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I think the stars, in conjunction with the planets, can give you a half decent fix. The Soviets started landing on the moon in the 1950s. It wasn't pretty, it

I think the stars, in conjunction with the planets, can give you a half decent fix. The Soviets started landing on the moon in the 1950s. It wasn't pretty, it was primitive, but it has been done. We (as a species) have since landed on asteroids and planets of sulphuric acid. Space is hard, but we're literally trying to replicate what has already been done.

DarmokJalad1701 3y ago
> I think the stars, in conjunction with the planets, can give you a half decent fix. What was lacking then was precision. The landers from the 60s (Soviet and US) targeted landing areas that were massive. You basically ensured that the initial descent trajectory would intersect a certain area (using ground-based orbit determination) and the terminal landing sequence just ensured a soft-landing ... wherever that might be. What is even more impressive is that they did all that without any digital computer on board. For example, in the Surveyor lander, the landing guidance was made up of analog electronics, using the radar signals to command a thrust-vector and throttle to the gimbaled rocket engines. Here is an interesting read about NASA's surveyor probe, if you want to know more: https://www.sciencedirect.com/science/article/pii/S1474667017691250 https://www.sciencedirect.com/science/article/pii/S147466701... In contrast, the new commercial landers are trying to land at very precise locations within hundreds, if not tens of meters of a certain point. And they are doing that with a fraction of the budget of the programs from the 60s. For example, the entire Surveyor program (with 7 landers) cost ~$469 million in 1966. That is nearly 4.5 billion in 2024 dollars with a large part of that going into R&D. The IM-1 lander in contrast, was awarded $118 million. The Japanese SLIM lander cost $121.5 million. So for what they have, they are doing really well!

DarmokJalad1701 3y ago

> I think the stars, in conjunction with the planets, can give you a half decent fix. What was lacking then was precision. The landers from the 60s (Soviet and US) targeted landing areas that were massive. You basically ensured that the initial descent trajectory would intersect a certain area (using ground-based orbit determination) and the terminal landing sequence just ensured a soft-landing ... wherever that might be. What is even more impressive is that they did all that without any digital computer on board. For example, in the Surveyor lander, the landing guidance was made up of analog electronics, using the radar signals to command a thrust-vector and throttle to the gimbaled rocket engines. Here is an interesting read about NASA's surveyor probe, if you want to know more: https://www.sciencedirect.com/science/article/pii/S1474667017691250 https://www.sciencedirect.com/science/article/pii/S147466701... In contrast, the new commercial landers are trying to land at very precise locations within hundreds, if not tens of meters of a certain point. And they are doing that with a fraction of the budget of the programs from the 60s. For example, the entire Surveyor program (with 7 landers) cost ~$469 million in 1966. That is nearly 4.5 billion in 2024 dollars with a large part of that going into R&D. The IM-1 lander in contrast, was awarded $118 million. The Japanese SLIM lander cost $121.5 million. So for what they have, they are doing really well!