It's easy to miss how clever the Apollo mission architecture was.
The moon is not so far away in terms of distance but it is very far away in terms of Δv because, not least, you have to land propulsively because there is no atmosphere to slow you down.
Trips to some near-Earth asteroids are easier than the lunar surface, Mars and Venus aren't that much harder because in any of those cases the Moon's gravity can be helpful.
The Apollo mission architecture was inspired. Going to the moon likely would have remained a fantasy if they hadn't done the only thing that could work. Any country with ambitions to land people on the moon in the future is facing the same laws of physics.
NASA is stuck with a complicated architecture because they are required to use a legacy system incapable of supporting an Apollo style campaign, not because they have some great vision. Both Blue Origin and SpaceX will need to reinvent space launch to make Artemis work which isn't necessarily a bad thing but I don't feel like NASA has made that clear to the public.
There’s so much cool stuff that was rejected before I was even born. It’s kinda bizarre how the space program is so in the dumps now.
The space shuttle, while expensive, was at least an icon. I grew up with it as a symbol of US spaceflight hegemony. Now NASA is just a really expensive organisation achieving very little.
> NASA is just a really expensive organization achieving very little.
Granted, human spaceflight is crazy expensive. And yet...
Jet Propulsion Labs, to pick a single NASA site, has never been more busy. I counted 30 spacecraft listed as "active" on their Current Missions page, but I think I missed a couple of them.
NOTE: I don't think that web page of 'Current' missions is up to date.
For instance, the VSOP project is still on there; that was using a spacecraft designed mostly by JAXA, I believe, as an element of the Very Long Baseline Array (VLBA).
I was still attending the VLBA Operations meetings, early 2000's, and at that time it seemed that they were winding that project down. Data reduction and analysis of VLBA itself had been difficult to implement and wasn't totally integrated into the standard software package. Adding a telescope that was moving at orbital velocity made things quite spicy. I found it to be a profoundly humbling experience.
It's wild to think the world of 2001 A Space Odyssey seemed very possible to the people of the late 1960's. They went to the moon in only about 10 years, so a Jupiter mission in another 30 years would just be a continuation of current progress. Little did they know that humans would lose the capability to leave orbit just a few short years later.
> The moon is not so far away in terms of distance but it is very far away in terms of Δv because, not least, you have to land propulsively because there is no atmosphere to slow you down.
Not least, but certainly the requirement to brake before you land must be on the small order compared to achieving escape velocity from the much bigger rock I'm on?
You gotta get off Earth no matter where you go in space. It's almost free to come home from LEO, you get a huge amount of free velocity change returning from the moon. (At the cost of rejecting the heat)
the required mass ratio is an exponential function of the velocity change so adding another 2.5 km/sec for this and another 2.5 km/sec for that you are making the mission much more difficult.
It's bad enough that it takes two stages to get to LEO comfortably but going beyond that adds cost and complexity pretty quick, for instance the large number of Starship launches required to get a Moon mission into the right orbit.
I like to think about what interstellar travellers would do if they wanted to land on the Earth on the assumption that they are accustomed to life in deep space and have spent 1,000 to 10,000 years "living off the land" off comets and rouge planets and are used to a lifestyle like cutting up a planet like Pluto and building a number of small ringworlds powered by D-D fusion.
I'd conjecture that despite having advanced technology they would still find the "reverse space shuttle" problem where you land with a full load of fuel and then take off from the ground to be difficult. It's not like they are going to haul a space shuttle along with them and would probably find it non-trivial to 3-d print one from plans that old. My take is that it would probably take them a decade to figure it out and that they might well come up with an alternative answer like
which depends on in-space infrastructure that they'd be experience with although it could work together with an air-breathing aircraft which would be something new for them.
Everything is on the small order of magnitude when compared with getting into Earth orbit. As the quote goes, "Once you get to earth orbit, you're halfway to anywhere in the solar system."
> As the quote goes, "Once you get to earth orbit, you're halfway to anywhere in the solar system."
In terms of delta-v, yes. Going to the moon only takes 50% more delta-v than going to LEO. But the rocket equation makes getting that extra 50% a lot harder. Time for more staging and complexity and still having terrible payload fraction.
That might be Heinlein's most annoying quote ever and boy does it have competition.
It is very expensive to change orbits. If you had two space stations like the ISS with ascending nodes 180 degrees from each other it would be about as expensive to transit between them as it is to launch a rocket from the Earth to begin with. See
You've got the advantage in space that you can use electric rockets with a high specific impulse. Back in the 1950s folks like von Braun imagined that manned space flight might use electric rockets but after they discovered the Van Allen belts they discovered this is much too slow to make it through the magnetosphere.
> If you had two space stations like the ISS with ascending nodes 180 degrees from each other it would be about as expensive to transit between them as it is to launch a rocket from the Earth to begin with.
1+1 = 2 2/2 = 1; technically halfway.
To interpret “halfway to anywhere” that way is missing the point. Going from LEO to LEO wasn’t the point of “halfway to anywhere”. Yes a bit exuberant but not far off.
> Not least, but certainly the requirement to brake before you land must be on the small order compared to achieving escape velocity from the much bigger rock I'm on?
The problem is all the fuel you use to break before landing also has to achieve earth escape velocity at first. And it makes the original problem much harder because the total mass that needs acceleration grow exponentially with delta speed.
When you say "Moon's gravity can be helpful." do you mean some sort of slingshot around the moon to get to a trajectory that is closer to a Mars orbital insertion?
and Luna is just the first stop on the way from Earth. That Wikipedia article doesn't explain the concept as well as I'd like but the papers it references do.
The moon is not so far away in terms of distance but it is very far away in terms of Δv because, not least, you have to land propulsively because there is no atmosphere to slow you down.
Trips to some near-Earth asteroids are easier than the lunar surface, Mars and Venus aren't that much harder because in any of those cases the Moon's gravity can be helpful.
Werner von Braun's early plans to go to the moon
https://www.scribd.com/doc/118710867/Collier-s-Magazine-Man-...
involved multiple launches, space stations, etc. The recognition that you could get there and back with 7 "stages"
* Saturn V 1 * Saturn V 2 * Saturn V 3 * Service Module * Command Module * Bottom half of Lunar Module * Top half of Lunar Module
was the key to realizing Kennedy's dream to do it in a decade.