Try this one...
Zeerust (to get the reference, click the word.)
It's similar to some I've done before, but it goes to different places.
On this Q6 Low Manna world an American antarctic expedition, in 1937, discovered a building. Subsequint examinations by Homeline agents have established the building is a pragmaclasp, a shattered remnant of an otherwise erased time line. Inside this mysterious building was discovered gates. Each is approximately sixteen feet in radius. They are 15 inch thick rings made of a metal that looks like silver although it isn't chemically reactive in any way and can't be scratched by diamonds or in any way be mared, scratched, melted, heated, cooled. or noticeably effected by any known force. These rings are only about one tenth the weight they should be given their size and seeming composition.
Anyone looking through the rings sees the lunar south pole. Anyone stepping through the rings is transported to the lunar south pole. Note; only things moving under their own power or moved by someone or something under its own power. All sixty gates were brought to the USA.
With relatively few serious accidents a team of scientists built an observatory on the moon by 1942 and turned their telescopes on the Earth. They had little effect on WWII. Their main effect on the early Cold War was to make Stalin wildly paranoid (even for him) about being seen from the moon.
Over the 1950s through the 2010s the sixty gates were shipped across the USA and America built a lunar infrastructure and poured money into moonbases.
The local year is 2020, the world is on the edge of TL9 (picture what you think of a realistic level of technology for 2040 and go with that). All across the moon robot factories are making
Sun Shades to cool the Earth. Solar power
satelites orbit the Earth, with America charging less and less as time goes on. There is agitation in America to make the power free to the developing world now. Russia fights this as an imperialist plot, China demands to be seen as a developing nation and be given first call on the power supply.
Because of the risk of being cut off from the moon by loss of the silver gates,
William Proxmire was overruled and America spent the extra money to have a fully reusable spaceplane. Asteriod mining started in the first decade of the 21st century.
The democracies are riding high in this world, Africa had a manufacturing boom in the 1990s. The Indian Ocean was the center of the richest trade network on Earth. The lands between the Nile and the Indus are poor and unimportant, generally ruled by bitter theocracies. The peoples of these lands and other impoverished areas like Russia, are desperately trying to emmigrate to any land that will have them. Given the reputations of the lands these ecconiomic refugees few want them. This has led to violence, human trafficking, and paranoia, the last on both sides.
Centrum believes it can use this fear of immigrants as a means to promote authoriterian government in the West. Homeline wants to stop this dirty tricks campaign. Homeline also wants to use this world's space program to figure out how to build sun shades for Homeline Earth.
The Cabal wants Homeline and Centrum to keep each other busy while they study Africa's occult lore which is much more easily availible in this wealthy, stable, and peaceful, Africa.
Basically, Espionage and dirty tricks in a very 1970s version of the 2020s.