Mars is a planet that has fascinated humanity since the discovery of the first telescope. This fascination is based on the hope that the Red Planet could harbor life. With this hope, exploration of Mars using robotic spacecraft began in the 1960s, when NASA's Mariner 4 flew past the planet.
There were new explorations by the United States, the then Soviet Union and the European Space Agency. However, NASA achieved spectacular success in 2003 when its two Mars Exploration Rovers, Spirit and Opportunity, successfully landed on Mars. This success was the impetus for the Mars 2020 mission with the Perseverance Rover.
So what is a Mars Exploration Rover (MER)? How it works? What are its main components and what factors need to be taken into account when building these rovers? Read on as we answer these questions and other important things you need to know about this robotic surface exploration device.
What is a Mars Exploration Rover?
A Mars Exploration Rover is an American robotic vehicle designed to explore the Red Planet. This vehicle is equipped with several high-tech devices, including cameras, microscope, gamma-ray, infrared and alpha particle spectrometers and a stone grinding tool.
The main objective of a Mars exploration rover is to study the physical and chemical composition of various surfaces on the Red Planet to determine whether life is possible there. To do this, the Mars rover analyzes soil, dust and rocks around its landing area and other areas on the planet.
How do Mars exploration rovers work?
A rover is a complex machine with many data collection instruments mounted on it. These instruments work simultaneously to achieve the desired results. Let's look at these components one by one and how they work.
Cameras
There are several cameras attached to the rover. These cameras capture images and videos of the Martian landscape to relay to scientists here on Earth. For example, MARDI, or Mars Descent Imager, provides scientists with geological data from the rover's landing. The MAHLI, or Mars Hand Lens Imager, on the other hand, works similarly to a handheld magnifying glass and takes images of Mars samples just 12.5 micrometers in size.
Another camera on the mast is the Rover Environmental Monitoring Station, or REMS. This instrument serves as Mars' weather station and measures atmospheric parameters such as wind speed and humidity.
analysis
Instruments for analyzing Mars samples on the rover include SAM, CheMin, alpha particle X-ray spectrometer, dynamic neutron albedo, and radiation detector. These instruments analyze samples of Martian rocks and soil for signs of life.
For example, SAM, also known as Sample Analysis at Mars, analyzes samples from Mars for elements such as carbon, hydrogen and oxygen. It also looks for compounds that contain carbon. CheMin, also known as the Chemistry and Mineralogy Instrument, analyzes various minerals found on Mars and their relative abundance.
On the other hand, the APXS or alpha particle X-ray spectrometer analyzes soil and rock for chemical elements and checks their abundance. Dynamical Neutron Albedo, or DAN, searches for ice and water-like minerals beneath the surface of Mars. At the same time, the RAD or Radiation Assessment Detector helps measure and identify various types of radiation on Mars and alert astronauts about the intensity of radiation on Mars.
Components of a Mars Rover
The rover is a vehicle with many components working together. It has parts similar to those that living beings need to survive. The components of a Mars Rover include:
1. Body
The body is the structure that surrounds the rover's interior and processing systems. Also called a hot electronic box, this body is resistant. It has a rover equipment deck that houses the rover's mast and camera.
2. Brain
This is the rover's computer module. Another name for the brain is Rover Compute Element. To avoid mission failure, there are always two Rover computing elements in the rover body.
The RCE controls the rover's technical functions through two networks. This interface follows the aerospace industry standard design for aircraft, including planes and spacecraft. In addition to technical functions, the rover calculates elements and controls the rover's instruments in terms of data exchange.
The rover's brain works similarly to a human's. It constantly checks the system to ensure the temperature is stable and adjusts accordingly if it becomes unstable. It also records the energy generated and stored during a Martian day and schedules the start and end of new activities.
Additionally, the rover calculates elements and plans and prepares communication sessions with local Mars and Earth orbiters.
3. Cameras
The rover is equipped with 23 cameras: 9 technical cameras, 7 scientific cameras and 7 entry, descent and landing cameras. These cameras act as the rover's other senses and eyes. Entry, descent and landing cameras record color video during the rover's final descent to the Martian surface. Data provided by these cameras includes:
- What happens when the rover lands?
- The exact location on the landing area where the rover landed;
- Aerial view of the landing area before landing, providing information about the rover's controls;
- How much sand and rock do braking rockets release into the atmosphere?
- Movement of the landing system when landing on the surface;
- How the parachute deploys and works in the Martian atmosphere.
On the other hand, technical cameras provide a lot of detailed information about the terrain around the rover. These cameras perform several functions, including surveying the ground around the rover to enable safe travel, assisting with sample collection, and monitoring the status of the rover's hardware.
Three technical cameras are used on a rover: hazard avoidance cameras or HazCams, navigation cameras or Navcams, and CacheCams. HazCams help the rover avoid hazards such as entering rocks, dunes and ditches. There are two NavCams that help the rover move independently without human intervention. CacheCam, on the other hand, takes photos of samples during sampling.
In addition to technical cameras, there are also scientific cameras such as SuperCam, PIXL, SHERLOC and WATSON. These cameras are used for analysis and sample collection. They also provide a better view of Mars' topography.
4. Ears
This rover's ears consist of two microphones that allow scientists to hear the sounds of Mars. There are two types of microphones on the rover: SuperCam and EDL microphones. The EDL microphone, also called the entry, descent and landing microphone, helps record the landing sounds.
The SuperCam microphone, on the other hand, comes with the SuperCam. The microphones allow scientists to hear the sound of the SuperCam laser as it hits the rock. The intensity of the tone is proportional to the relative hardness of the stone.
5. Legs and wheels
The rover has six wheels. And each wheel has its own motor. Additionally, the front and rear wheels have steering motors that, among other things, allow the rover to rotate 360 degrees on the spot.
6. Weapons
The rover features a 7-foot-long robotic arm with a shoulder, elbow and wrist for maximum extension and flexibility. With this arm, a rover can work in the same way as a geologist.
Case study: Parts for the robotic arm of an exploration rover
Main material: 7075 aluminum
This material, commonly used in the aerospace industry, has significant fatigue resistance. It is one of the strongest aluminum alloys and has strength comparable to many types of steel. In addition to strength, this alloy has good ductility, making it ideal for highly stressed structural applications, such as building the rover's robotic arm.
Process: CNC milling, wire EDM, etc.
The rover's robotic arm is manufactured by CNC milling and wire EDM and contains parts with high dimensional precision. The reason is that by creating complex shapes and patterns, this machining process produces parts with high precision and high-quality surface texture.
Surface treatment: anodizing
Choosing anodizing as the surface treatment for the rover's robotic arm is not a mistake, as this surface treatment improves its corrosion resistance. Furthermore, with this treatment there is no risk of calcination, which could introduce foreign objects to Mars and affect the results of the analysis carried out on the Red Planet.
Features and composition: available sample equipment, drilling system and dust removal tool
The robotic arm works similarly to a human hand, allowing the rover to maneuver instruments to collect samples from Mars. The arm ends in a multi-tool turret with a 360-degree rotation range.
There are five main devices mounted on the turret: alpha particle X-ray spectrometer, Mars Hand Lens Imager, CHIMRA, drilling system, and dust removal system. While the first two analyze samples in contact, CHIMRA (Collection and Handling for In-situ Rock Analysis) collects samples and transfers them to SAM and CheMin for analysis. The rover's arm uses the dust removal tool to remove dust from rocks or clean its observation platform.
Design review for manufacturing Rover robotic arm parts
Design for Manufacturing, also known as DFM, helps optimize part production. By performing a DFM analysis before parts are manufactured, problems in a manufacturing technique or process can be more easily identified before resources are committed to that specific technique. This helps save costs in the long run while ensuring that product parts are of optimal quality.
Here we will review the actual robotic arm part of the DFM rover. However, due to the confidentiality agreement, in this section we only show typical examples from this case study.
Here are examples of projects for manufacturing typical Rover robotic arm parts.
perpendicularity
The image above shows part of a robot arm that has been machined using wire EDM. Due to the use of this process, the perpendicularity tolerance on the cutting surface of the wire is an important consideration. Squareness is a dimensional tolerance that refers to the angle between two surfaces. Indicates the maximum angular deviation from true quadrature or 90 degrees that can occur between two surfaces.
Therefore, the perpendicularity of the arm part of the rover robot to the part above can only be 0.02. The reason is that when using wire cutting technology, there will be some distortion, which may cause slight deviations.
Wall thickness
In machining, wall thickness is a measurement of the thickness of the walls of a component or part. It is an important factor to consider when designing components as it determines their overall strength, stiffness and durability. Additionally, proper wall thickness helps ensure parts are secure and can withstand heavy loads without warping or cracking.
When designing the above part, it is best to increase its thickness to at least 0.7 mm. In the image above, the area pointed to by the arrow is very thin, with a build thickness of just 0.1 mm. Consequently, this can result in an easily broken wall.
Material specification
In this case, 7075 aluminum is the ideal material to machine this part of the robot arm. Additionally, it is one of the highest strength aluminum alloys, making it perfect for heavy-duty applications. This alloy contains 90% aluminum, 5.6% zinc, 2.5% magnesium and 1.6% copper.
Post-Treatment Options
For parts requiring surface treatment in this case study, Type II anodized aluminum is recommended. In this process, aluminum is immersed in sulfuric acid, which forms a layer of aluminum oxide on the surface and inside the material. This layer has the useful property of being an excellent electrical insulator.
It has Mil-A-8625 anodization. This surface coating is generally thicker than other oxide layers. The harsh environmental conditions make it ideal for Mars.
Another advantage of using Type II surface coating through anodizing is that it makes 7075 aluminum an excellent electrical insulator. This oxide layer not only prevents conductivity, but also protects the metal from corrosion, making it the ideal aftertreatment for rover robot arm parts.
Challenges and solutions for machining parts for an exploration rover arm
Environmental conditions on Mars differ significantly from those on Earth. They are infinitely more difficult, with daily temperature fluctuations of up to 100 degrees Celsius. When designing the rover, engineers had to take different conditions into account. Here are some challenges they encountered during construction and the solutions they proposed.
High precision and tight tolerances
The rover is a complex robot with large parts. Designing large parts with tight tolerances is challenging. However, regardless of size, Rover parts still require high precision and tight tolerances for optimal functionality. Therefore, engineers had to use several precision machining techniques, including CNC machining and wire EDM, to achieve this.
The difference in environmental conditions
Environmental conditions on Mars are harsher than on Earth. With temperatures ranging from -195°C (-320°F) during the polar night to 27°C (81°F) during the day at the equator, it's an extreme place for anything. Mars' atmosphere is much thinner than Earth's and represents just 1% of the air pressure at sea level.
Additionally, Mars' average global albedo (sunlight reflection) is 0.25. This means that the planet absorbs around 75% of all the light that reaches it, increasing its extreme temperatures.
Therefore, all components of the rover must withstand the stresses of the environment. Manufacturers must comprehensively consider the use of various parts of the scenery, material, processing, post-treatment, assembly and transportation methods to establish strict standards.
Part attributes
Rover parts have different properties. Some parts must be conductive, while others are insulators. This presented a challenge to the engineers and the solution offered was to polish some parts (marked in orange above) after the part's oxidation treatment. Polishing processes are precise here.
Complexity and precision of parts
Rover parts are complex because each part has its own precision requirements. However, regardless of the time spent testing accuracy reports, engineers must provide detailed data on the accuracy of each part.
Choose WayKen for your exploration rover project
With our professional ISO 9001 and DFM certified production process, we produce parts that meet and exceed industry standards. This ensures your parts and products are right the first time and reduces time spent correcting designs.
University Degree
The Mars Exploration Rover (MER) mission helped scientists understand the geology, climate and water potential of Mars. Data collected by the rovers provided evidence that liquid water once existed on Mars and that the surface changed drastically, possibly caused by large meteor impacts. This information could help us better assess the habitability of the Martian environment. They have revolutionized our understanding of Mars and its habitability potential.
Common questions
What is the purpose of Mars rovers?
The goal is to look for various rocks and soil properties that may contain evidence of past water activity.
What are the 2 rovers on Mars?
NASA's two robotic geologists on Mars are the Mars Exploration Rovers called Spirit and Opportunity.
How powerful is the Mars rover?
According to PCMag's analysis, NASA's Perseverance rover, which successfully reached Mars, has an outdated processor with approximately the same processing power as a 1998 iMac. More specifically, it has a 200 MHz, 256 MB processor. of RAM and 2 GB of memory.
Will Mars rovers return to Earth?
The return is done so that the containers are collected and sealed by the orbiter in orbit. It will then insert the sealed containers into an entry capsule on Earth using a robotic arm developed by NASA. During the Mars-Earth transfer window in 2033, it will accelerate its orbit, release the propulsion element and return to Earth.
