Author: Peter Hong

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Mars 2020 Perseverance Rover Structure Components Functions Power System of Mars 2020 Perseverance Rover

MMRTG of the Mars 2020 Perseverance Rover – part 1

The Mars 2020 Perseverance Rover’s Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) is the power supply for the Mars 2020 Perseverance Rover, which is located at the end of the Mars 2020 Perseverance Rover.

The weight of the Mars 2020 Perseverance Rover’s MMRTG is around 99 lbs or 45 kg. The diameter of the Mars 2020 Perseverance Rover’s MMRTG is around 25 inches or 64 cm, and the length is around 26 inches or 66 cm. For our 1:2 Perserance Mars Rover Replica, the diameter will be around 12.5 inches or 32 cm, and the length will be around 13 inches or 33cm.

The Mars 2020 Perseverance Rover’s MMRTG has mainly three jobs:

  1. Provide electricity to the Mars 2020 Perseverance Rover while operating during day and night. It is expected to generate 110 W in the beginning, and it will reduce only a few percent each year. Although the Mars 2020 Perseverance Rover’s MMRTG is designed to work over 10 years, with limited nuclear material, it will only actually going to run for one and a half Mars year, which is an equivalent of three Earth years. Therefore, the few percent reductions in power level are not a big deal.
  2. Charges 2 rechargeable lithium batteries. These 2 batteries are used when the demand power is larger than the Mars 2020 Perseverance Rover’s MMRTG can supply at the time. As a matter of fact, sometimes the demand power can go up to 900 W, but the Mars 2020 Perseverance Rover’s MMRTG can only make 110 W, so that’s when the 2 rechargeable lithium batteries come in to ensure the mission can continue.
  3. Warm up the instruments on the Mars 2020 Perseverance Rover. Mars, compared with Earth, is a cold planet. In order for the science instruments to operate, heat is needed to keep them at a workable temperature.

For our 1:2 Perseverance Mars Rover Replica, the operating power will not be 110 W because the science instruments on the rover are only decorations. Although the Perseverance Mars Rover Replica can simulate some of the real Mars 2020 Perseverance Rover‘s movements, the power required will be significantly small. 

If you are interested in our 1:2 Perseverance Mars Rover Replica, you can check out [1:2 Perseverance Mars Rover Replica Design and Building Diary].

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Mars 2020 Perseverance Rover Structure Components Functions Movement Structure System of Mars 2020 Perseverance Rover

Wheels of Mars 2020 Perseverance Rover

The Mars 2020 Perseverance rover has 6 wheels. Different from its predecessor, each of the Mars 2020 Perseverance rover‘s wheels has a total of 48 gently curved treads instead of 24 chevron-patterned treads. For the wheels of our Perseverance Mars Rover Replica, all the curved treads will be perfectly replicated.

Other than changing the wheel patterns, the Mars 2020 Perseverance rover‘s wheels are around 8.5mm thick, which is around 1mm thicker than the Curiosity rover, not including the pattern thickness on the wheel surface. Proportionally, the thickness of our 1:2 Perseverance Mars Rover Replica‘s wheel should be 1mm, but in order for the wheels to be strong enough to support the rover body and the loads onboard and bear the rocky terrain, we will make the thickness of the Mars Rover Replica‘s wheel 2 mm.

The diameter of the Mars 2020 Perseverance rover‘s wheels is 52.5 centimeters or 20.7 inches, which is a little bit larger than the Curiosity Mars Rover’s 50.8-centimeter or 20-inch wheels. The diameter of the wheels of our 1:2 Perseverance Mars Rover Replica is 26.25 centimeters or 10.35 inches.

The reason to change the tire pattern and to make the Mars 2020 Perseverance rover‘s wheels thicker is due to the wear and tear that the Curiosity Mars rover’s wheels experienced. And this actually affects Curiosity’s performance on the Martian sand. But now with the new design, the Mars 2020 Perseverance rover‘s wheels are more resistant to the harsh Martian surface condition. The wheels of our 1:2 Mars Perseverance Rover Replica are strong enough as well to survive many kinds of rock terrains.

While the spokes of the wheel were made of titanium, the PMars 2020 Perseverance rover‘s tires were machined from aluminum that is widely used in the airplane industry, and it is a type of shape memory alloys. This shape-memory aluminum allows the tires to adapt to the Martian terrain, which is very much like a shock absorption system to provide the Mars 2020 Perseverance rover with a stable ride and minimize damages to the tires and hence to the instruments carried by the rover. The shape-shifting material makes the Mars 2020 Perseverance rover‘s tires light-weight, more durable and they have better traction performance while driving on the Martian rocky roads. For our 1:2 Mars Rover Replica, the spokes are made of aluminum and the wheel surface is made of steel. The reason we choose these two materials to build our Mars Rover Replica is explained in this post [Designing the Perseverance Mars Rover Replica’s Wheels].

With one full turn of the wheels, the Mars 2020 Perseverance rover can move forward a distance of 1.65 meters, or 65 inches. The Perseverance Mars rover can go as fast as 152 m/h, or 4.2 cm/s, which might not seem very fast compared to Earth’s vehicles, but the slow speed actually helps the Perseverance Mars Rover conserve energy for the long-term mission. In terms of our Mars Rover Replica, how fast it can go is still to be determined, but we will try to match the Mars 2020 Perseverance rover‘s speed.

Compared with the Curiosity Mar rover, the Mars 2020 Perseverance rover is much more autonomous in terms of driving. The software onboard allows the Mars 2020 Perseverance rover to decide which way it wants to go, which means the Mars 2020 Perseverance rover will travel much further without having to confirm with Earth each time about the driving paths. For our 1:2 Perseverance Mars Rover Replica, you will remotely control it with screens showing real-time video captured by the cameras mounted around the body of the Mars rover replica.

The Mars 2020 Perseverance rover‘s wheels work with a Rocker-Bogie suspension system when interacting with the surface of Mars. This Rocker-Bogie design allows the Mars 2020 Perseverance rover to go over obstacles twice the height of the wheel and allows the loads onboard evenly distributed on the 6 wheels. In our 1:2 Mars Rover Replica, the Rocker-Bogie feature is perfectly replicated, so you can expect that our Mars Rover Replica will also be able to drive over obstacles that are twice the height of its wheels and have the loads evenly distributed on 6 wheels.

Synonyms: cleats, raised treads, grousers

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1:2 Perseverance Mars Rover Replica Design and Building Diary

Building the Structure for the Drive Motor, the Wheel Fork, and the Steering Motor for the 1:2 Perseverance Mars Rover Replica

The Mars 2020 Perseverance Rover has six wheels, and each of them is connected to a stand-alone drive motor via the axle. And each of the front two wheels and the back two wheels is also connected to a stand-alone steering motor via a C shape structure called the wheel fork. Obviously, since the two middle wheels do not have steering motors connected, there are no C-shape wheel forks involved in the two middle wheels.

To test our design of the 1:2 Perseverance Mars Rover Replica, we 3D printed a prototype first including the structures for the drive motor, the wheel fork, and the steering motor for one wheel of our Perseverance Mars Rover Replica because the cost of 3D printing is much lower than machining, not just the material cost but the processing cost as well, and what’s more, 3D printing is much faster than machining. So if we find any design mistake when building the prototype, we can adjust the 3D design without wasting too much money. Of course, small issues don’t necessarily require re-3D-printing immediately, we can use all kinds of tools to do the fix in the physical world so that we won’t be stopped by these small issues.

After we complete the 3D printed prototype test and the design changes, which obviously may involve more than one round, we then proceed to build the final aluminum version wheel structure of the 1:2 Mars Perseverance Rover replica.

As you can see in the video above, all the 3D-printed parts are perfectly assembled. Some of the parts are already now machined with aluminum alloy.  Once we build the control PCB for the steering motor and drive motor, we will be able to activate the wheel via the code running in microchips.

We are now moving on to build the mast of the 1:2 Perseverance Mars Rover Replica.

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Mars 2020 Perseverance Rover Structure Components Functions Science Instrument of Mars 2020 Perseverance Rover

MEDA of the Mars 2020 Perseverance Rover – part 2

Radiation and Dust sensors

The radiation and dust sensor assembly for the Mars 2020 Perseverance Rover‘s MEDA is located on the top deck. Our 1:2 Perseverance Mars Rover Replica will perfectly replicate the appearance structure of the radiation and dust sensor assembly but they won’t be actual sensors.  This Mars 2020 Perseverance Rover‘s MEDA’s radiation and dust sensor assembly consists of photodetectors and a charge-coupled device, and the purpose is to study the characteristics of the Martian dust, such as its shape, size, or opacity. The Mars 2020 Perseverance Rover’s MEDA inherited a lot of features from previous space missions.

For example, from the Curiosity Rover mission, the rover environmental monitoring station (REMS) is applied on the Mars 2020 Perseverance Rover. It is a set of sensors that are designed to work and collect information on a low atmosphere, which includes air and ground temperature sensors, wind sensors, humidity and pressure sensors, and a photometer.

From the Mars MetNet Lander Mission, the solar irradiance sensor (MetSIS) is inherited. Mars is a cold planet compared to our Earth. Moreover, the entry, descent, and landing process for the Mars 2020 Perseverance Rover are extremely bumpy. Both harsh conditions could potentially affect the sensors. Therefore, this sensor is specially designed so that it can endure the landing impact and also operate normally at low temperatures. It consists of 32 detecting elements in 11 spectral bands. The sample rate and channels to be sample can both be manually and autonomously configured.

From the ExoMars 2016 Lander mission, DREAMS, which is short for Dust characterization, Risk assessment, and Environment Analyzer on the Martian Surface is inherited to the Mars 2020 Perseverance Rover. The Mars 2020 Perseverance Rover’s version of DREAMS has 7 detectors. These detectors are arranged so that a 360 ° azimuth is possible.

From the Mars Exploration Rover Misson and Mars Science Laboratory mission. the HazCams is applied to the Mars 2020 Perseverance Rover and now is renamed as SkyCam on the Mars 2020 Perseverance Rover.

Our Perseverance Mars Rover Replica will perfectly replicate the appearance structures of the REMS, MetSIS, DREAMS, and the HazCam, though they won’t have the functions as the real Mars 2020 Perseverance Rover.

The Mars 2020 Perseverance Rover’s MEDA’s radiation and dust sensors are the first set of sensors that are specially for studying the sun brightness and dust conditions. This will help scientists model the atmospheric conditions of Mars and prepare for human exploration in the future.

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Mars 2020 Perseverance Rover Structure Components Functions Science Instrument of Mars 2020 Perseverance Rover

MEDA of the Mars 2020 Perseverance Rover – part 1

The Mars 2020 Perseverance Rover’s MEDA is short for the Mars Environmental Dynamics Analyzer. You may think of it as a weather station, which essentially is a set of sensors for measuring and collecting mainly the following information:

  1. wind speed
  2.  wind direction
  3. temperature
  4. pressure
  5. humidity
  6. amount of dust particles
  7. size of dust particles
  8. radiation

The Mars 2020 Perseverance Rover’s MEDA has several components and they are located in multiple locations on the Mars 2020 Perseverance Rover:

  1. on the Mars 2020 Perseverance Rover’s mast’s neck
  2. on the Mars 2020 Perseverance Rover’s top deck
  3.  on the front left and right sides of the Mars 2020 Perseverance Rover’s body
  4.  on the interior of the Mars 2020 Perseverance Rover’s body

Our 1:2 Perseverance Mars Rover Replica will perfectly replicate the MEDA instrument’s appearance structure but there will not be any actual sensors and it is not a real weather station. 

The Mars 2020 Perseverance Rover’s MEDA’s sensors are air temperature sensors, radiation, and dust sensor, relative humidity sensor, thermal infrared sensor, wind sensors, and instrument control unit sensors. With these sensors, the Mars 2020 Perseverance Rover’s MEDA will be able to work as a weather station, not only to study the atmospheric condiction of Mars but also to predict Mars’s future weather. This has great meaning because one day, there is a chance humans will set foot on Mars, and they will need to know daily weather reports just like we do on Earth.

The Mars 2020 Perseverance Rover’s MEDA has a mass of 5.5kg or 12 lbs. and the maximum power it will consume is 17W which depends on the scale of the measurements. Our Mars Rover Replica‘s MEDA will be half the size as the Mars 2020 Perseverance Rover’s MEDA, but the weight is not half the weight. We aim to find materials that are strong but lightweight for that. 

If you are interested in our 1:2 Perseverance Mars Rover Replica, you can check out [1:2 Perseverance Mars Rover Replica Design and Building Diary].

 

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Sample Handling System of Mars 2020 Perseverance Rover

Adaptive Caching Assembly of the Mars 2020 Perseverance Rover – part 3

Theoretically, the Mars 2020 Perseverance Rover’s sample caching process for a rock or a regolith can be described as follows.

First of all, Mars 2020 Perseverance Rover will do an initial assessment on the sampling site by the science instruments on the rover. The Mars 2020 Perseverance Rover’s MastCam-Z will spot a potential sampling site and identify a rock for later investigation.

Secondly, the Mars 2020 Perseverance Rover’s SuperCam will exam the rock more carefully in greater detail. After SuperCam confirms that this site or this rock is worthy of caching, the Mars 2020 Perseverance Rover will move closer to the site. Then the abrading bit on the corer of the turret assembly will perform an initial abrasion so that PIXL and SHERLOC can do a close proximity analysis before the rock is decided to be a good potential caching target.

With our 1:2 Perseverance Mars Rover Replica, the users can control the rover to perform the same action as the above two steps. Although it won’t be the real scientific inspection, the movement will be the same.

Although the Mars 2020 Perseverance Rover’s PIXL and SHERLOC instruments have different functions and look for different features, in this step, they both work as the final step and a double-check for if the location is a valuable target for sample caching.

Next, the sample caching process will start. Below are the basic steps:

  1. The Mars 2020 Perseverance Rover’s sample handling arm in the adaptive caching assembly will get an empty sample tube from the sample tube assembly. The sample tube is then transferred to the Mars 2020 Perseverance Rover’s bit carousel’s interior door and inserted into a drill bit. The bit with the sample tube inside will then be transferred to the outer door, waiting for the turret’s corer to take it. Our Mars Rover Replica will perfectly replicate the sample handling arm and it will be able to perform the same action as the Mars 2020 Perseverance Rover’s sample handling arm.
  2. After the turret’s corer picks up the drill bit, the Mars 2020 Perseverance Rover’s robotic arm will start the drilling process and collect a rock core or regolith. Then the robotic arm will bring the filled sample tube back to the bit carousel, and the sample is transferred to the lower door, waiting for the Mars 2020 Perseverance Rover’s sample handling arm to move it back to the adaptive caching assembly.
  3. Different from when the sample tube is moved out of the sample tube assembly, this time, the sample tube with the rock or regolith sample will be moved to the volume assessment station, the vision assessment station, the seal dispenser, and the sealing station respectively before it is brought back to the sample tube assembly for storage.

For our Mars Rover Replica, although you will see how the turret and the tools on it interact with the bit carousel, you might not see the interactions between the tubes and the stations because it will be done inside of the rover’s body. But we will still try our best to replicate the stations and the ability to move for our Mars Rover Replica just like the real Mars 2020 Perseverance Rover’s actions. If you are interested in our Mars Rover Replica, you can check out [1:2 Perseverance Mars Rover Replica Design and Building Diary].

Ideally, these tubes will be dropped to a pre-decided location for the future retrieving mission and returning to Earth.

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Sample Handling System of Mars 2020 Perseverance Rover

Adaptive Caching Assembly of the Mars 2020 Perseverance Rover – part 2

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s stations are all made from titanium because the physical characteristics of the titanium can reduce the errors due to the temperature changes on Mars from affecting the operations during the sample caching process. The titanium caching component mounting deck is the interface between all the Mars 2020 Perseverance Rover‘s adaptive caching assembly’s stations to the rover. For the adaptive caching assembly’s station of our 1:2 Mars Rover Replica, the materials are still to be determined for the stations because the stations won’t have the actual functions, but we will try our best to also use titanium.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly was designed to fit inside of the Mars 2020 Perseverance Rover‘s body before launching on Mars, but after it lands, the belly pan directly below the adaptive caching assembly is dropped from the rover’s body, because the sample handling arm in the Mars 2020 Perseverance Rover‘s adaptive caching assembly will need to extend around 200mm, or 7.87 inches below the rover’s bottom pan during the sample handling process. Besides that, the rover’s system will do a scan to make sure the sample handling arm will not be obstructed during the operation. For our Mars Rover Replica, the belly pan can also be dropped, but it can be put back as well. The dropping mechanism will be the same as the Mars 2020 Perseverance Rover‘s belly pan’s dropping mechanism.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s bit carousel is located on the caching component mounting deck, and a part of it extends through both the top deck on the front and front panel to allow sample tubes and drill bits to exchange easily. Our Mars Rover Replica will perfectly replicate the Mars 2020 Perseverance Rover‘s adaptive caching assembly’s bit carousel.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly interacts with the turret assembly, such as drill bit exchange, through the docking assembly, which located on the front of the bit carousel. There are a rotational bearing mechanism and a return spring mechanism to make sure the docking assembly will return to its original position and re-center after the turret undocks to prepare for the later operations. For our Mars Rover Replica, users can simulate a full interaction between our Mars Rover Replica‘s adaptive caching assembly and turret with the remote control.

Inside of the Mars 2020 Perseverance Rover‘s adaptive caching assembly’s bit carousel, there are 9 drill bits: 6 coring bits, 1 regolith bit, and 2 abrading bits, which are securely locked onto the bit holder. They not only need to survive the drop when the Mars 2020 Perseverance Rover touches down on Mars but also they need to not break when the rover is driving on the bumpy Martian road. Besides these, the bit carousel will need to cooperate perfectly with the corer when each time a sample tube is inserted into the drill. If misaligned, it could be disastrous for the assembly. For our Perseverance Mars Rover Replica, it is not recommended to drop it like the Mars 2020 Perseverance Rover is dropped on Mars, but our Mars Rover Replica can take a certain amount of impact.

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1:2 Perseverance Mars Rover Replica Design and Building Diary

Building and Testing the Wheel Skeleton of the Mars Perseverance Rover Replica

We have completed the machining of the wheel spokes of the 1:2 Mars Perseverance Rover replica. All the parts are assembled. It is really exciting to hold the assembled wheel skeleton in my hands and feel its weight. Although the structure successfully passed the computer simulations, we still anticipated seeing its bearing ability in the physical world.

We designed a special tool to test the entire wheel of the 1:2 Mars Perseverance Rover replica, including the steering motor structure, the ‘C’ shape connection structure, the wheel hub, and the spokes. In this stage, we only completed the wheel skeleton which is composed of the wheel hub, and the spokes so we cannot take advantage of that special tool to do the test. However, we did find a very primitive but effective way to test the strength of the wheel skeleton of the Perseverance Mars rover replica.

We were worrying whether this skeleton structure can bear the weight of the entire Perseverance Mars rover replica so it’s really nice to see the structure is STRONG. LOL.

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Sample Handling System of Mars 2020 Perseverance Rover

Adaptive Caching Assembly of the Mars 2020 Perseverance Rover – part 1

The Mars 2020 Perseverance Rover‘s adaptive caching assembly is one of the three main components of the sample caching system. The other two main components are the robotic arm and the turret assembly, which are introduced in more detail in [Robotic Arm the Mars 2020 Perseverance Rover] and [Turret of the Mars 2020 Perseverance Rover].

The Mars 2020 Perseverance Rover‘s adaptive caching assembly is located inside of the rover and on the front of the body. There are mainly 6 sub-assemblies of the Mars 2020 Perseverance Rover‘s adaptive caching assembly: the sample tube storage assembly, the sample handling arm, the dispenser, volume, tube assembly, the vision station, the sealing station, and the bit carousel. For our 1:2 Mars Rover Replica, we will replicate the part on the front of the body, and we will try our best to perfectly replicate the part that is inside of the rover’s body.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s sample tube storage assembly is for storing both empty sample tubes and filled sample tubes. Although they are placed together, there are sheaths to protect them from contaminating each other. There are a total of 39 sample tubes in the sample tube storage assembly.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s sample handling arm is for transferring the sample tubes to different stations in the adaptive caching assembly or for moving the sample tubes to the bit carousel so that the sample tubes are inserted into the drill bits for sample caching purposes.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s dispenser, volume, tube assembly is to calculate the number of samples collected and to reduce possible contamination. There are 3 sample tubes in the dispenser, volume, tube assembly. There are 7 seal dispensers, and each seal dispenser has 7 seals, so there are 49 seals in total, 7 of which are spares.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s vision station not only takes photos of the sample cached but also performs a second-time calculation for the amount of each sample collected.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s sealing station is to seal a sample permanently by triggering seals in the sample tubes.

The Mars 2020 Perseverance Rover‘s adaptive caching assembly’s bit carousel is to keep all the drill bits and helps to insert a sample tube into a drill bit for sample caching.

For our 1:2 Mars Rover Replica, we will try our best to perfectly replicate these 6 sub-assemblies. Although they will not have the same functions as the real Mars 2020 Perseverance Rover‘s adaptive caching assembly, they will be fully motorized and you can simulate the sample handling movement with the remote control.

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Science Instrument of Mars 2020 Perseverance Rover

MOXIE of the Mars 2020 Perseverance Rover – part 3

The Perseverance Mars Rover‘s MOXIE runs the oxygen-making experiments autonomously and there are two challenges it is facing.

The first challenge is from the harsh Martian environment. The temperature can fluctuate for over 65 Celsius or 150 Fahrenheit during day and night, and it is yet to find out how the Perseverance Mars Rover‘s MOXIE will react to this abrupt temperature change. Moreover, in every Winter, around 30% of the Martian atmosphere vanishes and the temperature is so low that carbon dioxide solidifies and drops to the Martian surface. Ideally, the Perseverance Mars Rover‘s MOXIE should be able to operate at all times without stopping since it is designed to produce oxygen for human survival. Therefore, the record for how the Perseverance Mars Rover‘s MOXIE will respond to Mars’ harsh environmental condition will be extremely valuable data for MOXIE’s developers and researchers, so that the future MOXIE can be designed to work smoothly no matter the environmental changes. The Perseverance Mars Rover‘s MOXIE is planned to run 10 times totally during the mission under as many different conditions as possible. Our 1:2 Mars Rover Replica may or may not replicate the MOXIE instrument. If we do replicate it, it will not be able to make oxygen, and will not produce that much heat. But we may design it so that it will make the motor running sound effects.

If you are interested in our 1:2 Mars Rover Replic, you may check [1:2 Perseverance Mars Rover Replica Design and Building Diary].

The second challenge the Perseverance Mars Rover‘s MOXIE instrument faces is the byproduct generated. Theoretically, the carbon dioxide will be split into oxygen and carbon monoxide. However, scientists are still researching how to properly run the Perseverance Mars Rover‘s MOXIE instrument. If operating it too gently, the carbon dioxide will just go through the instrument and not produce enough oxygen so the oxygen conversion rate will be very low. But if operating it too heavily, not only will you get carbon monoxide, but also there will be some single carbon atoms. For now, the unwanted solid carbon is cleaned manually to avoid it from blocking the normal operation.

In the future, if humans can set foot on Mars, a much larger version of the Perseverance Mars Rover‘s MOXIE will need to make around 30,000 kg, or 66,000 lbs of oxygen to support a trip home from Mars to Earth. If the Perseverance Mars Rover‘s MOXIE is successful, this means it will save 4 to 5 trips from Earth to Mars for transferring that much liquid oxygen.