How Computers and Space Exploration is connected to each other?
Well, computers, nowadays we see it all around us, whether it’s in a calculator, a phone or even just a computer, everything mentioned above has a great computing capacity. By computing capacity I mean they can perform multiple calculations in a very restricted amount of time. We use computers in many areas to get the work done very quickly and to avoid human errors. One such area where computers are very critical is space exploration and/or rocket science.
Space exploration and rocket science both are different things, kind of dependent on one another. But, both of these fields requires sophisticated computing for performing various functions like controlling navigation, signal transmission or performing some tests, etc. Space exploration was started in the late ’60s by Soviet Russians and Americans. To carry Americans on the moon they were using Saturn-5 rockets which had Launch Vehicle Digital Computer (LVDC) for autopilot.
This computer was capable of executing 12,190 instructions per second, compared to today’s computers with 3GHz chip can execute 12 billion instructions per second over million times the instructions performed by a rocket which helped man walk on the moon. This is clear evidence that computers have evolved a lot today and it also suggests that without powerful computers we have achieved so much in the past.
In the early days, computers were used to perform only a few calculations, only those which humans can’t really do by themselves. Just to give you an example they used to update the navigation course sent from earth, gathering data and sending it back to us. Other things like stage separation, pressure control were fixed and controlled from the earth. But, as modern missions started becoming more complex, the requirement of computing also increased. Which caused huge research and development in computer science in the Apollo era. With the use of Integrated Circuits, the size of computers got reduced which made it possible to install powerful computers on weight-sensitive rockets.
Imagine, if you are traveling to a completely unfamiliar territory where you have no idea how its environment will be like, what elements will be there on the surface, and with such conditions, we have to send a rover to land on it. In such cases, we are totally dependent on computers mounted on rovers/satellites to perform calculations and take necessary decisions. It has to calculate parameters like surface hardness, temperature, radiation level, wind speed, and density, after calculating all such parameters then it can decide when and where to land.
US’s MARS Reconnaissance Orbiter was using a space flight computer with a 133 MHz PowerPC processor. Well, the speed seems to be very less as compared to GigaHertz processors we used here while streaming this video. But with space standards its moderate enough for an orbiter. Also, unlike on earth, these computers have to go through different environmental conditions and sustain throughout the mission. Just to point out another big thing, there are radiations in space that can affect communication and normal processing of any computer. Even the data recorder for such missions has to be different from conventional recorders on earth. The one used in this mission is called Solid State Recorder as it was not having any moving parts, no tapes, and no hard disks. This device uses an array of more than 700 memory chips, each with 256 mega bites capacity to store the data.
The total storage capacity for MARS Reconnaissance Orbiter is 160 Gigabytes. At first glance, it might seem good enough but when you calculate the size of a single image captured from it, you might have to think again. The size of a single image is around 28 GB as it has to with high resolution, because of which it can’t store much data at once. So, what it does is, it collects the data stores it until it is transferred to earth and then overwrite it.
This was about the computers sent with rockets but what about computers here on earth? How they are used in space exploration? Computers on earth play a much bigger role in space exploration, as once the satellite is sent out there in space you can’t really modify its physical specifications in mid-travel. Hence, everything has to be calculated precisely on earth before launching it. When NASA was launching Hubble Telescope it was launched with a minuscule error on its lens. There was something wrong with the polishing of its lens due to which images captured from Hubble were getting blurry. NASA had to invest billions of dollars for launching it into space but for correcting that minuscule error NASA had to invest even more.
This was the perfect example of computer simulations that can save us money on space travel. Many tests were performed on a physical model of Hubble off course considering all the parameters, which costs a lot due to the actual model. Still, Hubble was sent with an issue in space. When this is compared with India’s Mars Orbiter Mission (MOM), ISRO sent Mangalyan into Mar’s orbit in their first try at a fraction of cost compared to NAS’s similar mission. All of this was achieved because of rigorous testing and simulations. When NASA and the European Space Agency (ESA) uses three prototype models before one into space, the Indian Space Research Organization (ISRO) uses only one model. They had a similar experience with their moon lander mission Chandrayan-1 as well.
Over the years we have improved a lot of computer science, we were using analog switches and controls over digital touch screens in shuttle and capsule programs as a failsafe mechanism. For example, if we are using touch screen control and suddenly something happened to screen then we can lose all our controls with spacecraft. But, in SpaceX’s recent crew mission they used touch screen controls for the first time, which shows how failsafe mechanisms have improved as well.
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