OpenLuna talk:Community Portal
An all-important aspect of any mission to the Moon is payload mass. It is not clear to this new member here what kind of payload mass is being considered for the project or whether this is still an open topic. I will assume it is an open topic until I here otherwise.
I have always ascribed to the 'smaller is better' philosophy. In this context it leads me to ask: What is the smallest payload we could reasonably contemplate for a manned vehicle to the lunar surface? I don't know that there is a single 'right' answer to this but there are certainly some answers that are better than others.
A minimum manned lunar mission would be a single astronaut weighing, say, 100 kilograms. His food, water and oxygen for the round trip will be 10 kilograms per day, or about 100 kilograms total for five days out and five days back. This astronaut will need a spacesuit able to protect him from space conditions. This can be as little as 20 kilograms if we assume he only needs a pressure suit with thermal control and oxygen supply. For actually working on the Moon, however, the astronaut will need better thermal management, longer life-support capability and portable communications capability plus power to maintain all this. A strategy of pre-delivering lunar elements of a space suit and relying on the lightweight flight suit would keep the mass to the 20 kilograms noted above.
To this point we have 220 kilograms for payload.
Structure to protect the astronaut during flight and heat shielding to enable Earth re-entry would come to about 1,500 kilograms. Internal systems equipment for communications, navigation and life support are going to be around 100 kilograms.
So now we are at 1820 kilograms, or about 30% more than the Mercury spacecraft used in the '60's weighed. Landing gear, tank structure and landing engines would round out the mass to about two metric tonnes even, or about 4400 pounds.
Just a note, We are considering even less weight, and some items are much lower. For example, we are looking at a lunar lander in the 35 kilo range, and an inflatable heat shield of project moos type landing, in the 20 kilo range.
Very good questions, Please continue. --Paul 18:29, 25 September 2008 (UTC)
All topics are open, hence the name of the website! :)
Well, yes and no. Do we need to land the food, water, air that we used on the trip out? That saves 50 Kg right there. (Don't get me started on margins.) But that makes the landed payload mass at 170 kg, or if you pre-deliver, maybe only the 120kg. (I don't like this plan, but it deserves mentioning.)
Looking at structure is really wide open to debate. How much does an aircraft weigh compared to it's payload? Consider a skydiving pack (15kg) which includes 2 'aircraft' for a 100kg person.
In Apollo, most navigation was done from Earth. Attitude determination was done by an on-board inertial platform and updated by astronaut star sightings.
The heat shield debate is a good point. The Lunar orbit Rendezvous mission was selected for Apollo to keep all this in lunar orbit and not land it on the Moon. The Moose program was trying to make it incredibly light.
Until we finish hard designs with testing, it is really hard to say anything, let alone defend it. Current lander design is 140kg payload with 25kg of empty structure.
The big problem with this kind of mass breakdown is that the propellant is a huge factor. Basically, every time you do something, land, takeoff, go to the moon, enter orbit, etc you double the mass of the vehicle to include the propellants.
One Idea we have discussed is to use a restartable descent engine for all propulsion maneuvers and drop appropriately sized tanks as they are expended. This keeps the unused engines to a minimum (dead mass) and also only takes along the tankage that is full at any time. For a return flight, you weigh less and the acceleration off the Moon could get pretty high, but it only starts at 1/6 gee, so high might be much less than a normal flight from Earth.
Nothing saves, like saving weight.
so goes some of our thoughts.... -Gary
O.K., Thanks for the info. Guess I'm looking downrange a bit to the manned phase. With regard to landing the mass of food, air and water used on the trip out, unless it is ejected from the vehicle enroute, it will be landed on the Moon in one form or another. I'd consider it as a bonus supply of valuable life-support material for that time when an ecological life-support system is operating. I would not regard it as a burden or waste of propellant.
For the manned vehicle described above, I assumed use of light-weight composites as much as possible and a very minimal landing gear that was separated at launch from the lunar surface. The idea is to make the landing gear the most minimal possible percentage of the vehicle's total dry mass.
Drop tanks sounds right, but drop them on the Moon. By this I mean stage them along with the landing gear. You then have these available for integration into the Base's propellant production/storage system. This saves having to ship them or something like them later.
There is an interesting alternative to this discussion: A rather strange concept of launching a torus-shaped spacecraft with the payload mounted in the center void, the torus itself being divided by bulkheads into propellant masses specified for each flight phase. The rationale for this is the torus remains intact during the entire flight and is retained for use on the Moon as habitat volume. The payload could be manned or not. A graphic would do a better job of relating what I mean here. Just how do you load one onto this site anyway?
Some thoughts on weight (two classes of vehicles)
I thought I'd put this here because the distinction between man-rated and non man-rated vehicles will impact everything that goes into thinking about Moon and Mars missions.
A man-rated vehicle is many times more expensive than a non-man rated vehicle. So why be foolish enough to use a man-rated vehicle to do ANYTHING other than get flesh and blood from surface to space and vice-versa (plus just enough supplies for that)? Everything else can be done by robot vehicles. We had robots landing on the moon before Apollo (surveyor) and the Soviets landed an automated sample return rocket not long after. So this is old technology and not something we can't do now, whenever we need to.
The antithesis is what killed the shuttle program: NASA made the mistake of carrying big clunky satellites in a man-rated vehicle, every flight. Eventually, this resulted in loss of crew. Twice.
Even in the Apollo mission, we wasted man-rated boost capacity, and return heat sheild capacity, carrying rocks! We had to vacuum insulate moon rocks so they wouldn't be exposed to the oxygen inside the vehicle, because they were INSIDE with the crew! How dumb is that? For larger amounts of stuff, we cannot let that happen.
So, please keep in mind: we want all major supplies and machinery and shelter to go down to the moon by robot craft. If it crashes, just send another one. No people till it's all down and working. When sending stuff back from the moon, automated sample-return is the way to do it (even more so, for Mars). Astronauts coming back from the Moon or Mars need bring nothing back but their clothing. No data (all has been sent ahead, digitally), and no samples (all have been split and gone ahead in sample return vehicles).
For humans, think small, minimal, and safe. No radiation shield needed, because time of use is only from orbit to surface, vice versa, and a few hours for Earth re-entry. An Orion without the big toilet suffices for Earth return from Mars (and for transit to the Moon). Small LEM-type stuff for all the rest. For everything else: supplies, sample rockets, digging equipment, etc, think, big, heavy, open to vacuum, unshielded also when appropriate, and robotic. For the moon, your radiation sheild is either sent ahead, constructed out of moon materials, or both. But you don't send any down with crew.
You might think all this is obvious, but I've seen proposals for stuff like having the crew landing vehicle fall on its side, to be used as part of a shelter on the surface. That's crazy. Why carry all that heavy surface-living stuff on a man-rated landing vehicle? It should ALL go down ahead, and be tested, before humans ever depart from Earth. And so on.
Think double! Two classes of rockets for everything you plan.
Steve Harris Sbharris 19:13, 5 February 2010 (UTC)
My 1st post! Possible future working space...
Hello, this is Eric Boethin from Denver, and this is my first post to the Open Luna wiki! I'm still acquainting myself with the project, but looking down the line, I'd like to know what's in mind for hardware fabrication, for acquiring materials but mostly for working space.
If you haven't considered it already, one idea for working space could be a DIY workshop. Here in Denver a new business started late last year called Club Workshop (www.clubworkshop.com) that for either a pass or more likely a monthly fee lets people come in to work on their various miscellaneous building projects (for noncommercial, meaning nonproduction use). It's the first DIY shop in Denver, and from what I was told there's not too many like it in the country.
It occurred to me that this or something like it would be a great place for an OPEN SOURCE hardware organization to work on things and meet as well, since it's just prototypes that need to be built by the organization first, and it's also meant in a way to be a community resource where paying members can collaborate on a project, and even take classes on construction/machining.
Would such an outfit be useful to an organization like the Open Luna Foundation? Let me know, and I look forward to being of assistance to the project in the future, as well as spreading the word about it to others I'm affiliated with and hopefully getting them involved too!
Ad Luna! Ad Ares! Ad Astra!
Eric Boethin, President, Denver Space Society (NSS Chapter in Denver)
Hmmm, this looks like a jibber-jabber page more than a "community portal"? A CP has a brief, I said brief, introduction and directions to features of the website. This Wonderful Wiki doesn't work for the public because there's no Index or access guide. PLease, ifyou are an organizer, give us an index!!Navigaiter 17:06, 30 December 2010 (UTC)