Assuming your tug is in the translunar orbit (going in a figure 8 around the Moon and Earth with the intersection being the Earth-Moon L1 point. And assuming the tug is significantly more massive than your cargo. As you cross the L1 point you can use a mass driver on the tug to 'shoot' the cargo out behind you which would decelerate it to a low delta-v relative to the elevator base (and slightly boost the tug on its way) and when you came around the other side you hook the cargo through a loop like the old mail planes did [1] and pulling it away (which would impart a small deceleration on the tug as it headed back to earth). Depending on masses and how closely you could match things, the amount of delta-v you would need for the tug to keep its orbit true should be very manageable.
[1] https://postalmuseum.si.edu/collections/object-spotlight/sky...
You might save 2km/s if you can use an elevator on the moon. Which is not a lot compared to a space elevator on Earth, but it would definitely be useful. That could be half your delta-v budget if you're going between the moon's surface and an orbit around Earth/Mars/Venus.
Wouldn't you get the same benefit from a Mass Driver, since the moon is a vacuum body?
This makes me question whether you actually understand how orbital rendezvous works. How about as an exercise, you explain why I would say this. Otherwise, I think the resulting conversation would be tiresome and not worth my time.
The relative speed of a capsule and the mass driver will be very high IF you're using the mass driver to slow down substantially. That's in the definition, you're using it to slow down so the initial relative speed at contact must be high. The higher the speed the less energy you have to waste lowering your orbit (slowing down beforehand). If you're slowing down beforehand enough that your relative speed of contact is low then you don't need the mass driver to brake.
If you can't explain my analogy, then I'm just going to conclude you're trolling based on my previously stated disdain for DK syndrome.
> There are two points in space where an elevator's docking port could maintain a stable, lunar-synchronous position: the Earth-Moon Lagrange points L1 and L2. L1 is 56,000 km away from the Earth-facing side of the Moon, (at the lunar equator) and L2 is 67,000 km from the center of the Moon's far side, in the exact opposite direction <snip />
> Both of these positions are substantially farther up than the 36,000 km from Earth to geostationary orbit. Furthermore, the weight of the limb of the cable system extending down to the Moon would have to be balanced by the cable extending further up, and the Moon's slow rotation means the upper limb would have to be much longer than for an Earth-based system, or be topped by a much more massive counterweight. To suspend a kilogram of cable or payload just above the surface of the Moon would require 1,000 kg of counterweight, 26,000 km beyond L1.
So, we're talking an ~80,000 km one?
> the engineering requirements for constructing a lunar elevator system can be met using currently available materials and technology.
Just because something is theoretically possible doesn't mean it's feasible or practical to build in real life. For example, we have known that it's theoretically possible to build vacuume sealed trains, aka the hyperloop, since before the first airplane took flight. And yet whilst you see planes fly everywhere, you don't see any vacuum sealed trains.
Just because something ticks the checkbox of being theoretically possible doesn't mean it's practical or feasible to build.
Maybe in a few hundred years we'll have the means to build something on that scale. It still takes $10k to put 1kg in LEO, imagine the cost of transferring to the Lagrange points.
We have already gone to the Moon. Given that the travel time is relatively short, radiation is far less of a concern.
This is why the Moon is attractive. We know how to get there already and it's not too difficult, all things considered. The problem of how to get there and back with humans aboard has already been solved. It's never been done to Mars.
http://onlinelibrary.wiley.com/doi/10.1029/2009GL041721/abst...
It's only 360km across though...
That seems okay for probes and maybe problematic for people.
Although the poor slob plan comes to mind:
https://books.google.com/books?id=7ejGJaFjLccC&lpg=PA154&ots...
[1] https://youtu.be/Jv5LjA62Uw8?t=3480 [2] https://youtu.be/Jv5LjA62Uw8?t=3644
They're both definitely too far for a rescue mission or evacuation that wasn't planned for in advance. In terms of the old eggs/basket metaphor, it becomes a question of whether you want to use half your straw to weave a second basket, just in case the first one breaks, or if you want to use all of the straw to make your one basket as strong, redundant, and well designed as possible.
From LEO to the surface of the moon is 5.9 km/s
From LEO to the surface of Mars is 4.1 km/s
Source: https://en.wikipedia.org/wiki/Delta-v_budget#Delta-vs_betwee...
Transit time is lower, but the currency of space travel is delta-V, and by that measure, Mars is just as close or closer.
I would guess that the Moon still slightly wins as far as transport costs, but the advantage is much smaller than you'd think, and the far greater resources available on Mars (as well as effective immunity to solar particle events and micrometeorites that Mars' atmosphere provides) tilts the situation strongly in favor of Mars for actual settlement. Joy trips may be cheaper to the Moon, however.