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  2. Timeline of space exploration - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_space_exploration

    This is a timeline of space exploration which includes notable achievements, first accomplishments and milestones in humanity's exploration of outer space. This timeline generally does not distinguish achievements by a specific country or private company, as it considers humanity as a whole.

  3. Timeline of spaceflight - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_spaceflight

    Due to its large size, the timeline has been split into smaller articles, one for each year since 1951. There is a separate list for all flights that occurred before 1951. The list for the year 2024 and for its subsequent years may contain planned launches, but the statistics will only include past launches.

  4. Space exploration - Wikipedia

    en.wikipedia.org/wiki/Space_exploration

    Aldrin held that reusable spacecraft were the key in making space travel affordable, stating that the use of "passenger space travel is a huge potential market big enough to justify the creation of reusable launch vehicles". [76] Space tourism is a next step in the use of reusable vehicles in the commercialization of space.

  5. List of time periods - Wikipedia

    en.wikipedia.org/wiki/List_of_time_periods

    Depending on the continent, the era generally falls between the years AD 200–600 and AD 1200–1500. The major classical civilizations that the era follows are Han China (ending in 220), the Western Roman Empire (in 476), the Gupta Empire (in the 550s), and the Sasanian Empire (in 651). Middle Ages – Lasted from the 5th to the 15th century.

  6. Outline of space exploration - Wikipedia

    en.wikipedia.org/wiki/Outline_of_space_exploration

    Space and survival – Idea that spacefaring is necessary for long-term human survival; Space vehicle – Combination of launch vehicle and spacecraft Launch vehicle – Rocket used to carry a spacecraft into space; Spacecraft – Vehicle or machine designed to fly in space; Spaceflight – Flight into or through outer space

  7. Timeline of Solar System exploration - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_Solar_System...

    This is a timeline of Solar System exploration ordering events in the exploration of the Solar System by date of spacecraft launch. It includes: It includes: All spacecraft that have left Earth orbit for the purposes of Solar System exploration (or were launched with that intention but failed), including lunar probes .

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    The search engine that helps you find exactly what you're looking for. Find the most relevant information, video, images, and answers from all across the Web.

  9. Hemiacetal - Wikipedia

    en.wikipedia.org/wiki/Hemiacetal

    Hemiacetals form in the reaction between alcohols and aldehydes or ketones. Using an acid catalyst, the reaction proceeds via nucleophilic attack of the carbonyl group by the alcohol. [4] A subsequent nucleophilic attack of the hemiacetal by the alcohol results in an acetal. [2] Solutions of simple aldehydes in alcohols mainly consist of the ...