The Exploration of Space

Project Mecury

Project Mecury was initiated in 1958. This spacecraft made Alan Shepard, the pilot of the freedom 7, the first American in space. At this time, the Soviet Union was leading the space race. 3 orbital flights were made by this project.
Source: https://www.nasa.gov/mission_pages/mercury/missions/overview-intro.html

X-15 Rocket Plane

The X-15 Rocket Plane was one of the first space vehicles. It made almost 200 flights and gave information that proved vital to both the space race and the creation of the space shuttle.
Source: https://commons.wikimedia.org/wiki/File:X-15.jpg

Apollo Program

The Apollo program is one of the most expensive programs ever at about 191 billion dollars in present day USD. It used larger launch vehicles called Saturn rockets. The Apollo made major milestones in human space flight. It's one of the few missions that has successfully gotten men beyond low Earth orbit and placed humans on other celestial bodies. The Apollo 8 was the first manned spacecraft to orbit another celestial body.
Source: http://abyss.uoregon.edu/~js/glossary/apollo_program.html

The Lunar Revolving Vehicle

The Lunar Revolving Vehicle (LRV) was the first rover landed on the moon.

Source: https://nssdc.gsfc.nasa.gov/planetary/lunar/apollo_lrv.html

Pioneer 10

Pioneer 10 was the first spacecraft to cross asteroid belt launched.

Source: https://www.nasa.gov/centers/ames/missions/archive/pioneer.html

Skylab

Skylab was the first and only space stations that the U.S. built independently. It was 169,950 lbs and was launched on May 14, 1973. It was damaged during launch: it lost its protection and one electricity-generating solar panel. It was repaired by the first crew. It was occupied for 171 days by 3 successful crews in 1973 and 1974. It was used to study microgravity.
Source: https://www.nasa.gov/missions/shuttle/f_skylab1.html

Apollo-Soyuz Test Project

The Cold War was ending when the Apollo-Soyuz Test Project was introduced. It was a group of Soviet Union and U.S. space programs. It was the last U.S. Apollo flight in addition to being the last manned space launch until the space shuttle. This project provided useful engineering experience for future joint US-Russian space flights, such as the International Space Station.
Source: http://www.space.com/20833-apollo-soyuz.html

Voyager

Voyager caried golden records containing sounds intended to reach extraterrestrial life form.

Source: http://voyager.jpl.nasa.gov/

Space Shuttle Program

The space shuttle was originally thought of as the most fequently launchable and most reusable vehicle. Four space shuttle orbiters were built by 1985. Missions could last from 5-17 days with crews of 2-8 astronauts. The program lasted for 30 years and sent over 300 astronauts into space. Source: https://en.wikipedia.org/wiki/Space_Shuttle_program

Challenger

Space shuttle Challenger disaster kills 7 members. challanger exploded less than a minuite after being launched. If it had suceeded, it would have caried the first "commoner" into space.

Source: http://www.history.com/topics/challenger-disaster/videos/engineering-disasters---challenger

Hubble Space Telescope

The Hubble Space Telescope was launched into orbit aboard the space shuttle Discovery.

Source: https://www.spacetelescope.org/

Pathfinder

Mars Pathfinder launched it's rover mission. The rover landed on Mars on July 4, 1997

Source: https://en.wikipedia.org/wiki/Mars_Pathfinder

Columbia

Space shuttle Columbia disaster kills 7 crew members. Chang'e, was China's first Earth orbiter.

Source: http://www.bbc.com/future/story/20150130-what-caused-the-columbia-disaster

Private Vehicle

This was the first privately funded vehicle to reach space.

Source: http://www.natureworldnews.com/articles/27957/20160901/spacex-rocket-launches-facebook-satellite.htm

India's First Unmanned Lunar Probe

India's first unmanned lunar probe discovered traces of water on the moon.

Source: http://www.dailymail.co.uk/sciencetech/article-1215721/Water-moon--Indias-lunar-mission-detects-it.html