This is one of the most successful research programs in the history of aviation.
60 years ago, Robert Michael White returned from space, but unlike most astronauts, he did not go there in a spacecraft.
Instead, he flew in a modern rocket-powered aircraft known as the X-15. This made him the first American astronaut to reach space without a traditional spacecraft. His flight on July 17, 1962, paved the way for space tourism and sparked a debate about what is called the edge of space.
One of the unique aspects of Robert Michael White’s (1924 – 2010) journey to space was that for the first time in history, this American pilot could control his own trajectory – from takeoff to landing.
The four Americans who reached space before Robert Michael White were all members of NASA’s Mercury Seven astronaut team based in Langley, Virginia, and their launches were remotely controlled by ground control teams.
To achieve that record in 1962, as well as many other records set thereafter, Americans diligently developed a supersonic flight program called the X-15. What exactly was this program?
The US-Soviet Rivalry: Paving the Way for New Records
The missions in NASA’s Mercury Program were largely an effort to balance the Soviet Union’s advancements in space after it successfully launched the artificial satellite Sputnik 1 in October 1957.
Following that event, the Cold War (1946-1991) escalated as Americans feared losing the space race against the Soviets. After its inception, the supersonic rocket plane X-15 restored the US-Soviet balance and paved the way for human-controlled space flight.
The Mercury Seven and the Mercury missions were conducted under NASA’s guidance. However, astronaut Robert Michael White was part of a separate collaborative program between the US Air Force and NASA to test a rocket-powered aircraft known as theX-15 Program.
The X-15 program represented an unprecedented acceleration in the development of American aviation. The X-15 set records for speed and altitude in the 1960s, reaching the edge of space and returning with valuable data used in the design of later aircraft and spacecraft.
Achieving supersonic speeds (far exceeding the speed of sound) was no small feat. These aircraft, developed in the 1960s, were specifically designed and tested to fly faster than the speed of sound. These types of planes created Mach waves by breaking the sound barrier.
Michelle Evans, author of “X-15: Rocket Plane Flying the First Wings into Space,” emphasized the extraordinary success of the X-15 Program, even by today’s standards.
Robert Michael White quickly set records in the X-15 Program, flying at a speed of 3,661 km/h. He was also the first to reach Mach 4 (approximately 4,939 km/h), and within eight months thereafter, he further piloted the X-15 to reach Mach 5 (6,173 km/h).
In history, Robert Michael White is credited as the first pilot to achieve Mach speeds of 3, 4, and 5. However, it was his space flight in the X-15 on July 17, 1962, that landed him on the cover of Life Magazine that August and made him a celebrity.
Robert Michael White is credited as the first pilot to achieve Mach speeds of 3, 4, and 5. (Source: PhotoQuest/Archive Photos/Getty Images)
While Robert Michael White held the record at that time (1962) for the highest altitude reached by a winged aircraft, the world record for the fastest speed ever achieved by a crewed aircraft was set by another pilot in the X-15 Program on October 3, 1967, namely William J. Knight (1929 – 2004), when he reached Mach 6.7 (approximately 7,274 km/h) – an extreme supersonic speed.
A Mach unit is the ratio of the speed of an object to the speed of sound, thus pilot William J. Knight flew the X-15 faster than 6.7 times the speed of sound – the highest speed ever achieved in an aircraft. The speed record for the crewed X-15A-2 that William J. Knight set still stands today after 55 years, as recorded by NASA.
“Everyone knows about the Blackbird – the long-range strategic reconnaissance aircraft developed by Lockheed Corporation, used by the US Air Force and NASA. However, the Blackbird only flew at half the speed of the X-15. Over 50 years have passed, and no vehicle has achieved what the X-15 accomplished (in terms of speed and altitude). It wasn’t until 2004 that ‘something’ surpassed the X-15 in altitude,” Michelle Evans explained.
William J. Knight – the pilot of the X-15 who achieved a speed record that remains unbroken after 55 years.
It turns out that the X-15 Program, and Robert Michael White’s historic flight to space, not only paved the way for advancements in the military field but also for space tourism.
The ‘something’ that Michelle Evans referred to in surpassing the X-15 in altitude in 2004 was SpaceShipOne, a privately owned rocket-powered aircraft capable of reaching suborbital heights, which won the Ansari X-Prize worth $10 million and ushered in a new era of space travel.
The altitude achieved by SpaceShipOne in 2004 was 112 km, breaking the record that the X-15 had held continuously for over 40 years (at an altitude of 108 km).
[The Ansari X-Prize is awarded to the first non-governmental organization that can build a vehicle capable of carrying passengers into space multiple times].
SpaceShipOne gradually evolved into SpaceShipTwo, a spacecraft owned and operated by the American space tourism company Virgin Galactic.
Where Does Space Begin?
The definition of space for tourists, pilots, and governments is not without controversy. However, international law has never defined the actual boundary of space. There are various definitions depending on the institution regarding the meaning of the space boundary.
To date, there are 2 conventions defining the “Edge of Space”:
- The Fédération Aéronautique Internationale (FAI) defines space as starting at an altitude of 100 km above the Earth – According to this convention, the Kármán Line at an altitude of 100 km is the edge of space.
- Meanwhile, NASA, the National Oceanic and Atmospheric Administration (NOAA), and the United States Air Force (USAF) typically agree that the altitude from 80 km above the Earth is the edge of space.
In 2021, the SpaceShipTwo spacecraft from Virgin Galactic, owned by British billionaire Richard Branson, flew to an altitude of over 80 km above the Earth, while the New Shepard spacecraft from Blue Origin, owned by American billionaire Jeff Bezos, flew to an altitude of 101 km.
SpaceShipTwo returning from a test flight. (Photo: GENE BLEVINS / AFP / Getty)
The Kármán Line attempts to define the threshold between space and Earth’s atmosphere. It is named after Theodore von Kármán (1881-1963), a Hungarian-American physicist and engineer who worked in aviation and space travel. In 1957, Theodore von Kármán was the first to attempt to define the altitude limit between the atmosphere and space of the Earth.
This concept aims to determine a threshold where an object is more influenced by atmospheric forces than by gravitational forces. As the atmosphere – and the objects within space – are inherently variable, selecting a specific boundary is inherently relative.
Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Institute (USA), part of the Chandra X-ray Observatory research team, supports the USAF’s convention on the edge of space (at an altitude of 80 km).
In a 2018 article titled “The Edge of Space: A Look Back at the Kármán Line,” Jonathan McDowell wrote a code to simulate atmospheric changes, taking into account parameters dependent on factors such as solar activity, time of day, and location. He ran that model 30 million times to obtain atmospheric density relative to altitude.
For Michelle Evans, the 80 km threshold seems more reasonable than the 100 km one.
However, strangely, Michelle Evans explains that while the US Air Force pilots from the X-15 project received the American Astronaut Badge (after completing training and successfully conducting a space flight), NASA pilots who crossed the 80 km boundary but not the 100 km did not receive the American Astronaut Badge until 2005 when the SpaceShipOne pilots were recognized as astronauts.
Some NASA astronauts in the “50-61 Mile Club” received the American Astronaut Badge posthumously. However, fortunately, Robert Michael White was part of the United States Air Force and is recognized as the first astronaut in the Air Force.
Bill Dana, a civilian X-15 pilot who received the American Astronaut Badge in 2005. (Photo: Smith Collection / Gado / Archive Photos / Getty Images)
Setting aside relationships, Robert Michael White was one of the first pilots to see Earth from such a fresh and magnificent perspective.
“The sky was an endless blue-black. I could see the San Francisco Bay area all the way to the coast of Mexico. And I could see the curvature of the Earth more clearly than ever. It was a breathtaking sight.” – Robert Michael White shared his feelings after the historic flight in 1962 in Life Magazine.
For professionals, two key elements stand out: an outstanding piece of machinery operated by exceptionally brave and skilled pilots – this is the remarkable legacy of the X-15 Program.
Hugh L. Dryden (1898-1965), who served at NASA as Deputy Administrator, wrote in a nomination letter for the X-15 Program for a major award in the U.S. in 1962:
“To the X-15 Research Aircraft Team, the scientists, engineers, technicians, and pilots of the National Aeronautics and Space Administration (NASA); the U.S. Department of Defense; and North American Aviation – those who conceived, designed, developed, manufactured, and operated the flights of the X-15 research aircraft.
You have contributed valuable research information on supersonic and hypersonic regimes to the edge of space, thereby making an outstanding contribution to the leadership of the U.S. in the field of aerospace science and technology and in the operation of manned space flights.
This vehicle has made invaluable technological contributions to the advancement of flight, while also highlighting the remarkable skills and courage of test pilots. The X-15 is clearly one of the most successful research programs in the history of aviation.”
