The Engineering Marvels of NASA’s Perseverance Rover: RTG, MOXIE and SuperCam Laser
NASA’s Perseverance rover and Ingenuity helicopter (components of Mars 2020 mission) successfully landed on Mars after a 7 month-long journey on 18th February 2021. Perseverance rover is the largest and heaviest rover NASA Jet Propulsion Laboratory has ever sent to Mars. The rover will be a crucial part of humankind’s first steps on the Red Planet. To accomplish this tough task, it is equipped with several advanced technologies like improved optical sensors feeding data to machine learning vision algorithm for better navigation on Mars. These technologies are backed up by upgraded ground navigation systems. This article will feature some of the amazing gadgets and technologies installed in the rover.
Radioisotope Thermoelectric Generator (RTG)
The RTG is a type of nuclear battery that supplies power to all instruments of the rover. It uses an array of thermocouples to convert the heat released by the natural decay of radioisotopes into electricity by the Seedback Effect. A similar kind of battery was used in the Curiosity rover sent in 2012.
The principle basically allows us to generate an electric current through heat differential. That means when the heat is applied, the positive (holes) and the negative charge carriers (electrons) move towards the colder side. Hence, we can develop a potential difference by using two different semiconductors; one having holes (P-Type) and the other having electrons (N-Type). This potential difference will lead to a flow of current. It is necessary that these semiconductors should be of both thermally insulating and electrically conducting nature. Usually, the thermal and electrical properties of a material are directly proportional. So, it is hard to find a compatible material. In this rover, Lead Telluride (PbTe) is used for the N-Type and an alloy of Tellurium, Antimony, Germanium, and Silver (known as TAGS alloy) is used for the P-Type. The rover uses 4.8 kilograms of Plutonium Dioxide as its heat source. The main reason for this is that it mainly emits alpha radiations. This form of radiation is most efficiently converted to heat energy. It also releases beta and gamma radiations in a very small amount. This characteristic decreases the chance of ionization of electric components of spacecraft and hence reduces the weight of shielding required to protect the components. In case of a launch failure, Plutonium 238 develops into ceramic material and breaks into chunks rather than vapourising into the atmosphere and causing serious health hazards.
Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE)
MOXIE is an exploration technology experiment that will produce a small amount of pure oxygen from Martian atmospheric Carbon Dioxide (CO2) in a process of solid oxide electrolysis. It is manufactured by Massachusetts Institute of Technology (MIT), NASA’s Jet Propulsion Laboratory, and OxEon Energy. It is an In-Situ Resource Utilization (ISRU) type of instrument. This means it will contribute to the production of an essential resource like oxygen and will replace materials to make oxygen that would otherwise be brought from Earth. The approach of MOXIE to generate oxygen would different than that of the International Space Station because ISS does not recycle oxygen. They do not have a closed-loop system and require a regular resupply of water. Carrying a heavy element like water to Mars would be a difficult task. Hence, in order to maintain a continuous supply of oxygen, a solid oxide electrolysis process is used. The first test of MOXIE will be conducted during Mars 2020 mission as it rides aboard the Perseverance rover. It is also powered by the RTG which was discussed earlier in this article.
SuperCam Laser
SuperCam is an upgraded and powerful version of ChemCam laser used in the Curiosity rover. It was developed by Thales and Los Alamos National Laboratory (LANL), USA. SuperCam laser works on the principle of laser-induced breakdown spectroscopy and uses an infrared beam to heat the material to a temperature of around 10,000°C and vaporize it. With the help of a special camera installed on the rover, we can determine the chemical composition of Martian rock samples by measuring the colors of light in the created plasma. SuperCam laser can also emit a green laser beam, which will determine the molecular composition of surface materials. The beam excites the chemical bonds in samples and produces different signals according to their various linked components. It works on the technique of Raman spectroscopy. It will be tested for the first time on Mars and will enable scientists to detect any signs of life on Mars. The laser will induce fluorescence in organic compounds and help in determining the constituent components with high accuracy.
It is no doubt that these technologies are the outcome of humankind’s perseverance and now they will serve as the answer to human mind’s curiosity. We are excited to discover what Mars has in store for us.
