The US now has two independent launch systems to ferry astronauts between
Earth and LEO. If one of the two must be grounded, the other one can step up
to replace it. Is this the first time this has happened?
Definitely the first time for the US. There was a year between Gordon
Cooper's Mercury flight and the unmanned test flight of Gemini 1, and
another year before Gemini 3 (Grissom, Young) became the first crewed
flight of the "sports car", and Gemini XII (Lovell, Aldrin) took place
after 2 unmanned Apollo Block 1 flights and 2 1/2 months before the
Apollo 1 fire (A1 launch was to be in another month). And after
Apollo, there was ... well, 9 years to Shuttle and STS-1.
For the Soviets, Vostok was built 10 times 1960-1963, Voskhod 5 times
1964-1966 (2 human crewed missions, 1 canine crewed, and none had an
LES). The first version of Soyuz, Soyuz 7K-OK, first flew unmanned at
the end of 1966, and manned 4 months later (Komarov died in the
landing) and Soyuz 2 & 3 (uncrewed 2, Beregovoy in 3) after another 18
months.
Buran had only 1 spaceflight, uncrewed, in 1988, but overlapped the
Soyuz 7K-STM era. The non-orbital jet-powered Buran OK-GLI had 25
atmospheric flights.
I think China has had just one capsule, similar to a Soyuz (which
versio?), but with its own enhancements.
India has not yet crew-rated its capsule.
ESA has not produced a crewed vehicle other than test articles.
/dps
--
"What do you think of my cart, Miss Morland? A neat one, is not it?
Well hung: curricle-hung in fact. Come sit by me and we'll test the
springs."
(Speculative fiction by H.Lacedaemonian.)