Land 2 or 3 times at the same place and it becomes a spaceport. Once empty the lander becomes a man made rock messing up a prime landing area. The hazard needs removing. Something like the ATHLETE is needed to move the lander to the side of the crater awaiting recycling.
There are various VTVL machines that can be space-rated to land small cargoes, which would allow new machines on the Moon within 5 years.By putting several engines together you get a larger cargo lander.On Earth the VTVL melt their concrete landing pads. This heat will tend to damage any cargo near the nozzles.
Quote from: redliox on 03/31/2014 10:07 amI'll discuss the first element in my architecture: the cargo lander.[...]Whether or not orbiting/LaGrange elements are later employed, a one-way cargo lander should be a must for either Mars or Luna, just to ensure something long-lasting is established at the intended destination.Could you discuss the thinking behind this a bit? What provides your certainty that a non-reusable lander is required?
I'll discuss the first element in my architecture: the cargo lander.[...]Whether or not orbiting/LaGrange elements are later employed, a one-way cargo lander should be a must for either Mars or Luna, just to ensure something long-lasting is established at the intended destination.
I'll discuss the first element in my architecture: the cargo lander.All together, it would be the most straightforward spacecraft in that it is meant to fly directly from Earth to the Lunar surface. Much of my thinking about it stems from the Mars Direct Habitat. Unlike Altair or Boeing's current concept for a reusable lander, access to the surface is the priority so that the autonomous utility rovers can embark and crews unload equipment as well as enter the base hab. Fuel tanks, containing oxygen and methane, would sit atop either a habitat or container module with twin descent nozzles on either the sides or beneath the lander.Being a cargo vehicle, there is no concern about needing an emergency escape or separate sets of tanks for descent/ascent stages. The Altair engineering was impressive in coming up with ATHLETE as a means for offloading cargo from the descent stage, but it seems simpler just to put it low to the ground with the sides of the container unfolding into ramps. Naturally there are concerns for obstacle clearance, but given the thought that goes into site selection (including polar sites) and our increasing database (thanks chiefly to LRO, SELENE, ect.) a rock smaller than a foot isn't a show stopper. Fuel tanks and cargo, it would be a solid piece with minimal deployment mechanisms.
Reuseable for crews is applicable, but for the moment I discuss the cargo vehicle [capable of] bringing a 25 ton habitat down.
Unless you have a reason to return to Earth, it is more cost effective to put it on a one-way trip.
I'm beginning to understand your perspective! You seem to be saying, "For this architecture let's take as a given the use of an expendable, 25 t payload, cargo lander." Discussing what could be accomplished with such a vehicle, and at what cost, is definitely fun and probably worthwhile.QuoteUnless you have a reason to return to Earth, it is more cost effective to put it on a one-way trip.That's possibly a straw-man argument. Proponents of reusable lunar landers rarely propose returning them to Earth. They are usually seen as doing purely "surface to orbit and back" duty.
It's going to be hard enough to build one base, so don't propose building two. Remember also, that there is plenty of regolith available at the poles for ISRU demos along those lines.
Most of the mass to maintain a Space Station is unmmaned, so I think that the best approach is to use a ion tug and use only Earth-LEO conventional transport and use some ion ultraefficient tugs to reach the final destination. Xenon could be refilled.
Otherwise regarding ion propulsion it may not be necessary for landers. An SLS in either the 105 or 130 range can send a payload to the Moon on a 3 day trip directly whereas SEP demands weeks of slow boating. Once the landers begins descent furthermore, it needs a chemical system to touchdown, and even in lunar gravity some of the giant solar arrays would be as frail as butterfly wings.I'm a fan of SEP, but if there's a simple, clean way to reach the Moon in under a week use that avenue.
Quote from: redliox on 04/02/2014 02:42 pmOtherwise regarding ion propulsion it may not be necessary for landers. An SLS in either the 105 or 130 range can send a payload to the Moon on a 3 day trip directly whereas SEP demands weeks of slow boating. Once the landers begins descent furthermore, it needs a chemical system to touchdown, and even in lunar gravity some of the giant solar arrays would be as frail as butterfly wings.I'm a fan of SEP, but if there's a simple, clean way to reach the Moon in under a week use that avenue.Ion is not appropriate for manned, but weeks is not a problem for unmanned cargo.The idea is to try avoid to create new expensive rockets that we could not use for other thing instead massive and costly missions.
Quote from: JohnFornaro on 04/02/2014 01:11 pmIt's going to be hard enough to build one base, so don't propose building two. Remember also, that there is plenty of regolith available at the poles for ISRU demos along those lines.The truly hard part, if any, is convincing an administration to return to the Moon.I suggest 2 bases because there is more than one region to study and mine; some 99% of the Moon is nothing like the poles. If 99% of the Moon is dry, we must work with it. Ice or not, I don't think isolating flights to one site alone is the best way to return. Suggesting a dozen bases is unpractical, but proposing one primary base supplemented by a smaller base combines the strengths of 2 regions.
There is one major problem an ion drive would encounter within Cis-Lunar space: the Van Allen radiation belts. Smart-1 used it in similar fashion but had to pass through the belts numerous times, and this was a factor in it's design. Even with an improved set of thrusters, cargo sized for human expeditions would take even longer with the risk of damaging elements needed at the Moon like electronics and solar panels. Given the choice, I would pick a swift path to the Moon versus the slow SEP.
{snip}I'll give a dry description. The core would be a crew cabin akin to a slightly enlarged ISS module, except for the fact it would be octangular, not cylindrical, in cross-section. At the base of the core cabin would be a single oxygen tank with a single LOX/CH4 main engine. Meshing with 4 sides of the core's octagon are 4 slightly skinny methane tanks, each with a fuel line running to the main engine. A separate line for oxygen runs vertically up one side of the core cabin, meeting with a port on top near the docking adaptor atop the vehicle to allow for LOX transfer between the lander and the LOX depot. 4 landing legs are spaced under each methane tank, though not directly supporting them. The core cabin would be split into 2 parts internally: the upper part with the docking port and crew rooms while the lower part is storage and the airlock for lunar excursions.{snip}
If you are willing to use 4-5 engines instead of one the prototype LOX/CH4 engine was flying around KSC last week.