The United States has been at the forefront of space exploration for decades, launching a plethora of missions to explore the unknown reaches of our solar system. From sending humans to the moon to studying the outer planets, the US has been a major player in the history of space exploration. In this article, we will take a comprehensive look at the history of US space missions, exploring the number of missions launched, the objectives of these missions, and the impact they have had on our understanding of the universe. So, buckle up and get ready to explore the incredible world of US space missions!
The Early Years: Exploring the Solar System
The First US Space Missions
The early years of US space missions were marked by a series of pioneering efforts aimed at exploring the solar system. These initial forays into space laid the groundwork for future achievements and helped establish the United States as a leader in space exploration. Among the first US space missions were Explorer 1, Pioneer 1, and Vanguard 1.
Explorer 1
Explorer 1 was the first successful satellite launched by the United States. Designed and built by the Jet Propulsion Laboratory (JPL) in collaboration with the California Institute of Technology (Caltech), the satellite was launched on January 31, 1958, aboard a Juno I rocket. Explorer 1’s primary mission was to study the Van Allen radiation belt, a ring of charged particles surrounding the Earth. The satellite was equipped with a simple instrumentation package, including a Geiger counter and a cosmic ray detector, which provided valuable data on the radiation belt’s characteristics.
Pioneer 1
Pioneer 1 was the first of a series of unmanned spacecraft launched by the United States as part of its early space exploration efforts. Launched on March 11, 1958, aboard a Juno I rocket, the spacecraft was designed to test various technologies required for deep-space missions. Despite its failure to achieve Earth orbit, Pioneer 1 represented an important milestone in the development of space exploration technology. The spacecraft was equipped with a variety of instruments, including a telemetry system, a radiation detector, and a camera, which were used to study the Van Allen radiation belt and test the spacecraft’s performance.
Vanguard 1
Vanguard 1 was the second satellite launched by the United States and the first to be successfully placed in orbit. Launched on March 17, 1958, aboard a Vanguard rocket, the satellite was designed to study the effects of the solar wind on the Earth’s magnetic field. Vanguard 1 carried a simple instrumentation package, including a magnetic field detector and a radio transmitter, which allowed it to transmit telemetry data back to Earth. The satellite remained in orbit until 1964, when it reentered the Earth’s atmosphere and burned up.
These early US space missions laid the groundwork for future achievements in space exploration. They demonstrated the United States’ commitment to advancing its technological capabilities and expanding its understanding of the universe. As the country continued to develop its space program, it would go on to achieve a series of remarkable milestones, cementing its position as a leader in space exploration.
The First Satellites Launched into Space
In the early years of space exploration, the United States, along with the Soviet Union, was involved in a race to launch the first satellites into space. These satellites were crucial in expanding our understanding of the universe and paved the way for future space missions.
Sputnik 1
Sputnik 1 was the first artificial satellite launched into space on October 4, 1957, by the Soviet Union. It was a 184-pound aluminum sphere that orbited the Earth once every hour and transmitted radio signals back to Earth. The launch of Sputnik 1 marked the beginning of the Space Age and sparked intense interest in space exploration around the world.
Sputnik 2
Sputnik 2 was launched on November 3, 1957, by the Soviet Union. It was larger than Sputnik 1, weighing about 1,100 pounds, and carried a live dog named Laika on board. Laika was the first living being to be sent into space and unfortunately did not survive the mission due to the extreme temperatures outside the satellite. Sputnik 2 also carried a variety of scientific instruments that provided valuable data about the Earth’s atmosphere and space.
Explorer 5
Explorer 5 was the first satellite launched by the United States on August 23, 1958. It was a 4-foot-tall metal sphere that weighed about 6.5 pounds and was designed to study the Earth’s magnetic field. Explorer 5 was launched into a polar orbit, which allowed it to study the Earth’s magnetic field from all directions. The data collected by Explorer 5 helped scientists understand the Earth’s magnetic field and how it interacts with space.
These first satellites launched into space marked a significant milestone in the history of space exploration and paved the way for future space missions. The United States and the Soviet Union continued to compete in space exploration in the following years, leading to a series of groundbreaking discoveries and technological advancements.
The Dawn of the Space Age: Project Mercury
Mercury-Redstone 3
On November 20, 1961, the United States launched its first human spaceflight, Mercury-Redstone 3, carrying astronaut Alan Shepard into suborbital space. This mission marked the beginning of America’s journey into space and demonstrated the nation’s ability to send humans beyond Earth’s atmosphere.
Mercury-Atlas 6
On February 20, 1962, John Glenn became the first American to orbit the Earth aboard the Mercury-Atlas 6 mission. This historic flight lasted just under five hours and helped to establish the United States as a leader in space exploration.
Mercury-Atlas 9
On May 24-25, 1963, astronaut Gordon Cooper completed a 34-hour solo flight in space aboard the Mercury-Atlas 9 mission. This mission was the longest spaceflight to date and demonstrated the capability of humans to perform extended space missions.
Through these early missions, Project Mercury laid the foundation for future human spaceflight programs and inspired a new generation of space explorers.
The Race to the Moon: Project Apollo
The Goal: Landing on the Moon
The United States’ quest to land on the Moon was the central goal of the Project Apollo program. The Apollo 1, Apollo 4, and Apollo 8 missions were all critical steps in achieving this goal.
Apollo 1
Apollo 1 was a tragic setback for the program. During a pre-launch test on January 27, 1967, a fire broke out in the command module, killing three astronauts: Gus Grissom, Ed White, and Roger Chaffee. The accident occurred due to a combination of factors, including a faulty electrical wire and the presence of a pure oxygen atmosphere inside the capsule. The loss of life was a sobering reminder of the risks involved in space exploration. However, the accident also led to significant improvements in safety procedures and design.
Apollo 4
Apollo 4 was the first test flight of the Saturn V rocket, the powerful vehicle that would carry astronauts to the Moon. The mission was launched on November 9, 1967, from Kennedy Space Center in Florida. The rocket successfully reached Earth orbit and then reentered the atmosphere, demonstrating its capabilities and the capabilities of the ground support team.
Apollo 8
Apollo 8 was the first manned flight to orbit the Moon. The mission was launched on December 14, 1968, with astronauts Frank Borman, James Lovell, and William Anders on board. The astronauts spent several days in orbit around the Moon, where they conducted experiments and took photographs. One of the most iconic images of the mission is the photograph of the Earth rising over the Moon’s horizon, which captures the fragility and beauty of our home planet from space. The success of the mission provided a major boost to morale and helped to cement the United States’ position as a leader in space exploration.
The Giant Leap: Apollo 11
The Mission
On July 20, 1969, NASA’s Apollo 11 mission made history as the first successful manned landing on the moon. The mission was led by astronauts Neil Armstrong, Buzz Aldrin, and Michael Collins, who embarked on a journey that captivated the world and marked a significant achievement in human history. The primary objective of the mission was to demonstrate human exploration and habitation of the moon, while also conducting scientific experiments and gathering data.
The Crew
The Apollo 11 crew consisted of three astronauts: Neil Armstrong, Buzz Aldrin, and Michael Collins. Neil Armstrong, the mission’s commander, was a naval aviator and test pilot with over 2,500 hours of flight experience. Buzz Aldrin, the lunar module pilot, was a former U.S. Air Force pilot and a doctoral candidate in astronautics at MIT. Michael Collins, the command module pilot, was a military pilot and a former astronaut who had flown on the Gemini 10 mission. The crew underwent extensive training to prepare for the rigors of space travel and the challenges of landing on the moon.
The Impact
The Apollo 11 mission had a profound impact on human history, capturing the imagination of people around the world and inspiring generations to pursue careers in science, technology, engineering, and mathematics (STEM). The successful landing on the moon demonstrated the power of human ingenuity and the potential for space exploration, leading to increased investment in space research and development. The mission also sparked international cooperation in space exploration, with countries around the world collaborating on projects such as the International Space Station. Additionally, the Apollo 11 mission paved the way for future space missions, including the development of spacecraft for long-term habitation and the exploration of other planets in our solar system.
The Lunar Rover and Beyond: Apollo 15
The Apollo 15 mission was launched on July 26, 1971, and was the third mission to land on the Moon. The mission’s primary objective was to conduct extensive geological surveys and experiments on the lunar surface. The mission was also significant as it marked the first time that a lunar rover was used to explore the Moon’s terrain.
The Lunar Rover
The lunar rover was a four-wheeled vehicle that was designed to allow the astronauts to explore the Moon’s surface more effectively. The rover was equipped with a range of scientific instruments, including a scoop for collecting samples, a drilling tool, and a camera. The rover could travel up to 12 miles per hour and had a range of 120 miles.
The lunar rover was critical to the success of the Apollo 15 mission, as it allowed the astronauts to explore a much larger area of the Moon’s surface than would have been possible on foot. The rover also enabled the astronauts to collect a vast array of scientific data and samples, which helped to further our understanding of the Moon’s geology and composition.
The Scientific Discoveries
The Apollo 15 mission was a significant scientific success, with the astronauts collecting a vast array of data and samples from the Moon’s surface. The lunar rover allowed the astronauts to explore the Moon’s terrain in detail, and they discovered a range of interesting geological features, including a massive 4-mile-wide mountain.
The astronauts also discovered evidence of ancient volcanic activity on the Moon, which helped to further our understanding of the Moon’s geological history. The samples collected during the mission provided valuable insights into the Moon’s composition and helped to advance our knowledge of lunar geology.
Overall, the Apollo 15 mission was a significant milestone in the history of US space missions, and the lunar rover played a critical role in the mission’s success. The data and samples collected during the mission continue to provide valuable insights into the Moon’s geology and composition, and the mission helped to advance our understanding of space exploration and scientific research.
The End of the Apollo Era: Apollo 17
- The Mission
Apollo 17 was the last mission of the Apollo program, launched on December 14, 1972, and concluded on December 14, 1972. It was the sixth lunar landing mission and the second longest mission, lasting for 10 days. The mission was led by Commander Eugene Cernan, Command Module Pilot Ronald Evans, and Lunar Module Pilot Harrison Schmitt. - The Last Steps on the Moon
During the mission, Cernan and Schmitt spent three days on the lunar surface, conducting experiments and collecting samples. On December 14, 1972, Cernan and Schmitt took the last steps on the Moon as humans, before returning to Earth. - The Legacy
Apollo 17 marked the end of the Apollo program and the end of the first era of human space exploration. The mission also provided valuable scientific data and geological samples that helped to further our understanding of the Moon and the early history of the solar system. Additionally, the mission inspired a new generation of scientists, engineers, and explorers, and cemented the United States’ position as a leader in space exploration.
The Shuttle Era: Exploring Low Earth Orbit
The Beginning: Columbia
The Launch
The Columbia, the first space-rated orbiting and landing vehicle in the world, was launched on April 14, 1981, from Kennedy Space Center in Florida. It was a momentous occasion, not only for the United States but for the entire world, as the Columbia marked a significant step forward in the nation’s space program. The launch was broadcasted live, and millions of people around the globe watched as the shuttle ascended into the sky, heralding a new era of space exploration.
The Columbia’s maiden voyage was designated as STS-1, and its primary objective was to test the orbiter’s systems and capabilities. The mission was a resounding success, as the Columbia performed flawlessly throughout its 2-day, 14-hour flight. The crew, comprising of commander John Young and pilot Robert Crippen, conducted a series of tests and maneuvers, demonstrating the shuttle’s ability to orbit the Earth and land safely back on Earth. This historic mission marked the beginning of a new era of space exploration, as the United States embarked on a journey to advance its knowledge and presence in space.
The Tragedy
Despite the successful launch and mission of the Columbia, tragedy struck on January 28, 1986, when the shuttle broke apart during re-entry into the Earth’s atmosphere, killing all seven crew members on board. The accident was a profound loss for the United States and the global space community, as it marked the first loss of a space shuttle and its crew. The disaster led to a thorough investigation and significant improvements in safety measures, ensuring that future space missions would be conducted with a greater degree of caution and care.
The Challenger Disaster
On January 28, 1986, the Space Shuttle Challenger was scheduled to launch from Kennedy Space Center in Florida. The mission, designated STS-51-L, was set to be the 25th flight of the Space Shuttle program and the first mission of 1986. The crew included five NASA astronauts: Commander Francis R. “Dick” Scobee, Pilot Michael J. Smith, Mission Specialists Ellison S. Onizuka and Judith A. Resnik, and Payload Specialist Christa McAuliffe, who was selected to become the first teacher in space.
The launch was delayed several times due to various issues, including a malfunctioning fuel cell and high winds at the launchpad. Despite these setbacks, the mission was given the go-ahead for launch on January 28th. At 11:38 AM EST, the Challenger lifted off from the launchpad, carrying with it the hopes and dreams of a nation.
Just 73 seconds into the flight, however, disaster struck. Witnesses on the ground reported seeing a plume of smoke rising from the right side of the rocket, followed by a loud explosion. The spacecraft broke apart, killing all seven crew members on board. The tragedy was later found to be caused by a failure in one of the solid rocket boosters, which caused the O-ring seals to malfunction and allow hot gases to leak into the fuel tank, causing a massive explosion.
The Challenger disaster was a profound tragedy that shocked the nation and brought attention to the dangers of space exploration. It also marked a turning point in the history of the Space Shuttle program, leading to significant changes in safety protocols and an increased focus on risk management.
The Hubble Space Telescope
The Hubble Space Telescope (HST) was launched on April 24, 1990, aboard the space shuttle Discovery (STS-31). Its primary mission was to study the universe and investigate the mysteries of space, but the HST’s scientific success was almost jeopardized by a catastrophic malfunction in its main camera, the High Resolution Camera (HRC). The failure of the HRC’s optics caused a blurry, out-of-focus image that frustrated astronomers and put the future of the mission in doubt. However, NASA engineers devised a unique solution: the Wide Field and Planetary Camera (WFPC), a new instrument designed to be compatible with the HST’s other three cameras.
The WFPC’s installation during the STS-61 servicing mission in December 1993 marked the beginning of a new era for the HST. This dramatic rescue mission, performed by the space shuttle crew, captured the world’s imagination and showcased the ingenuity of the HST team. With the WFPC, the HST could capture stunning images of the universe, including the first direct evidence of black holes, the first detailed observations of the environment around a planet outside our solar system, and the discovery of distant galaxies.
The HST’s impact on science was immense. The data gathered by the HST revolutionized our understanding of the universe, from the age of the universe itself to the evolution of galaxies, stars, and planets. The HST also revealed the beauty of the cosmos through its iconic images, such as the “Pillars of Creation” in the Eagle Nebula and the “Deep Field” images that showcased the vastness of the universe.
In 2003, the HST’s remarkable achievements were celebrated with the release of the IMAX film “Hubble: Space Telescope, The”, which captivated audiences worldwide. The HST continued to deliver groundbreaking science until 2009, when it was replaced by the successor, the James Webb Space Telescope (JWST), set to launch in 2021. The HST’s legacy continues to inspire future generations of scientists and explorers, showcasing the power of human ingenuity and the quest for knowledge.
The International Space Station
The Partnership
The International Space Station (ISS) is a remarkable achievement in international cooperation, bringing together NASA, the European Space Agency (ESA), the Canadian Space Agency (CSA), and the Russian Space Agency (Roscosmos) to collaborate on a single project. Since its inception, the ISS has been a symbol of peaceful cooperation in space, providing a platform for scientific research, technology development, and human space exploration.
The Construction
The assembly of the ISS began in 1998, with the launch of the first module, Zarya, by NASA and Roscosmos. Over the next several years, more modules were added, including the Unity module, which housed the first American crew to live aboard the station in 2000. The ISS continued to grow, with modules being added by all partnering agencies, and the completion of the station’s main truss structure in 2011. The construction of the ISS required over 30 shuttle missions, countless hours of engineering and design work, and the coordination of numerous international partners.
The Research
The ISS has been the site of numerous scientific and technological research projects, spanning a wide range of disciplines, including biology, physics, astronomy, and engineering. Scientists have conducted experiments on the station to study the effects of microgravity on the human body, the behavior of fluids and materials in space, and the study of Earth and its environment. The ISS has also been used as a platform for testing new technologies, such as solar panels, which provide the station with power, and new propulsion systems, which will be needed for future space exploration.
The ISS has also provided valuable data on the long-term effects of space travel on the human body, which will be invaluable for future missions to Mars and beyond. The station’s unique position in low Earth orbit has made it an ideal platform for observing Earth and its environment, providing unparalleled views of the planet and helping scientists to better understand our planet’s complex systems.
In summary, the International Space Station is a remarkable achievement in international cooperation and a testament to the power of collaboration in space exploration. Its construction and ongoing research have provided invaluable data and insights, paving the way for future space missions and human space exploration.
The Future of US Space Missions
Commercial Space Travel
The Companies
A growing number of private companies are entering the space industry, with a focus on commercial space travel. Some of the leading companies in this field include:
- SpaceX: Founded by Elon Musk, SpaceX is a private aerospace manufacturer and space transport services company. Its primary goal is to reduce space transportation costs and enable the colonization of Mars.
- Blue Origin: This private aerospace manufacturer and spaceflight services company was founded by Jeff Bezos, the CEO of Amazon. Blue Origin is developing technologies to enable private space travel and the exploration of space resources.
- Virgin Galactic: Richard Branson’s company is working on commercial space travel, with a focus on suborbital flights for space tourism and research.
- Axiom Space: This company plans to build a space station in low Earth orbit, which will be available for research, tourism, and business activities.
The Goals
The primary goal of these companies is to make space travel accessible to the general public. By offering suborbital flights and even space hotel stays, these companies aim to democratize space exploration and make it a viable industry. Other goals include:
- Tourism: Providing opportunities for wealthy individuals to experience space travel and view Earth from space.
- Research: Enabling scientists to conduct experiments in microgravity environments, which can provide valuable insights into the effects of space on living organisms and materials.
- Economic development: Creating new business opportunities and industries in space, such as mining of rare-earth elements and helium-3, a potential fuel for fusion reactors.
The Challenges
Despite the excitement and potential of commercial space travel, there are several challenges that these companies must overcome:
- Safety: Ensuring the safety of passengers and crew during space travel is of paramount importance. Companies must invest in robust safety protocols and reliable technology to minimize risks.
- Cost: Space travel is incredibly expensive, and companies must find ways to reduce costs while maintaining safety and reliability.
- Regulation: As the space industry grows, there is a need for clearer regulations and international agreements to ensure safe and responsible operations.
- Infrastructure: Developing the necessary infrastructure for commercial space travel, such as spaceports and orbital facilities, requires significant investment and collaboration.
Overall, the future of US space missions involves a growing partnership between government agencies, private companies, and international organizations, with a focus on making space travel accessible, safe, and sustainable for all.
Mars Exploration
The Plans
The United States has been actively pursuing the exploration of Mars for several decades. In the coming years, there are several ambitious plans in place to further advance our understanding of the Red Planet.
The Technology
Advancements in technology have played a crucial role in the development of space missions. With the rise of private space companies, there has been a significant increase in the availability of advanced technologies that are being utilized in space exploration.
The Timeline
The timeline for Mars exploration is rapidly approaching, with several missions planned for the coming years. These missions aim to gather valuable data about the planet’s geology, atmosphere, and potential for supporting life.
Lunar Exploration
The Moon has been a focal point for space exploration for many years, and the United States has plans to continue exploring this celestial body in the coming years.
The development of new technologies has made it possible to explore the Moon in ways that were previously not possible. Advanced robotics and sensors are being used to gather data about the Moon’s surface and subsurface.
The timeline for lunar exploration is also rapidly approaching, with several missions planned for the coming years. These missions aim to gather valuable data about the Moon’s geology, resources, and potential for supporting human habitation.
Commercial Space Industry
The commercial space industry has grown significantly in recent years, with private companies entering the market and offering a range of services, from satellite launches to space tourism.
The development of reusable rockets and other advanced technologies has made it possible for private companies to enter the space industry. These companies are also investing in research and development to advance space exploration.
The timeline for the growth of the commercial space industry is uncertain, but it is clear that this industry will play a significant role in the future of space exploration. Private companies are expected to play a key role in the development of new technologies and the exploration of new frontiers in space.
Beyond Mars: The Quest for Interstellar Travel
The Idea
The idea of interstellar travel has captivated the imagination of humans for centuries. Since the first successful human spaceflight by NASA’s Mercury program in the late 1950s, the US space program has been exploring the possibilities of traveling beyond our solar system. With the discovery of exoplanets orbiting other stars, the possibility of human travel to these distant worlds has become a viable goal for the future of space exploration.
Interstellar travel presents a significant challenge for human spaceflight. The distance between the Earth and other star systems is vast, and the journey would take many years, if not decades, to complete. In addition, the harsh conditions of space travel, such as radiation and microgravity effects on the human body, would need to be addressed to ensure the safety and survival of astronauts on such a mission.
Furthermore, the technology required for interstellar travel is still in its infancy. Developing a propulsion system that can accelerate a spacecraft to the necessary speeds for interstellar travel is a significant technological challenge. In addition, the development of advanced life support systems, efficient energy sources, and advanced communication systems are all necessary for a successful interstellar mission.
Although interstellar travel is still a long way off, NASA and other space agencies have already begun research and development efforts to make it a reality. In the near term, NASA plans to explore the Moon and Mars, with the goal of establishing a sustainable human presence on the Red Planet by the end of the 2030s. This will provide valuable experience and technology for future interstellar missions.
By the middle of the 21st century, NASA plans to develop the necessary technology for interstellar travel, including the development of a new propulsion system, advanced life support systems, and efficient energy sources. In the latter half of the century, NASA envisions sending crewed missions to the nearest exoplanets, which are expected to be discovered in the coming decades.
While the timeline for interstellar travel is still uncertain, it is clear that the US space program is committed to exploring the possibilities of human travel beyond our solar system. With continued research and development efforts, the dream of interstellar travel may become a reality within our lifetime.
The New Frontier: The Future of US Space Missions
The Opportunities
As the United States continues to advance its space exploration capabilities, a new frontier of opportunities has emerged. The future of US space missions is set to bring about new discoveries, advancements, and benefits to humanity.
Despite the exciting prospects, the future of US space missions also comes with its fair share of challenges. From funding constraints to safety concerns, there are several obstacles that must be overcome to ensure the success of these endeavors.
The Future
As the US space program looks towards the future, there are several exciting missions planned that aim to push the boundaries of space exploration. From returning to the moon to establishing a sustainable presence on Mars, the future of US space missions is set to be an exciting and ambitious one.
FAQs
1. How many space missions has the US had?
The United States has had numerous space missions over the years. The exact number of missions is difficult to determine, as it depends on how one defines a “space mission.” However, as of 2021, NASA has launched over 150 space missions, including both crewed and uncrewed missions.
2. What was the first US space mission?
The first US space mission was the Army’s “Explorer 1,” which was launched on January 31, 1958. The mission was a joint effort between the Army and the Jet Propulsion Laboratory (JPL), and its primary goal was to study the Earth’s magnetic field.
3. How many crewed space missions has the US had?
As of 2021, the United States has had a total of 14 crewed space missions. These missions have included trips to the Moon, trips to the International Space Station (ISS), and trips to other planets in our solar system.
4. What was the first crewed US space mission?
The first crewed US space mission was the Mercury-Redstone 3 mission, which was launched on May 5, 1961. The mission was designed to test the safety of manned spaceflight, and it carried astronaut Alan Shepard to an altitude of 116 miles.
5. How many trips to the Moon has the US made?
The United States has made a total of six trips to the Moon. The first trip was made by Neil Armstrong and Buzz Aldrin during the Apollo 11 mission in 1969. The most recent trip was made by the Apollo 17 mission in 1972.
6. How many trips to Mars has the US made?
As of 2021, the United States has made a total of seven trips to Mars. The first trip was made by the Viking 1 and Viking 2 missions in 1975 and 1976, respectively. The most recent trip was made by the Perseverance rover in 2020.
7. What is the International Space Station (ISS)?
The International Space Station (ISS) is a habitable artificial satellite that orbits the Earth at an altitude of around 250 miles. It was built and is maintained by a partnership of five space agencies: NASA, Roscosmos, the European Space Agency (ESA), the Japan Aerospace Exploration Agency (JAXA), and the Canadian Space Agency (CSA). The ISS has been continuously occupied by astronauts since November 2000 and has hosted over 200 different crew members from 19 different countries.
8. How long has the ISS been in orbit?
The International Space Station (ISS) was launched on November 20, 1998, and has been in orbit since then. As of 2021, it has been in orbit for over 22 years.
9. What is the purpose of the ISS?
The primary purpose of the International Space Station (ISS) is to provide a platform for scientific research and technological development. The station is equipped with a variety of laboratories and facilities that allow scientists to conduct experiments in microgravity, which can provide valuable insights into the behavior of materials, fluids, and other phenomena. The ISS also serves as a testbed for new technologies and systems that could be used in future space missions.
10. How many people have visited the ISS?
As of 2021, a total of 242 people have visited the International Space Station (ISS). Of these, 218 have been American astronauts, while the remaining 24 have been astronauts from other countries.
