Beginning of the Space Age

Steven Dutch, Professor Emeritus, Natural and Applied Sciences, University of Wisconsin - Green Bay


How Rockets Work

Newton's Laws of Motion are:

Newton's Laws are all contained in a more general principlecalled conservation of momentum. Momentum is mass timesvelocity, and in a system that is not disturbed from outside, thetotal momentum stays constant. Thus:

Suppose you are standing on very slick ice. You weigh 50 kg.You fire a 1 gram (.001 kg) bullet at 1000 m/sec. Its momentum is.001 x 1000 = 1 (the units are kg-m/sec, if you're curious). Tokeep the total momentum of the original system zero, you have toacquire -1 momentum. Since you weigh 50 kg, your velocity will be-1/50 or -.02 m/sec. You will start sliding backward on the iceat 2 centimeters per second. This is why a rifle has a kick.

As an aside, what matters are instantaneous changes. Once thebullet leaves the gun, it's no longer part of your system, andwhat happens to it doesn't affect you. You don't feel a momentumchange when the bullet strikes its target. Likewise, whenfriction eventually slows your slide on the ice, that doesn'taffect the bullet. Okay, go back to what you were doing.

Rockets and jets work according to Newton's Third Law. Theyfire mass out at high speed and acquire velocity in the oppositedirection. Thus, we can dispel one common myth about rockets andjets: they do not need something to push against.A rocket does not take off because it is pushing against theground, nor does a jet fly because it is pushing against the air.They move because they are expelling exhaust gases at high speeds.If you like, the rocket or jet is pushing mass away, and the massis pushing back (equal and opposite reaction.)

Rockets and jets expel mass by burning fuel. A rocket differsfrom a jet in that a jet gets the oxygen for combustion from theatmosphere, and a rocket carries oxygen in some form with it.Thus rockets can function outside the Earth's atmosphere; jetscan't.

When a rocket or jet takes off, it has to carry all itsremaining fuel with it. Most of the mass of the Space Shuttle isfuel, and most of that is used to get the remaining fuel off theground. The miles-per-gallon fuel efficiency of the Space Shuttlein its first foot off the ground is pretty terrible!

About Orbits and Satellites

Satellites travel elliptical paths with the center of theEarth at one focus (A below - Kepler's First Law, again).Anything shot from the surface of the Earth, a baseball, say, ora cannonball, travels an elliptical path, but the ellipse soonintersects the surface of the Earth again. Ballistic missiles dothe same thing except their ellipses intersect the surface of theEarth thousands of kilometers away. Nothing shot directly fromthe surface of the Earth can go into orbit; it will either fallback to Earth again or, if it's moving fast enough, escapecompletely.

Objects stay in orbit because of a balance between inertia,that would cause them to keep moving in a straight line, andgravity, that would pull them down. Isaac Newton conceived ofartificial satellites (B below). He pointed out that a cannon ona high enough mountain and firing ever faster cannonballs couldfire them to greater and greater distances. If fired with a greatenough velocity, the curvature of the cannonball's path would beequal to that of the Earth and the cannonball would circle theEarth.


satellite orbits

To get into orbit, you have to climb Newton's mountain first (C).Rockets are launched into orbit by launching them vertically toget them above the atmosphere, then accelerating themhorizontally to reach orbital velocity. It takes 29,000 km/hourto do this in low Earth orbit. You get 1670 km/hour of this forfree thanks to the Earth's rotation. That's why most satellitesare launched eastward.

Early Rockets

The Chinese invented both gunpowder and rockets over athousand years ago. Gunpowder is sulfur, carbon (charcoal) andsaltpeter (sodium nitrate - NaNO3). The oxygen for combustioncomes from the saltpeter.
(The reaction is something like: S + C + 8NaNO3 = SO2 + CO2 + 8NO2+ 4Na2O)
Chinese rockets were used for celebrations and in warfare forpsychological rather than destructive reasons.

The British encountered somewhat more dangerous rockets inIndia in the mid 1700's and began designing their own. Thestandard design was the Congreve rocket, which looks like thestereotypical Fourth of July skyrocket scaled up. It was acylinder with a conical nose and a stabilizing tail stick thatalso served to support it. The "rockets' red glare" inthe Star Spangled Banner were Congreve rockets. Themilitary advantage of rockets is that, unlike cannon, they haveno recoil, so can be launched in large numbers from a small ship.Throughout the 19th and 20th centuries rockets were usedoccasionally as artillery, more often for illumination, signaling,and occasionally carrying rescue lines and messages.

Three Pioneers of Rocketry

It is a remarkable fact that just about every majortheoretical question regarding spaceflight was worked out inadvance by amateur enthusiasts long before the technology wasavailable. The decision to put the Apollo spacecraft into lunarorbit and use a detachable lander was, in all practical respects,made before World War II. The three leading pioneers in rockettechnology were Konstantin Tsiolkovsky, Robert Goddard andHermann Oberth

Konstantin Tsiolkovsky (1857-1935), a Russianschoolteacher, was virtually unknown outside Russia for manydecades, but worked out just about every major theoreticalproblem connected with space travel. He is the theoretical fatherof space flight.

Goddard's rocket Robert Goddard (1882-1945) had his epochal vision of space travel in 1898 during the reign of Queen Victoria, and as Carl Sagan notes in Cosmos, "before anyone had ridden in an airplane or listened to a radio". Truly a remarkable goal for the time, all the more so for being able to carry much of it out. When one of his early lectures was ridiculed in the media, Goddard shunned publicity. Nevertheless he attracted funds and support from several sources, notably aviation pioneer Charles Lindbergh. Goddard launched the first liquid-fueled rocket and developed most major principles of rocket guidance. Goddard developed the rocket into a practical device.

Goddard's first prototype of 1926 is shown above.

Hermann Oberth was the only one of the three pioneersto live to see the full fruition of his ideas. In contrast toGoddard, Oberth and the German rocketry program hyped rocketry tothe fullest to raise funds and support. They found allies in theGerman military, with fateful results. Oberth can be consideredthe father of ballistic missiles.

In summary, Tsiolkovsky made rocketry theoretically possible,Goddard built the hardware, and Oberth made rockets operational.There were, of course, many other people contributing.

World War II

Future historians may well see World War II as a tremendouswatershed. Films set in the 1930's have an antiquated look aboutthem; films set in World War II seem modern. World War II saw theadvent in at least prototype form of computers, radar, jetaircraft, nuclear weapons, and missiles.

All the major powers developed and used rocket weapons inWorld War II, mostly as light artillery. The German rocketprogram was dramatically different. Set up at Peenemunde on theBaltic coast, its purpose was to develop the first strategicrocket weapons.

V-1 missile

The first German V weapon (V for Vergeltung:retaliation) was the V-1, a small pilotless jet aircraft thatcarried an explosive warhead and fell to Earth when it ran out offuel. It traveled slower than the speed of sound, could betracked on radar, and although it was faster than most aircraft,radar warnings enabled the British Royal Air Force to interceptthem and shoot them down regularly. The V-1 was the famous "buzzbomb", so called for the sound its engines made in flight.

V-2 rocket

The V-2 was a true rocket. It was about 15 meters long and twoin diameter and looked exactly like the standard depiction ofrockets in popular media of the time. It reached speeds of 5,000km/hour, altitudes of 150 km (well outside the atmosphere) andranges of several hundred kilometers. The V-2 traveled fasterthan sound, came down steeply, and hit without warning. None wereever intercepted. At the height of the V-2 campaign, they wereactually causing more casualties than the famous Blitz of 1940-41.But by this time, Germany was clearly losing and the V-2 did nothave the desired psychological effect. After D-Day, V-2's werealso fired at Allied facilities on the mainland, especially atthe port of Antwerp in Belgium. The other casualties of the V-2were the slave laborers who built the rockets and rocketfactories. More people may have died building the V-2 than diedfrom its use as a weapon.

In one incident that would do credit to Hollywood, the Polishunderground, acting in concert with the British, got to a crashedV-2 before the Germans, pushed it into a river to hide it, thenremoved key components and smuggled them to British Intelligencefor analysis.

As the Allies closed in, the German rocket program fled theadvancing Russians and most of the key personnel, includingWerner von Braun, surrendered to American forces.

The Germans, British and U.S. were all working on jet aircraftbefore or during the war, but only the Germans fielded anoperational weapon. Had it appeared early on, it would have beendevastating, but the German jets only appeared in small numbersnear the end of the war, the Germans did not fully realize theirpotential, and German production facilities were in no shape tosustain the manufacture of enough jets.

The Germans had conceived of most of the elements of a modernmissile program, if only on the drawing board. They experimentedwith underwater missile launches, developed an air-to surfacemissile that actually sank several ships, and were thinking oforbital launches and intercontinental missiles.

The Right Stuff

Although rocketry captured the news headlines in the late 1950's,many of the technical advances that made spaceflight possiblecame from the testing of high-performance aircraft. Tom Wolfe'sbook, The Right Stuff is a marvelous account of theconnections between flight testing and early space exploration.The title refers to the fact that a military jet pilot has abouta 25 per cent chance of being killed in his career, and pilotscope with this by cultivating a superstition of having "theright stuff" that will protect them from harm. The 25 percent figure, by the way, does not include combat; it is thefatality rate due to accidents and malfunctions.

X-1 supersonic aircraft

Chuck Yeager's pioneering supersonic flight was cloaked insecrecy, but after publication of Wolfe's book he becamesomething of a celebrity. Of course, long before then he was asuperstar among aviation enthusiasts. Occasionally the universedoes serve up justice. The culmination of the research inaeronautics was the X-15, one of the most successful researchaircraft ever flown. It flew about 200 times, reaching altitudesof 67 miles and speeds of 7,000 km/hour.

The Spaceflight video and writings by Wolfe andothers hint that the better approach of the X-15 was aborted bythe rush to get a human into space quickly, an error that wasonly recently corrected with the Space Shuttle. The maximumvelocity of the X-15 was only about one-fourth that required toreach orbit, and 1000 km/hr of that was provided by the B-52 thatcarried it. Since energy increases as velocity squared,the X-15 would have required 16 times as much fuel to reach orbit,plus the fuel needed to lift the additional fuel. It would be tooheavy to carry on a B-52, increasing fuel demands still more.Also, the X-15 had no life support for extended stays in spaceand had room for only one person. By the time we reconfigure theX-15 to be a viable orbital spacecraft, it would need a heavybooster to reach orbit, something developed to support the mannedspace program. The reality is that the Space Shuttle requires boththe aeronautical knowledge developed by the X-15, plus thevertical lift technology of the manned space program.

Sputnik and its Effects

early Soviet rockets The core of the Sputnik 1 launcher was an early ICBM, the SS-6. Its warhead was removed, an extra oxygen tank added in its place, and four additional boosters added around the outside.

Sputnik 1

Myth and Reality

Everyone knows that the Russians developed their space programby employing captured German scientists after World War II. Everyoneis wrong! Both the Russians and the U.S. built V-2'simmediately after the war - it was the only operational militarymissile in the world. The Russians used captured Germans to buildtheir V-2's but kept them tightly sequestered from their mainrocketry program. They were well treated and returned to Germanyin the early 1950's. And how do we know this? Because wedebriefed them after their return.

However, the often repeated story that the Soviet missile program (which in a relatively short time led to the world's first intercontinental ballistic missile and soon thereafter to Sputnik, the pioneering artificial satellite) had been the work of German rocket engineers taken into the Soviet Union after the war, is just plain nonsense. Wernher Von Braun's development team, which had fathered thc V-2, had left its Peenemunde rocket center on the Baltic before the Red Army arrived and was ultimately captured by the United States Army in southern Germany. The Soviet Army did draft a number of production engineers from the subterranean plant in the Harz Mountains back into service after the war to get the V-2 production moving again. Most of these men were indeed moved to the Soviet Union later, but, being production rather than development people, they could contribute little to more advanced missile concepts. There were a few first-class development engineers among them, but according to their own accounts (published years later), they were merely asked to offer their own ideas for possible technological improvements without being given access to secret Soviet plans for the future. Under these conditions, the work of the former Peenemunde men in the Soviet Union was mainly in support of the evaluation and improvement of the V-2. By 1953 all of them had been repatriated to Germany.

Why has the myth of the Soviet dependence of the Germanspersisted even though the truth has been in the openliterature for years? Because it's what we want to believe..Following World War II, Americans tended to believe that "Americanknow-how" would inevitably triumph. After the launch ofSputnik I, Americans were dumbfounded and simply could notbelieve that the supposedly backward Russians had gotten therefirst. The need for an explanation, plus the all-too-readytendency of the American public to believe in conspiracies,accounts for the durability of the myth.

The real hero of the Soviet space program was Sergei Korolev.Known as the "chief designer", his existence andidentity were tightly guarded secrets in the Soviet Union duringhis lifetime. He was an early pioneer of the Soviet rocketrymovement and was, in effect, a prisoner of his own brilliance,not permitted to travel abroad or appear in public. He wasfurther eclipsed by premier Nikita Krushchev's insistence ontaking the glory of the Russian space program for himself. In hisfinal years he fell from grace because of his clashes withKrushchev, but by then Soviet space technology was wellestablished.

"Sputnik", by the way, is a blend of three Russianroots: "s" means "with", "put"means "path", and "nik" meaning "one whodoes something"; in other words, someone who travels thesame path with you. It can mean "satellite" but also"fellow traveler". It's accurate to refer to theCommunist nations of Eastern Europe as satellites, but it carriesa different connotation in Russian.

Strategic Decisions

Russian view of the world, 1950's Looking at the world in 1957, the U.S. and Russia faced two different strategic challenges. We were consumed by fears of Russian advances in Europe and Asia, but the Russians had no bases close to the contiguous U.S (Cuba didn't become Communist until 1960). At that time there were no ballistic missile submarines. We, on the other hand, had military forces in Germany, Turkey, Japan, and many other places close to Russian soil, plus a huge advantage in aircraft carriers. A map centered on Russia shows them hemmed in by hostile forces. We can't entirely blame them for being a bit paranoid.

In 1950, the Russians actually were well ahead in the race todevelop the hydrogen bomb and we got there first only because ofa breakthrough by physicist Edward Teller. The Russian bombs werehuge; ours were smaller, plus we believed we could make them evenless massive. With huge bombs and a long way to enemy territory,the Russians were forced to develop massive rocket boosterscapable of lifting enormous loads. We, on the other hand,preferred to rely on bombers and our skill at miniaturization tomake smaller weapons requiring less massive rockets. Thus, whenthe first satellites were launched, the Russian satellites weremeasured in tons and ours in kilograms.

President Eisenhower is often disdained by intellectuals forpresiding over a rather bland period of U.S. history. Eisenhowerdid indeed fail badly by not reining in Joe McCarthy, but in someother ways he was well ahead of his time. More than anyone elsehe warned of the dangers of the Military-Industrial Complex andtried to avert a U.S.-Soviet arms race. He tried to allay publicfears of a "missile gap", but with little effect.

Cruise missile is a term most of us associate with thePersian Gulf War, but in fact the first cruise missile was the V-1.In the late 1940's and early 1950's, much of the U.S. missileeffort was devoted to cruise missiles before it was finallydecided they were not effective delivery systems (then) forintercontinental nuclear warfare. This factor further slowed U.S.development of heavy missiles.

Dark Days

The U.S. Army had come to Eisenhower in 1956 with a plan tolaunch a satellite, but Eisenhower insisted that U.S. spaceexploration be civilian. U.S. scientists were confident oflaunching a satellite before 1957 was out. Project Vanguard wasscheduled for launch in December, 1957, and, to the horror of anationwide news audience, toppled over and exploded on thelaunching pad.

The Army plan had already been dusted off and given the go-aheadafter the launch of Sputnik I. The satellite and upper stageswere designed, built and launched in the incredibly short time ofthree months. The first U.S. satellite, Explorer I, was launchedinto orbit on January 31, 1958.

The next few years were gloomy ones for American spaceenthusiasts. Launch failures were frequent. Soviet failures, manyfar more catastrophic than any we experienced, were hidden fordecades behind a thick veil of secrecy. In retrospect, it wasnever more than a year or so between some Soviet success and theU.S. equaling or surpassing it, but, speaking as one who livedthrough that time, it seemed like forever.

Essential Points


Illustrations of Important Rockets and Spacecraft

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Created 31 January 1998, Last Update 10 April 1998