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Figure 1. Dr. Robert H. Goddard before the flight of his first liquid- propelled rocket in Auburn, MA, on March 16, 1926. Photo available at go.nasa.gov/2MPRSCD.
could be used to lift rockets to higher altitudes, the so- called step rocket, was initially developed in the 16th cen- tury by a firework maker for enhancing firework displays (see bit.ly/2Ln7TLH). Its principles are still fundamental to the launch of orbital vehicles today. A significant break- through came in the 17th century when Sir Isaac Newton developed the scientific foundations for modern rocketry. His three laws governing physical motion explained how and why rockets work and could be used to inform future rocket design. However, improvements in rocket accuracy were not achieved for another two hundred years, until the technique of spin stabilization was developed. In spin sta- bilization, the exhaust gases strike small vanes, causing the rocket to spin as it travels. This is the same principle that bullets use today.
Still, modern rocketry belongs to the 20th century. Although early rockets were propelled by solid fuels, modern scientists thought (Tsiolkovsky, 1903; Goddard, 2002) that they could achieve greater speed and range by using liquid fuel. Ameri- can rocketry pioneer Dr. Robert H. Goddard (see Figure 1) achieved the first successful liquid-propelled rocket flight in Auburn, MA, on March 16, 1926 (see bit.ly/2Lr9FeI for video of the first liquid-fueled rocket launch). The outbreak
of World War II caused attention to shift almost exclusively to the development of rockets for use as weapons. They be- came such important elements of warfare that had research advanced more quickly on Germany’s V-2 rocket, designed by Wernher Von Braun, the course of the war would almost certainly have been significantly changed. Similarly, it was the military as well as the scientific uses of rocket technol- ogy that made Sputnik such a historic event. Its successful launch caused great anxiety for the Americans who feared a widening technological gap between the two so-called su- perpowers, the United States and USSR.
In December 1957, American scientists made their first at- tempt to launch a satellite into orbit. The Vanguard TV3 ig- nited and began to rise but immediately lost thrust and fell back to the launch pad (see bit.ly/1bvmJxp to view the un- successful Vanguard TV3 launch). Finally, in early 1958, the United States successfully launched its first satellite, Explor- er 1, which returned data for nearly four months and which remained in orbit until 1970 (see bit.ly/2P5dQPy that shows the US (National Aeronautics and Space Administration [NASA]) Space Explorations of 1958, including the first five US satellites). Following Explorer 1, satellite technology de- veloped quickly and by the mid-1960s, satellites were preva- lent and were being widely used for digital telecommunica- tions. To date, more than 6,600 satellites have been launched from 40 countries. There are currently approximately 3,600 in orbit, 1,000 of which are operational.
And We Have Liftoff...
Rocket “launch” is the liftoff phase in a rocket’s flight. Or- bital launch vehicles, rockets that are capable of placing pay- loads into or beyond Earth orbit, typically lift off vertically (or near vertically) before progressively leaning over as they use gravity to steer the vehicle onto the required trajectory in order to exit Earth’s atmosphere. Once rockets have com- pleted the transonic climb phase through the atmosphere, they reach the desired altitude by angling slightly below the horizontal. This maneuver also increases their horizontal speed until it reaches orbital speed, at which point the en- gine cuts out. Because single-stage orbital rockets require an excessive amount of fuel, all current rockets are multistage vehicles, meaning that they jettison hardware (stages) on the way to orbit. The jettisoned stages are either lost or recovered and reused as in SpaceX’s recently developed Falcon rockets.
The launch environment, which typically lasts only a few minutes, is the most severe dynamic environment that a spacecraft will endure during its normal life (Martinez-Val
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