The term “rocket” typically conjures the image of a towering cylindrical vehicle designed to soar into outer space. However, it’s important to clarify that the term “rocket” can refer to two distinct elements: a propulsion system and a vehicle powered by a rocket engine.
Understanding Rocket Engines
Similar to many other engines, a rocket engine generates thrust through the combustion of fuel. In the case of rocket engines, this process transforms the fuel into scorching hot gas. The expulsion of this gas from the engine’s rear propels the rocket forward, creating motion.
It’s important to distinguish rocket engines from jet engines. Jet engines require atmospheric oxygen for combustion, rendering them ineffective in space. Rocket engines, on the other hand, carry everything they need for combustion, enabling them to function in the vacuum of space where air is absent.
There are two primary categories of rocket engines. Some rockets utilize liquid fuel, such as the main engines on the space shuttle orbiter and the Russian Soyuz. Others rely on solid fuels, as exemplified by the white solid rocket boosters affixed to the space shuttle, as well as fireworks and model rockets.
The Science Behind Rocket Movement
In the absence of a medium to push against in the vacuum of space, how do rockets navigate and propel themselves? This is where Newton’s third law of motion comes into play. More than 300 years ago, Sir Isaac Newton established three fundamental Laws of Motion, with the third law stating that for every action, there is an equal and opposite reaction. When a rocket discharges its exhaust, it simultaneously pushes the rocket in the opposite direction. As the exhaust is expelled backward, the rocket is propelled forward. This principle is evident even on Earth – if a person stands on a skateboard and hurls a bowling ball, both the person and the ball move in opposite directions. Due to the person’s greater mass, the bowling ball travels farther.
The Historical Timeline of Rockets
The inception of rockets can be traced back to 13th-century China, where solid rockets were employed for both fireworks and military purposes. Over the next 600 years, advancements led to the development of more robust solid rockets, with many adopted for military applications.
In 1903, Konstantin Tsiolkovsky, a Russian educator, penned a paper outlining the concept of liquid-fuel rockets. In 1926, American scientist Robert Goddard conducted the inaugural flight of a liquid-fuel rocket. German scientists, under Hermann Oberth’s guidance, made further refinements to liquid-fuel rockets. During World War II, Germany deployed rockets for offensive purposes. In 1957, the Soviet Union introduced the first satellite into orbit using a rocket. In 1961, Soviet cosmonaut Yuri Gagarin made history by venturing into space aboard a rocket. In 1969, the United States utilized the Saturn V rocket to dispatch the first men to the moon, with Neil Armstrong and Buzz Aldrin making the historic lunar landing.
NASA’s Role in Rocketry
In NASA’s earlier missions, rockets produced by the military were employed. For instance, Alan Shepard became the first American in space, riding the U.S. Army’s Redstone rocket. John Glenn, the first American to orbit Earth, relied on the Atlas missile. Subsequent NASA missions, including the Gemini program, utilized the Titan II missile for astronaut launches. The Saturn I, Saturn IB, and Saturn V rockets were constructed by NASA to ferry astronauts to the moon during the Apollo missions. A Saturn V was also used for launching the Skylab space station. The space shuttle, incorporating rocket engines, facilitated astronaut transport into space. NASA continues to rely on a variety of rockets for satellite launches and interplanetary probes, encompassing the Atlas V, Delta II, Pegasus, and Taurus. Additionally, smaller “sounding rockets” are deployed for scientific research, following a suborbital trajectory.
The Future of Rocketry in NASA’s Vision
Presently, fresh rockets are in the pipeline, intended for future astronaut missions. These rockets will bear a closer resemblance to the classical rocket design – tall, cylindrical, and slender. They will transport astronauts and supplies to the International Space Station. NASA is also actively engaged in developing a potent heavy lift vehicle. This rocket will possess the capacity to transport substantial payloads into space. The collective capabilities of the heavy lift vehicle and other rockets will pave the way for exploring new frontiers, potentially enabling human missions to Mars.