Why the Perseverance mission is important?

As the countdown to mars continues the perseverance of humanity launching the next generation of robotic explorers to the red planet on July 30th 2020 a united launch alliance atlas v rocket lifted off from cape Canaveral Florida carrying the next generation of Mars exploration vehicles the Perseverance rover and the ingenuity helicopter and today on February 18 2021 if all goes to plan the two vehicles will land safely on the Martian surface after their long seven-month journey to the red planet only 40 of missions sent to Mars have been successful and perseverance will have to endure a vicious and complicated landing sequence as its creators wait powerless to intervene waiting for news of its success back in Pasadena the perseverance rover is the largest and heaviest rover JPL has ever sent to mars heavier than the curiosity rover by 100 kilograms and with that extra weight comes a whole host of new gadgets this isn't some slightly upgraded version of the curiosity rover perseverance is benefiting from almost 10 years of advancement of technology it's packed with fascinating and novel technologies that will form a stepping stone in humankind's eventual first steps on the surface of the red planet this is the insane engineering of the perseverance rove perseverance hopefully is now safely on the ground where it will live a long illustrious life on the red planet we have learned some things from the curiosity rover that will hopefully help perseverance avoid the struggles its predecessor is experiencing on the struggles of the curiosity rover wheels and how they've been gradually falling apart on the harsh Martian surface in the end the engineers of JPL did not opt for shape memory alloy wheels like the ones we discussed in that video but simply increase the diameter of the wheels decrease their width and increase their thickness while incorporating sturdier curved threads that will better resist crack growth than curiosity's sharp corner threads they have also forgone the rectangular cutouts which imprinted Morse code spelling out the rover's origins in the rusty dirt of its new home there is a whole host of new software upgrades too like the algorithm that determines when to open the parachute in the last mission the parachute simply deployed when the target speed of 1450 kilometers per hour was reached after most of the hypersonic reentry speed of 21450 kilometers per hour had been bled off for perseverance JPL wanted to increase the accuracy of their landing.

So, this time around the chute will open when it is approaching the optimal trajectory for the landing site it will also be scanning the surface of the landing site and correlating those images to its pre-existing map to allow the sky crane to choose the best landing site with minimal obstacles perseverance's ground navigation systems have also been significantly upgraded with its optical sensors feeding data to a machine learning vision algorithm allowing perseverance to find its own path through the rough terrain of mars where curiosity had to constantly stop and start with help from its earthbound controllers perseverance is benefiting massively from the past decade of improvements in autonomous flight and driving developed by the drone and automotive industries this will mean perseverance will be able to cover much more ground during its life here in Jessero crater a massive crater that was once home to a lake the same size as lake Tahoe, the remnants of this ancient riverbed and delta spilling into what may have once been a habitable body of water it is here that perseverance will scour for signs of life before we get into all the gadgets that we'll use to do this let's look at how perseverance will power them the perseverance rover features the same radio isotope thermoelectric generator as the curiosity rover RTGs work by converting the heat from the natural decay of radioisotopes into electricity it uses a simple principle called the sebec effect to generate electricity the sebec effect essentially allows us to generate an electric current through a heat differential as charge carriers both electrons and electron holes will move from hot to cold so if we have two semiconductors one would charge carriers in the form of electrons and one would charge carriers in the form of holes a potential difference between the two.

Semiconductors will form when a heat gradient is applied this potential difference causes a current to flow in the external circuit these two semiconductors need to be both thermally insulating to ensure the heat gradient is maximized but also electrically conductive to maximize the current these two material properties are typically linked copper is both a great electric and heat conductor while iron is a poor electric and heat conductor having a single material that is a great electric conductor and a poor heat conductor is extremely rare for this reason, two unique materials are used for the p and n type semiconductors lead telluride for the n-type and an alloy commonly called tags for the p-type which is formed from telluronium silver germanium and antimony.

Now we just need a consistent heat source thankfully radioactive substances generate heat as they decay the perseverance rover uses 4.8 kilograms of plutonium dioxide as its heat source this radioactive material primarily produces alpha waves which is essential as this form of radiation is most efficiently converted to heat in a compact space while plutonium-238 also releases minimal beta and gamma radiation decreasing the weight of shielding needed to protect the electronics on board from these more powerful kinds of ionizing radiation an essential characteristic for a lightweight spacecraft the plutonium-238 is also formable into a ceramic-like material that will break into large chunks rather than being vaporized and spread in the wind during a launch failure where it could be inhaled or introduced into the food chain.

The electricity this unit can provide will gradually degrade from its maximum of 110 watts at launch as its plutonium heart naturally decays losing half of its energy every 87.9 years which is much longer than the 138-day half-life of the early Polonium-210 RTG prototypes another advantage of plutonium-238 for this application this will power all of the instruments on board like the moxie which is one of the new devices I am most excited about aboard perseverance moxie is a new oxygen generation device that will test a vital technology for any future human mission to Mars.

You may wonder like I did how is this different from the oxygen generation present in the international space station there is obviously a limited supply of oxygen there why do we need to test this new? technology on Mars when we obviously have a tried and tested method of creating oxygen already surely the international space station does not really recycle oxygen is created on the international space station through electrolysis of water this produces hydrogen and oxygen the hydrogen is then reacted with carbon dioxide to form water and methane the methane is then simply exhausted into space while the water is fed back into the system the international space station requires regular resupply of water as we are losing two hydrogen atoms for every oxygen molecule we create this is not a closed-loop system and water is a pretty heavy material to be shipping to mars the perseverance rover will test a new method of oxygen creation using this device which will use solid oxide electrolysis to instead break the plentiful carbon dioxide in the Martian atmosphere into oxygen and carbon monoxide

Its operation is fairly simple air will be taken in through a dust filter by a specialized pump designed to be as light and compact as possible called a scroll pump scroll pumps are pretty cool they consist of two spiral scrolls one stationary and one rotating air is taken in at the inlet here and as the secondary scroll rotates it traps and squeezes air against the primary stationary scroll this continues to happen as the volume between the two scrolls decreases down the spiral causing an increase in pressure in this case it causes the variable pressure Martian air which is typically about 100 times lower than earth's atmosphere and compresses it to match earth's sea level pressure.

These kinds of pumps are lightweight energy efficient and reliable making them the perfect air pump for the perseverance rover the pump feeds the carbon dioxide rich air through a cell stack each stack consists of a catalytic cathode a solid electrolyte and an anode as air passes over the cathode which operates at 800 degrees Celsius the carbon dioxide is split into carbon monoxide and oxygen ions according to this reaction the oxygen ion passes through the solid electrolyte to the anode where it is oxidized combining with a second oxygen atom to form gaseous o2 which is then passed out of the anode cavity and tested for purity moxie can produce 20 grams of oxygen an hour however the unit will not run continuously as it draws too much electricity which will be needed for another operation in total the moxie system needs 168 watts which is actually more than the 110 watts the RTG can provide at any one moment.

So, this operation will need to be supplemented by two lithium ion batteries that are included on board to make up for the low power RTG allowing it to store excess power during downtime this device is exciting because it is a clear statement of intent oxygen is going to be a vital resource for any future mission and this is actually a scaled-down prototype of the full-sized version NASA eventually wants to send to mars along with an empty rocket the full-scale version will produce about 2 kilograms per hour which will gradually be stored inside the awaiting rocket over the course of a year and a half providing life-sustaining air for any future human missions and the oxidizer needed for the ride home the next device which is also depending on a future mars mission to complete its purpose is the core sampling drill the curiosity rover sampling system drilled and scooped soil into this instrument the Sam standing for the sample analysis at mars the Sam is located here on the rover it contained multiple tools that would be commonplace in many earthbound labs a mass spectrometer a gas chromatograph and a tunable laser spectrometer each looking for different signs of life on mars perseverance has replaced the space this unit took up with a totally new system the sample caching system the robotic arm of the rover features a coring drill which will cut out cylindrical core samples from the Martian surface once collected.

The robot head mates with the drill bit carousel where it transfers the bit and the sample tube into a rotating carousel that takes it to the belly of the rover where another robotic arm resides here a number of operations takes place first the arm pulls the sample tube out of the drill bit and takes multiple images of it before and after calculating the volume of the sample 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 this is where things get really interesting there are plans to send another rover designed by the ESA to mars in 2026 this rover will deliver the samples back to its NASA designed lander.