From the beginning of humanity, people have wondered: What's out there? It began as stargazing but eventually gave way to science, with human curiosity driving the discovery of new and more innovative ways to slip the surly bonds of Earth.

While rocket launch technology is now developing at a breakneck pace, it's worth taking a look back at the evolution of space exploration — where did we start? Where have we been? And where are we going next?

Eyes to the Skies

With rapid advances in rocketry largely coming over the last century, it's easy to suggest technology as the driving factor: Without the right materials and equipment, surely rocket launches were out of reach.

Not quite. Historical records show burgeoning interest in rocket precursors, such as steam-powered devices, around 400 B.C., and it's generally agreed that Chinese innovators developed the first real rockets in the first century A.D. Much like modern fireworks, these small rockets were often used in local and religious festivals, and so-called "Chinese fire arrows" were also used against Mongol invaders.

Further refinement over the next millennium led to more extensive use of rockets in warfare. For example, the Congreve rocket used in the late 1700s was a stick-guided rocket capable of carrying incendiary or antipersonnel munitions up to two miles. By 1844, spin stabilization techniques, which made rockets spin like a bullet using angled jet vents, were implemented for greater accuracy.

Making It Work

In 1898, Russian schoolteacher Konstantin Tsiolkovsky suggested that rockets might be capable of space travel if they could achieve great enough range and speed. His solution was liquid propellant. That way, rockets would only be limited by the velocity of escaping gases. To underpin this idea, he developed the Rocket Equation:

$\Delta v=v_{\text{e}}\ln {\frac {m_{0}}{m_{f}}}=I_{\text{sp}}g_{0}\ln {\frac {m_{0}}{m_{f}}}$

The equation applies to any device with the characteristics of a rocket — that is, it can apply acceleration to itself using thrust generated by expelling its mass at high velocity. For his substantive contributions to the field, Tsiolkovsky is often called the father of modern astronautics.

Next came work from Robert H. Goddard and Hermann Oberth. Oberth helped develop Germany's suite of advanced V-2 rockets that could achieve massive thrust over short distances by burning one ton of alcohol and oxygen every seven seconds, while Goddard developed plans for both two-stage and three-stage rockets along with gyroscope flight instruments and parachute-equipped cargo containers. He was the first to launch a rocket powered by liquid and gasoline.

Up, Up and Away!

It all came together on October 4, 1957 when the Soviet Union successfully launched the first rocket into space. The R-7 ICBM rocket carried Sputnik, humanity's first satellite, into orbit. Being about the size of a beach ball, Sputnik only transmitted a signal for just over two weeks and burned up in the atmosphere on January 4, 1958 after its orbit decayed.

By January 31, 1958 the United States launched a rocket of its own, Explorer I, and in October 1958, the National Aeronautics and Space Administration (NASA) officially launched.

The Race to Space

These ongoing efforts also launched the space race. Both Russia and the United States threw everything they had into creating better, faster and safer rockets that were capable of sustained space travel.

The US began with the Mercury program. The Mercury-Redstone launch vehicle used a combination of liquid oxygen and alcohol to produce 78,000 pounds of thrust — enough to send astronaut Alan Shepard into space. The Mercury-Atlas launch vehicle, meanwhile, lifted John Glenn into orbit with 365,000 pounds of thrust.

The Gemini program came next and saw the world's first spacewalk and in-orbit rendezvous. Getting there required the Gemini-Titan II launch vehicle, which boasted an impressive 430,000 pounds of thrust.

This paved the way for the iconic Apollo program and moon landing, but getting from Earth to its small, rocky companion was no easy task. To accomplish this goal, the Saturn V rocket weighed more than 6.1 million pounds at launch and generated 7.5 million pounds of thrust — more than 17 times the thrust of the Gemini-Titan II. The familiar space shuttle, meanwhile, which was used to carry crews into space from 1981 to 2011, clocked in at 7.8 million pounds of thrust.

Passengers Come on Board

The rockets themselves weren't the only things getting upgrades. What began as unmanned space flights eventually led to rocket launches that included primate passengers as human analogues to assess the impact of spaceflight on circulatory, nervous and skeletal systems.

First was Albert the rhesus monkey in 1948, followed by his successor Albert II in 1949 and then Albert III through VI in quick succession. Sadly, all died either in space or shortly after their return. In 1959, the United States successfully recovered Able the rhesus monkey and Baker the squirrel monkey alive after their flight and did the same with a chimpanzee named Ham in 1961.

This paved the way for Alan Shepard's historic flight into space on May 5, 1961, followed by John Glenn's orbit of Earth in February 1962. In 1963, cosmonaut Valentina Tereshkova was the first woman in space aboard the Vostok 6, and in 1983, mission specialist Sally Ride became the first American female astronaut in space on the seventh space shuttle mission.

All Systems Go

What's next for rockets? First up is even more power. With NASA looking to send astronauts back to the moon and eventually to Mars, a new space shuttle launch system (SLS) was required. While it bears some visual similarity to the retired space shuttle, it's taller and heavier, and it will generate up to 8.8 million pounds of thrust — 15% more than its Saturn V counterpart.

There's also a push to make rockets reusable. Historically, the first stages of multi-stage rockets were unrecoverable after being jettisoned when they ran out of fuel. Now, companies are working on reusable stage one and two boosters that can return to Earth intact and upright. Not only could this reduce the total amount of rocket launch waste being created, but it's much more cost- and time-efficient to refuel and reuse these boosters than it is to build new ones from scratch.

This is rocket science — two millennia worth. While launch efforts are finally hitting their stride as technology and innovation collide, they're built on a platform of human curiosity that's always been determined to discover what lies beyond.

Being on the forefront of change, especially regarding space, physics, and engineering has been part of the Northrop Grumman culture for generations. Click here to search jobs in these areas of scientific innovation.

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Gemini

Rocket Launch Rundown: Exploring Two Millennia of Space Travel

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