We do not need the most powerful microprocessor in the world to conquer the universe. The real secret is to make the most of your device’s operating characteristics, even if it’s a bit old and doesn’t have excellent performance. Let’s see how the Tenacity craft landed on Mars safely and intactly. Mankind is closer to Mars after millions of kilometers, NASA’s persistent rover landed on Mars on February 18, 2021. We can consider the event a historic mission because, despite the distance, the exorbitant conditions of the universe and the weak devices, a human apparatus that smoothly reached the Red Planet. Remember that light travels the same distance, on average, in about 12 minutes. Hence, the radio signals, images and information collected take the same time. For this “impossible” task, NASA used a processor installed in the 1997 Apple iMac G3 computer with a computational frequency of only 200 MHz and a RAM of 256 MB. It is not even among the fastest processors in the same commercial series. Why is this low technology? There is always a reason to choose. Aircraft designers were more concerned with the reliability and durability of the on-board computer than with the power of computing. A simple smartphone is much faster. Mission Mars needed the CPU always running. Bombardment of radiation can seriously and easily damage the electronics of a modern processor. On the other hand, G3 processor is not destroyed by radiation and is able to withstand intense radiation and temperatures. On the ground, processor speeds can be dramatically increased without any problems. The electrical, thermal, atmospheric and magnetic conditions are very comfortable and the Earth’s atmosphere defends us with a hard protective shield. However, the situation is completely different in the universe. The presence of radiations of enormous energy, ranging from 100 MeV to 1 GeV, can modify the functioning of the circuits, and the effect of a single ionized particle on the processor is sufficient to create or even destroy arithmetic errors. Slow but reliable processor The rover’s chip is slow by modern standards, but meets all reliability tests (see Figure 1). Even prolonged exposure to radiation does not harm its function. The G3 with its 200MHz speed is clearly disappearing in the presence of today’s microprocessors with over 3GHz clocks, however, it is appropriate to say, “slow and steady win the race”. High reliability is the most premium component of the processor, even in critical conditions. This is a specially designed, radiation-resistant version. It can operate in temperatures between -55 ° C and + 125 ° C (-67 ° F to +257 ° F) and the Martian atmosphere is extremely cold. It is also very thin, causing all kinds of radiation to penetrate. RAD750 can safely withstand these conditions. Applications for spacecraft are very critical. Saving a few millimeters of space or a few grams of weight is key. Memory was kept very low, with 2 GB of flash, 256 MB of working RAM and 256 KB of EEPROM. The processor “only” contains 10.4 million transistors, 1,000 times less than current smartphones. The rover has two brains, one of which starts if a problem occurs with the first processor. Figure 1: Highly Reliable and Safe Processor Sensors The Tenacity Carriage is equipped with an Inertial Measurement (IMU) system that provides 3-axis information about its position for precise vertical, horizontal and lateral movements. The sensors connected to the computer record many parameters, such as temperature, voltage, storage of solar cell energy and energy, in order to keep all operating conditions stable. With this data, it is possible to control exchanges of information, snapshots, and other useful commands for exploring the new environment. Conclusions This is not the first time that this type of processor has been used. Earth is surrounded by RAD750s on over a hundred satellites, and none of them have failed so far. Today, we use mobile devices (laptops, smartphones, etc.) with extraordinary capabilities that have incredible computational power. A very important space mission could be managed with much less. .
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