The science of flight and space

Bridging Earth’s atmosphere and beyond

The concept of aviation and space exploration can be traced back to classical antiquity, where dreams of soaring through the skies and beyond captivated the human psyche. Even before the advent of modern technologies, visionaries like the famous artist Leonardo da Vinci had already pondered the principles behind flight. In his 15th-century paintings, Da Vinci sketched the first drafts for a rational aircraft on which the concept of the modern-day helicopter is based. Furthermore, Greek mythology tells the story of Daedalus, an inventor, who created wings from feathers and wax to escape from captivity with his son, Icarus, and challenge the gods. While ancient humans lacked the technology to accomplish their ambitions, this did not stop them from experimenting. Their quest led to the invention of kites, hydrogen-powered hot-air balloons and eventually the successful motoroperated aeroplane of the Wright brothers.

While aviation focuses on conquering Earth’s atmosphere, space exploration aims to explore the cosmos. The journey began in 1957 with the launch of the Soviet Union’s Sputnik 1, the world’s first artificial satellite. This event marked the beginning of the Space Age. In the following years, significant milestones were achieved, including the first human spaceflight by Yuri Gagarin in 1961 and the historic Apollo 11 mission in 1969, which saw Neil Armstrong and Buzz Aldrin become the first humans to set foot on the Moon. As technology advanced, space exploration expanded beyond the Moon, with robotic missions exploring other planets and moons in our solar system. Notable examples include the Voyager missions to the outer planets, the Mars rovers and the Cassini spacecraft’s exploration of Saturn.

One fundamental concept that sets space travel apart from aviation is escape velocity, which is the minimum speed an object needs to break free from a celestial body’s gravitational pull – in this case, the gravitational force of Earth. Unlike aeroplanes, which rely on lift and thrust to counteract gravity, spacecraft must attain tremendous speeds to escape from Earth’s gravity well. The escape velocity of Earth is approximately 40,270 km/h, or 11,186 m/s. Rocket engines operate on Newton’s third law of motion, expelling high-velocity exhaust gases to generate thrust in the opposite direction. This allows launch vehicles to achieve these enormous speeds.

From Da Vinci's sketches to Sputnik's launch, the intertwined evolution of flight and space exploration illuminates humanity's relentless pursuit of the skies and beyond, a testament to innovation and determination.

Aeroplane engines require oxygen from air to burn fuel. However, spacecrafts have propulsion and manoeuvring systems that use reaction propulsion and do not need to be immersed in air to fly; they are ruggedly built and can be pressurised in the absence of air. Like an aeroplane’s jet engine, a spacecraft uses rocket boosters to provide the means of acceleration. Liquid-fuelled rocket engines burn fuel mixed with an onboard oxidiser, while solid-fuel rocket engines have the propellant and oxidiser mixed; once ignited they burn till the propellant supply is exhausted. In addition, aeroplanes must rely on the principle of aerodynamics to generate lift and overcome the forces of gravity and drag. The wing shape and angle of attack coupled with Bernoulli’s principle – which states that the pressure within a moving fluid (liquid or gas) decreases as its speed increases – allow air to flow faster over the curved upper surface, creating lower pressure and producing lift. On the other hand, spacecraft must employ orbital mechanics to navigate in space. Orbital mechanics focuses on spacecraft trajectories, including orbital manoeuvres, orbital plane changes and interplanetary transfers. The Cassini spacecraft, which was launched in 1997, used a technique called gravity assist or gravitational slingshot to gain momentum and adjust its trajectory through the gravitational pull of Venus, Earth and Jupiter. This technique is a fundamental application of orbital mechanics.

Space travel presents numerous challenges that differ significantly from aviation. Spacecrafts must endure extreme temperature fluctuations, radiation and micrometeoroid impacts. Thermal control systems, shielding materials and robust structural designs are essential to protect the spacecraft and its occupants or payloads. Additionally, longduration space missions demand careful consideration of life support systems, nutrition and psychological well-being.

While aircraft and spacecraft differ significantly in terms of their operating environments and specific design requirements, there are similarities. Both aircraft and spacecraft are complex machines with numerous interconnected systems. These systems include power generation, fuel storage, environmental control, electrical systems and avionics. Sophisticated navigation and control systems are crucial for both aircraft and spacecraft, as they utilise onboard sensors and computerised systems to monitor and adjust their flight paths, orientation and trajectory. Whether it is a GPS for aircraft or celestial navigation for spacecraft, accurate positioning and control are essential for safe and efficient operations.

The science of flight and space exploration share a deep connection, with each discipline building upon the principles and technologies developed by the other. By understanding the similarities and differences between these two realms, we gain a greater appreciation for the challenges and achievements of both aviation and space travel.

Victoria N Nakafingo