Knowledge Atlas

Universe · Depth 2 · Introductory · 1 min read

Space Exploration

How people explore beyond Earth with satellites, robotic probes and crewed missions, from Sputnik in 1957 to the International Space Station.

Evidence Level 2 · AuthoritativeOpen on the map
On this page
  1. Getting off the ground
  2. The first satellites
  3. Robots to the planets
  4. People in space
  5. More than space
  6. Real-life examples
  7. Evidence & sources

Getting off the ground

Leaving Earth is mostly a battle with gravity. A spacecraft needs about 8 km/s just to stay in a low orbit, and about 11 km/s to escape Earth altogether.[1]

The first satellites

The space age began on 4 October 1957, when the Soviet Union launched Sputnik, the first artificial satellite.[1] A year later, on 1 October 1958, NASA opened its doors as the U.S. agency responsible for the civil space program.[2]

Robots to the planets

Travelling between planets relies on clever use of gravity: spacecraft can use gravity-assisted encounters with the planets they pass. Voyager 2 used a series of such flybys to visit all four giant planets between 1979 and 1989.[1] To stay at a destination rather than fly past, a spacecraft has to slow down with its rocket when it arrives.[1]

People in space

NASA’s programs include human spaceflight, and the International Space Station is one of its major facilities.[2] Like every satellite, the station stays up by falling around Earth rather than onto it.[1]

More than space

Space agencies study Earth too. NASA’s research ranges from Earth’s climate to the wider universe and new aviation technologies.[2] See Satellites for how orbiting instruments help track our planet.

Real-life examples

  • Voyager 2's grand tour

    Using a chain of gravity assists, Voyager 2 flew past Jupiter (1979), Saturn (1980), Uranus (1986) and Neptune (1989).[1]

  • A laboratory in orbit

    NASA operates the International Space Station as one of its major facilities.[2]

  • Not only rockets

    NASA's work also includes aeronautics research and studies of Earth's climate as well as the wider universe.[2]

Go deeper

1 of 3 topics below this one are written so far. The rest are uncharted: on the map, but not yet written. The Atlas is growing.

Connected across the map

Learn more

Short descriptions are our own summaries. The resources belong to, and are run by, their publishers.

Evidence & sources

Level 2 · Authoritative

Supported by highly reputable institutions such as government agencies, universities or standards bodies.

Why this level? The historical facts here (Sputnik, NASA's founding, Voyager 2's flybys) come from NASA and a peer-reviewed astronomy textbook.

This is a Knowledge Atlas editorial classification of the sources we could find, not a certificate of truth. How we evaluate knowledge

Sources

Based on 2 sources from 2 institutions: OpenStax, NASA.

Show all 2 sourcesHide the list
  1. ScholarlyOpenStax (Rice University)· Academic publisherAstronomy 2e, 3.5 Motions of Satellites and SpacecraftOpened and checked against this page on 28 Sept 2026 · License: CC BY-NC-SA 4.0
  2. AuthoritativeNational Aeronautics and Space Administration· Government agencyAbout NASAOpened and checked against this page on 28 Sept 2026