2 Robert H. Goddard

Excerpt from A Method of Reaching Extreme Altitudes

Published by the Smithsonian Institution in 1919; also available at Clark University (Web site)

Since the late seventeenth century, scientists have been fascinated with the idea of space travel. The initial scientific work that allowed scientists to dream about traveling to the stars was performed by Sir Isaac Newton (1642–1727). His ideas were built upon in the eighteenth and nineteenth centuries, allowing for the development of primitive rockets—not for space travel, however, but for use in wartime. These rockets changed the face of modern warfare, but they were so inaccurate that large numbers were required to destroy a single target. By the end of the nineteenth century, warfare rockets momentarily became obsolete. Once again, some scientists turned their attention to the sky, believing rockets were the perfect vehicles to explore the cosmos. However, a majority of scientists believed that no rocket could travel outside of the upper atmosphere of Earth. American scientist Robert Hutchings Goddard (1882–1945) challenged this view.

Goddard had dreamed of space travel since he was a young boy. He trained as a physicist and in 1908 obtained a doctor of philosophy degree (Ph.D.) from the prestigious Worchester Polytechnic Institute in Worchester, Massachusetts. The following year, he joined the faculty at the Institute and began work that revolutionized the field of space travel. In 1912 he developed the complicated and detailed mathematical theory of rocket propulsion; that is, what conditions and elements are required to propel a rocket successfully into space. In 1914 he received two patents for rockets: one for a rocket that used solid fuel and one for a rocket that used liquid fuel. In 1915 he publicly declared that space travel was possible. Although his work was sound, many of his fellow scientists continued to doubt him.

Despite skepticism, in 1916 the Smithsonian Institution granted Goddard funds to continue his work on rockets. He began his research as World War I (1914–18) raged across Europe, and, like his predecessors, he developed rocket technology for use on the battlefield. His development of several types of solid-fuel rockets that could be fired from handheld devices or from devices mounted on tripods (three legged supports) forever changed modern warfare. The bazooka (a portable military weapon consisting of a tube from which antitank rockets are launched) and the immensely powerful rockets used in World War II (1939–45) were developed as a result of Goddard's work.

Goddard's most important work was not in the field of weapons development, but in space travel. In 1916 he used the funds awarded him by the Smithsonian Institute and began work on liquid rocket propulsion. He initially felt that liquid hydrogen and liquid oxygen were the best fuels for rocket propulsion, but after conducting extensive research, he concluded that oxygen and gasoline, because of their less volatile (less explosive) compositions, were superior. He theorized that using these fuels in a properly designed apparatus (a rocket), the upper atmosphere, which was impossible to reach by hot air balloon, could be reached. The rocket would have to travel at the speed of 6.95 miles (11.18 kilometers) per second (in a vacuum without air resistance) to overcome the pull of Earth's gravity and soar into space. He also stated that, by using his calculations, human beings could reach the Moon. In 1919, he published these findings in the classic study A Method of Reaching Extreme Altitudes.

Goddard was ridiculed by his fellow scientists and the popular media. The New York Times was extremely critical, questioning Goddard's scientific training and dismissing him as a misled dreamer in an editorial published on January 18, 1920. The following is an excerpt of Goddard's revolutionary paper, A Method of Reaching Extreme Altitudes.

Things to remember while reading an excerpt from A Method of Reaching Extreme Altitudes:

• Goddard wrote during a time when space travel was an idea in science fiction. Stating that human beings could actually send someone to the Moon and have that person return safely was revolutionary.
• In this excerpt, Goddard discusses the amount of fuel necessary to carry a rocket away from Earth and into space. He reaches these conclusions by conducting experiments based on the amount of flash powder (powder that, once ignited, produces a large flash of light) needed to produce visible light at certain distances. With these figures he makes his fuel calculations.

Excerpt from A Method of Reaching Extreme Altitudes

It is of extreme interest to speculate upon the possibility of proving that such extreme altitudes had been reached even if they actually were attained. In general, the proving would be a difficult matter. Thus, even if a mass of flash powder, arranged to be ignited automatically after a long interval of time, were projected vertically upward,the light would at best be faint, and it would be difficult toforetell, even approximately, the direction in which it would most likely appear.

The only reliable procedure would be to send the smallest mass of flash powder possible to the dark surface of the moon when in conjunction (i.e., the "new moon"), in such a way that it would be ignited on impact. The light would then be visible in a powerful telescope. Further, the larger theaperture of the telescope, the greater would be the ease of seeing the flash, from the fact that a telescope enhances the brightness of the point sources, and dims the faint background.

An experiment was performed to find the minimum mass of flash powder that should be visible at any particular distance. In order to reproduce, approximately, the conditions that would obtain at the surface of the moon, the flash powder was placed in small capsules … held in glass tubes, closed by rubber stoppers. The tubes wereexhausted to a pressure of from 3 to 10 centimeters of mercury, and sealed, the stoppers being painted with wax, to preserve thevacuum. Twoshellacked wires, passing to the powder, permitted the firing of the powder by an automatic spark coil.

It was found that Victor flash powder was slightly superior to a mixture of powderedmagnesium andsodium nitrate, in atomic proportions, and much superior to a mixture of powdered magnesium andpotassium chlorate, also in atomic proportions.

In the actual test, six samples of Victor flash powder, varying in weight from 0.05 gram to 0.0029 gram were placed in tubes … and these tubes were fastened in blackened compartments of a box. The ignition system was placed in the back of the same box…. This system, comprised of a spark coil, operated by three triple cells of "Ever-ready" battery, placed two by two in parallel. The charge was firing on closing the primary switch at the left. The six-point switch at the right served to connect the tubes, in order, to the high-tension side of the coil.

The flashes were observed at a distance of 2.24 miles on a fairly clear night; and it was found that a mass of 0.0029 grams of Victor flash powder was visible, and that 0.015 gram was strikingly visible, all the observations being made with the unaided eye. The minimum mass of flash powder visible is thus surprisingly small.

From these experiments, it is seen that if this flash powder were exploded on the surface of the moon, distant 220,000 miles, and atelescope of one foot aperture were used—the exit pupil being not greater than the pupil of the eye (e.g., two millimeters)—we should need a mass of flash powder of

2.67 pounds, to be just visible, and

13.82 pounds or less, to be strikingly visible.

If we consider the final mass of the last "secondary" rocket plus the mass of the flash powder and its container, to be four times the mass of the flash powder alone, we should have, for the final mass of the rocket, four times the above masses. These final masses correspond to the "one pound final mass" which has been mentioned throughout the calculations.

The "total initial masses," or the masses necessary for the start at the earth, are at once obtained from the data given in table VII [not included]. Thus if the start is made from sea-level, and the "effectivevelocity of ejection" is 7,000 feet/second, we need 602 pounds for every pound that is to be sent to "infinity. "

We arrive, then, at the conclusion that the "total initial masses" necessary would be

6,436 pounds or 3.21 tons; flash just visible, and 33,278 pounds or 16.63 tons (or less); flash strikingly visible.

A "total initial mass" of 8 or 10 tons would, without doubt, raise sufficient flash powder for clear visibility.

These masses could, of course, be much reduced by the employment of a larger telescope. For example, with an aperture of two feet, the masses would be reduced to one-fourth of those just given. The use of such a large telescope would, however, limit considerably the possible number of observers. In all cases, the magnification should be so low that the entire lunar disk is in the field of the telescope.

It should be added that the probability of collision of a small object with meteors of the visible type is negligible….

This plan of sending the mass of flash powder to the surface of the moon, although a matter of general interest, is not of obvious scientific importance. There are, however, developments of the general method under discussion, which involve a number of important features not herein mentioned, which could lead to results of much scientific interest. These developments involve many experimental difficulties, to be sure; but they depend upon nothing that is really impossible.

Summary

1. An important part of the atmosphere, that extends for many miles beyond the reach of sounding balloons, has up to the present time been considered inaccessible. Data of great value inmeteorology and insolar physics could be obtained by recording instruments sent into this region.
2. The rocket, in principle, is ideally suited for reaching high altitudes, in that it carries apparatus without jar, and does not depend upon the presence of air for propulsion. A new form of rocket apparatus, which embodies a number of improvements over the common form, is described in the present paper.
3. A theoretical treatment of the rocket principles shows that, if the velocity ofexpulsion of the gases were considerably increased and the ratio of propellant material to the entire rocket were also increased, a tremendous increase in range would result, from the fact that these two quantities enterexponentially in the expression for the initial mass of the rocket necessary to raise a given mass to a given height.
4. Experiments with ordinary rockets show that the efficiency of such rockets is of the order of 2 percent, and the velocity of ejection of the gases, 1,000 feet/second. For small rockets the values are slightly less.

With a special type of steel chamber and nozzle, an efficiency has been obtained with smokeless powder of over 64 percent (higher than that of any heat engine ever before tested); and a velocity of nearly 8,000 feet/second, which is the highest velocity so far obtained in any way except in electrical discharge work.

• 5. Experiments were repeated with the same chamber in vacuo, (in a vacuum) which demonstrated that the high velocity of the ejected gases was a real velocity and not merely an effort of reaction against the air. In fact, experiments performed at the pressures such as probably exist at an altitude of 30 miles gave velocities even higher than those obtained in air at atmospheric pressure, the increase in velocity probably being due to a difference inignition. Results of the experiments indicate also that this velocity could be exceeded, with a modified form of apparatus.
• 6. Experiments with a large chamber demonstrated that not only are large chambers operative, but that the velocities and efficiencies are higher than for small chambers.

• 7. A calculation based upon the theory, involving data that is in part obtained by experiments, and in part what is considered as realizable in practice, indicates that the initial mass required to raise recording instruments of the order of one pound, even to the extreme upper atmosphere, is moderate. The initial mass necessary is likewise not excessive, even if the effective velocity is reduced by half. Calculations show, however, that any apparatus in which ordinary rockets are used would be impracticable owing to the very large initial mass that would be required.
• 8. The recovery of the apparatus, on its return, need not be a difficult matter, from the fact that the time of ascent even to great altitudes in the atmosphere will be comparatively short, due to the high speed of the rocket throughout the greater part of its course. The time of descent will also be short; but free fall can be satisfactorily prevented by a suitable parachute. A parachute will be operative for the reason that high velocities and small atmospheric densities are essentially the same as low velocities and ordinary density.
• 9. Even if a mass of the order of a pound were propelled by the apparatus under consideration until it possessed sufficient velocity to escape earth's attraction, the initial mass need not be unreasonably large, for an effective velocity of ejection which is without doubt obtainable. A method is suggested whereby the passage of a body to such an extreme altitude could be demonstrated.

Conclusion

Although the present paper is not the description of a working model, it is believed, nevertheless, that the theory and experiments, herein described, together settle all points that could seriously be questioned, and that it remains only to perform certain necessary preliminary experiments before an apparatus can be constructed that will carry recording instruments to any desired altitude.

What happened next …

The negative response to Goddard's findings did not stop the scientist from conducting more work. Although he became more reclusive and was rarely seen in public, Goddard was awarded 214 patents (documents securing to an inventor for a term of years the exclusive right to make, use, or sell an invention) in the area of rocket science. He built the first

liquid-fueled rocket, and his designs for fuel pumps, motors, and other essential components provided the foundation upon which all future rockets were built. On March 16, 1926, Goddard launched his first rocket, powered by oxygen and gasoline. The apparatus took only 2.5 seconds to rise 184 feet (56 meters). Most historians regard this event as the birth of modern rocketry. Not satisfied with this accomplishment, Goddard achieved another first on July 17, 1929, near Auburn, Massachusetts, when he flew the first instrument carrying a rocket; aboard was a camera to record the readings of an aneroid (liquidless) barometer (an instrument for determining the pressure of the atmosphere and for assisting in forecasting weather and determining altitude) and a thermometer. However, the launch was a failure. After rising 90 feet (27.43 meters), the rocket crashed. The fire caused by the crash was so severe that the neighbors complained and Goddard was forbidden to launch rockets in Massachusetts in the future.

Goddard was able to continue his work, however, largely due to the interest of Charles Lindbergh (1902–1974), who conducted the first solo airplane flight across the Atlantic. Goddard was awarded fifty thousand dollars by a private philanthropist, and used the money to establish a private experiment station near Roswell, New Mexico. There, from 1930 to 1941, Goddard launched a number of rockets, each more complex and advanced than the last. He developed the technology that allows a rocket to be steered by propelling the exhaust with a rudder like device. In 1941, Goddard achieved his greatest success when he successfully launched a rocket to an altitude of 9,000 feet (2,743 meters). That same year, he worked with the naval service to develop rockets to assist jet planes taking off from aircraft carriers. He died in Baltimore, Maryland, on August 10, 1945, but his research affected science for decades to come.

Did you know …

• Long before the first person walked on the Moon or even traveled in space, Goddard thought that human beings could travel to the Moon and many other planets.
• Goddard theorized that jet planes could take off from aircraft carriers with minimal runway distance. He also envisioned a rocket-borne, or transported mail and express delivery service and pioneered research into nuclear-powered rockets.
• After World War II, the United States wanted to develop its own rockets, but Goddard had died by that time. His work, however, allowed them to understand the intricacies of rocket science.
• In 1960, the U.S. government officially recognized Goddard's pioneering work by awarding his estate one million dollars for his 214 patents.

Consider the following …

• Imagine you are a scientist living in the first half of the twentieth century. Automobiles are still a recent invention; airplane travel is less than fifty years old; more Americans listen to the radio than watch (or own) a television. How would you respond to someone who claimed that we could travel to the Moon? Would you believe this person? Why or why not?
• Many scientists have worked closely with the armed forces to develop weapons. Some, such as Albert Einstein (1879–1955), later regretted such work. If you were a scientist, would you want to work in weapons development? Why or why not?
• Goddard's pioneering rocket research led to several advancements in space travel. If you could invent something for your own personal use that used rocket technology, what would it be?

For More Information

Books

Goddard, Robert H. The Autobiography of Robert Hutchings Goddard, Father of the Space Age; Early Years to 1927. Worcester, MA: A. J. St. Onge, 1966.

Goddard, Robert H. Rockets. Mineola, NY: Dover Publications, 2002.

Lehman, Milton. Robert H. Goddard: Pioneer of Space Research. New York: Da Capo, 1988.

Winter, Frank H. Rockets into Space. Cambridge, MA: Harvard University Press, 1990.

Periodicals

Crouch, Tom D. "Reaching Toward Space: His 1935 Rocket Was a Technological Tour de Force, But Robert H. Goddard Hid It from History." Smithsonian (February 2001): p. 38.

Web Sites

Goddard, Robert H. A Method of Reaching Extreme Altitudes. Washington, DC: Smithsonian Institution, 1919; also available at Clark University.http://www.clarku.edu/offices/library/archives/GoddardSources.htm (accessed on July 19, 2004).

"Robert H. Goddard: American Rocket Pioneer." Goddard Space Flight Center, NASA.http://www.gsfc.nasa.gov/gsfc/service/gallery/fact_sheets/general/goddard/goddard.htm (accessed on July 19, 2004).

"Robert Goddard (1882–1945)." About.com.http://inventors.about.com/library/inventors/blgoddard.htm (accessed on July 19, 2004).

"Robert Goddard and His Rockets." Goddard Space Flight Center, NASA.http://www-istp.gsfc.nasa.gov/stargaze/Sgoddard.htm (accessed on July 19, 2004).

Foretell: Predict.

Aperture: Opening.

Exhausted: Emptied.

Vacuum: A space devoid of matter; emptiness of space.

Shellacked: Sealed with a varnish like substance.

Magnesium: Metallic element used in chemical processes.

Sodium nitrate: Form of salt used as an oxidizing (combined with oxygen) agent.

Potassium chlorate: Oxidizing agent used in explosives.

Velocity: Quickness of motion; speed.

Infinity: Unlimited extent of time, space, or quantity.

Meteorology: Science that deals with the weather or weather forecasting.

Solar physics: Science that deals with matter and energy and their interactions relating to the Sun.

Expulsion: Ejection.

Exponentially: Rapidly increasing in size.

Ignition: Act of igniting; starting a fire.