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Home›Astronomy and space

Spaceflight

A rocket pushes gas down so the gas pushes it up. Follow the physics from Goddard's 12-metre hop in 1926 to orbit at 7.7 km/s, the Moon, the International Space Station and Voyager 1, a light-day from Earth in November 2026.

Progress

About this course

On 16 March 1926, on a snowy farm in Auburn, Massachusetts, Robert Goddard launched the world's first liquid-fuelled rocket. According to the Town of Auburn, it reached 41 feet, about 12.5 m, flew for two and a half seconds and landed 184 feet from its launching frame. A rocket pushes gas down so the gas pushes it up, and the whole course follows that physics from the 12-metre hop to Voyager 1, a light-day from Earth in November 2026.

The six units go outward. How a rocket works comes first, then orbits as falling round the Earth, where at 400 km a satellite must travel about 7.7 km every second. Satellites run from Sputnik 1, 58 cm across, 83.6 kg, circling Earth in about 98 minutes, to GPS. Getting to the Moon covers Apollo 11, which left Earth on 16 July 1969 and splashed down eight days later. The space station unit notes that people have lived aboard without a break since 2 November 2000. One story there is Yi So-yeon, an engineer chosen from more than 36,000 applicants, who lifted off in a Soyuz from Baikonur on 8 April 2008 and spent 11 days in space running 18 experiments. The last unit covers probes, and Voyager 1, launched in 1977, will be about 26 billion km away in November 2026. The labs show the Earth and Moon not to scale, a sky view of Seoul on 18 October 2026, and the planets Voyager 1 passed.

Before you start

Newton's laws carry most of this course, so a first pass through Forces and Motion makes the rocket equation and orbital speed easier to follow. Many quizzes ask for answers to one or two decimals with square roots, so keep a calculator nearby.

When you finish

You will be able to work out a rocket's change in speed from exhaust speed and mass ratio, calculate orbital speed and period with v = √(GM ÷ r), and find the altitude of geostationary orbit. You can also explain why ISS astronauts float, how GPS fixes a position from four satellites, and what a gravity assist does for a probe like Voyager.

  1. 1How a rocket worksThe first liquid-fuelled rocket flew for two and a half seconds and rose about 12.5 m.
  2. 2Orbits: falling round the EarthAt 400 km up, a satellite must travel about 7.7 km every second to stay in orbit.
  3. 3Satellites: from Sputnik to GPSSputnik 1, the first satellite, was 58 cm across, weighed 83.6 kg and went round Earth in about 98 minutes.
  4. 4Getting to the MoonApollo 11 left Earth on 16 July 1969 and its crew splashed down eight days later, on 24 July.
  5. 5The International Space StationPeople have lived on the space station without a break since 2 November 2000.
  6. 6Space probes to the planets and beyondVoyager 1, launched in 1977, will be one light-day from Earth, about 26 billion km, in November 2026.

Related courses

  • The solar system
    Eight planets, one star, and distances so large that a true-scale model will not fit on any screen. Spin the 3D model, switch to true scale, and compare the planets with real numbers.
  • The Moon
    The Moon is 384,400 km away on average and shows us the same face all month. Move the 3D Sun, Earth and Moon through one 29.53-day cycle, line them up for eclipses, and watch the tides follow.
  • Stars
    The Sun is an ordinary star 109 Earths wide, and Betelgeuse would hold hundreds of millions of Suns. Compare real star sizes in 3D, place stars on a Hertzsprung-Russell diagram, and follow a star from a gas cloud to a white dwarf, neutron star or black hole.
  • Galaxies
    The Milky Way is a barred spiral more than 100,000 light-years across, and the Sun takes about 230 million years to go round it once. Spin a 3D galaxy, compare spirals, ellipticals and irregulars, meet our neighbours and see how the expanding universe was found.
Sources for this course (17)
  • Town of Auburn MA, Robert Goddard (auburnma.gov/693/Robert-Goddard)
  • History.com This Day in History, 16 March 1926 (Tsiolkovsky 1903 treatise)
  • NASA "What Was the Saturn V?" (nasa.gov/learning-resources/for-kids-and-students/what-was-the-saturn-v-grades-5-8)
  • NASA Earth Fact Sheet (nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html, GM 0.39860 × 10⁶ km³/s², escape velocity 11.186 km/s, sidereal rotation 23.9345 h)
  • NASA History "The Dawn of the Space Age" (nasa.gov/history/dawn-of-the-space-age)
  • NASA "April 1961, First Human Entered Space" (nasa.gov/image-article/april-1961-first-human-entered-space)
  • GPS.gov Space Segment (gps.gov/space-segment)
  • KARI (kari.re.kr: KOMPSAT-1 1999, Chollian, Nuri launch dates, Danuri contents/193, 194, 196 and news release 2022-12-28)
  • Korea.kr policy news on the Nuri second launch, 21 June 2022 (korea.kr/news/policyNewsView.do?newsId=148902762)
  • Korea AeroSpace Administration (kasa.go.kr, founded 27 May 2024)
  • NASA International Space Station Facts and Figures (nasa.gov/international-space-station/space-station-facts-and-figures)
  • ISS National Lab on Zarya and Expedition 1 (issnationallab.org/iss360/celebrating-the-20th-anniversary-of-the-first-international-space-station-module)
  • Korea Herald and Korea.net on Yi So-yeon, 8 April 2008 (koreaherald.com/article/10711787, korea.net/NewsFocus/HonoraryReporters/view?articleId=264742)
  • NASA Apollo pages (nasa.gov/the-apollo-program, nasa.gov/history/apollo-11-mission-overview, nasa.gov/mission/artemis-ii)
  • NASA Voyager 1 (science.nasa.gov/mission/voyager/voyager-1) and "What is a light-day" (science.nasa.gov/mission/voyager/voyager-1/voyager-1-what-is-a-light-day)
  • NASA Stennis Lagniappe July 2015 on New Horizons at Pluto (nasa.gov/wp-content/uploads/2015/05/julylagniappe.pdf)
  • NASA SVS 5534 Parker Solar Probe (svs.gsfc.nasa.gov/5534).

Checked: 2026-10-18