So in 3 we learn about the Virgo II lander, but really not much else in the space program. What else happened? Were there space stations, probes to other planets?
Ultimately, we have speculative evidence that Project: Safehouse, aka the Societal Preservation Program, which tasked the Enclave to oversee the vaults, had but one supreme objective.
The purpose of the vault experiments was to help prepare the Enclave for either re-colonizing Earth or colonizing another planet if Earth turned out to be uninhabitable.
Space flight was always part of the plan but it's unclear how far that part had been developed during the 23 years the program operated before the bombs fell.
Cool stuff in space:
Archimedes, New Vegas
It should be distinguished from Archimedes II, the second iteration of the system, which is an orbital based laser system and can target any outdoor location in the Mojave Wasteland.
Highwater-Trousers, Fallout 3
Highwater-Trousers is a computer program that was meant as a last resort, to be activated when an invading enemy had the SatCom Arrays under siege. From SatCom Array NW-05a it was possible to activate the program from the control terminal and call in nuclear strikes from an orbiting platform.
B.O.M.B., Van Buren Project (game canceled)
The Ballistic Orbital Missile Base 001 (abbreviated B.O.M.B.-001) is a large, donut shaped U.S. space station capable of firing twenty-four nuclear-tipped ballistic missiles. While it is currently staffed with eight individuals, it is capable of housing six people long term. A sister station, B.O.M.B.-002, existed alongside B.O.M.B.-001 until some point after the Great War. The layout for B.O.M.B.-001 shows areas designated for living, recreation, medical treatment, and a separate area for the station's true purpose; a nuclear missile control and launch center.
USSA, Fallout 2 (unreliable source, although it does present a possible tie-in with the Hubologists having a space shuttle)
United States Space Administration
The following is based on Fallout 2 cut content and has not been confirmed by canon sources.
The U.S. government's real plan to survive a nuclear war was simply to find another planet to live on after having helped to destroy the Earth. A spacecraft designed to ferry the human race to another planet was either under construction or ready to go before the Great War broke out. The plan was for the government to flee to the Enclave's Oil Rig, wait out the conflict and then pack up the populations of the Vaults to head into space. The Vaults were funded by the U.S. government and, accordingly, the government had control over them. Ostensibly, they were intended to allow a selection of privileged United States citizens to survive the Great War. Secretly, however, a large part of the Vault Project (Project Safehouse) had a far more sinister goal.
Come Fly With Me is a side quest in Fallout: New Vegas, primarily conducted at the REPCONN test site, which still has three somewhat functional rockets.
REPCONN Aerospace (Rocket Engineering and Production COmpaNy of Nevada) was an up-and-coming regional aerospace firm based in Nevada that specialized in rocket manufacture, primarily for the U.S. government. Its original purpose was to develop orbital propulsion systems.
The company was purchased by the giant RobCo company just before the Great War, in a hostile takeover. New security countermeasures were installed, and more militaristic plans were undertaken, especially after the discovery of a special radioactive igniting agent that interested senior RobCo management staff.
ArcJet Systems, Fallout 4
ArcJet Systems was a pre-War military and civilian aerospace contractor in the United States, specializing in communications, propulsion systems, and custom-built high-tech aviation equipment. One known facility is located in Cambridge. They produced electronics and rockets used by the USSA until 2077.
In 2075, ArcJet began working on a nuclear-powered rocket, the XMB booster engine, in hopes of convincing the United States Space Administration to award them the lucrative contract for their Mars Shot Project.
The Mars Shot Project, was a plan by the USSA for a manned mission to Mars, and was scheduled for launch in July of 2078.
Space probes are the real question.
Did we launch the Voyager space probes or their equivalents during the once every 175y planetary alignment? If we could find a representation of Saturn in the Fallout universe with one solid ring around it, then we would know that we did not launch them, as only after Voyager 2 visited Saturn did we learn that it had many separate rings.
That's a somewhat moot point though, considering it's a game made by a company whose logo is a V2 shaped '50s rocket orbiting the Earth, and that building space probes without transistors is highly unlikely. See divergence, which demarcates the critical point at which our history divides with the Fallout universe, as the invention of the transistor.
Some of the late '70s tech that the Voyagers employed was digital and necessarily so. The fragility and power consumption of vacuum tubes is too great to achieve what we've come to expect from modern space probes. In Fallout:
Miniaturized electronic capacity was never developed past [American society's] prime. This is why small television, radio, newspapers and even word of mouth are still prevalent. (reddit)
Even the Apollo Program rockets used integrated circuits; tubes were almost nonexistent on-board them. Be that as it may, man did land on the moon in the Fallout universe, and the Great War of 2077 left many years leading up to itself in which we probably began exploring the cosmos.
All your histories are belong to us now.
Of noticeable lack are basically all Soviet accomplishments (Wiki), which were exemplary in the real world. Here (below) we have evidence of a possible re-write of history as apposed to a divergence. To the victor may have gone the spoils:
Defiance 7 was the space capsule in which Captain Carl Bell of the United States Space Administration (USSA) made his historic flight, becoming the first human in space, on May 5, 1961. This claim was disputed by both the Soviet Union and China. Captain Bell's flight lasted twelve minutes and seven seconds, and made a full revolution around the Earth. Bell died when the capsule crashed on its return to Earth.
It is not possible to complete an orbit of the Earth in a "coasting" spacecraft in less than 89 minutes. Most likely this is a minor writing error; otherwise, an implausibly complex explanation would be required. It should also be noted that the 1950s-esque science of the Fallout universe differs from the actual physics of our universe, so this is another explanation. It is also entirely plausible that the US government lied about this "accomplishment", and the error was in fact a subtle hint towards this fact.
Carl Bell, Note:
In the real world, May 5, 1961 was the date of the flight of the first American in space, Alan Shepard. Unlike the Fallout universe, the actual first man in space was Soviet cosmonaut Yuri Gagarin, who became the first person to orbit the Earth on April 12, 1961.
Maybe the moon landings were faked after all; the Russians beat us to it.
All links are in-site or from fallout.wikia.com unless noted.
There was Hubology in Fallout 2, with the questionable goal of leaving Earth in an old pre-war space shuttle. In Fallout New Vegas the ghouls in the quest 'Come Fly With Me' use three pre-war rockets to leave Earth. And if you join Mr House in Fallout New Vegas I believe one of the ending slides mentions a return to space.