In recent days the name of the next robot that will land on Mars has finally been decided: Perseverance. Perseverance is a gem of aerospace engineering, and this long article will try to prove it to you. Even the name is a whole program, evocative and full of hope and ambition, like that of its predecessor.
The task entrusted to Perseverance is not simple: it will have to prove that it is more autonomous than Curiosity, more resistant and more efficient: part of his job will be to collect soil samples and leave them there, waiting for a next mission to go to recover.
Is the body all? Almost
The main body of Perseverance is called "Warm Electronic Box", or even WEB. The task of WEB it is essential: to protect the internal components made of cables, memories, computers, sensors and extremely delicate circuits. The main body is therefore a fundamental shield to allow the rover to "live" on the surface of the red planet.
The Warm Electronic Box is positioned on the top of a structure called "Rover equipment Deck", that is a structure from which different vehicle extensions start, such as the suspension of the six wheels (which we will discuss shortly) and the robotic arm which allows the cameras to lean as far as possible from the rover (to frame the ground or horizon free of obstacles). Some technical data: The warm electric box is 3 meters long and 2.7 meters wide, for a height of 2.2 meters and a weight of 1,025 kilograms.
The concept of the Perseverance rover is based on that of the Mars Science Laboratory Rover, for the "Curiosity" friends. Reusing a design based on previous missions is obviously not intended as "laziness"by the designers, but it is a procedure often used in cases where a particular design or an engineering solution has been particularly effective and successful in the past. Nevertheless, Perseverance can show off a series of improvements and innovations.
The large robotic arm, about 2 meters long, is placed on the front and differs from that of Curiosity in two aspects: Perseverance will collect rocks; will have to collect rock samples e pack them leaving them in specific places of the surface of Mars, so that a future mission can recover for possible studies by scientists. Curiosity instead studied the samples collected on site, using the rover's on-board laboratory.
Perseverance will operate very differently from Curiosity. The new rover will collect 20 samples of Martian rocks and soil. To do this, he was given a larger robotic "hand", and in general a more advanced arm. This arm has a drill for operations coring as well as a color camera to inspect close surfaces. This cam is also capable of making "selfies"(" selfies "have one purpose: to check if the external structure is clean and free of damage to the components).
Inside the body of the spacecraft there is an internal work area dedicated to the collection, movement and positioning of drills from drill and test tubes for the conservation of the finds. New engines were then added to better maneuver the movements, much more advanced than those of Curiosity.
Perseverance's arm can count on five degrees of freedom, made possible by small engines called "rotary actuators". In addition, the main body has a special sensor that warns the rover every time the arm finds itself in contact with the surface. The contact sensor orders the stopping of the arm if it inadvertently touches the ground, to avoid accidental damage.
New software to operate the Rover
The team is building new software for the rover. In addition to managing the new sampling operations, the latter influences all its daily activities more efficiently, alternating between on-site scientific measurements and at the same time the collection of samples for potential future analyzes. To do this, the driving software has been modified to give the rover more independence than how much Curiosity has ever had.
This allows Perseverance to walk and analyze portions of land in autonomy, receiving instructions from Earth less frequently. In addition, the engineers added a "planner" to the onboard software. This addition allows a more effective and autonomous use of the rover's electricity, allowing it to independently organize some activities to better exploit the various daytime and night time slots.
New wheels
Engineers have redesigned the wheels of Perseverance to make them more robust, having noted the wear and tear that the wheels of Curiosity have undergone during the various passages on the ground made of rocks particularly sharp. Perseverance wheels are narrower than Curiosity wheels, but larger in diameter and made thicker aluminum. The co-presence of a large suite of instruments, the new sampling system and the modified wheels makes the next spacecraft that will explore Mars heavier than its predecessor.
The Mind behind Mars 2020
The rover's "brain" – his computer – is located inside of of his square body. The form is called Rover Compute Element (RCE) – there are actually two identical RCEs in the body, so there is always a "brain" of reserve. The processor works at a maximum frequency of 200 megahertz, 10 times the speed of the Spirit and Opportunity computers. It has 2 gigabytes of flash memory (8 times greater than Spirit or Opportunity) and there is a "special" memory to counteract the effects of radiation that exists in space and on the Martian surface.
Balance and position
The Perseverance rover carries an inertial unit of measurement (IMU) which provides information about your orientation in space (position with respect to a triaxial system) and its location, which allows the rover to make precise movements vertical, horizontal and from side to side (called "yaw"). The device is used during navigation of the vehicle to assist it during the passage on uneven soils and estimate the degree of inclination of the vehicle on the surface of Mars.
Just like the human brain, Perseverance computers record "vital signs", such as i temperature levels and the residual power, together with other factors that keep the vehicle "alive".
This main control circuit constantly follows systems to ensure that the rover is able to communicate effectively during the mission and that it always remains thermally stable. Like? Periodically checking the temperatures, in particular in the body of the vehicle; the computer also takes care of recording the energy generated and the data on the accumulation of energy throughout the Sol (one Martian day) for decide which new activities they can be started or completed; and finally to plan and prepare the communication sessions with the Earth or with the orbiters around Mars.
Activities such as photographing, guiding and using the tools are performed based on commands transmitted sequentially by the "Perseverance team" on Earth. The rover constantly generates technical data on the structure, on the instrument cleaning and on periodic analysis and reports of events, all stored in system memories. It does these things so you have them already ready for transmission as soon as the team on Earth requests it.
Rover eyes
The spacecraft possesses several cameras, each with its own specific task. Some are used to monitor the phases of landing, others to observe the conformation of the soil and rocks, others to check the environment and the surrounding atmosphere. When Curiosity landed on Mars, he recorded the descent and landing with his Mars Descent Imager or "MARDI".
Observing this phase was extremely important to him engineers; allowed him to understand what happens during one of the riskier stages of a mission like this.
This camera shot a color video of Curiosity's journey through the atmosphere to the Martian surface. He provided the rover's scientific team with a privileged viewpoint on the landing site, helping them to accurately identify the landing point and plan the first activities.
For Perseverance, the engineering team is adding several cameras and one microphone to document entry, descent and landing in even more detail. They will shoot videos a colors during his descent on the Martian surface. Some of the things that cameras see along the way help mission planners make decisions about landing point or on emergency maneuvers.
The cameras and the microphone are piloted as "discretionary payload", which means it's an add-on optional which will be an advantage, but not required for the mission.
In addition to providing technical data, the cameras and microphone can be considered a "audience engagement payload", which means that these images could be shared with the" social "audience. Almost everyone remembers the memorable videos that describe Curiosity's" Seven Minutes of Terror "during his entry, descent and landing on the rover on Mars became viral online, and they were only computer generated images: the idea of being able to observe a real event this time is much more exciting.
Mars 2020 uses a new generation of cameras. These "improved" cameras provide much more detailed, color information of the terrain around the vehicle and have various functions: they measure the terrain around the rover to improve driving, check the hardware status of Perseverance … but there is more.
Advanced cameras help human operators on Earth drive the rover more precisely and ad target better the movements of the arm, the drill and other tools that approach rocky elements on Mars. The viewing angle has been improved: a much wider field of view gives cameras a better view of the rover itself and its surroundings.
This is important for checking the health the various parts of the rover and measure the changes in the amount of dust and sand which can accumulate on vehicle surfaces. The new cameras can also take pictures while Perseverance is on the move.
These navigation cameras, or NavCam, show a pile of rocks taken from a distance of about 15 meters in the "Mars Yard" test area at the JPL. The images illustrate how the camera data can be used to reveal the contours of an element placed at a certain distance. These measurements provide the rover and his team with the information they need to plan precise movements and arm movements.
Avoid risks with HazCams
The rover also has six hazard detection cameras called HazCams: four in the front and two in the back of the body. HazCams detect risks for the advancement or the retreat of the medium, like large rocks, ditches or sand dunes.
While driving, the rover stops frequently to acquire new ones three-dimensional images the path to follow to avoid potential dangers. The images in 3D give the robot the ability to make autonomous decisions where to go without asking for directions each time to the team on Earth.
Two sets of color stereo navigation cameras, called NavCams, help engineers navigate safely on Mars 2020, particularly when Perseverance operates autonomously, making their own navigation decisions without consulting controllers on Earth.
Located high on the rover tree, these two sets of black and white stereo cameras help engineers drive around Mars. They can see an object as small as a golf ball 25 meters away.
CacheCam
"CacheCam" is a single camera positioned to frame freshly sealed soil samples. Take photos of the sampled materials and tubes as they are being prepared for sealing. This helps scientists "monitor" the samples as they are obtained and keeps a record of the whole process for each sample collected. Here is an example of what frames:
MastCam-Z
MastCam-Z is the name given to one pair of cameras which acquires color images and videos, three-dimensional stereo images characterized by a powerful zoom. Like the Mastcam cameras on the Curiosity rover, these installed on Perseverance are also located next to each other and point in the same direction, offering a vision three-dimensional similar to what they would see human eyes but obviously improved.
SuperCam
SuperCam has a directional laser towards mineral "targets" that are beyond the reach of the rover's robotic arm. As the history ChemCam on the Curiosity rover, the SuperCam issues laser pulses on very small surfaces, of side 1 mm and distant approx 7 meters, while spectrometers examine the chemical composition of the rock.
It also looks for organic compounds that may be related to development of life, or traces of past life on Mars. When the laser hits the rock, it generates del plasmaor an extremely hot gas made of ions and floating electrons. An on-board spectrograph records the spectrum plasma, which reveals the composition of the material.
SHERLOC
SHERLOC's main tools are spectrometers and lasers, but it also uses a type camera macro to shoot close up extremes of the areas under analysis. All this to provide visuals insider which could help tell the story of the environment and the conditions in which the Martian rock was formed.
WATSON
The WATSON camera is one of the tools placed on Perseverance's robotic arm. It is very similar to the MAHLI camera on Curiosity. WATSON captures large images for build a detailed picture on the Martian mineral elements, it offers a privileged view of the "plots"and mining facilities on a small scale of Martian rocks, or on the surface layer of rocky debris. Since WATSON is installed on the robotic arm, it helps trigger those "Selfies" we talked about earlier.
For now we stop here: we have introduced the autonomous driving system and the software through which it will carry out its research activities, the instrumentation prepared for drilling and the collection of samples, the three-dimensional laser camera system for the mapping of the surrounding environment, with a look at the main body of Perseverance and the iconic robotic arm.
There is still a lot to be analyzed, such as the series of microphones installed along the entire rover structure: through these microphones it will be possible to listen to the sound produced during the descent into the Martian atmosphere, the thud of the landing, the hum of the instruments in operation. It therefore seems clear that NASA engineers want to bring to Mars the five senses of the human being bringing them together in a single robotic entity: Perseverance.