杏吧传媒

03/14/2021
By Edwin L. Aguirre

How did Mars form? How did it become the frozen desert that it is today? Did liquid water last long enough on the Martian surface to potentially support the development of microbial life?

These are just some of the questions that NASA鈥檚 latest and most sophisticated rover, named 鈥�,鈥� will try to answer as it embarks on a multiyear exploration of the red planet.

Noureddine Melikechi, dean of the Kennedy College of Sciences and a professor in the Department of Physics and Applied Physics, is part of the science team for SuperCam, one of the main instruments onboard Perseverance that will be conducting experiments on the surface of Mars.

鈥淧别谤蝉别惫别谤补苍肠别 aims to better understand the planet鈥檚 geology, geochemistry and climate, and to seek signs of ancient life,鈥� says Melikechi. 鈥淧revious missions have revealed that a few billion years ago, Mars had liquid water that formed lakes and rivers on its surface.鈥�

The one-ton, SUV-sized rover successfully made a pinpoint landing on Feb. 18 inside Jezero Crater, a 28-mile-wide, dried-up impact basin located in the Martian northern hemisphere. Around 3.5 billion years ago, a river flowed into the crater, forming a body of water about the size of Lake Tahoe and depositing clay, sand, gravel and other sediments in a fan-shaped plain called a delta. Scientists chose Jezero as Perseverance鈥檚 landing site because they believe the crater鈥檚 ancient river delta and lake deposits could have accumulated and preserved organic compounds and other potential evidence of microbial life.

Aside from Melikechi, the SuperCam science team includes dozens of researchers from Los Alamos National Laboratory, the U.S. Geological Survey, NASA鈥檚 Jet Propulsion Laboratory, Caltech, Johns Hopkins University Applied Physics Laboratory and NASA鈥檚 Goddard Space Flight Center, as well as the French space agencies CNES and IRAP, the University of Valladolid in Spain, the University of Copenhagen in Denmark, the University of Winnipeg and McGill University in Canada, and other institutions.

A Window to the Red Planet鈥檚 Past

Melikechi is also involved with the laser experiment onboard 鈥�,鈥� a NASA rover that preceded Perseverance. Curiosity landed inside Mars鈥� Gale Crater on August 6, 2012, and is still operational today.

鈥淭he two rovers have different, but complementary, scientific goals,鈥� says Melikechi, who is an expert on optics and laser spectroscopy.

Like Curiosity, Perseverance鈥檚 SuperCam will use a remote-sensing technique called laser-induced breakdown spectroscopy, or LIBS, to examine the chemical and mineral composition of Martian rocks and soils by zapping them with a powerful infrared laser.

SuperCam will fire intense laser pulses at distant rocks, boulders or sediments, vaporizing a small portion of the target material. The resulting flash of light is picked up by a detector, called a spectrometer, which identifies the atomic and molecular makeup of the target. The data is then transmitted to Earth for analysis.

鈥淪uperCam can fire the laser at targets as small as a pencil point from more than 20 feet away. This enables Perseverance to study areas it can鈥檛 reach with its mechanical arm,鈥� says Melikechi.

However, since the targets are located at different distances from the laser, each measurement is made under a different condition, which complicates the data analysis.

鈥淚n collaboration with my colleagues, I study the effect of the varying distances between the laser and the targets on their quantitative analysis,鈥� Melikechi says. 鈥淥ur goal is to develop a mathematical model that corrects for the varying distances so that the analysis can be performed as if all Martian targets zapped with the laser are located at the same distance from the rover and under the same measurement conditions.鈥�

Water is key to supporting life, so SuperCam will look at rock textures and identify types of chemicals to find those that formed during Mars鈥� wet period.

鈥淧别谤蝉别惫别谤补苍肠别 , so we鈥檒l be basically analyzing spectral data from SuperCam,鈥� says Melikechi. 鈥淲e will be looking at the kind of data that are coming in and what they tell us, and do the analysis with my colleagues in the SuperCam team remotely via Zoom. We鈥檙e interested in what the spectroscopy will tell us about possible biosignatures of past life on Mars.鈥�

Assisting Melikechi in the spectral analysis at 杏吧传媒 will be postdoctoral researchers Ebo Ewusi-Annan and Rosalba Gaudiuso, former physics student Alyre Blazon-Brown (who graduated last May and has continued to work on the NASA project), and undergraduate students Joshua Landis, Khaoula Ouarrak and Rasha El Ghazal.

Melikechi and his research team have also used the LIBS technique in a wide range of applications on Earth, including cancer research. They have successfully demonstrated the use of LIBS in detecting biomarkers for both ovarian cancer and melanoma through a single drop of blood. Recently, they were awarded a seed grant by the university to evaluate the technology鈥檚 use as a quick and simple test in detecting spectral signatures of SARS-CoV-2, the virus that causes COVID-19, in blood, saliva and urine samples.

A Martian Invasion

Perseverance is not the only spacecraft studying Mars. Space probes from China and the United Arab Emirates (UAE) are now also circling the red planet 鈥� the first interplanetary mission for both nations.

China鈥檚 Tianwen-1 spacecraft, which entered Mars orbit on Feb. 10, is carrying a rover that will attempt to touch down in May or June. The UAE鈥檚 Al Amal probe (the name means 鈥淗ope鈥� in Arabic) arrived Feb. 9 and will remain in orbit to study the Martian atmosphere and climate during its planned two-year mission.

鈥淚鈥檓 very proud of China and the Emirates鈥� accomplishment 鈥� it鈥檚 good to have more countries involved in space exploration,鈥� says Melikechi, who is a native of Algeria. 鈥淎l Amal is the first Mars attempt for the country and the region, and it serves as an inspiration for students who want to pursue careers in the STEM fields.鈥�

Melikechi鈥檚 role in the Perseverance mission attracted media interest not only in New England but also overseas. His Feb. 20 interview was broadcast by , a U.S. government-funded, public Arabic-language satellite TV channel that serves audiences in the Middle East and North Africa.