Just like Sherlock Holmes solved complicated criminal cases, a scientific instrument named SHERLOC is being prepared to investigate one of the most essential mysteries of the Red Planet. The tool will be one of the most important instruments of NASA’s Mars 2020 rover which is slated to study the possibility of past life on Mars.
SHERLOC stands for the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals. It is an ultraviolet Raman and fluorescence spectrometer which will be mounted on the rover's robotic arm and will search for organics and minerals that may be signs of past microbial life.
“I think SHERLOC is a key instrument on Mars 2020 rover. It will be able to detect and classify organic material on the rover arm at microscopic scales (100 micron, about the diameter of a human hair). That is important in order to identify potential biosignatures on the surface of Mars,” Luther Beegle, Principal Investigator for SHERLOC at NASA’s Jet Propulsion Laboratory (JPL) told Astrowatch.net.
Built by JPL, SHERLOC has dimensions of 10.2 by 7.8 by 2.6 inches (26 by 20 by 6.7 centimeters) and a mass of about 3.55 lbs. (1.61 kilograms). It will be mounted on a turret at the end of the rover’s robotic arm. It will utilize a 248.6-nanometer deep ultraviolet laser with a 100 micron spot size and an autofocusing/scanning optical system, co-boresighted to a context imager with a spatial resolution of 30 micrometers.
In that configuration, SHERLOC will be able to conduct non-contact, spatially resolved, and highly sensitivity detection and characterization of organics and minerals in the Martian surface and near subsurface. The instrument’s main goals are to assess past aqueous history, detect the presence and preservation of potential biosignatures, and to support selection of return samples.
“We expect to understand the aqueous (water) history of a site and determine if any organic material is on the surface. Furthermore, because of our spatially resolved spectra, we can potentially determine where that material came from. For example, if we find organic concentration equally spread over a sample, we might infer that it was meteoritic infall but not something that could have been created through biological processes,” Beegle said.
Therefore, SHERLOC will be an essential tool for identifying and studying the so-called astrobiologically relevant minerals (ARMs), which could improve our understanding of the formation and history of a particular site on the Martian surface. ARMs are mainly hydrated minerals and also minerals that can only form when the site had liquid water.
While SHERLOC’s capabilities will be very useful in searching for biosignatures of life on the Red Planet, does it actually mean that this instrument could also determine if any potential microbial organisms are still there?
“This is a difficult question to answer. If we came across something we do not expect to be there, like a microbial mat, we would certainly be able to identify that. However, we expect life on Mars, if it is present today to be extremely rare. In that case, we do not think we would be able to definitively identify life,” Beegle told Astrowatch.net.
Sherlock Holmes solved crimes together with his sidekick Dr Watson. The same goes with SHERLOC as its imager was named WATSON (Wide Angle Topographic Sensor for Operations and eNgineering). It is a build-to-print camera based on the Curiosity rover’s Mars Hand Lens Imager (MAHLI). WATSON will allow project scientists to coordinate the measurements of different instruments together, which can result in a better understanding of a sample.
“It is a vital component, and we are glad we added it! WATSON serves an invaluable task, it allows us to put all of the 100 micron measurements in context of the site and combine them with measurements that the other Mars 2020 rover instruments, including PIXL and SUPERCAM are making. Additionally, the color microscopic images will also allow us to study rocks and identify textures and grain size, which is important in identifying where material comes from. Finally, WATSON allows us to monitor the rover with ‘eyes’ that can move,” Beegle noted.
The SHERLOC instrument has already passed the Critical Design Review (CDR), which took place in mid-February 2017. This was its third major review as it had earlier completed the Instrument Accommodations Review and the Preliminary Design Review (PDR).
The completion of CDR means that the SHERLOC team was given the green light to start building the Engineering Model (EM) of the instrument. The EM will be then tested under all relevant conditions, including shake, thermal cycling from -135 to 60 degrees Celsius - to simulated the conditions that occur for the period of three Martian years. After these tests, Beegle and his colleagues will build the flight model and hand it over to NASA’s Mars 2020 rover team.
Mars 2020 mission is expected to deliver important information about the potential habitability of the Red Planet. Besides testing method for producing oxygen from the atmosphere, the rover is designed to identify other resources such as water, improve landing techniques, and characterize weather, dust, and other potential environmental conditions that could affect future astronauts on Mars. The mission, managed by JPL in Pasadena, California, is currently slated to be launched in July 2020, atop an Atlas V booster, from Cape Canaveral Air Force Station in Florida.