![]() To get the most out of the delta-v, rockets need to be as efficient as possible, and this means only firing for short periods at key moments. Delta-v in space works similarly to gas in a car here on Earth – you can use it until it’s gone, and then you can’t do anything else. For this reason, most rocket scientists use a concept called ‘delta-v,’ which quantifies the ability of a rocket to change its speed, and in turn, its orbit. But in space, as a rocket burns fuel, it gets lighter, which allows it to do more with the fuel that remains. When we drive a car, we know how much fuel we have and roughly how far that fuel can take us. With orbital mechanics, fuel doesn’t work the same way it does in a car on the ground. With only a fraction of its fuel left, how can a spacecraft go anywhere? The answer is that the typical rules of the road don’t apply in space, and motion is governed by a field of physics known as Orbital Mechanics. It was big and heavy, and it needed two boosters and a big rocket, containing 20 times its weight in fuel, just to get it into orbit around the Earth. By the time they have reached space, they’ve shed 80–95% of their size and weight as fuel is burned and empty fuel cells are dropped. On the launch pad, rockets are tall, heavy, and powerful. STS-120 launch of the Discovery Space Shuttle on October 23rd, 2007. This is what an orbit is – an object falling toward the Earth, but moving so quickly horizontally that it avoids a collision and keeps falling. For this reason, most rockets start tilting only a few seconds after they clear the launchpad so they can get enough horizontal speed to fall aroundthe Earth. Have you ever noticed that rockets don’t launch directly upward? If they did, they would definitely reach space, but then they’d fall right back down, never actually circling the Earth. Once you’re in space, it gets a lot easier to move around. In fact, the most difficult part of everyspace flight is leaving the Earth. The first human space flight took decades of research, money, technological development, and trial and error, a big part of which came from German rocket development during World War II. The short answer is that flying into space is really difficult. Yet with all our real-world technological prowess, why haven’t any of these dreams become reality? Science fiction has captured humanity’s dreams of travelling to distant stars, colonizing new worlds, accessing new dimensions, encountering hostile aliens, and surviving a galaxy far, far away. ![]() ![]() Ryan Marciniak, Astronomy and Physics Co-Editor ![]()
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