Vulcan? But that’s not logical…

The news that “Vulcan” topped the poll results taken by the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California as a possible name for one of the two tiny moons newly discovered to be orbiting Pluto has gotten quite a bit of press this week. In 2012, Mark Showalter of SETI, working with scientists on the New Horizons mission sending a probe to Pluto, found a tiny fifth moon orbiting the icy world. Showalter was also the lead author of the discovery of a fourth moon in 2011 using observations from the Hubble Space Telescope.

Pluto

This image, taken by NASA’s Hubble Space Telescope, shows five moons orbiting the distant, icy dwarf planet Pluto.

As SETI contemplated what names to propose for these two newly-discovered moons, they opened the question to the public in an on-line poll.  Inspired by a tweet from William Shatner, the actor who became famous playing Capt. James T. Kirk in the original Star Trek television program (1966-69), Vulcan, Pluto’s mythological nephew and the name of a fictional world in Star Trek’s imagined universe, became the top vote getter.  Leonard Nimoy, who played Spock, the most famous Star Trek Vulcan, reportedly tweeted that naming one of the two moons “Vulcan” would be the “logical choice.”

shatner

nimoy

But did you know that there already was a Vulcan?  Or, actually, there wasn’t.  But astronomers thought that there was.

Since the 18th century, astronomers worried that the orbit of the innermost planet in the solar system, Mercury, did not behave the way that they expected.  By the mid-nineteenth century they knew that perturbations in the orbit of Uranus had just (in 1846) resulted in the discovery of Neptune, the first planet to be predicted mathematically before it was confirmed through observation.  Could that also apply to Mercury? Was there another planet orbiting between Mercury and the Sun that could explain Mercury’s orbit?  Urbain Jean Joseph Leverrier, whose calculations had been used to discover Neptune, thought so.  By 1859, amateur and professional astronomers started searching.

And they found some things.  Some scientists reported seeing a bright, star-like object orbiting near the Sun.  And others saw circular shapes transiting (or crossing) the face of the Sun. It must be Vulcan, they thought!  Some textbooks printed in the 1860s and 1870s even listed Vulcan as a planet. (For, indeed, Pluto is not the first body to have been considered a planet and then reclassified. Ceres, the spherical body in the asteroid belt, was also called a planet when it was discovered in 1801 but then reconsidered when the many other bodies discovered in that same region of space became known as the asteroid belt.)  But the observations of Vulcan did not compute.  They were not consistent.  According to Newton, and to vast experience, planets, above all, were predictable in their orbits. Any deviation was not acceptable.  That’s how Kepler decided that planets did not travel in circular orbits. So when scientists looked for Vulcan where it was predicted to be visible and they could not find it, they started to doubt that Vulcan existed.

When something does not move as predicted, astronomers start looking for a perturbing mass.  That is in fact how dark matter was detected, and after almost 50 years, finally accepted as a major factor in controlling the motions of things like stars and galaxies in the universe.  In the early 20th century, astronomers thought that the existence of a faint disk of material around the sun, called the Zodiacal Light, might be massive enough to make Mercury’s orbit shift in the way it appeared to do.  But in the end, Einstein solved the problem (literally) and Vulcan was no more.  In 1915, Einstein’s General Theory of Relativity explained the shifts in Mercury’s orbit without the presence of another world orbiting nearer to the Sun.  Vulcan, which had never existed, entered the history books.  But astronomers still use the name: NASA’s project to detect new planets has been called “Project Vulcan.”

The names of Pluto’s moons have still not been decided.  The International Astronomical Union, the worldwide professional organization of astronomers, will make the final choice.  They may choose “Vulcan.” Or they may decide that there was already a Vulcan. Except that there wasn’t.

Margaret Weitekamp and David DeVorkin are curators in the Space History Department of the National Air and Space Museum.

Two Years Ago Today

Two years ago today, the space shuttle Discovery was launched for the last time.  My friend Nicole Gugliucci scored a quartet of tickets for the launch and shared them with me, along with our friends and classmates Joleen Carlberg and Gail Zasowski.  Facing an overwhelming load of graduate school work, we decided that a road trip from Virginia to Florida was exactly what we needed!

Kennedy Space Center

Joleen, Gail (with Buzznaut), Nicole, and myself (with Meteor Shower), at the Kennedy Space Center.

Many hours later, the six of us found ourselves in sunny Florida.  Yes, six.  The other two road trippers were the mascots for an astronomy outreach club that we helped found in Virginia.  Nicole was the only one among us who had witnessed a launch before.

Our tickets let us watch from the Visitor Center, seven miles from the launch pad.  We spent the day exploring the Visitor Center, and found a spot in the rocket garden to watch the launch.  We couldn’t see the launch pad itself from there, but we could watch final preparations on a big screen showing a close-up view.

Rock Garden

Waiting for launch in the rocket garden.

Due to a computer problem on the ground, the launch was delayed.  We knew we could still see it if it were postponed one day, but if there were further delays, we would probably have to abandon the effort and drive home.  The tension in the crowd built until the countdown clock started again, with just three seconds to spare in the launch window. The audience erupted into cheers.

The experience didn’t start to feel real to me until I saw the cap lift off the shuttle’s nose cone, leaving it free to launch.  Sparks were fired around the main engines to burn up any stray fuel, preventing accidental fires.  Then, on the screen, we saw the engines light!

launch

Ignition of main engines, as seen on a big screen from the Visitor Center. Video of Discovery’s last launch can be seen in the Moving Beyond Earth gallery or online.

The red flames from the engines focused in to sharp white points, causing the shuttle to “twang,” rocking forward a bit.  When it rocked back to a vertical position, the more powerful solid-fuel rocket boosters (SRBs) lit off.  I was expecting that, but it still made me jump.

Moments later, we felt the ground shake, and then the shuttle rose into view, the flame from its SRBs shining nearly as brightly as the Sun. It hurt to look at it.  A few moments later, as we jumped around and cheered, the rumble and roar of the launch reached us.

Discovery

My first glimpse of Discovery. The white strips are the solid-fuel rocket boosters.

It was awesome to see this feat of engineering with my own eyes, and to think that there were six people in that shuttle, with an incredible amount of flame and power below them.  As Discovery arcked out of sight into a clear blue sky, I found myself crying.

Discovery

Discovery reappears from behind its own contrail, on the last gasps of power from the SRBs. Moments later, the empty SRBs detached and fell back to the ocean.

But that was not the last flight of Discovery that I got to witness.  More than a year later, on April 17, 2012, I was working as an astronomy educator at the National Air and Space Museum. The whole city of Washington, DC was buzzing with excitement about Discovery, which was en route to its final home with us.

Riding piggyback atop a modified Boeing 747, Discovery cruised the DC area, making three loops around the National Mall before heading to Virginia.  From the top of the National Museum of American History, I was lucky enough to watch its final flight.

Discovery

Flying above the Smithsonian Castle, Discovery acquires an extra honor guard.

Anyone can now visit Discovery at the National Air and Space Museum’s Steven F. Udvar-Hazy Center.  When I visit, what impresses me most is how beaten up it looks, compared to the pristine Enterprise which used to reside there. Discovery is a well-used workhorse of a space vehicle, the one that took the Hubble Space Telescope into orbit for us.

Discovery

Visiting Discovery at its new home.

I’m not sad that the space shuttle program is over.  I believe that ferrying people and equipment from Earth to low orbit is now a routine (if still astonishing!) task, one that private industry will excel at. I can’t wait to see where scientists and engineers will take us next. What would you like to see in the future of space exploration?

Geneviève de Messières is an Astronomy educator at the National Air and Space Museum in Washington, DC. All photographs by Geneviève de Messières.

Civil War Planes

In a recent post, Tom Paone described the plans of William Powell, a resident of Mobile, Alabama, for a Confederate helicopter. In fact, Powell’s scheme was only the tip of the iceberg. In researching a scholarly paper on Civil War Planes, I have catalogued a score of plans for powered flying machines developed on both sides of the battle lines. Perhaps the most interesting of these was the work of Colonel Edward Wellman Serrell , a professional engineer serving with the Union Army of the James in 1864. Inspired by the well-known hand-held helicopter toy, Serrell had begun studying aeronautics several years before the War. Once in uniform he conducted full-scale tests of metal rotor blades in the field, then convinced his commander, General Benjamin Butler, to order him to duty in Philadelphia, where he raised the money with which to build his Reconoiterer, a flying machine designed to conduct reconnaissance missions over enemy lines.

 

Reconoiterer

The Serrell Reconoiterer. Credit: Greg Bryant.

The machine would be lifted into the air by twin rotary wings set above and below the fuselage, and driven forward by propellers at the front and rear. Two large flat copper plates, each measuring nine feet in span and 45 feet, 8 inches long, were to be positioned on either side of the shell. The two plates were connected to a crank running through the fuselage, so that the crew could incline or depress the wings up to six degrees above or below the horizontal to provide additional lift.

Plans called for the fuselage to be a cigar-shaped copper shell measuring 52 feet long, with landing runners on the underside. A chamber at the bottom of the shell would serve as a reservoir for the boiler water, with a second chamber above it for the coal. A light-weight, high pressure vertical steam engine with a vertical boiler were housed in the rear of the shell. A series of moveable balls were to be used to balance the Reconnoiterer. The designer estimated the total weight at take-off, with a crew of three on board and enough water and fuel for an eight-hour flight, at 8½ tons.

 

Reconoiterer

Serrell’s drawing of the rotors, steam engine and transmission of the Reconoiterer

Unlike William Powell, and most other armchair aviators of the Civil War era, Serrell conducted serious engineering tests, obtained what he thought would be a suitable steam power plant, and had large sections of the hull of a smaller three-man demonstration craft under construction when hostilities ended. He continued his effort for a time, corresponding with leading aeronautical researchers in Europe, but ultimately abandoned the venture when it became apparent that steam propulsion was inadequate.

Serrell

Edward Wellman Serrell (1826-1906)

While Serrell and others who dreamed of winged flight during this era were destined never to get off the ground, the number of flying machine projects that appeared during the middle years of the nineteenth century underscores American enthusiasm for technology, even for the possibility of a machine that most feet-on-the-ground citizens regarded as something akin to a perpetual motion machine.  Dreamers and doers like E.W. Serrell deserve to be remembered.

Fortunately, the collection of research materials regarding what might be thought of as the pre-history of aviation continues to grow. During the course of research on aeronautical experimentation in nineteenth century America, and with the help of my colleague Mark Ragan, an important cache of Edward Wellman Serrell’s papers relating to his flight experiments was discovered in the hands of his descendants. Through the generosity of the family, the records of this pioneering foray into heavier-than-air flight are now safely preserved in the archive of the National Air and Space Museum, where they will be available to researchers in generations to come.

Tom Crouch is a senior curator in the Aeronautics Department of the National Air and Space Museum.

When Worlds Collide

A particularly bright fireball was observed earlier today over a wide area in Russia. Of even greater significance was the very strong sonic boom associated with the passage of the meteor through Earth’s atmosphere.

News out of Russia is reporting that ‘hundreds’ of casualties resulted from people being hit by falling glass, caused by the breaking of windows by the pressure wave associated with the sonic boom. Meteors are quite common around the Earth, but one of this magnitude is fortunately a rare event. The light of the meteor trail that we see in the sky is caused by friction between the incoming fragments and Earth’s atmosphere, which rapidly heats the surface of the fragments to the point that they give off visible light. The intensity of the light is a complex interplay between the speed of the object and the increasing density of the atmosphere as it moves lower into the atmosphere. The sonic boom is a clear indication that the fragments are moving much faster than the speed of sound, and just like jets that exceed the speed of sound, it is the inability of the air molecules to move fast enough to get out of the way of the fast object that generates the shock wave that we hear as a sonic boom. If the shock wave is intense enough, it can break panes of glass, which appears to have been the case today over a large area in Russia.

On June 30, 1908, a rock estimated to about 100 meters (328 feet) in diameter exploded (because of the rapid build-up of pressure as the object got lower into the atmosphere) above the Tunguska region of Siberia, which flattened trees over 2000 square kilometers (800 square miles) and produced a shock wave that knocked people to the ground at a distance of tens of kilometers (tens of miles) from the detonation point.

This image is from the Leonid Kulik expedition in 1927.

Today’s incoming rock likely was quite a bit smaller than the Tunguska rock, although it will take time for Russian scientists to assess what damage has taken place. NASA scientists are confident that the close passage of an asteroid to Earth later today and the trajectory (the flight path) of the Russia meteor were very different, so the two events are not connected, even though they will occur within hours of each other. Both the Russia meteor and the close flyby of an asteroid are reminders that space is not completely empty; whenever Earth happens to cross the path of some solid material in space, whether the size of a sand grain or a large building, the fast-moving objects are going to interact strongly with our atmosphere.

Jim Zimbelman is a geologist in the National Air and Space Museum’s Center for Earth and Planetery Studies

Amelia Earhart and the Profession of Air Navigation

The recent seventy-fifth anniversary of the disappearance of Amelia Earhart and her navigator, Fred Noonan, stirred up considerable media attention – particularly in light of another expedition to the South Pacific in the hopes of solving the mystery. While the fate of Earhart has enthralled the public since 1937, the story of how Earhart figures into the larger history of air navigation and long-distance flying is often overlooked.

Amelia Earhart

Amelia Earhart and her Lockheed 10E Electra.

Viewed as a stand-alone episode, the tale of Earhart’s last flight is confusing. Did she have the right training and equipment? If Fred Noonan was one of the greatest aerial navigators of the time, how did they get lost? The evidence for these questions is often vague and contradictory. One way to come to terms with the moment is to look at the larger historical context of air navigation at that time. This musing is not meant to provide definitive clues to the disappearance, but rather to provide some further topics of discussion that might be useful for future scholarship. How did Earhart’s planning fit with other flights over the South Pacific? How did their navigational training compare with that of other aviators? And, what was the professional standard of air navigation at the time?

In less than two months, the National Air and Space Museum will unveil a new permanent gallery – Time and Navigation: The Untold Story of Getting From Here to There – that will in part chronicle the development of air navigation as a profession. Today, the navigator as a crew member has largely disappeared from most commercial and military long-distance operations, replaced by microprocessors in the form of GPS and inertial navigation systems, but from the 1930s to the 1980s, the navigator was an essential crewmember on many long-distance commercial and military flights. Understanding how Earhart fits into the story of this profession provides some useful insights into the evolution of long range flight on the eve of World War II.

While Europe and the United States were developing networks of radio beacons and direction finding stations over their own territory, transoceanic navigation was only reliable with proficiency in celestial and dead reckoning navigation. Though these techniques were tried and true in maritime navigation, adapting them to the aerial environment was a new challenge. The cramped confines of aircraft, high speeds, variable weather, and turbulence greatly complicated the process of fixing position.

Charles Lindbergh’s reliance on nothing more than an earth inductor compass and a simple clock for finding his way during his 1927 solo transatlantic flight was emblematic of the often dangerous or ineffective state of air navigation. Though it worked well for Lindbergh who was the beneficiary of ideal wind conditions at the time of his flight, almost half of his peers attempting long distance flights that year either lost their lives or had their flights end in near disaster. However, the decade between Lindbergh’s Paris flight and the disappearance of Amelia Earhart witnessed a transformation of aerial navigation technology and practice. A small community of innovators worked to find better tools and techniques. One of these was a Navy Lt. Commander named Phillip Van Horn Weems. He developed simplified methods of celestial navigation that, when combined with improved sextants, provided a reliable means of determining position (either a fix or a “line of position) when the sun or stars could be seen.

By 1928, Weems had gone into business teaching air navigation. His initial students and clients included Charles Lindbergh, eager to find a better way than simply relying on luck to cross oceans (see the author’s article in Air & Space Magazine on this topic), polar explorer Lincoln Ellsworth, and Harold Gatty, the soon-to-be-famous navigator of Wiley Post’s Winnie Mae on its around-the-world record stating flight of 1931.

Despite the efforts of Weems and Gatty (who managed the Weems System of Navigation for a period), by 1937, the navigator as a dedicated non-pilot aircrew member was still a largely untested idea. While both the Army Air Corps and (to a lesser extent) Navy, were teaching air navigation with the tools and techniques advanced by Weems, Gatty and Albert Hegenberger (the Air Corps’ navigation authority), navigation was still seen as the responsibility of the aircraft commander or pilot. Rather, it was Pan American Airways and record-setters like Wiley Post that were defining the role of a dedicated non-pilot air navigator. Fred Noonan was on the cusp of this transition and his competence earned him a place as Pan Am’s lead navigator for the trans-pacific trials of a new class of “Flying Clipper.”

Earhart, like most distance fliers of the time, elected to concentrate on piloting and intended to leave the technical aspects of her flight to two navigators – Noonan and Harry Manning. Manning lacked the aerial expertise Noonan had acquired from Tornich and Weems, but was a celebrated maritime navigator and had the radio skills that both Earhart and Noonan lacked. Originally, Earhart intended on having Noonan along only for the dangerous Hawaii – Howland Island leg on her original westbound route. She also intended on dropping Manning after completing the remainder of the Pacific hop. Unfortunately, Earhart became dissatisfied with Manning before her final around-the-world attempt so that Noonan became the sole navigator and the expedition was left without an experienced radio operator when she set off on her second around the world attempt in June 1937.

Earhart’s first around-the-world attempt ended in near disaster on March 21, 1937, when she substantially damaged her Lockheed Electra 10E after losing control during takeoff from Hawaii’s Luke Field bound for Howland Island. While the plane was being repaired, Weems wrote the letter below to Earhart encouraging her to undergo navigation training in the manner of Britain’s top female aviator, Amy Johnson. He also called out what has been widely regarded as one of Earhart’ and Noonan’s greatest failings in anticipation of the flight – their lack of proficiency in the use of Morse code, which was essential for gaining long range bearings from the Coast Guard cutter specially stationed at Howland Island for this purpose. However, even though critical for navigation, Weems’ suggestion is somewhat remarkable as radiotelegraphy was considered an unusual specialization for an aviator, or even a navigator, at the time. Well into the World War II era, navigators and radio operators were considered two entirely different occupational tracks. In the military, the radio operator was considered a less technically demanding skillset and was usually assigned to enlisted personnel, while navigators were usually officers (often washed-out pilots).

Weems Letter to Earhart

Weems wrote this letter to Earhart after her near-disastrous takeoff attempt in Hawaii in 1937. Extra navigation training may not have kept Earhart from disaster, but it might have allowed to her appreciate shortcomings in planning an equipment.

Putnam's response to Weems

George Putnam’s response to Commander Weems

After Weems’ initial offer to Earhart, her publishing magnate husband, G. P. Putnam, responded the next day to Weems’ offer, kindly rejecting it. This brief and forgotten exchange of letters sheds further light on the frequent criticism of Earhart from both her contemporary peers and from historians of her tendency to be dismissive of training in the more technical aspects of aviation. Weems’ invocation of Amy Johnson’s navigational skill demonstrates that there was indeed a cadre of very competent female aviators skilled in navigation in a way that Earhart was not. In addition to Johnson and Anne Morrow Lindbergh, several other prominent female aviators of the time learned under the Weems System of Navigation. Among these were the Romanian Baroness Lisette Kapri, Dorothy “Dot” Lemon, and Mary Tornich, who was one of the Weems System of Navigation principal instructors in the late 1930s, and who appears to have undertaken much of Noonan’s air navigation instruction. From this perspective, Earhart may be seen as inadequately trained. However, there was certainly no clear consensus on what standard of navigational skill was required for distance fliers at the time. For instance, Wiley Post, at the height of his fame in 1933 (earned for his solo around-the-world flight in the Winnie Mae), was no more a navigator than Earhart. He employed Gatty in 1931 in the same manner as Earhart did with Noonan. In 1933, Post, like Earhart in 1937, put blind faith into new technology – a new Air Corps radio compass and a Sperry autopilot. The gamble paid off for Post, but not Earhart. The most obvious distinction between the two is that Post seemed to have a greater interest, familiarity and comfort with the technology.

Amy Johnson and PVH Weems

Amy Johnson with PVH Weems. Weems is showing her a drift meter.

Whether or not Weems’ instruction would have helped Earhart cannot be known. Perhaps it may have made her realize that her “flying laboratory” was that in name only. The Lockheed was not well fitted for navigation. It lacked a rooftop hatch or viewing port for unobstructed celestial observations and none of their navigational equipment, save for a Bendix direction finding radio, could be considered state-of-the-art. Unfortunately, Earhart struggled with the Bendix radio during the flight. Its newness, mechanical unreliability and Earhart’s inexperience with the equipment likely reduced its utility. However, the most vivid illustration of how poorly equipped the Electra was can be seen in the following year with Howard Hughes’ around-the-world flight in a Lockheed 14 that was similar to Earhart’s 10E, but which was truly a flying laboratory that accommodated two navigators and a host of new navigational equipment. This included a new averaging sextant, a new drift sight, new dead reckoning computers, a special observation portal, and a remarkable (and secret) line of position computer made by Fairchild-Maxson (see photo). If the loss of Earhart and Noonan had any impact on the navigational community, it may well be the thoroughness with which Hughes pursued the Army Air Corps supported flight (including filling the voids in the aircraft structure with 35,000 ping pong balls to stay afloat in the event of a ditching). The Hughes flight did much to pave the way for the approach to navigation used so effectively by bombers and other long-range aircraft over the ocean expanses during World War II, most notably by encouraging the mounting of Plexiglas astrodomes.

Fairchild-Maxson Line-Of-Position Computer

The Fairchild-Maxson line-of-position computer was an amazingly engineered mechanical computer in which the data sets of different celestial tables were coded onto gears and cams in cassettes that plugged into the main unit. By inputting the elevation of a celestial body and the time, the device would compute a line of position eliminating a number of mathematical calculations. Unfortunately the unit was very expensive and took up valuable space. Nonetheless, it was very useful for Howard Hughes’ 1938 around-the-world flight.

Astrodome

The astrodome was a major innovation for celestial navigators. While earlier aircraft had observation hatches or even cupolas, the aerodynamic astrodome was well suited to the increasing speeds of aircraft and offered great visibility. Air Corps navigation engineer Thomas Thurlow began pushing for their development after his 1938 around-the-world flight with Howard Hughes. They did not last much past World War II as they were a weak point for pressurized aircraft and added significant drag as aircraft began moving closer to supersonic speeds.

By the time of Earhart’s disappearance, the necessity of training in celestial navigation touted by Weems, Gatty, and Hegenberger over the previous decade had finally been heeded by many with Lindbergh being the most prominent acolyte. Lindbergh was so convinced that in 1930 he had his wife, Anne Morrow, learn celestial navigation from Gatty in her third trimester of pregnancy and then demonstrate it on a transcontinental flight. Earhart’s desire to distinguish herself led her to select a Southern route that most of her predecessors, had carefully avoided. By doing so, she also sidestepped the poor weather often found from Siberia to Alaska and perhaps alleviated her known discomfort with instrument flying. If celestial navigation was not necessarily an expected trait for distance flyers of the time, skill in “blind flying” had become mandatory.

Effective navigation across the South Pacific was indeed possible in 1937, but only one person had demonstrated it could be done safely – Charles Kingsford Smith. Overshadowed by Lindbergh in the United States, Kingsford Smith’s achievements are arguably more spectacular. In 1928, he made the first Pacific crossing from the United States to Australia in the Fokker F.VII Southern Cross with three additional crewmembers. In 1935, he repeated the achievement flying eastbound in the Lockheed Altair Lady Southern Cross with P.G. Taylor as navigator. What stands in stark contrast between “Smithy’s” flights and Earhart’s attempt is that Kingsford Smith chose an aircraft with adequate range. This allowed him on both flights to make the “jump” between Fiji and Hawaii – very large targets. For reasons that can only be speculative, Earhart selected the fast and flashy Lockheed 10E. It was an extremely attractive aircraft at that time for distance flying – except for crossing the South Pacific, for which it did not have the range. The issues of range and geopolitical considerations forced Earhart into the selection of the remote, isolated, and tiny Howland Island. Perhaps most importantly, the 10E’s twin engines gave Earhart a false sense of security. In many situations, the ability to sustain flight on one engine was highly desirable as it could prevent forced landings in unforgiving terrain. Unfortunately, over the open South Pacific, it was a major liability as it doubled the chances of engine failure, and the degraded single engine performance provided virtually no hope of reaching land in the event of a problem on the legs to and from Howland Island. Earhart would have likely been far better off with Smithy’s obsolescent single-engine Altair than the flashier 10E. However, high-profile accidents such as the fatal one in 1935 that killed Wiley Post and famed humorist Will Rogers had convinced many distance fliers that twin engine aircraft were preferable, unfortunately without much analysis of their risks.

The Time and Navigation exhibition is not intended to give a lengthy exploration of the challenges faced by Earhart or speculate as to her fate, but we do represent the issues surrounding her disappearance as a cautionary moment which warned other distance fliers that lack of preparedness could be deadly. The exhibit features several of these key “Navigation Gone Wrong” episodes that prompted navigators of the time to pause briefly and reconsider the state of their profession. My own conclusion is that is that the accident chain started with the selection of a South Pacific route and the choice of the Lockheed 10E with inadequate range that then locked in the poor choice of Howland Island as the expedition’s most critical way-station. The great shortfall in the Earhart’s and Noonan’s approach was the inability to see the magnitude of the risk they were taking in selecting Howland and gambling on the reliability of largely untested radio equipment. We may never solve the question of the final whereabouts of Earhart and Noonan, but we can understand the world in which they operated by examining the circumstances of their disappearance.

Roger Connor is a museum specialist in the Aeronautics Division of the National Air and Space Museum and co-curator of the upcoming Time and Navigation exhibition.

If you would like to learn more, view an archive of our online conference, “Thinking Critically About Amelia Earhart’s Disappearance.