[marvin]

So Earth can receive heliograph messages very quickly. How long until a large enough mirror/light can be orbited to respond. I'd say with a major effort 6 months. NASA could send up a large Mylar reflector with some sort of system to create Morse code rather quickly I would imagine.

How many years for there to be an unmanned "care package". This could obviously replace the Vikings. So they arrive as per OTL in June and August of 1976. What do we send? Weapons? Medicine? Coffee?

I'm hoping for a non-NERVA Venus fly-by proof of concept mission by 1980. If there is an orbital elevator on Mars (my idea, not something in canon Space:1889) than getting humans to and from the surface of Mars is much easier. As are launching deep space missions from Mars due to the increase in velocity at the top of the tether.

Perhaps a manned mission to Mars could be pushed up a bit due to the Mars tether making it a bit easier. I'd have a manned mission no later than 1983 using a Saturn V / NERVA combination.

Ben