takes images and picks out the next targets without grounding the loop. “If the rover can drive to a new spot, take pictures and begin acquiring spectra, a whole day can be saved,” says Wiens.

Roger Wiens has authored a book, Red Rover: Inside the Story of Robotic Space Exploration . Wiens does not have much time to watch movies, but he enjoyed The Martian starring Matt Damon as it showed a more realistic portrayal of Mars as compared to other science fiction movies.

In 2016, the government of France knighted Wiens for his contribution in forging strong bonds between the French and American scientific communities. Wiens is one of a few hundred non-French citizens to be awarded this distinction by L’Ordre des Palmes Académiques, originally instituted by Napolean I in 1808.

Wiens has faced challenges both technically and politically, but he’s learned that one has to weather the difficult times in order to reap the rewards. His optimism has always carried him through. To maintain a strong and healthy mindset, Wiens plays the piano, prays and practices gratitude. He is grateful that the things he was naturally drawn to aligned with his childhood aspirations. He wanted to do something to help the world and ended up doing something that inspires the world.

Although Wiens believes that it will one day be possible for human exploration on Mars, he is perfectly content studying the red planet from his terrestrial living room.

References:

1) B. Marty, M. Chaussidon, R.C. Wiens, A.J.G. Jurewicz, D.S. Burnett, A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples, Science 2011, 332(6037), 1533-1536.

2) R.C. Wiens, S. Maurice, et al., The SuperCam Instrument Suite on the NASA Mars 2020 Rover: Body Unit and Combined System Tests. Space Sci. Rev. 2021, 217:4.

3) S. Maurice, R.C. Wiens, et al., The SuperCam instrument suite on the Mars 2020 rover: Science objectives and mast-unit description. Space Sci. Rev. 2021, 217:47.

4) N. Mangold et al., Perseverance rover reveals an ancient delta-lake system and flood deposits at Jezero crater, Mars, Science 2021, 374(6568), 711-717.