Today’s topic, space. As I mentioned yesterday, this week, I would like to discuss topics related to technology, but also innovation and business, coincidentally, the areas in which my research is positioned.
I have always been intrigued by space exploration, not only because of the fantastic photos that the Hubble telescope has produced, or the gigantic rockets used to accelerate humans into escape velocity (cool name) but mostly for the sheer notion of stepping into the unknown. In a way, that is the reason why I decided to do a PhD. I believe that the primary purpose of a doctoral degree is to prepare scholars to deal with uncertainty. And what could be more uncertain than everything that lies beyond a couple of hundreds of kilometres above us? But first, let’s consider what space is, and what it means to go to space.
Unless quantum mechanics or extra-terrestrial life proves me wrong. We all are very lucky to live at the exact time and the precise corner of the universe; where the temperature is just right, there is enough water to support life and hasn’t been hit (lately) by any of the myriads of objects floating around. These conditions, along the millions of years that nature used to experiment with the elements of life, has brought us to this moment. Life on Earth is also possible thanks to the protection of the atmosphere and magnetosphere; also enabled by the conditions as mentioned earlier.
The atmosphere is also the closest thing that we have to a distinction between Earth and space; however, it is not a concrete barrier or boundary. Instead, the atmosphere is a set of layers of gases, such as nitrogen, oxygen, among many others. We call this mix of gases air, and its exact composition varies along with its distance from the Earth’s core. This variation is created by a little force called gravity. As you might have heard, gravity is the thing holding our feet on the ground, but it also pulls the heaviest gases in the atmosphere closer to the core whereas lighter elements can stretch farther into space. Gravity is also the force making it extremely hard to leave Earth.
But it turns out that humans have been thinking about how to escape gravity’s force for quite some time. Sir Isaac Newton has been credited with a counterintuitive thought experiment describing the principle behind escaping gravity. First, imagine a cannon firing to the air, there is nothing in the path of the cannonball, and the air resistance is negligible. Once shot, the cannonball has two forces acting upon it. The force from the cannon and the force of gravity, the former pushing it forward and the latter pulling it downwards. Close to the surface, gravity is mostly constant, which means that in an infinitely flat surface, the cannonball will always end up in the ground. However, one could increase the distance that it travels by adding more force from the cannon.
For the second part, let’s change the flat surface for a round one; such as the surface of the Earth. Also, in this scenario gravity is pulling towards the centre. Similar to the flat surface, gravity is pulling the cannonball to the ground; however, the more force we add to the cannonball, the farther it gets. Since the surface is round, instead of distance, we can measure how far the ball goes by the arc of the surface it covers. An interesting note about gravity is that at a given altitude, it remains constant parallel to the round surface. As a result, the cannonball always takes the same amount of time to fall to the ground. Every time we add force to the cannonball, we increase its speed; thus, it reaches farther in the same amount of time. If we keep increasing its speed, and there is no other disturbance, there will be a point where the ball will keep going without hitting the surface. This speed is called escape velocity because an object would need to accelerate beyond this point to get away from the gravitational pull. Earth’s escape velocity is around 11.2 km/s.
Reaching this speed is not an easy feat. The International Space Station orbiting the Earth at about 400 km above the surface travels 7.6 km/s, circling Earth every 90 min. Enough speed to avoid falling onto the surface, but enough to keep it orbiting. Conversely, Voyager, a satellite especially designed to get as far as possible from Earth, is travelling at almost 17 km/s. Designer of both space missions had to consider these and many, many more variables to succeed.
Space exploration has been an outstanding field for discovery, innovation and human progress. Unfortunately, I’m am running beyond my word limit, so, I will make this a two-part series. Tomorrow, I will discuss the successes and failures of the space era. Also, let me know if my explanation of space velocity made sense to you. In any case, read you tomorrow.
Carlos Carbajal 