What's inside the Curiosity rover
On August 6, 2012, the Curiosity apparatus landed on the surface of Mars. In the next 23 months, the rover will study the surface of the planet, its mineralogical composition and radiation spectrum, look for traces of life, and also evaluate the possibility of a person landing.
The main research tactic is to search for interesting rocks with high-resolution cameras. If such appear, then the rover from a distance irradiates the rock under study with a laser. The result of the spectral analysis determines whether a manipulator with a microscope and an X-ray spectrometer should be taken out. Further, Curiosity can extract and load the sample into one of the 74 cups in the internal laboratory for further analysis.
For all its great body kit and external lightness, the device has a mass of a car (900 kg) and weighs 340 kg on the surface of Mars. To power all the equipment, the decay energy of plutonium-238 from the Boeing radioisotope thermoelectric generator, whose resource is at least 14 years, is used. At the moment, it produces 2.5 kWh of thermal energy and 125 watts of electrical energy, over time, the electricity output will decrease to 100 watts.
Several different types of cameras are . Mast camera - This is a system of two uneven cameras of normal color rendition, which can take pictures (including stereoscopic) with a resolution of 1600 × 1200 pixels and, which is new for rovers, record a hardware-compressed 720p video stream (1280 × 720). To store the resulting material, the system has 8 gigabytes of flash memory for each of the cameras - this is enough to fit several thousand pictures and a couple of hours of video recording. Processing photos and videos goes without load on the control electronics of Curiosity. Despite the fact that the manufacturer has a zoom configuration, the cameras do not have a zoom, since there was no time for testing.
Illustration of images from MastCam. Colorful panoramas of the surface of Mars are obtained by gluing together several images. MastCam cameras will be used not only to entertain the public with the weather of the red planet, but also as an aid in the extraction of samples by the manipulator and when moving.
A part of the ChemCam system is also attached to the mast . This is a laser-spark emission spectrometer and an imaging unit that work in pairs: after evaporation of a tiny amount of the test rock with a 5-nanosecond laser pulse, the spectrum of the obtained plasma radiation is analyzed, which will determine the elemental composition of the sample. There is no need to extend the manipulator.
The resolution of the equipment is 5-10 times higher than that installed on the previous Mars rovers. From 7 meters, ChemCam can determine the type of rock being studied (for example, volcanic or sedimentary), the structure of soil and stones, track the predominant elements, recognize ice and minerals with water molecules in the crystal structure, measure traces of erosion on stones and visually help in the study of rocks with a manipulator.
ChemCam cost $ 10 million (less than half a percent of the total cost of the expedition). The system consists of a laser on the mast and three spectrographs inside the housing, the radiation to which is fed through an optical fiber.
The Mars Hand Lens Imager is installed on the rover manipulator, which is capable of obtaining images of 1600 × 1200 pixels in size, on which details of 12.5 micrometers can be seen. The camera has a white backlight for working both day and night. Ultraviolet illumination is necessary to cause the emission of carbonate and evaporite minerals, the presence of which suggests that water took part in the formation of the surface of Mars.
For mapping purposes, we used the Mars Descent Imager (MARDI) camera, which during the descent of the device recorded images of 1600 × 1200 pixels per 8 gigabytes of flash memory. As soon as several kilometers were left to the surface, the camera began to take five color photographs per second. The data obtained will make it possible to map the habitat of Curiosity.
Two pairs of black and white cameras with a viewing angle of 120 degrees are installed on the sides of the rover. The Hazcams system is used to perform maneuvers and extend the arm. The Navcams system is located on the mast, which is two black and white cameras with a viewing angle of 45 degrees. Mars rover programs are constantly building a wedge-shaped 3D map based on the data from these cameras, which avoids collisions with unexpected obstacles. One of the first shots from Curiosity is a picture from a Hazcam camera.
A Rover Environmental Monitoring Station has been installed on the rover to measure weather conditions. ), which measures pressure, atmospheric and surface temperatures, wind speed and ultraviolet radiation. REMS is protected from Martian dust.
CheMin ( Chemistry and Mineralogy ) is a device for studying the chemical and mineralogical composition using an X-ray fluorescence instrument and X-ray diffraction. Roughly speaking, it will help to find the minerals that Mars is rich in, which will show what were the conditions on the planet.
The main tool for researching the obtained samples is Sample Analysis at Mars , whose mass is half the mass of all scientific equipment. SAM includes a mass spectrometer, gas chromatograph and a custom laser spectrometer. Also, an alpha-particle x-ray spectrometer is used in the work . Samples will be irradiated with alpha particles, and their complete elemental composition will be obtained in two to three hours, and ten minutes will be enough to review the main components.
A radiation detector is installed inside the rover to assess the possibility of people visiting Mars and a hydrogen detection device . It is interesting that the scientific equipment was developed not only in the USA, these are projects of organizations from France, Canada, Russia and several other countries.
All this equipment is controlled by a small duplicated computer with 256 MB of RAM, 2 GB of ROM in the form of flash memory and a RAD750 processor, which is capable of performing 400 million operations per second, which, roughly speaking, is comparable to a regular smartphone. The system capacity is enough to generate 15-40 thousand 3D-points from stereo images. The memory of Curiosity is about eight times more productive than the memory of Mars rovers of previous generations. Although the system configuration is similar to the stuffing of a cheap single-board computer, you should take into account the operating conditions of the electronics and the radiation tested by it, which Raspberry Pi clones do not have protection against.
Used VxWorks. It is a proprietary real-time operating system that managed the previous three Mars rovers - Spirit, Opportunity and Mars Pathfinder, as well as the SpaceX Dragon ship . Кроме космических аппаратов VxWorks. используется в авиалайнерах, робототехнике, медицинской технике и других встраиваемых высоконадежных системах (например, в роутерах Apple та же операционная система, что и в марсоходах).
The control programs are divided into 150 modules, each of which is responsible for a separate function. Connected modules are combined into components that organize the collaboration of the modules included in them. In total, there are less than 10 high-level components. Most of the code is automatically generated or inherited from previous rovers.
But in these 2.5 million lines of C code , autonomous control of many systems with only rare human interventions is implemented - a signal from the Earth takes several minutes. Based on the testimony of several cameras and sensors, the computer itself controls the driving of the device, photographing and filming, the cooling system, sample extraction and the operation of scientific equipment.
The code, of course, is not available to the public, and the data on the software of the rover is scarce. But who knows what to expect from NASA: they have long had an account on Github .