Author Topic: Another Alternative Exploration Architecture (Read 65657 times)

meiza · « **on:** 08/27/2006 05:38 pm »

I made a small document describing how one could avoid building any new launchers and still go to the moon. It is done by a depot in low Earth orbit, where you send about 90 tons of LOX by tanker rockets (That's how much LOX is in the EDS and the LSAM descent stage). The EDS, LSAM and CEV then go to LEO each with their own rocket, and LOX is tanked from the depot and you assemble the stack and fly to the moon normally.

Here is the document.

Feedback and discussion please.

astrobrian · « **Reply #1 on:** 08/27/2006 06:07 pm »

While it is true that the development costs of a new rocket would be curbed by going this route, overall the program cost would be higher because of all the amount of tanker launches and assembly ready modules. Just my initial assesment of the idea. I will let the real engineers have at it though with the real numbers of things. It is an interesting concept either way. I think one could build an ISS style fuel depot hanging in a LaGrange point for similiar moon shots. I think L2 if memory serves is the one about 2/3 the way to the moon.

meiza · « **Reply #2 on:** 08/27/2006 07:20 pm »

But you wouldn't have standing armies for Ares I and Ares V. The marginal cost of existing rockets would be low.

How much does the space shuttle program cost on a year there is a few launches vs if there is none...

gladiator1332 · « **Reply #3 on:** 08/27/2006 08:10 pm »

It isn't that bad of an idea actually. Somewhat a simplified version of the old "Battlestar Galactica" plan. And when you think about it, it does make sense to have some form a fuel depot in LEO. This will all come in handy when it comes time for the Moon Base and Mars missions.

I also like the idea of using the existing Delta IV Heavy. That is one option that we always seem to forget. We already have an Ares I class vehicle built and flying. And multiple launches aren't a bad thing. We won't always be able to launch large scale missions in one shot. To get to Mars we are going to need multiple launches. Why not start practicing now, as that is the purpose of going to the Moon before Mars.

mong' · « **Reply #4 on:** 08/27/2006 09:11 pm »

the biggest advantage of this plan is that it could encourage higher launch rates and reduced launch cost that's evident, but I think it's still a little risky. 2 launches should be the maximum allowed for a single mission IMO.

BUT your plan could be great AFTER the moon base is established. because once such a base appears NASA will likely focus on mars missions, and that ain't gonna be cheap.
they are going to need cheaper alternatives to support the moonbase than Ares I/Ares V. this is where competition will kick in to try and provide the lowest launch costs/highest launch rates. when it happens a plan like yours for crew rotations and cargo delivery will be a good solution.

True reductions in launch and operating costs will appear because The less they spend on the moon, the more they can spend on mars.

AndyMc · « **Reply #5 on:** 08/27/2006 10:55 pm »

It seems like a reasonable and cost effective plan, that could be executed a lot faster than ESAS. More suited to smaller players, perhaps with a small group of international partners. It reminds me of the Mars for Less Project, that I and some colleagues have nearly completed for the Orbiter Spaceflight Simulator. Maybe for Mars, the payloads would beed to be in the order of 40t each in place of the 20t-25t proposed.

Hopefully it should be releaded within the next few weeks. http://www.aovi93.dsl.pipex.com/mars_for_less.htm

I think the problems associated with ISS assembly, have acted as a strong deterent against the idea of assembling multiple module spacecraft in orbit. The time scale for ESAS seems to be too long for me with the current budget. This plan (FLEX) would be lot quicker.

kraisee · « **Reply #6 on:** 08/28/2006 06:17 am »

This approach doesn't seem to offer a solution to the 450mT spacecraft mass required to perform Mars missions.

Doing it at 25mT, you're talking about at least a years worth of continual EELV-class launches, and praying none of them go wrong, or you end up screwing-up the schedules really badly. Not to mention the complications involved in automated assembly of about 20 separate modules each the size and complexity of an ISS module - but doing it without extra crew missions to solve any difficulties it will make things a lot trickier. Not to mention the tons and tons of docking adapters required to link 20 modules together strongly enough to be launched towards Mars on a 2-year long mission where if anything serious goes wrong, the crew has no way to get home.

IMHO, that's a recipe for disaster, sorry.

Ross.

lmike · « **Reply #7 on:** 08/28/2006 06:19 am »

Quote

kraisee - 27/8/2006 11:04 PM

...Doing it at 25mT, you're talking about at least a years worth of continual EELV-class launches...

What's the flight rate? The EELVs manufacturing can do at least 25 vehicles per year, AFAIK. Bulk purchase, you save money. It's at least "rudimentary", like in the very real actual MRO, flying. Not a model.

kraisee · « **Reply #8 on:** 08/28/2006 06:28 am »

18 to bring up 450mT of useful payload mass. Plus whatever the surplus is for the tons of docking adapters you need to connect everything together. Plus whatever TMI propellant is needed to offset that extra mass too.

Oh, and also any manned assembly missions which are required. Plus the crew in the end too.

I figure 25 as an absolute minimum, which is a year's worth on its own, without factoring in the DoD missions which need to be flown too.

Assuming $300m per flight for each Heavy today (its actually slightly more than that for a Heavy BTW), and assuming that through mass-production you can reduce those costs to 81% of current levels through tripling current production numbers, then you're talking about this solution costing about $5.5Bn in LV costs alone for each Mars mission.

CaLV can do each Mars mission it for less than $1.8Bn.

Direct could do it for the $1.65Bn, and we could actually start developing the Mars architecture with the money we were going to use to develop CaLV...

Ross.

lmike · « **Reply #9 on:** 08/28/2006 06:36 am »

It seems you agree that 18X25mt=450mt I don't understand, what's the problem with that scheme? 450mt is bigger than the current ISS. The price is low. The launchers exist. The pads do too. I'll tell you, if we can't do docking adapters and are squemish at connecting things in space, we are better off not going to the Moon altogether. I don't think we are that dumb.

lmike · « **Reply #10 on:** 08/28/2006 06:42 am »

Perhaps it's the number 18 as such. It's a scary number all and out of itself, I agree. 1+8=9 which is a reversed figure of 6. 666

MATTBLAK · « **Reply #11 on:** 08/28/2006 07:04 am »

Look how many years behind schedule ISS is, with all those dozens of launches. If you were stocking a propellant depot for a Mars mission, the amount of boiloff in a year (or 2) plus the multitude of opportunities for all that hardware to fail and leak (perfection or near-perfection needed) makes this a shaky proposition. Not impossible, just very, very hard. You'd be better off uprating the Atlas & Deltas to the maximum payload capacity possible, whilst preserving the launchpads & infrastructure: 3x core Delta IV-Heavy with uprated RS-68s, GEM-60 Solid strap-ons, 2x RL-60 upper stage and Aluminium/Lithium structures would boost the payload from 25 to about 40 tons, with Pads etc. largely standard.

THAT would be the most sensible option for expendables. EELV studies I read opined that 40-50 metric tons is just about the 'sweet spot' for EELVs & infrastructure, cost and operational-wise.

lmike · « **Reply #12 on:** 08/28/2006 07:11 am »

The only reason the ISS is behind the schedule is because the STS was put in the critical path. There have been proposals to put up components by Protons and Ariannes... Don't use the ISS as an example of the wrongness of the multi-launch approach. It's a wholly multi-national political beast. It's not a space station. I might as well use the Skylab as the wrongness of the HLV approach. (and personally I don't) Look! The darn thing just fell out of the sky.

lmike · « **Reply #13 on:** 08/28/2006 07:16 am »

40-50 mt may be too large for a launch. Let's have the markets determine the sweet spots.

kraisee · « **Reply #14 on:** 08/28/2006 07:24 am »

Read section 6.4.4 of the ESAS for a detailed explanation of why a maximum of 5 launches is practical any sort of manned mission. Between 5 and 10 missions, you hit a criticallity issue which reduces likelyhood of all flights being successful to virtually zero by the time you require ten launches.

You end up with items loitering in LEO for months and months before the mission can even start, and with a concept like this you'll have some propellant (half the LEO payload prior to TLI) having to be stored in LEO for more than 6 months. Boil-off and insulation breakdown in the harsh conditions of hard vacuum get ridiculous.

Also docking adaptors mass a lot, and that mass is in addition to the basic useful mass required to go anywhere. You're talking about ~5% additional mass. On 450mT that's 22.5mT worth - which is an extra flight worth right there.

That extra mass has to go with you through the TLI or TMI burn, depending on wherever you're going. For Lunar missions, the rule of thumb is about 1 ton of propellant for every ton you want to send, so you'd need yet one more flight. For Mars missions the propellant:mass requirement is more like 3:1, so you've added four extra flights just because of all the docking adapters.

And there's a BIG difference between ISS and a Mars ship. The ISS has to support its structure in micro-gravity, with the odd boost to its orbit utilising just two 6,000lb thrust engines. A Mars ship is going to have to be put under some serious thrust to break out of Earth's gravity well, not to mention it must loiter for about six months transit, brak at Mars, loiter again for another six months, boost back towards Earth and loiter during transit back. That's huge stresses and strains involved to the structure compared to what the ISS ever has to go through. So we won't be using such small and light-weight connections - we'll be using stuff that has to be a lot beefier - and heavier because we can't risk a single failure in any one of the 24 connections.

I think that asking something like ISS to fly to Mars is asking for trouble. I'd rather just have just two solid connections between three larger modules and reduce the risks and complexity.

Ross.

kraisee · « **Reply #15 on:** 08/28/2006 07:26 am »

Quote

lmike - 28/8/2006 3:03 AM

40-50 mt may be too large for a launch. Let's have the markets determine the sweet spots.

Good point.

Oh yeah - the only market for Lunar traffic is... (can y'a guess who it is yet?) ... NASA! And that market wants 150mT missions launched on two flights.

The "Market" seems to have spoken.

The unmanned "Market" does not seem to require anything larger than the EELV's can already deliver. Heck, even the DoD only want about 6 "Heavy" EELV's over the next 14 years. And there is absolutely zero commercial interest at all in even that ~25mT capacity.

Ross.

lmike · « **Reply #16 on:** 08/28/2006 07:31 am »

Quote

kraisee - 28/8/2006 12:13 AM

Quote
lmike - 28/8/2006 3:03 AM

40-50 mt may be too large for a launch. Let's have the markets determine the sweet spots.

Good point.

Oh yeah - the only market for Lunar traffic is NASA... And that market wants 150mT missions launched on two flights.

The "Market" seems to have spoken.
...
Ross.

No. It doesn't. Dr. Griffin does (and his Planetary Society study)

[edit] just to keep things up to date... Griffin/ESAS != VSE

lmike · « **Reply #17 on:** 08/28/2006 07:37 am »

To be frank, I've read the entire ESAS and I don't give a flying f'k what it says (mostly due to the results we are witnessing). If we can do one docking, we can do any number of dockings. If we can't do any, we are better of staying put on the Earth. Number 5 as the magic number strikes me as weird. Let's pick 18.

MATTBLAK · « **Reply #18 on:** 08/28/2006 07:37 am »

Skylab worked just fine: there merely were no funded CSMs or a finished Shuttle to reboost it. Besides, Skylab was only ever a finite, prototype station anyway.

But I digress: What I should have said was 40-50 tons is the 'sweet spot' minimum sizes for designing and engineering manned modules/landers for Mars missions (unless you use a crew of only 2 or something silly like that).

Also, if ISS was launched and outfitted purely with ELVs, I'd bet REAL money they would have lost 1 or 3 of them along the way, with shutdowns, investigations and delays as bad in their own way as Shuttle stand-downs...

MATTBLAK · « **Reply #19 on:** 08/28/2006 07:42 am »

Quote

lmike - 28/8/2006 6:24 PM

To be frank, I've read the entire ESAS and I don't give a flying f'k what it says (mostly due to the results we are witnessing). If we can do one docking, we can do any number of dockings. If we can't do any, we are better of staying put on the Earth.

Multiple dockings, yes of course. But not cartoonish, look-its-easy-in sci-fi quantities of dozens for just one Mars missions. And before you go thinking I've purely got a hard-one for Heavy lift: don't forget that many Mars mission studies have implied that an 80 ton-to-LEO booster (Magnum, Shuttle C) would have sufficed.

Unless Nasa suddenly dumps all the Shuttle-derived hardware (which 'mostly' works fine) and goes for EELV, this discussion is fun & academic at best, and a deadhorse-flogging, argument-causing waste of time at worst.