Sally Ride: First U.S. Woman in Space, and More


To mark the thirtieth anniversary of Sally Ride’s historic first spaceflight, here is an updated version of a previous post.

Sally Ride

Sally Ride was the first American woman in space.

As she became the first American woman in space in June 1983, Sally Ride’s presence on Challenger for the seventh space shuttle mission truly was a ride into history, for it broke the sex barrier in U.S. human spaceflight. Granted, it occurred 20 years after Valentina Tereshkova soared into orbit for the Soviet Union and almost 20 years after the Barbie doll became an astronaut. Yet after that milestone passed, the space shuttle and then the International Space Station became places where women could work alongside men and also take command.

The priority of Sally Ride might have been otherwise; any of the six women accepted into the 1978 class of astronauts might have been chosen as the first to fly. Anna Fisher, Shannon Lucid, Judith Resnik, Sally Ride, Rhea Seddon, and Kathryn Sullivan completed training and qualified for flight assignments together. All flew in space within two years. These six women navigated together through the ways of an all-male astronaut corps.

women

NASA’s first women astronauts. Left to right: Shannon W. Lucid, Margaret Rhea Seddon, Kathryn D. Sullivan, Judith A. Resnik, Anna L. Fisher, and Sally K. Ride.

Yet, by flying first, Sally Ride represented all of them and inspired others to come. These first women had already embarked on careers as scientists—four with PhDs and two with MDs—in fields dominated by men. In their wake, 41 more U.S. women became astronauts, accounting for almost 20% of the 256 astronauts selected for the shuttle-space station era and including women of African-American, Hispanic, and East Indian descent. Countless more girls and women began to imagine themselves in those roles.

Women piloted or commanded nine shuttle missions and, thus far, two space station expeditions. Women set long-duration records in space, conducted laboratory research, and helped build the space station. Astronaut Sunita “Suni” Williams is the world’s leading female spacewalker and ranks near the top among American spacewalkers.

Sunita Williams

NASA astronaut Sunita Williams, Expedition 33 commander, talks on a microphone in the Destiny laboratory of the International Space Station.

Thirty years after Ride’s historic flight, the active U.S. astronaut corps has shrunk to 49 members, of whom 12 are women, the highest percentage yet. Seven other women astronauts are serving in NASA management positions. This week NASA announced its twenty-first class of astronaut candidates—eight selected from more than 6,000 applicants—and for the first time there is an equal balance of four women and four men.

These numbers attest to the growing presence of U.S. women in space, joined by female astronauts from Europe, Canada, Japan, and most recently China. Even more, they hint at the increase in numbers of women qualified as scientists, engineers, and pilots who can compete for and earn their place in space.

Although NASA’s selection of female candidates in 1978 and Sally Ride’s first flight in 1983 opened the door for more women to become astronauts, the greater effect has been to model science and engineering as pursuits for ambitious young women.  Ride admitted that she had always loved and done well in science, long before she aspired to be an astronaut.  With a strong academic and professional record in science, she and many other women were ready for the opportunity of spaceflight.

To reinforce the importance of competence in science, after leaving NASA, Ride devoted more than 20 years to science education, teaching at the university level and also encouraging younger people, especially girls, to develop their curiosity and knowledge. The programs and products developed by her namesake company, Sally Ride Science, aim to stimulate a lasting interest, if not passion, for science that may prepare youngsters to achieve their dreams in space or elsewhere.

Accomplished American women have flown in space since 1983, and more are preparing to follow them into the future. Inspiration continues to flow from Sally Ride the astronaut and Sally Ride the educator. That legacy is the real result of her first six days in space.

Valerie Neal is the curator for space shuttle-space station era human spaceflight in the Space History Department of the National Air and Space Museum.

 

American Military Aviation in the Interwar Years and After: Some Historical Reappraisals


In 1987, the historian Michael S. Sherry published a groundbreaking and controversial book titled The Rise of American Air Power: The Creation of Armageddon (Yale UP, 1987). Sherry in effect reinterpreted the history of American air power in a way that was more contextually based and fiercely critical. The result was not to every military historian’s liking because it deviated so dramatically from what was considered the master narrative of American air power, which traditionally had focused on combat tactics and weaponry, and which had neglected the broader implications of air power and its employment. Moreover, Sherry upset the “Good War” narrative (mistakenly from Studs Terkel’s ironically titled The Good War: An Oral History of WWII) that emphasizes the heroic side of war and downplays its destructiveness, death, and tragedy.

Thus, The Rise of American Air Power could be seen as representative of what has been termed the “New Military History,” an attempt to bring military history into line with other academic historical endeavor. In a larger context, historian Peter Paret has written in Parameters: The Journal of the Army War College, “the New Military History refers to a partial turning away from the great captains, and from weapons, tactics, and operations as the main concerns of the historical study of war. Instead we are asked to pay greater attention to the interaction of war with society, economics, politics, and culture.” (Autumn 1991,10)

The recent publication by military historian Mark Clodfelter of Beneficial Bombing: The Progressive Foundations of American Air Power, 1917-1945 (U of Nebraska P, 2010) is a fitting occasion to reconsider some of the ideas put forth by Sherry a quarter century ago. In his book Clodfelter argues that consciously or unconsciously the developers of American air power theory and strategy were a reaction to a Progressive (as in Progressive Era) way of thinking. Clodfelter argues that the advocates of progressive air power, looking back on the slaughter brought about in WWI, believed that air power could put an end to an enemy’s ability to wage war by destroying its industrial, communication, and transportation centers. Clodfelter also points out that the airmen wanted a reformation of the U.S. defense structure and they believed that a separate autonomous air force was a necessity if the country was to carry out such precise aerial warfare. In addition, the airmen believed that an independent air force would be capable of winning future wars entirely on its own, without the assistance of armies or navies.

While Clodfelter should be lauded for his attempt to place the study of American air power in a wider context, his view of it in regard to American Progressivism is somewhat narrow. Progressivism is a multifaceted and often contradictory movement typically characterized by activism for social justice, political reform, and efficiency. It may be difficult to tie American air power to a single motivation.

Nevertheless, I would like to follow up on Clodfelter’s (and Sherry’s) ideas in light of recent historiography, and in particular to focus on what might be termed the unintended consequences of early American air power theory.
(Technology’s accidental aspects have been examined most notably by historian Edward Tenner in Why Things Bite Back: Technology and the Revenge of Unintended Consequences [Vintage, 1997]). Two psychological facets of un-intention are

“cognitive dissonance,” and “groupthink” (terms developed later by the social psychologist Leon Festinger (When Prophecy Fails, 1956) and the research psychologist Irving L. Janis (Victims of Groupthink: Psychological Studies of Policy Decisions and Fiascoes, 1972); these describe various states of single-mindedness and collective rationalization in group behavior.

Festinger had studied under Kurt Lewin at the University of Iowa and during WWII he had worked for the National Research Council Committee on the Selection and Training of Aircraft Pilots at the University of Rochester. Janis had worked on problems of military morale during WWII for the U.S. Army. In 1951 when he was a professor at Yale University he published Air War and Emotional Stress: Psychological Studies of Bombing and Civilian Defense under the auspices of the RAND (Research and Development) Corporation). Both men made revolutionary contributions to the way that social scientists comprehend and explain complex patterns of human motivation and behavior, particularly as they apply to organizations.

In her book Rhetoric and Reality in Air Warfare: The Evolution of British and American Ideas about Strategic Bombing, 1914-1945 (Princeton UP, 2002), Tami Davis Biddle explains how cognitive theory relates to military decision making.
Biddle believes that “All decision makers use cognitive processes to make sense of their complicated and stressful environments. … rather than revisit the original choice, decision makers discount, misinterpret, or ignore new information … in addition to seeing what [they] want to expect to see, and not seeing what [they] find too stressful to absorb, [they] often see what it is in [their] interest to see. Decision makers with powerful organizational goals or self-interests may discount or minimize incoming information that conflicts with those interests, and highlight information that supports them.” (4-5) In a very broad sense, the work of Festinger, Janis and others on cognitive processes in organizational thinking so aptly summarized by Biddle go a long way toward explaining what happened to air power theory during the interwar years and throughout WWII.

General William “Billy” Mitchell

Contributing to the “cognitive dissonance” and “groupthink” mentality of the strategic bombing theorists was their feeling of superiority, a kind of “cult of the airmen” mentality. This mindset was characterized by their feelings of elitism—their “us versus them” position— in regard to the regular Army establishment, which wanted them to concentrate on tactical air power or battlefield support. Another quality was their belief in superior knowledge in being able to pilot an aircraft; that only airmen really understood the potential of air power and that those outside their select group, even if they were military men, did not have the requisite experience require to wage aerial warfare. Add to this the aura of “prophet” that surrounded General William “Billy” Mitchell, their erstwhile leader during the 1920s, and you begin to understand the cultish dimensions of the air power theorists.

If one accepts Biddle’s line of reasoning, the so-called American air prophets of the interwar years were so convinced of the rightness of their cause that they ignored or dismissed any evidence to the contrary that did not conform to prescribed views. More than that, they refused to test their ideas empirically in more than a superficial fashion, and trusted that the military aviation technology that supported their ideas would more than make up for any mistakes in their thinking. Moreover, American air power theorists were unable or unwilling to admit that enemy technologies might be developed to counteract their theoretical plans, even while the testing of such technologies were going on underneath their noses. Another, perhaps more significant factor was the desire of the airmen to form an independent air service, free of interference from the army, and able to carry out its own independent mission.

Whatever the reasons, the theorists failed on a number of fronts. For example, the apparent truth of the received wisdom that “the bomber will always get through,” initially espoused by British Prime Minister Stanley Baldwin in a 1932 speech to Parliament, was accepted without question by the bomber advocates. In fact, a year later, assistant chief of the Air Corps Brigadier General Oscar Westover reiterated Baldwin’s claim: “No known agency can frustrate the accomplishment of a bombardment mission.” Subsequent events proved these undisputed assumptions questionable at best.

With their eyes securely fixed on precision bombardment, the airmen ignored the role of fighter aircraft in combat. A lone voice for the role of fighter aircraft was that of Claire Lee Chennault, an Air Corps officer assigned to instruct at the Air Corps Tactical School at Maxwell Field, Alabama. Chennault believed in fighters and their role in a coordinated ground-air aerial defense system. In his memoir, Way of a Fighter (G.P. Putnam’s Sons, 1949), Chennault recalled that in 1933 bomber versus fighter test, “fighters intercepted and ‘attacked’ the bombers by day and by night, using high, intermediate, and low altitudes on every attempt that was made.” While one should perhaps take what Chennault says with a grain of salt, it is apparent (in light of later developments) that the airmen did not place much emphasis on fighter aircraft either as effective countermeasures to bombers or as protective bomber escorts. (23-24)

Likewise, the bomber advocates never envisioned or easily dismissed defensive countermeasures like RADAR (Radio Direction and Ranging, which was being developed primarily in Great Britain during the 1930s, and FLAK (Fliegerabwehrkanone, or antiaircraft artillery). RADAR was used effectively in the Battle of Britain to track German aircraft and direct Fighter Command to scramble and attack them. FLAK became a significant part of German air defenses during WWII and was used to direct lethal artillery fire from the ground to the air against attacking Allied.

Flak Bait

Although not as iconic as the Boeing B-17 Flying Fortress, the Martin B-26 Marauder Flak Bait, a medium bomber, survived 207 operational missions over Europe, more than any other American aircraft during World War II.

Moreover, the lessons of the Spanish Civil War, which might be considered a major laboratory for aerial warfare in the interwar years, were largely ignored by American strategic bombing theorists. In “The Spanish Civil War: Lessons Learned and Not Learned by the Great Powers,” military historian James S. Corum (The Journal of Military History, April 1998) writes that “the interest shown by the Air Corps as a whole in the major air war of the period can be described as minimal.” (318)

Giulio Douhet

Corum goes on to say that “Several of the Army officers offered the conclusion—clearly unwelcome in the Air Corps—that the strategic bombing of enemy cities and industries had had no decisive effect in Spain and that civilian populations had quickly learned to adapt to bombardment from the air, a judgment that contradicted the theory of the popular air power prophet Douhet.” (Douhet’s il dominio dell’ariaThe Command of the Air—published in 1921 and made available in English translation in 1923 advocated the bombing of population centers as well as industrial targets and the use of incendiaries and poison gas.) Other army commentators noted the lack of bombing accuracy—the inability to hit specific targets. “This completely accurate analysis”, Corum says, struck right at the heart of the Air Corps’ doctrine which emphasized the destruction of small, specific industrial targets such as power and transformer stations in order to paralyze an opponent and shut down his industries.” (322)

The Air Corps Tactical School’s insistence on a strategy of high-altitude precision bombing of strategic targets, or what became known as the “industrial web theory,” in which the destruction of one critical industry—power plants, oil refineries, ball bearing factories, etc.—would create a choke-point that would severely limit or curtail the enemy’s war-making capacity and eliminate the need to take out the enemy’s entire industrial output or harm civilians. This idea was fine in theory, but it suffered from a number of deficiencies. As Stephen L. McFarland points out in America’s Pursuit of Precision Bombing, 1910-1945 (Smithsonian Institution Press, 1995) the theorists at ACTS did not have access to accurate intelligence about potential foreign enemies; they based their ideas on data from American cities. Moreover, the theorists pinned their hopes on the Norden bombsight, as yet unproven in combat and tested only under the most optimal conditions. (See McFarland, 89-104)

Norden Bombsight

Norden Bombsight prototype, 1923.

Finally, and ironically, the theorists believed that by targeting critical industries, the death of civilians by what was euphemistically termed “morale bombing”; i.e., the idea that the enemy population’s will to fight would be severely compromised by attacks on civilian centers, could be avoided. (In a largely Isolationist country like the United States in the interwar years, the idea of using air power as anything other than a defensive weapon was repugnant.) There were attempts to limit the bomber—the Hague Rules of Aerial Warfare drafted in 1923, for example, made it illegal to employ aerial bombardment to terrorize civilians or damage private property. The use of bombardment would only be legitimate if it were directed at military objectives. Moreover, the bombing of towns, villages and dwellings or building adjacent to military forces was prohibited. The Hague Rules were never ratified, largely because of the objections of the military. Nevertheless, the theorists walked a fine line in their advocacy of precision bombing. Evidently, they did not consider (or chose to ignore) the fact that the “industrial web” might be in the midst of population centers or that factories, power plants, oil refineries, etc. might employ thousands of civilian workers.

Nevertheless, President Franklin D. Roosevelt’s belief in strategic air power gave the theorists the green light to proceed. The culmination of Air Service-Air Corps-USAAF air warfare planning—AWPD-1—came from the Air War Plans Division, made up of former officers from the Air Corps Tactical School. AWPD-1 (Air War Plans Division Plan 1) put great emphasis on pinpoint strategic bombing at high altitude. Stephen McFarland notes that “the American air war in World War II was the fruit of six staff officers working with adding machines … largely without intelligence information, divorced from the exploding bombs, burning fuel, smoke, and torn flesh of war. They based their calculations on practice bombings flown in clear weather and at low altitudes. Practice bombings were only one bomb at a time, making multiple passes to achieve higher accuracy. In wartime, enemy defenses would make such practices impossible.” (103)

The shortsightedness of the theorists in these matters was to play a significant role when the United States entered WWII. After fitful attempts at high-altitude precision bombing, the USAAF was forced by the very circumstances that the theorists had ignored during the interwar years to resort to what became known as “area bombing,” or the bombing of population centers in which strategic targets were located. Despite the fact that there were strategic targets in these areas, the result usually was a high civilian casualty rate.

Regardless of the type of bombing employed, the air attacks were wrought at a terrible cost. In Masters of the Air: America’s Bomber Boys Who Fought the Air War against Nazi Germany (Simon & Schuster, 2006) historian Donald L. Miller points out that “There were two sets of victims in the European bomber war: those who were bombed and the men who bombed them.” (21) The U.S. Strategic Bombing Survey estimated that 305,000 Germans were killed and 780,000 wounded. In addition, 485,000 residential buildings were completely destroyed by air attack and 415,000 heavily damaged. Accurate American bomber and bomber crew loss statistics are very hard to come by, but estimates for the USAAF 8th Air Force put bomber and fighter crew member losses at 44,000 and heavy bomber losses at more than 4,000.

In Japan, the idea of high-altitude precision bombing was abandoned completely in favor of the low-altitude incendiary bombing of Tokyo in March 1945 and other Japanese cities. The civilian death toll was steep: estimates place the number at 330,000 to 400,000. Bomber crew casualties were not as high in the Japanese bombing campaign as in the European Theater of Operations. Estimates run at more than 2,600.

In some respects, the genie had been let out of the bottle when writers like H.G. Wells wrote apocalyptic works about aerial warfare. His novel The War in the Air (1908) imagined the German bombardment of New York City by airship. (Historically, one could cite the Austrians’ haphazard attempt to bomb Venice by balloon in 1849 as a significant step in initiating aerial warfare.) From there it was only a matter of time and improved technology until fiction became reality.

London

In London (December 1940) St. Paul’s Cathedral survived Nazi Germany’s sustained bombing campaign on British cities, aka “The Blitz.”

In World War I, for example, Germany bombed Britain with Zeppelins (1915-16) and Gotha aircraft (1917). The German bombardment of Guernica in the Basque region of Spain in April 1937 during the Spanish Civil War was another pivotal event, as were the Japanese bombing of Chunking (now Chongqing) during the Second Sino-Japanese War (1937-1945), and the German bombing campaign against British cities (“The Blitz” and later the V-Weapons attacks) during World War II.

In the actual warfare of WWII, the precise, clean warfare envisioned by the interwar year strategic bombing theorists ran up against the contingencies of wartime. These unforeseen events created situations in which the effectiveness of strategic bombing both in Europe and Japan have become hotly contested issues because of the high cost both in military and civilian casualties and the precedents set in regard to making civilians targets of warfare.

In the post-World War II era, there have been numerous attempts to restrict the bombing of civilians (see Adam Roberts and Richard Guelff, Documents on the Laws of War, eds. 2d ed. (Oxford UP, 1989), either directly or as a result of “collateral damage” (unintentional damage to civil property and civilian casualties) and also to control or prohibit nuclear warfare. The United States has devised precision-guided munitions (PGM) to minimize “collateral damage, intentional or otherwise,” and an ambiguous position on internationally-recognized restrictions on aerial warfare in regard to civilian casualties. Likewise, the U.S. has developed UAVs (Unmanned Aerial Vehicles) for a variety of reasons (initially for surveillance) but when it was realized that these vehicles could keep pilots and crew members out of harm’s way, they began to be employed as offensive weapons.As a result, they have become controversial because of their involvement in situations that have caused “collateral damage” in the attempt to targeted individuals suspected of being terrorists. In the effort to avoid the hazards of bombing like those experienced in WWII, other, more subtle problems have arisen, not the least of which is an ambiguous position on internationally-recognized restrictions on aerial warfare in regard to civilian casualties.

As Sahr Conway-Lanz points out in Collateral Damage: Americans, Noncombatant Immunity, and Atrocity after World War II (Routledge, 2006), “forsaking the norm of noncombatant immunity promised international condemnation and distrust. It also threatened Americans’ perceptions of themselves as a humane people. Giving up massively destructive war threatened to heighten Americans’ sense of vulnerability and insecurity. Instead, Americans kept their devastating weapons and adapted the international tradition of noncombatant immunity to their circumstances and purposes.”(211)

Dominick A. Pisano is a curator in the Aeronautics Department at the National Air and Space Museum.

Dominick Pisano will explore this subject and others in his upcoming book, “To Slip the Surly Bonds of Earth: Significant Features of the Cultural History of Aviation in the United States, 1910-1939.

Solar Impulse

Solar Impulse

What flies using power from the Sun, at the speed of an ultralight, on wings longer than a Boeing 777 airliner? Answer: Solar Impulse! A team of Swiss entrepreneurs, engineers, pilots, and enthusiasts began to design the Solar Impulse in 2003 with the goal to demonstrate flying day-and-night powered only by the electricity that more than 11,000 individual solar cells generate. The electricity is stored in batteries when not used, and spin the propellers on four 10-horsepower electric motors when in flight.  On July 7, 2010, pilot Markus Scherdel flew Solar Impulse 26 hours 10 minutes 19 seconds nonstop. Several more record-setting flights followed and now, psychiatrist, explorer, and pilot Bertrand Piccard, and the co-founder of the project, André Borschberg, are flying Solar Impulse across the United States. In 1999, Piccard and Brian Jones made the first non-stop around-the-world balloon flight aboard the Breitling Orbiter 3 now on display in the National Air and Space Museum in Washington DC.

If weather conditions are favorable across the central United States, Solar Impulse will land early next week at Dulles Airport. The team will then move the airplane to a spot outside the Steven F. Udvar-Hazy Center for public display during this year’s Become a Pilot Family Day and Aviation Display on Saturday, June 15, and the following day, Sunday June 16 (please, check the Museum’s website and social media platforms for updates and weather delays).

The Solar Impulse team has already started building a second Solar Impulse that will incorporate the lessons learned from the first. An attempt in the second Solar Impulse to circumnavigate Planet Earth nonstop is planned for 2015.

I will discuss how the Solar Impulse compares to some of the ultralight, and ultra-heavy aircraft on display at the Udvar-Hazy Center during the Become a Pilot Day social. Join the conversation on Twitter by following #PilotDay2013.

Find out more about Solar Impulse’s flight across the United States.

Find out more about the Solar Impulse project.

Russ Lee is a curator in the Aeronautics Department of the National Air and Space Museum.

GPS – A Hollywood Actress, a Player Piano, and Hip-Hop

Given the enormous popularity of GPS among civilian users, and the critical applications for the military, it is not surprising that a large body of literature has arisen about the origins of this remarkable technology. The curators of the new Time and Navigation exhibition discuss this history, and we have illustrated it with a few select artifacts, such as the engineering model of the Navy’s NTS-2 satellite, one of the key demonstrators of the technology that led to the deployment of the GPS constellation.

GPS is the result of a collaboration among many contributors. Rather than try to sort out the various claims, I would like to take a closer look at one component of the system, namely the method by which signals from the constellation of satellites are encoded and transmitted to receivers on Earth. The technique is known as “spread spectrum,” and it is widely employed not only by GPS but also by WiFi and Bluetooth wireless connections to computers, by cordless telephones, and by most cell phones in the United States. In fact, spread spectrum and its cousins have created a revolution in communications, which may in a few years relegate traditional narrowband radio to our sister museum, the National Museum of American History.

Hedy Lamarr

Hedy Lamarr

Most histories of GPS credit the US Air Force, correctly, with suggesting this coding scheme for GPS. They also credit the genesis of the idea to the Austrian actress Hedy Lamarr, dubbed by Hollywood producer Louis B. Mayer (of MGM Studios) as “the most beautiful woman in the world” after she emigrated to the U.S. in 1937. I will pass on commenting on her contribution to the cinema, but it is worth exploring just what she did regarding secret coding, and how that relates to GPS.

In 1940, Lamarr met the American avant-garde composer George Antheil, who just returned to America from Paris, where he had created a sensation pushing the boundaries of classical music. Among his more outrageous compositions was one in which he placed a number of player-pianos on the stage, each producing “canned” sounds. For us the relevance of this story is that Lamarr later emigrated to the US and became a fiercely patriotic champion of the Allied cause after America’s entry into World War II in 1941. While living in Austria she had been married to an industrialist named Fritz Mandl, and over dinner conversations he had with his colleagues, she became acquainted with some of the advanced weapons the Nazis would later employ to such great effect. Among them were radio-controlled glide bombs—the predecessors to the “smart bombs” so much in the news today.  Inspired by Antheil’s compositions, she came up with the notion of using perforated paper tape (not as wide as a player-piano roll), to rapidly switch the frequency of the transmitter on a ship that launched the torpedo. An identical tape on the torpedo would switch, or “hop,” the frequency of the receiver, to match the transmitter. Think of a car radio, with which you can rapidly select a radio station by pushing a button, and not twist the tuning dial. The technique depended on the precise synchronization of the two tapes, but for a torpedo that only had to work for a short period of time. And of course it depended on the enemy’s not knowing the sequence of frequency hopping—the sequence had to appear random, although it was not.

Lamar applied for and was granted a patent for a “secret communication system” in 1942, but the Navy did not use her invention. Decades later it was rediscovered and became the basis for secure communications. The paper tapes are now replaced by digital computer circuits, which generate sequences of “pseudo-random numbers” (PRN) that hop the frequencies of the transmitter and receiver in synch. Because the technique requires a wider band of frequencies than a normal radio transmission (think again of the car radio), it is called “spread spectrum,” as it spreads the signal across a wider band.

patent

Patent # 2,292,387 for a “Secret Communication System,” Hedy Kiesler Markey. At the time it was filed, in 1941, Lamarr was married to Gene Markey, a Hollywood screenwriter. She felt that having her married name on the patent would give it more credibility.

Now back to GPS.  GPS uses spread spectrum. It requires a larger bandwidth than a narrowband radio would require to transmit its signals. The satellites transmit primarily on two frequencies, 1575.42 MHz and 1227.60 MHz, but if you tune an ordinary radio scanner to those frequencies, you hear nothing but background noise.  The frequency does not hop, however. The signals are multiplied by a pseudo-random sequence, which is transmitted and recovered by the receivers using the same sequence. There are two main pseudo-random codes, a short one used in civilian receivers, and a longer one used by the military. Like the system proposed by Lamarr, this also spreads the signal out; it also trades bandwidth for power, which is why a normal receiver hears nothing—the signal is well below the noise threshold.  The adoption of this technique gives GPS a number of advantages: the receivers do not need a dish or otherwise large antenna to pick up the signals, and the different codes allow for both civilian and military use of the same system. The low power also means that the signals cannot be received indoors or under dense tree cover, a drawback that future generations of GPS satellites may address.

So if this technique did not come from Hedy Lamarr, where did it come from? Of that we know less. But there are hints that it may have come from another system developed during World War II. If true, that story is every bit as mysterious and intriguing as Lamarr’s. Much of the initial research apparently was done by the cryptographic community and remains classified. But there are some tantalizing hints. A few years ago, The U.S. National Security Agency (NSA) published a pamphlet describing a method of scrambling speech, which was used during World War II by Winston Churchill and Franklin D. Roosevelt, among others. The NSA claims this “SIGSALY” system was “The Start of the Digital Revolution.”[1] For an agency known for its reticence, this publication represented a major revelation. The invention introduced pseudo-random noise, which was recorded mechanically on a phonograph disk, and superimposed this on the speech channels.  At the other end an identical disk, synchronized to start at the exact same moment, subtracted the noise. The disks were destroyed after each use.  The system was installed in several locations by 1943, including one in the Pentagon and one at Churchhill’s command post under the Admiralty Building near Number 10 Downing Street.

SIGSALY

A SIGSALY installation, ca. 1943, in an undisclosed location. Note the twin turntables, which allowed rapid switching from one recording to another. The recordings contained random noise generated by mercury-vapor vacuum tubes. The noise was injected into the signal at the transmitting site, while at the receiving site, an identical recording, playing in perfect synchronization, subtracted the noise, revealing the voices of FDR, Churchill, and others

Grandmaster Flash

Grandmaster Flash (Joseph Saddler), hip-hop pioneer and inductee into the Rock and Roll Hall of Fame. His creative use of twin turntables, with a switch he developed to alternate between the two, has been credited as a seminal moment in the creation of hip-hop music.

The NSA pamphlet shows a system of two phonographs, each of which contained one of the platters. For some of us, seeing this photograph immediately evokes another phenomenon—the use of twin turntables by hip-hop musicians to sample and otherwise electronically alter sounds on the dance floor. Is there a connection?  Possibly—the methods of speech scrambling, developed in the 1930s and 1940s primarily by Bell Telephone Laboratories, have been cited as direct ancestors to current pop music. So the next time you use your car GPS receiver to tell you how to get to a restaurant, think of Hedy Lamarr, or better yet, Grandmaster Flash.



[1] US National Security Agency, For Meade, Maryland: “The Start of the Digital Revolution: SIGSALY, Secure Digital Voice Communications in World War II. Undated pamphlet, 19pp. SIGSALY is not an acronym but a nonsense word.

Paul Ceruzzi is chair of the Space History Department at the National Air and Space Museum.

On Assignment for Time and Navigation

What’s missing when you sit in front of a computer all day? Adventure! Luckily, three
Time and Navigation photography missions took me across the country last year, giving me the chance to escape the office.

My first destination was Beer Bottle Pass in the Mojave Desert. This is where Stanley, the autonomous car, navigated its way to victory during the 2005 Defense Advanced Research Projects Agency (DARPA) Grand Challenge race. I needed a photo of the pass to cover the 27-­foot wall behind Stanley in the Time and Navigation gallery. I was confident about this trip until I discovered how precarious this pass could be. The fact that Stanley was able to navigate these sheer drop-­offs and steep inclines is remarkable.

Ashley Hornish

Ashley Hornish in the Mojave Desert

After studying Google Earth for several weeks, my husband, Cory, and I were ready to go. We drove our rented Jeep Wrangler to our starting point outside Primm, Nevada. This area had received a record rainfall the previous week so we had to negotiate washed-out areas and large stones. It took us 45 minutes to travel the seven miles to the pass.

Such a large mural requires more than just one photo; I needed a series that I could stitch together into a panorama. As we gradually moved into the pass, I looked for the best composition. Unfortunately, the road conditions got worse as we progressed, so we never made it to the most treacherous areas (fine with me!). Nevertheless, the trip was a success, and I was relieved to make a safe return to Primm.

Ashley Hornish

Ashley Hornish in the Time and Navigation exhibition. Behind her are Stanley and the mural she photographed in the Mojave Desert.

Since Cory and I were “in the neighborhood,” we arranged a visit to the Goldstone Deep Space Network complex. Located about 35 miles north of Barstow on the Ft. Irwin Military Base, the NASA Deep Space Network is an international network of antennas that supports interplanetary missions and radio and radar astronomy observations for exploring the universe.

I wanted to photograph an old hydrogen maser at the Mars 70­-meter antenna. Now a backup, this maser was the primary frequency standard for the racks of Goldstone timing equipment we have on display in Time and Navigation.

Now used as a backup, this hydrogen maser frequency standard was the primary frequency reference for the Goldstone timing equipment on display in the Time and Navigation exhibition.

Visiting Goldstone is no simple task. Hidden away in the middle of the desert, Goldstone is a 45-minute drive from the nearest highway. Disconcerting signs warned of tank crossings and live ammunition areas. After a safety briefing (don’t touch the snakes and don’t drink the water), our guides escorted us to the timing vault of the massive 70-­meter antenna. The best part about the old maser is that it has a small hole at the top that allowed us to view the purple plasma glowing inside the equipment. After a few quick photos, we were allowed to take a brief look into the control room for the Curiosity rover.

I found myself in a very different landscape for my third trip: the middle of a cornfield in Rippey, Iowa. I needed photos of farmer Roy Bardole harvesting his crops using equipment guided by GPS. Museum photographer Dane Penland agreed to accompany me on this adventure, and we headed to the drought­-stricken area hoping there would actually be crops to photograph.

Roy Bardole

Dane Penland photographs farmer Roy Bardole in a harvester near Rippey, Iowa.

Dane and I ended up spending an entire day in the field with Roy and his two sons as they methodically worked their way through the stalks. We took turns riding inside the combine, watching as the enormous machine drove itself down the lengthy rows without wavering. Farming is much more involved than you might imagine, and I was impressed by the Bardoles’ business sense.

Overall this trip was a success: the weather held, the Bardoles’ yield was better than expected, and the motel wasn’t as bad as I thought it might be. I even got a special sendoff at the Des Moines airport, home to the Des Moines Air National Guard. As my airplane taxied to the runway, we passed several F­-16s that were awaiting takeoff. As we passed, the pilots waved to us. It was a great way to end my adventure.

Ashley Hornish is a graphic designer in the National Air and Space Museum’s Exhibits Department.