Rocketology - Artistry and Engineering at work!
At T-minus 6.6 seconds, as the 120-ton space shuttle sits, surrounded by almost 4 Million pounds of rocket fuel is ready to defy gravity as its on board computers take in the command.
As its pressure sensors, pumps, temperatures are nominal the computers give the order to light the main engines and the choreography of incredible engineering happens as each of the three engines fire off precisely at 160 milli seconds apart, tons of super-cooled liquid fuel pouring into combustion chambers, the ship rocking on its launch pad, held to the ground only by bolts.
It is always an absolute beauty to watch a shuttle take off, as the time goes T-minus 0 seconds. At this time the on-board computers check all the sensor data, they give the order to light the solid rocket boosters. In less than one second, the rocket achieves 6.6 million pounds of thrust!
And the spacecraft majestically takes off its launch pad!
No human pushes a button to make this happen, there is no astronaut sits with a joy stick to set the shuttle in orbit, it's an awesome display of power of computers and software doing its job in a well-choreographed manner.
But how much work does the software does? what makes this remarkable?
By the time the shuttle achieves the escape velocity, there would have been billions and billions of sensor data flowing across the 5 on-board computers. The on-board systems would have taken millions of decisions based on these data.
Just to explain in detail on how these machine's computers work. Four identical computers, running identical software’s, get real time information from thousands of sensors, make hundreds of milli-second decisions. A fifth computer with a different software stands by to take control if other four malfunction!
Anyone who has witnessed a shuttle launch would have seen the dramatic belly roll the shuttle does soon after it clears the tower, it is the software which gives the orders to gimbals in the main engines to execute this maneuver.
It is the software which keeps track of where the shuttle is, orders the solid boosters to fall away, makes minor course corrections, and after about 10 minutes, directs the shuttle into higher orbit.
Even the smallest error in space can have enormous consequences! the orbiting space shuttle travels at 17,500 miles per hour; a bug that causes a timing problem of just two-thirds of a second puts the space shuttle three miles off course.
If you are an engineer or someone who has a little experience in designing electronic systems, by this time you should be blown away with all the design and planning that had gone through to such a detail!
What is remarkable is how well the software works. This software never crashes, it never needs to be re-booted, it is bug free. I feel like I am experiencing the first sight of Superman in the movies!
I was able to pull out this information, the last three versions of the program — each 420,000 lines long-had just one error each. The last 11 versions of this software had a total of 17 errors. Just to give a comparison a commercial program of equivalent complexity would have 5,000 errors!
This software is perfect, as perfect as human beings have achieved.
But the real ‘mind = blown’ moment is not realizing all the things I said till now, it’s when you think about SpaceX's Falcon 9, not does it launches the space craft in orbit also gets back the solid boosters back so that it can be reused!
I so want to write about SpaceX's Autonomous spaceport drone ships (ASDS) and its reusable boosters!!! - This is the actual beauty of embedded systems and rocket science in action!