INTRODUCTION

A United Launch Alliance Atlas V rocket launched from Cape Canaveral, Florida, on July 30th, 2020. Launching the next generation of Mars Exploration Vehicles to the Red Planet. The Ingenuity Helicopter and the Perseverance Rover.

On February 18th 2021, the two vehicles landed safely on the Martian surface after their long 7-month journey to the Red Planet. Only around 40% of missions dispatched to Mars have succeeded, and will have to face a brutal and complex landing sequence. The Perseverance rover is the largest and heaviest rover ever launched to Mars by NASA's Jet Propulsion Laboratory. Greater in weight than the Curiosity Rover by 100 kilos, bringing with it a slew of additional accessories.

This isn't just a more powerful version of the curiosity rover. Perseverance is a virtue.

Taking advantage of nearly a decade of technological improvement. It's jam-packed with intriguing and remarkable technologies that will serve as a stepping stone towards humanity's eventual first steps on Mars' surface. This is the insane engineering of the Perseverance Rover.

We've gained a lot of knowledge from Curiosity Rover's struggle that will help Perseverance avoid the problems that its predecessor is facing. After learning about the Curiosity Rover wheels' struggles and how they have been gradually falling apart on the harsh Martian surface, JPL engineers decided to increase the diameter, decrease the width, and increase the thickness of the wheels, while also incorporating sturdier curved threads that will better resist crack growth than Curio's. They've also eliminated the rectangular cut-outs that used to spell out the Rover's origins in Morse code.

There are also a bunch of great new software upgrades. Like the algorithm that determines when the parachute should be opened. After most of the hypersonic re-entry speed of 21,450 kilometres per hour had been drained off, the parachute was simply released when the target speed of 1450 kilometres per hour was attained. For the benefit of perseverance, JPL sought to improve the accuracy of their landing, so the parachute will open this time when it is approaching the landing site's optimum trajectory. It will also scan the landing location's surface and compare the photographs to its pre-existing map, allowing the sky crane to select the optimum landing place with the fewest obstructions.

The ground navigation systems on Perseverance have also been upgraded, with optical sensors supplying data to a machine learning vision algorithm. Perseverance was able to forge its own course over the difficult terrain of Mars, whereas Curiosity was forced to stop and start with the assistance of its earthbound operators. Perseverance has benefited greatly from the drone and automotive industries' breakthroughs in autonomous flight and driving over the last decade. This will mean Perseverance will be able to cover a lot more ground in Jezero Crater as a result of this. A gigantic crater that previously housed a lake the size of Lake Tahoe. The remains of a historic river bed and delta may be seen spilling into what may have once been a liveable body of water so Perseverance will sweep the area for signs of life.

Radioisotope Thermoelectric Generator

Let's take a look at how Perseverance will power all of these devices before we get into the specifics. The Curiosity Rover and the Perseverance Rover both have the same Radioisotope Thermoelectric Generator. RTGs work by transforming the heat generated by a radioisotope's natural decay into electricity. It generates energy via a basic principle known as the Seebeck Effect. Because charge carriers, both electrons and electron holes, migrate from hot to cold, the Seebeck effect allows us to generate an electric current through a heat differential. So, let's say we have two semiconductors, one with charge carriers in the form of electrons and the other with charge carriers in the form of holes. When a heat gradient is applied, a potential difference between the two semiconductors develops. A current flows in the external circuit as a result of the potential difference. These two semiconductors must be thermally insulating in order to optimise the heat gradient, as well as electrically conducting in order to maximise the current. Typically, these two material qualities are interrelated. It's incredibly rare to find a single material that is both a good electric conductor and a poor heat conductor.

For this reason, two unique materials are used for the p and n-type semiconductors. For the n-type, lead telluride is used, while for the p-type, an alloy called Tags is used, which is made up of tellurium, silver, germanium, and antimony. All we need now is a reliable heat source. The decay of radioactive elements produces heat. The heat source for the perseverance rover RTG is 4.8 kilos of plutonium dioxide. This radioactive substance mostly creates alpha waves, which is crucial because this type of radiation converts to heat the most efficiently in a small space. Losing half of its energy every 87.9 years, which is substantially longer than the early polonium 210 RTG prototypes' 138-day half-life. Another benefit of Plutonium 238 in this application is that it is non-radioactive.

MOXIE (Mars Oxygen ISRU Experiment)

This will power all of the instruments onboard, including the Moxie instrument, which is one of the new items aboard Perseverance that I am most enthusiastic about. Moxie is a revolutionary oxygen generator that will be put to the test as part of any future human journey to Mars.

You might be wondering, how this differs from the oxygen production onboard the International Space Station. There is definitely a finite amount of oxygen available. Why are we testing this new technology on Mars when we already have a tried-and-true technique of producing oxygen?

The International Space Station does not recycle oxygen in any significant sense. On the International Space Station, oxygen is produced through the electrolysis of water. This results in the production of hydrogen and oxygen. Water and methane are formed when hydrogen reacts with carbon dioxide. The methane is then simply expelled into space, while the water is re-introduced into the system.

We lose two hydrogen atoms for every oxygen molecule we make, thus the international space station needs to be resupplied with water on a regular basis. This is not a closed system, and water is a fairly heavy commodity to transport to Mars. The perseverance rover will utilise this equipment to test a new way of producing oxygen, which will use solid oxide electrolysis to break the copious carbon dioxide in the Martian atmosphere into Oxygen and Carbon Monoxide instead. Its operation is quite straightforward.

 A scroll pump, a highly specialized pump designed to be as light and unobtrusive as possible, will take in air through a particulate filter. Two spiral scrolls, one stationary and the other revolving make up scroll pumps. Air is drawn in by the inlet, and as the secondary scroll rotates, it traps and squeezes the air against the immovable primary scroll. This process continues as the volume between the two scrolls lowers down the spiral, increasing pressure; in this example, it compresses the fluctuating pressure of Martian air, which is normally roughly 100 times lower than Earth's atmosphere, to approximate Earth's sea level pressure. Pumps of this design are lightweight,  

energy-efficient and reliable. Making them the perfect air pump for the Perseverance Rover. The carbon dioxide-rich air is pumped into the cell stack by the pump. An anode, a solid electrolyte, and a catalytic cathode make up each stack. Carbon Dioxide is divided into carbon monoxide and oxygen ions as air travel over the cathode, which operates at 800 degrees Celsius. The oxygen ion travels through the solid electrolyte to the anode, where it is oxidised, forming gaseous O2, which is then passed out of the anode cavity and checked for purity. Moxie has the ability to generate 20 grammes of oxygen each hour. The unit, however, will not run indefinitely because it consumes too much electricity, which will be required for other tasks. The system requires a total of 168 watts, which is more than the RTG's maximum output of 110 watts at any given time. As a result, the two lithium-ion batteries on board will be used to compensate for the RTG's low output, allowing it to store excess power during downtime.

For any future human expeditions, oxygen will be a critical resource. And, along with an empty rocket, this is a scaled-down prototype of the full-sized version NASA eventually hopes to send to Mars. The full-scale model will produce around 2 kg every hour, which will be gradually stored within the waiting rocket over the course of a year and a half, providing life-sustaining air for any future human missions as well as the oxidizer required for the return journey.

The Core sampling drill

The core sampling drill is the next gadget, which is also reliant on a future Mars expedition to perform its mission. The soil was drilled and scooped into this instrument, the SAM (Sample Analysis at Mars), using the curiosity rover sampling system.

It had a number of tools that would be found in many earthbound laboratories. A tunable laser spectrometer, a mass spectrometer, and a gas chromatograph On Mars, they're all seeking distinct indications of life. Perseverance has installed a completely new system in the location that this unit previously occupied, The Sample Caching System.

The Sample Caching System is a system for storing samples. The rover's robotic arm is equipped with a coring drill, which will be used to extract cylindrical core samples from the Martian surface. When the drill bit and sample tube are retrieved, the robot head mates with the drill bit carousel and transfers them to a revolving carousel that transports them to the rover's belly, where another robotic arm dwells. A variety of operations take place here. Before and after estimating the volume of the sample, the arm pulls the sample tube out of the drill bit and takes numerous photographs of it. Then it stores it in one of the 42  slots under the belly of the rover, where they  

will remain until the rover deposits them in these sample tubes at a designated caching  

spot on the surface of Mars.

In 2026, the European Space Agency (ESA) aims to send another rover to Mars. The samples will be returned to the rover's NASA-designed lander, which will be loaded into a mars ascending vehicle. The samples will be launched into orbit, where they will be met by an ESA Earth Return Vehicle.

Robots are being used to carry soil back from Mars.

The SHERLOC equipment on the robotic head will use Raman and Luminescence spectroscopy to search for biosignatures, which both detect chemicals depending on how they interact with UV light. It will perch about 5 cm from the ground, focusing its UV laser on the soil and detecting molecules that indicate the presence of previous life. The Rover also carries an x-ray imager called PIXL, which can see the texture of the ground under it and look for small changes in geology that could suggest that microbial life has changed the environment, as well as to detect chemical compositions by examining the fluorescence of the target under x-ray electromagnetic radiation.

Other Sensors

Other sensors, such as the ground-penetrating Radar imager positioned at the rover's rear, will provide us with representations of the composition of geology up to 10 metres beneath the surface, and may even find water resources buried beneath. Future human expeditions will rely on this resource. These are just a few of the sensors on board; there are also high-definition colour cameras that will transmit back incredible photos to Earth, as well as a microphone that will allow us to hear what life on Mars might sound like in the future. It could even pick up the distant whirr of helicopter blades.

Ingenuity helicopter

The ingenuity helicopter is the most exciting feature of this mission. After all, if the mission is successful, humanity will have proven controlled powered flight on another planet for the first time. The powered flight on Mars is fraught with difficulties. Because the atmosphere is only around 1% the density of the Earth's, there is less air to push down to generate lift. To counteract this, the propeller blades, which are counter-rotating to eliminate the need for a tail rotor, spin at roughly 2400 RPM, significantly faster than a standard helicopter blade. That's nearly 5 times faster than a comparable RC helicopter on the ground.

The blades must be composed of high-strength carbon composites to withstand the centrifugal forces that come with it. These blades also have a significantly greater angle of attack than standard blades, allowing them to force a much greater volume of air downward.

This helicopter needs its own power source because it will detach from the Perseverance rover. This aircraft, unlike the Dragonfly mission to Titan, will not have its own RTG. It's extremely difficult to develop an RTG small enough to fit into this 2-kilogram chopper. Instead, it has these solar panels, which will charge the six lithium-ion batteries on board, which will then power the motors and cameras. With a maximum flight time of 90 seconds. This is merely a technology demonstration intended to provide NASA and JPL with the information they require to authorise and develop a future flying rover.

References-

https://theconversation.com/mars-perseverance-rover-set-for-nail-biting-landing-heres-the-rocket-science-154886

https://mars.nasa.gov/mars2020/

https://www.space.com/perseverance-rover-mars-2020-mission

https://scholar.google.co.in/scholar?hl=en&as_sdt=0,5&as_vis=1&q=perseverance+rover

Image credits-

https://mars.nasa.gov/mars2020/multimedia/raw-images/