Katherine Johnson’s calculations of orbital mechanics were critical to the success of NASA’s space exploration programme. She was known for her mastering of complex calculations and helped pioneer the use of computers. Through the story of Katherine Johnson we will look at the history, and future of space exploration.
Katherine G. Johnson was born in 1918 in West Virginia, USA. Johnson showed a strong ability for mathematics from a young age, so much so that she was enrolled in high school when she was only 10 years old. At the age of 14, she attended College and took every maths course that was offered. Eventually, Johnson was offered a job with the National Advisory Committee for Aeronautics (NACA – which would soon become NASA). At first she worked in a pool of women performing maths calculations. Their main job was to read the data from the black boxes of planes and carry out other precise mathematical tasks. Then one day, Katherine (and a colleague) were temporarily assigned to help the all-male flight research team. Katherine’s knowledge of analytic geometry helped make quick allies of male bosses and colleagues. While the racial and gender barriers were always there, Katherine says she ignored them. Katherine was assertive, asking to be included in editorial meetings (where no women had gone before). She simply told people she had done the work and that she belonged. The 2016 film ‘Hidden Figures’ tells the story of her involvement in the early days of NASA.
From 1958 until her retirement in 1986, Johnson worked as an aerospace technologist, moving during her career to the Spacecraft Controls Branch. She calculated the trajectory for the May 5, 1961 space flight of Alan Shepard, the first American in space. She also calculated the launch window for his 1961 Mercury mission. She plotted backup navigation charts for astronauts in case of electronic failures. When NASA used electronic computers for the first time to calculate John Glenn’s orbit around Earth, officials called on Johnson to verify the computer’s numbers; Glenn had asked for her specifically and had refused to fly unless Johnson verified the calculations. The calculations carried out by Katherine Johnson helped launch a new era in space exploration.
The greatest advances in rocket technology happened in the 1930s and eventually lead to manned spaceflights a few decades later. The most important developments in rocket technology are:
- Engine nozzle size and shape
- Research on escape velocity and rocket staging
- Re-entry technology and techniques
In rocketry, the chemicals used in the rocket engine are called propellants. When they are ignited, the propellants create a lot of exhaust gases which shoot out of the bottom of the rocket, sending it flying upwards. The propellant comes in two forms, a fuel and an oxidiser. Both are required to create upward thrust. They can come as liquid propellants or solid propellants. Solid fuels give a greater amount of thrust but once it is ignited, it cannot stop. Solid fuels are best used for missiles, or to boost rocket engines. Liquid fuels can be controlled in a much more precise way so they are used in the main engines of the space shuttle.
The escape velocity is the speed a rocket needs to achieve to escape the force of Earth’s gravity. Because the earth is so massive compared to any object on it (including a space shuttle), the force of gravity acting on that object is huge. This is why rockets need a large thrust force upwards to overcome this. If the escape velocity is not reached, the rocket will eventually fall back to earth and not make it in to outer space. Spaceflight can be very complicated, especially if you were trying to land on the moon (that has its own gravitational pull) so a space rocket has to have different stages to deal with each step in the journey.
As well as trying to escape from the earth’s gravitational field, rockets can have difficulty when they are trying to re-enter earth’s atmosphere on their way back to earth. The atmosphere can cause friction problems when they try to land. There are three key things that a spacecraft has to take into account and they are:
- The shape of the nose of the aircraft
- The angle of attack
- The re-entry angle
Space Technology Spin Offs
Space exploration can get very complicated. The physicists who design spacecrafts have to come up with creative solutions to problems they would never have imagined. Some of these solutions have turned into technology that we use in our everyday lives. Things like the cordless drill, the horse riding helmet, freeze dried food and Kevlar body armour would not be in our lives today without first being invented for use in spaceships.