A timeline similar to Alan Shepard, first man in space, but what if Soviet rocket chief designer Sergei Korolev didn't die from his operation in 1966?
1946-1947: British Interplanetary Society manned rocket proposal "Megaroc" intrigued the British Government, causing the government to not deny the proposal outrightly. This is the divergence point from our main timeline.
1947: The British government attempted to propose to the government of the United States for a collaboration of the Megaroc project. Truman, who was the US president at that time, decided to turn the proposal down citing lack of funds, after some ponderings on the project made by him. Though the turn-down effectively kill off the project for good, the idea of the potential implications if taking a lead in space technology would sip into Truman's mind. As in our timeline, USA launched a group of fruit flies into space, making them the first animals in space.
1957: In October, the Soviets launched Sputnik 1 satellite into orbit. This results in a "Sputnik Moment" as in our timeline and confirming some of Truman's convictions.
1958: Partially as a result of the aforementioned Sputnik Shock, DARPA and NASA were created in 1958 to have America to compete against Soviets. For the same reasons and as in our timeline, funding for STEM education in the U.S. is increased. Besides that, 1st American satellite "Explorer 1" is launched and discovered the Van Allen belt.
1959: Soviet Union's Luna 1 become the first spacecraft to enter heliocentric orbit. At the same year, Luna 3 becomes the first spacecraft to photograph the far side of the moon.
1961: In January 1961, monkey Ham becomes the first hominid in space after being launched by American Mercury rocket into a suborbital trajectory. Later in March 24th, Alan Shepard, an American astronaut, becomes the first man in space, albeit being launched in a suborbital trajectory akin to Ham's. Shepard would receive a ticker tape parade for the feat of being the first person in space.
The bigger shock to the American public came in April when the Soviet Union responds by launching cosmonaut Yuri Gagarin into orbit, which prompt US president Kennedy to set a national goal for a manned Moon mission.
1962: NASA's robotic spacecraft Mariner 2 successfully fly by Venus.
1963: US President Kennedy is assassinated. Cosmonaut Valentina Tereshkova is the first woman in space.
1965: First space rendezvous is achieved by the Americans, meanwhile cosmonaut Alexey Leonov made the mankind's first spacewalk.
1966: First space docking is done with an American Gemini spacecraft and an American Agena Target Vehicle. Luna 9, a Soviet Union spacecraft, is the first spacecraft perform a soft landing on the Moon. Divergence point from Alan Shepard, first man in space timeline occurs when Sergei Korolev survives his medical operation.
1967: Apollo 1 disaster.
1968: Astronauts Frank Borman, James Lovell and Bill Anders, who are travelling in the Apollo 8 mission, becomes the first humans to travel out of Earth's gravitational influence and into the Lunar influence.
1969: On July, NASA astronaut Neil Armstrong landed on the moon with astronaut Buzz Aldrin in Apollo 11 mission. Armstrong is the first human to step his foot on moon, saying: "That's one small step for man, one giant leap for mankind". At the same year, a Soviet N1 moon rocket prototype is successfully launched, causing NASA and the American Government to implement the Integrated Program Plan or Space Transportation System.
1971: The Soviets finally responded to the success of Apollo 11 by launching cosmonaut Alexei Leonov with LK spacecraft to the Moon. The event generate a huge amount of shock to the American public, regardless of Apollo 11. Prior to this moon landing, Yuri Gagarin, who did not get killed in a plane crash in 1968 due to the butterfly effect caused by Korolev's survival, flew a Soyuz spacecraft around the moon, just as what Apollo 8 did earlier. The Integrated Program Plan is accelerated as a result of this.
1972: The American NERVA program and the Mars Expedition 1969 program has regained interest among the NASA officials due to its capability to send a manned spacecraft to Mars.
1975: The first Martian sample return missions Mars 4NM and Mars 5NM are launched by the Soviet Union and successfully conducted its missions, generating even more shock to the Americans.
1977: Voyager interstellar spacecrafts are launched and Voyager 1 will become the first spacecraft to enter interstellar space.
1983: After much testings, the American Manned Mars mission is finally launched. When the NASA spacecraft, equipped with NERVA booster finally reached to Mars, Neil Armstrong, who volunteered to participate in the manned program to Mars, becomes the first man to step foot on Mars after walking out from the Martian Excursion Module. Armstrong is joined with astronauts Buzz Aldrin and Alan Shepard while on Mars.
The astronauts in the Martian manned program will successfully return to Earth later.
1987: As a sign of detente, the American space shuttle docks with a Soviet Soyuz spacecraft.
1990: Since too much funding is spent on space exploration programs at this timeline, the nuclear stockpiles of US and USSR is far lesser than OTL.
1991: The Soviet Union disintegrates.
1998: International Space Station is launched into orbit around Earth.
2015: LIGO, with help and contributions from American scientists and international scientists who come from countries like Australia and Italy, detected the first gravitational wave.
2016: A rotating wheel space station is being added into the International Space Station. LIGO announced the first gravitational wave discovery.