Tag: Mars 2020 Perseverance Rover sample caching process

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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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Sample Handling System of Mars 2020 Perseverance Rover

Robotic Arm the Mars 2020 Perseverance Rover

The Mars 2020 Perseverance Rover‘s robotic arm is located on the front of the rover’s chassis. It has a length of 7 feet or 2.1 meters, which is the same length as its predecessor, the Curiosity rover.  Our 1:2 Mars Rover Replica‘s robotic arm has a length of 3.5 feet or 1.05 meters. The Mars 2020 Perseverance Rover‘s robotic arm wields a rotating 45kg (or 99 lbs) turret assembly, which is 15kg (or 34 lbs) heavier than the Curiosity rover’s turret assembly because it carries bigger science instruments and a bigger corer for drilling compared to the Curiosity rover. The weight of our Mars Rover Replica‘s robotic arm will not be that heavy, because the instruments on it will only be decorations (but ultra-realistic decorations), and the material we use will be lightweight.

The purpose of the Mars 2020 Perseverance Rover‘s robotic arm is to help with exploring the Martian surface and collecting valuable Martian samples. It mimics the human arm – it has joints at its “shoulder”, “elbow” and “wrist” for maximum degrees of freedom. Our Mars Rover Replica‘s robotic arm will also have as many degrees of freedom as the real Mars 2020 Perseverance Rover‘s robotic arm. If the Mars 2020 Perseverance Rover is a human scientist, then the robotic arm is his human arm. At the end of the robotic arm, there is a turret assembly or a hand, and on the hand, there are the science instruments (SHERLOC, WASTON, PIXL), the gDRT, the Corer, and the ground contact sensor which are for Martian rock and soil sample caching. The gDRT and the ground contact sensor are introduced in [Turret of the Mars 2020 Perseverance Mars Rover].

There are some small motors or rotary actuators on the Mars 2020 Perseverance Rover‘s robotic arm, and with these actuators, the Mars 2020 Perseverance Rover‘s robotic arm has 5 degrees of freedom or 5 flexible joints: the shoulder azimuth joint, the shoulder elevation joint, the elbow joint, the wrist joint and the turret joint. Our Mars Rover Replica‘s robotic arm will also have these motors – not the same type or the same size, but the function of the motors is the same –  so that the Mars Rover Replica‘s robotic arm is also 5 degree of freedom. The flexibility of the Mars 2020 Perseverance Rover‘s robotic arm allows it to rotate the turret accurately to a location of interest so that the corer can start its initial abrading operation for the later sampling process, or for the science instruments analyzing process.

After the science team on Earth decides which rocks or regolith to sample, Mars 2020 Perseverance Rover will give the robotic arm the “go” for sample caching. The Mars 2020 Perseverance Rover’s robotic arm will rotate the corer to an angle that is best for the drill bit to operate. Depending on the condition of the drilling site, the drill will choose the rotary mode or the percussive mode for the sample caching. After the sample rocks or regolith are collected, the Mars 2020 Perseverance Rover’s robotic arm will transfer the sample tubes to the bit carousel for the later processes. Although the Mars Rover Replica‘s robotic arm doesn’t have the function like the real Mars 2020 Perseverance Rover, users can control the Mars Rover Replica to drive and mimic the movement of the robotic arm.

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Sample Handling System of Mars 2020 Perseverance Rover

Turret of the Mars 2020 Perseverance Rover

The Mars 2020 Perseverance Rover‘s turret is located at the end of the 2.1-meter-long, 5-degree-freedom robotic arm. It carries the science instruments SHERLOC, WASTON, and PIXL to help with the sample handling process. Besides the three instruments, there are also the gDRT(Gaseous Dust Removal Tool) and the Corer. The Corer is positioned in the middle of the instruments. SHERLOC and WASTON are by one side of the Corer, while gDRT and PIXL are on the opposite side of the Corer. Collectively, they form the Mars 2020 Perseverance Rover‘s turret assembly. Our 1:2 Perseverance Mars Rover Replica will perfectly replicate the structure appearance of the Turret including the SHERLOC, WASTON, and PIXL instruments, the gDRT, and the Corer. 

The Mars 2020 Perseverance Rover‘s SHERLOC, WATSON, and PIXL instruments are introduced in more detail in [PIXL of the Mars 2020 Perseverance Rover Part 1], [PIXL of the Mars 2020 Perseverance Rover Part 2], [SHERLOC of the Mars 2020 Perseverance Rover], and [WATSON of the Mars 2020 Perseverance Rover]. With these scientific instruments the Mars 2020 Perseverance Rover‘s turret carries, the Mars 2020 Perseverance Rover is able to analyze the minerals and chemicals to study whether or not there was life or if it will be possible for humans to live on Mars by carefully and scientifically selecting the most valuable rock and soil samples to collect. Our Perseverance Mars Rover Replica‘s PIXL and the tools on it won’t have the functions as the real Mars 2020 Perseverance Rover, but the Perseverance Mars Rover Replica‘s PIXL replica will stimulate the movement when operating.  

After the Mars 2020 Perseverance Rover‘s robotic arm accurately transports the turret assembly to the location of interest, depending on what this specific mission’s purpose is, the corer will get one of the bits and will do an initial abrading operation. The Mars 2020 Perseverance Rover‘s turret then will rotate and find a position for gDRT to remove dust from the surface to prevent contamination preparing for the sample caching process. The gDRT is a sophisticated tool that consists of the following 7 components:

1. A supply tank with 159g of gaseous Nitrogen

2. A gas tank, or plenum tank which fills gas before every operation

3. Two supplementary supply valves for transferring gas from the supply tank to the plenum tank

4. A valve that releases the plenum tank’s gas

5. A nozzle that will blow the gas to the target surface

6. A valve that acts as the supply tank’s switch for releasing and loading gas before launch

7. A pressure transducer for the pressure reading

In the end, the Mars 2020 Perseverance Rover‘s turret will rotate to positions to allow SHERLOC, WASTON, and PIXL to work.

Our 1:2 Perseverance Mars Rover Replica will perfectly replicate the appearance structure of the gDRT down to very fine details, but it will not have the dust-removing function or the many components. 

Other than the mentioned tools, the Mars 2020 Perseverance Rover‘s turret assembly carries a sensor, the Ground Contact Sensor. The Ground Contact Sensor’s job is to prevent the Mars 2020 Perseverance Rover‘s turret from accidentally touching the ground by giving the robotic arm signals to stop if the turret gets too close to the ground. Our Perseverance Mars Rover Replica will perfectly replicate the appearance structure of Ground Contact Sensor but it will not actually be a sensor.