Space exploration represents humanity's quest to understand the universe. I've always been fascinated by the little knowledge I had about our place in the cosmos. Last week, I dove into the history of space exploration and human spaceflight to satisfy my curiosity. Along the way, I documented the questions I’ve always wondered about and prepared this FAQ-style document to share what I learned.
First, what does space mean? How far from the earth surface?
Space is everything that exists beyond Earth's atmosphere. It begins at a boundary called the Kármán line , which is approximately 100 kilometers above sea level.
This line is named after Hungarian-American physicist Theodore von Kármán who calculated a theoretical limit of altitude for airplane flight at 83.8 km (52.1 mi) above. At this altitude, the atmosphere becomes too thin for conventional aircraft to maintain lift, marking the edge where space begins.
How high do planes fly? When did the first aircraft cross the Kármán line?
Planes usually fly between 9–12 kilometers above the sea-level where the air is thin enough to reduce drag but still dense enough for efficient engine operation.
The first human-made object to cross the Kármán Line was the German V-2 rocket(MW 18014) in June 10 1944 , reaching an altitude of 176 kilometers.
It was a vertical test launch, and was not intended to reach orbital velocity, so it returned and impacted Earth, making it the first sub-orbital spaceflight.
What is orbital velocity?
Orbital velocity is the minimum speed an object must achieve to enter and remain in orbit around a planet or celestial body. This speed allows the object to counteract the pull of gravity by continuously "falling" around the planet rather than being pulled back to the surface.
For Earth, orbital velocity near the surface is approximately 7.9 kilometers per second. At higher altitudes, it is slightly less because gravity weakens.
Achieving orbital velocity is essential for satellites, space stations, and spacecraft to maintain stable orbits and function effectively in space.
What was the first spacecraft to reach orbital velocity?
The first successful orbital launch was of the Soviet uncrewed Sputnik 1 ("Satellite 1") mission on 4 October 1957 .
It was an uncrewed satellite that orbited Earth and transmitted radio signals, or “beeps,” for about three weeks.
The satellite weighed about 83 kg, and is believed to have orbited Earth at a height of about 250 km. It had two radio transmitters (20 and 40 MHz), which emitted "beeps" that could be heard by radios around the globe.
Sputnik 1 was launched by an R-7 rocket. It burned up upon re-entry on 3 January 1958.
Why did Germany and the Soviet Union develop rockets?
The German V-2 rocket program, developed during World War II under Wernher von Braun's leadership, was primarily designed as a weapon—the world's first long-range ballistic missile.
The Soviet Union's Sputnik program emerged from the Cold War rivalry between the USSR and the United States. After World War II, both nations recruited German rocket scientists and raced to demonstrate their technological superiority. The Soviets, under chief rocket engineer Sergei Korolev, transformed their R-7 ballistic missile into the launcher that would carry Sputnik 1. The successful launch in 1957 wasn't just a scientific milestone—it was a powerful political statement that shocked the Western world and launched what became known as the "Space Race."
Human SpaceFlight
Who was the first human to go to space?
The first human to travel to space was Yuri Gagarin , a Russian cosmonaut, on April 12, 1961 . He orbited Earth once during his 108-minute flight aboard Vostok 1 .
The spacecraft reached a maximum altitude of about 327 kilometers (203 miles) before safely returning to Earth.
After Yuri Gagarin, how did human spaceflight evolve?
Following Gagarin's historic flight, the Space Race accelerated with both Soviet and American achievements:
The first woman in space was Soviet cosmonaut Valentina Tereshkova (1963)
The first spacewalk was performed by Alexei Leonov (1965)
The Gemini program (1965-1966) demonstrated crucial capabilities like spacewalking and orbital rendezvous
The first space station, Salyut 1, was launched by the USSR in 1971
Skylab became America's first space station (1973-1979)
The International Space Station (ISS) has maintained continuous human presence since 2000
What is the International Space Station (ISS), and why is it important?
The International Space Station (ISS) orbits Earth about 400 above the surface. It’s a laboratory where astronauts from different countries work together to study science, test technology, and prepare for missions to the Moon and Mars.
Astronauts conduct experiments on topics ranging from biology to material science, paving the way for missions to the Moon, Mars, and beyond.
The Moon
When did we go to the moon?
The Soviet Union launched Luna 1 on January 2, 1959 , aiming to impact the Moon. However, due to a navigation error, it missed the Moon and became the first human-made object to escape Earth’s gravity and orbit the Sun instead.
The Soviet Luna 2 mission successfully impacted the Moon on September 14, 1959 , becoming the first human-made object to reach its surface.
The Soviet Luna 9 achieved the first soft landing on February 3, 1966 , sending back the first images from the lunar surface.
First artificial satellite of the Moon (Luna 10, 1966)
The first humans to see the Moon up close were the crew of Apollo 8 (Frank Borman, James Lovell, and William Anders), who orbited the Moon in December 1968 . They became the first humans to witness "Earthrise" and see Earth's full disk from space.
The first crewed landing on another celestial body was performed by** Apollo 11** on 20 July 1969 , landing on the Moon. neil armstrong and buzz aldrin became the first humans to walk on its surface.
What were the apollo missions, and what did they achieve?
The Apollo program (1961–1972) aimed to land humans on the Moon and bring them back safely. Six missions successfully landed astronauts on the Moon:
apollo 11 (1969): first moon landing (armstrong and aldrin).five subsequent missions (apollo 12–17) brought back lunar samples, conducted experiments, and expanded scientific knowledge.
the final mission, apollo 17 , in december 1972, was the last crewed Moon mission.
Other Planets Mission: Venus, Mars
What was the first mission to another planet?
The first attempt to send a rocket to another planet occurred on August 27, 1960, when the Soviet Union launched Korabl 4 , part of the Marsnik program (Mars 1960A). This mission aimed to fly past Mars, but the rocket failed to reach Earth orbit.
The first successful interplanetary mission was NASA's Mariner 2 , launched on August 27, 1962 , which performed a flyby of Venus and transmitted scientific data about the planet's atmosphere and surface conditions.
For Mars , the first successful attempt was Mariner 4 , launched on November 28, 1964, which performed the first Mars flyby, returning 21 images of its surface.
When did we first land a spacecraft on another planet?
The first successful landing of a spacecraft on another planet was achieved by the Soviet Union's Venera 7 mission, which landed on Venus on December 15, 1970 . It was the first spacecraft to transmit data from the surface of another planet.
Venera 7 survived for about 23 minutes under Venus's extreme conditions, where the surface temperature is approximately 462°C , and the atmospheric pressure is about 90 times that of Earth .
For Mars , the first successful soft landing was achieved by NASA's Viking 1 mission on July 20, 1976 . Viking 1 transmitted high-resolution images, conducted soil experiments, and searched for signs of life on the Martian surface.
Venus Missions
What was the first Venus mission?
The first successful Venus mission was the Venera 1 by the Soviet Union, launched in 1961. However, it lost contact before it could reach Venus. The first successful mission to Venus was Venera 7 (1970), which became the first spacecraft to transmit data from the surface of Venus, revealing its extreme temperatures and dense atmosphere.
Venus Missions
Soviet Venera program began in 1961
Mariner 2 became first successful Venus flyby (1962)
Venera 7 achieved first successful landing (1970)
Pioneer Venus missions provided detailed atmospheric data (1978)
Magellan mapped 98% of the surface (1989-1994)
What have we learned about Venus?
Extreme surface conditions (462°C, 90 atmospheres pressure)
Thick atmosphere of mostly carbon dioxide
Possible signs of past oceans
Volcanic activity and unique geology
Recent phosphine detection suggesting possible microbial life
Mars Missions
What was the first Mars Mission? The first successful Mars mission was Mariner 4, launched by NASA in 1964. It was the first spacecraft to fly by Mars, sending back 21 images of the planet's surface. These images revealed a cold, cratered landscape and were humanity's first close-up views of Mars.
What were the early Mars exploration milestones?
Mariner 4 performed first successful flyby (1964)
Mars 2 and 3 were first to reach surface (1971)
Viking 1 and 2 conducted first successful landings (1976)
Mars Global Surveyor began detailed mapping (1996)
How has Mars exploration evolved?
Spirit and Opportunity rovers (2004)
Phoenix lander studied polar ice (2008)
Curiosity rover (2012) studying habitability
Perseverance rover (2021) searching for past life
International missions from Europe, China, and India
Plans for human missions to Mars
Telescopes, Probes
What are telescopes used for in space?
Telescopes like the Hubble Space Telescope help scientists study distant stars, galaxies, and planets. They work better in space because there’s no atmosphere to blur the images.
The first space telescope was the Orbiting Astronomical Observatory (OAO-2) , launched in 1968 , designed to observe objects in ultraviolet light.
Major Space Telescopes:
Hubble Space Telescope (1990) : Captures visible, ultraviolet, and near-infrared light.Chandra X-ray Observatory (1999) : Focuses on high-energy X-ray emissions from cosmic sources like black holes and supernovae.Spitzer Space Telescope (2003-2020) : Specialized in infrared observations, helping study distant galaxies, star formation, and exoplanets.James Webb Space Telescope (2021) : The successor to Hubble, designed to observe infrared light, studying early galaxies, star formation, and exoplanets in unprecedented detail.
What are space probes?
Space probes are uncrewed spacecraft designed to explore space beyond Earth's orbit. They collect data about planets, moons, asteroids, and other celestial bodies, sending it back to Earth.
Major Space Probes:
Voyager 1 & 2 (1977) : Explored outer planets; Voyager 1 is now in interstellar space.Pioneer 10 & 11 (1972–73) : First to cross the asteroid belt and explore Jupiter and Saturn.Cassini-Huygens (1997–2017) : Studied Saturn and its moons; Huygens landed on Titan.
New Horizons: Flying past Pluto and into the Kuiper Belt.New Horizons (2006) : Conducted a historic flyby of Pluto in 2015.New Horizons (2006) : Conducted a historic flyby of Pluto in 2015.Perseverance Rover (2020) : Explores Mars, searching for signs of ancient life.
