There are a couple of articles with policy implications in this week’s issue of The Space Review. First, I report on a recent panel that grappled with the question “Why are space stations so hard?” As you might expect, panelists mentioned a combination of technical and management issues, from the difficulty of trying to test on the ground components designed to interface with items already in orbit to ever-shifting requirements. One issue that many panelists agreed upon was a desire to develop a heavy-lift vehicle that could launch a complete station in just one or two flights, avoiding the complexity of on-orbit assembly as much as possible: a topic that is less relevant to the ISS per se than for exploration mission architectures, particularly those that eschew HLLV development in favor of multiple flights of smaller vehicles to stage lunar and other missions.
Taylor Dinerman, meanwhile, addresses the critical but often-overlooked issue of ground infrastructure as it relates to the Vision for Space Exploration. Dinerman in particular makes the case for replacing the existing Vehicle Assembly Building, four decades old and vulnerable to hurricanes, in favor of a new facility that is better suited to shuttle-derived launch vehicles (as well as the Florida weather). The VAB is not the only infrastructure aspect that NASA and Congress will need to address: there will also need to be renovations of the shuttle launch pads to support shuttle-derived vehicles, and perhaps even replacing the aging crawlers that transport the shuttle from the VAB to the pad.
The funny thing is that “One issue that many panelists agreed upon was a desire to develop a heavy-lift vehicle that could launch a complete station in just one or two flights, avoiding the complexity of on-orbit assembly as much as possible” does not work as a pragmatic statement at all.
One cannot avoid “the complexity of orbital assembly”, if one is to promote a space-fairing society. One can launch a 2-block space station instead of 1-block space station with an HLV (a questionable in its mathematical rigor term), but one cannot escape the proverbial “complexity of orbital assembly”, if one to lay claim to The Moon, Mars, “and beyond”.
But if one to be serious about human space exploration, one is to be serious about *promoting* orbital/super-orbital space assembly (the suits, the interfaces, the procedures, etc…)
Aggregation of n-flights into one is not the ultimate solution, it’s the cloud of “right here, right now” delaying approach kicking our shins as a space fairing society.
I’m not sure I understand the last paragraph, but I emphatically agree with Sirrus’ wider point. It is one of the reasons I think we should go with the EELVs or some other existing vehicle. The main reason is that it’s cheaper up front, but it also forces us to continue learning how to assemble complex structures in microgravity and to do more with less. We aren’t going anywhere beyond Earth’s moon without the former capability and probably not without the latter; we’ve started learning and we might as well continue now. That said, we definitely need to learn to do it more cheaply.
— Donald
Regarding the VAB, to paraphrase a certain President, Here they go again. Already, folks are trying to ride every perceived “need” of NASA onto the VSE.
We’ve been there before and it doesn’t work. The only way the VSE will succeed is to get to a Lunar Base with the absolute _minimum_ up-front investment. Once the base is there — a market, a constituency, a logistics requirement, whatever you want to call it — then and only then can you justify additional infrastructure. We can build a new VAB, new launch pads, new rockets, et cetera, _after_ we’ve returned to Earth’s moon and have something to show for our past investments.
— Donald
I’m in agreement that we do need to learn better how to do the things we need to do in space to be space-faring and not just space-visiting.
I read the article, but the whole time I’m thinking to myself “The Russians have adopted a modular approach and have had space stations in orbit since the early 1970s.” We (the U.S.) have tried an all in one (Skylab, a successful failure because we put people on-site to fix it) and a modular (ISS with the Russians, a failing success?).
How much of the delay in construction of the ISS since the first elements were put into place has been as a result of STS launch issues? I’m too lazy to look it up myself, but I imagine it’s not insignificant. Now with as much time as everyone’s had all of the remaining elements should be lined up and ready for launch at the first available opportunity, right? If someone can build a truss and fairing that “emulates” the shuttle cargo bay, they should be given the opportunity to at least bid to put the asset in orbit.
How much then of the frustration with modularity is a result of latent shuttle issues? With the EELVs it looks as if by the 2010 time-frame we’re going to have three launcher capabilities in the 20 mt payload range. What’s needed is for someone to offer the various governments to take hardware that they may have given up on off their hands, finish it out, and launch it for lease to all comers.
Thus, the Brazilian (IIRC) Express Pallets could end up seeing use, and quite useful they would be. I once had the delusion of a small business that would create “vacuum globes” of glass in orbit in a GASCan or Hitchhiker set-up, which would interface with the ExPa. It’s the perfect capitalist creation, selling nothing for a fair price.
A single launch space station is not necessarily the right solution. Besides, how many vessels do they envision docking with it? I’m guessing not many at any one time. Oh, and what’s this “if” on replacing the crawlers? Those things were decrepit when I visited KSC with the NASA Academy back in 2002 (and got to see them up close).
The ideal for the space station is to be set it up with a Management Company (Not a Port Authority though, that’s a bad model) to manage the comings and goings of the station, docking fees, import/export excises, oxygen tolls, utlity bills for the racks, and so forth (oh, and provide their own superintendent). These guys would deal with the logistical hassles and developing markets while NASA goes traipsing down the trail to Mars.
Ah, if only…
Donald, I disagree with this sentence- The only way the VSE will succeed is to get to a Lunar Base with the absolute _minimum_ up-front investment.
I think we need to minimize reoccuring costs not up front costs. The biggest problem with the shuttle is that we skimped on development costs which drove up the cost of use. So we ended up spending far more money in the long run.
If commercial entities will ever develop on the Moon it will be because NASA has invested in infrastructure necessary to keep the cost of lunar activity low.
We must spend our money wisely and avoid being penny wise and pound foolish at all costs.
Karen, I don’t disagree with your view of financial wisdom. However, the Lunar Base is different from the Space Shuttle. The latter had high recurring costs. The Lunar Base will not in and of itself. _Transportation_ to Lunar Base may well, and here I fully agree with you that long-term investment is essential to lower costs.
However, I believe the key requirement achieving that long-term investment is the existance of the Lunar Base itself. We need to get it started while the national consensus and finances are still in place to do it. That won’t necessarily last through a lot of development. Once the base is there, it’s existance will drive the investment to lower costs.
The true lesson I think we should have learned is that attempting to finance cheap transportation before you create a destination puts the cart before the horse. The Space Shuttle was a transportation system to nowhere so the only political support it had was to keep aerospace engineers busy, employed, and voting for those who voted for it. That proved not to be enough to fully fund the project, or to give it the kind of Administration attention needed to force NASA to scale it down to something affordable.
Possibly accademic question: What would have happened if NASA had been allowed to build a Space Station using the Saturn-V (or even Titans) _before_ proposing to lower costs with the Shuttle. I think the Nixon Administration, having a destination in hand requiring supplies, would have been under far greater pressure to fully fund the Shuttle and produce a vehicle that would work.
We can see it today. A lot of the pressure to create a quick-and-dirty CSV that works is driven by requirements to supply the Space Station. The same would hold true of a Lunar Base. If we build an intial bare bones base with what we’ve got (EELV, Ariane, and just possibly the minimum possible Shuttle-derived vehicle though I’d like to avoid that), the next Administrations will be under a great deal of pressure either to fund efficient transportation or to make a conscious, politically expensive decision to terminate the United States’ presence on the Lunar surface.
Build the minimum base and transportation will come, which will allow a bigger base. Try to do it all at once by spending our money designing efficient transportation to nowhere, we’re likely to never actually get to the base.
— Donald
A bare bones lunar bases will have sky high reocuring costs.
Food, water, Oxygen, nitrogen and spare parts.
A lunar base done with proper investment in necessary R&D and shipping up a proper life support system and ISRU equiptment will only need spare parts.
I am worried that without a real heavy lift vehicle we will have to go with the bare bones aproach.
If we are going to get launch rates up it will only be with comercial development and that requires low resupply costs.
As for having a space station affecting shuttle development. NASA did have a space station, Sky Lab and they wasted the oppertunity to reboost it which might have made it last until the shuttle was ready.
… Food, water, Oxygen, … >
There may be enough water at the lunar south pole to support humans on the Moon. Given water and plenty of Sol, moon dwellers ought to be able to grow enough food to feed themselves, at least food of the hippie vegetarian variety.
Nitrogen? Grow a lot of peanuts, and recycle human
wastes.
Given sufficient solar derived electric energy, the Moon may yield hydrogen and oxygen. This may be an excellent demonstration project for a terrestrial mass market hydrogen industry.
…. “One issue that many panelists agreed upon was a desire to develop a heavy-lift vehicle that could launch a complete station in just one or two flights, avoiding the complexity of on-orbit assembly as much as possible” does not work as a pragmatic statement at all. …
What station are they referring to? Are they proposing to build an HLV in order to finish the ISS, or is an additional space station proposed — Solaris, maybe — or is the first Moon base or Mars spaceship supposed to be a monolithic 100-plus tonne Battle Star Galactica?
To put things in context, recall that the Saturn V missile did not land 100 tonnes at a time on the Moon.
We were talking about ISS, nitwit. Read Jeff’s article. Its all there.
Karen: “A bare bones lunar bases will have sky high reocuring costs. Food, water, Oxygen, nitrogen and spare parts. A lunar base done with proper investment in necessary R&D and shipping up a proper life support system and ISRU equiptment will only need spare parts.”
That is precisely why I am worried that Mr. Griffin is proposing to spend all his money on launch vehicles, rather than on learning to “live off the land” on Earth’s moon and practicing it with an initial, minimal base.
“I am worried that without a real heavy lift vehicle we will have to go with the bare bones aproach.”
I am worried about precisely the opposite, for two reasons. First, if we spend our money on launch vehicles we won’t have any money for even bare bones. More importantly, if we simply launch pre-configured payloads on giant launch vehicles from Earth, we’ll never have to learn to live off the land, conduct inter-base trade, get by with less, or do any of the other things a successful colonization attempt in the Solar System will require. Colonization the Solar Systems does not require heavy lift from Earth (though that may be nice to have); it does require learning how to live in deep space and that is where we should be spending our money.
“If we are going to get launch rates up it will only be with comercial development and that requires low resupply costs.”
But, we will get neither high launch rates nor low resupply costs from giant rockets that do nothing but support deep space exploration. The EELVs were designed for high launch rates (I just read in Spaceflight that the third Atlas-V was launched only eleven hours after it reached the launch pad; who needs new launch pads?). High-rate production of EELVs benefits everyone.
You and Cecil can argue until you’re blue in the face that an HLV is a technological requirement of a successful lunar base, and you could even be right. It doesn’t matter one whit if that’s more than the nation is willing to spend on human spaceflight. We would-be space colonists have to live within our means, and here and now that’s circa $8 billion a year. If we blow it all on launch vehicles — again — there won’t be any spaceflight.
— Donald
I am very worried that we will commit ourselves to a launch system which makes large scale lunar mining impossible simply because of the maximum size and mass of a payload. To do large scale development you will need big mining machinces which can handle tons of regolith at a time. You can do that with a machince that weighs less than several tons. On Moon assembly is a very bad idea because of the highly abraisive regolith, at least until we have regolith fusing machinces on the surface paving areas around the base.
One of the products of mining would be nitrogen which is needed for air preasure.
As for life support an all vegatarian diet is not very effiencent since plants produce 50% humanly non-edible biomass which can be hard to break down into a form useable by plants. One excelent device for breaking down this waste biomass is called a cow, it has the side bennifit of producing milk and at end of life can be dismantled into steaks. There are other similar devices which can recycle other parts of the waste stream and produce eggs and fish fillets. These devices can drastically reduce the photosysthetic area required to feed a human which is important because light and water pumps require lots of power.
Oops. I ment you Can NOT mine several tons of regolith a time with a machine weighing less than several tons.
“One excelent device for breaking down this waste biomass is called a cow, it has the side bennifit of producing milk and at end of life can be dismantled into steaks.”
Aha! Perhaps those extra CEV seats were for a cow and a goat
Alternatively, I might just take some cellulose metabolizing enzymes with me and use that spare half of the biomass to produce alcohol to run the rovers.
Internal combustion engines adapted to the lunar environment will be intereting.
I am sure some people will have other possible uses for the alcohol.
Metabolizing enzymes would probably need to be replentish which requires shipping.
“I am very worried that we will commit ourselves to a launch system which makes large scale lunar mining impossible simply because of the maximum size and mass of a payload. To do large scale development you will need big mining machinces which can handle tons of regolith at a time.”
I fully agree with you, but the last thing we need now is large-scale lunar mining. That would be way too big a first step. What we need now is a very small number of scientists and engineers on site to determine what and how to mine. That can be done with the EELVs. The HLV and its giant mining tools can be developed after the base is established.
If we develop and build all of this fancy equipment _before_ we go back to the moon, we’ll spend all of our time and money developing and never get there. Also, we won’t really know what to develop. Complex mining economies and their supporting equipment require detailed knowledge of the material you are mining. Again, you are putting a very expensive cart before what needs to be a very inexpensive horse.
My partner runs a ranch where she runs cattle; the land is so dry and rugged you can’t do anything else. (If anyone wants to buy some free-range, grass-fed beef, let me know and I can probably put you in touch with her rancher.) Cattle are _very_ inefficient machines at turning biomass into food; you’d be far better off sending vegitarian astronauts. If that is unacceptable, think small chickens, or at most goats.
— Donald
Anyway, Karen, what’s this “commit to a launch system.” I think one of the breakthroughs of Mr. O’Keef’s original ideas were that they did not commit you to one launch system; early plans for the CEV allowed launch on any medium-class vehicle.
Learning to confidently travel to the moon and over its surface, and work there, is a project that at best will take many decades and will probably last for centuries. There should be no commitment to any particular launch system. We should use the best launch vehicles available at any given time. Right now, those are the EELVs, or just possibly the cheapest possible Shuttle-derived vehicle.
— Donald
Speaking of space mining, the Japanese are actually doing something about it. This on their asteroid sample return mission from SpaceRef this morning,
— Hayabusa Hovers Near Asteroid Itokawa
http://www.spaceref.com/news/viewsr.html?pid=18064
We can develop mining equiptment without astronauts or at least get pretty far. Send up prototypes and see how the do.
I think we will need a large piece of mining equiptment to make any human occupation of the moon cost efective, just to mine enough regolith to produce water for life support, nitrogen for preassure and oxygen for rocket fuel. I don’t see mining as optional.
The question is how large and the anwser to that question will take a lot of work and a lot of assumtion making.
The cow is not so much to produce food as to recycle waste plant biomass effiently. It will however increase the food supply by 5%, which is significant especially when the power costs are considered. Goats would be fine too. I would like to see chickens in addition to ruminents but chickens are not good at grinding and breaking up tough plant parts.
If we start planmning our lunar activities around our launch system instead of planning our launch system around our lunar activities it will be a big mistake.
I don’t think we can safely do a lunar program with either the EELV or the SDHL. I don’t like them, I don’t think the are safe or powerful enough.
Karen: “Send up prototypes and see how the do.”
That’s exactly what I’m advocating, but do it now. Develop some prototypes, launch them with a small crew to fix things and to do the science on EELVs. Then, you’ll have the knowledge to develop first-generation operational equipment.
“If we start planmning our lunar activities around our launch system instead of planning our launch system around our lunar activities it will be a big mistake.”
No, that is the way it has always worked in the past. No one built a special ship to explore Greenland; they took what ships they had and got started. We’ve spent all the years since the special-case Apollo failing to develop vessels to nowhere and proving to ourselves that you _have_ to design your base around existing ships. There are real economic reasons for that. Why would anyone pay to build ships to get to a place that doesn’t exist and may never exist?
“I don’t think we can safely do a lunar program with either the EELV or the SDHL. I don’t like them, I don’t think the are safe or powerful enough.”
But they are what we have. Congress doesn’t really care whether you like them; after the experience of the last thirty years they aren’t going to pay for anything else until and unless there is a real good physical reason — that is, a base needing supply. Congress certainly isn’t going to pay what it would take to do it with the resources and levels of safety you appear to want. If we want to see a Lunar Base in our lifetimes, it’s adapt existing vehicles or nothing, and we’d better get real and start planning a base that will fit into what we’ve got.
I’m sorry Karen, but if you’re planning a Lunar Base avoiding _both_ EELVs or a Shuttle-derived vehicle, I really do think you’re not living in anything like the real world, at least not politically.
— Donald
While I am not familar with sailing ships, I bet green land is a special case if you are right. I am certain that there were ships built for a specific expeditions. There is such a wide variety of wooden ships for different purposes.
Why would anyone build a ship to a place that doesn’t exist that is a good question, why in the hell did we build the shuttle?
The Moon exists and has existed for billions of years and isn’t going anywhere.
It is NASA that isn’t interested in looking beyond the present fleet not congress. I don’t think congress has discussed it at all. I am certain though the last thing they want is to loose any more americans in space and I am almost certain that is what will happen with in the first ten missions with either an EELV or SDHL.
New Moon Rising : The Making of America’s New Space Vision and the Remaking of NASA: Apogee Books Space Series 42 (Apogee Books Space Series) (Hardcover)
by Frank Sietzen Jr., Keith L. Cowing
“… One of the authors, Keith Cowing, ran a website for many years called ‘[redacted]’ which did a very important, in fact a vital job in pointing out many of the sillier bureaucratic decisions during the Goldin era. It appears that, with a change of administration, any critical thinking skills he had vanished, and he has now become the kind of apologist he once criticized. … ”
Recommended – with reservations., September 21, 2004
Reviewer: Hartmann – See all my reviews
I warily recommend this book as a very interesting and informative read, but one that is pretending to be something other than it is. In the Authors’ Note at the beginning of the book the writing duo strenuously claim strict impartiality, saying of their central characters, Bush and O’Keefe, “The authors make no attempt to judge their actions as being good, bad or indifferent to the nation’s interest.”
This supposed impartiality is quickly shown to be an utter charade. Within a few pages, former NASA Administrator Dan Goldin is described as being in charge of a “nuthouse,” a “Machiavelli” who is “dripping with ego and suspicion.” Throughout the book he is described as demonic and incompetent in his personal and professional life. Others such as Bill Nelson suffer similar treatment, and even peripheral characters just as John Kerry are hauled into the fray to be swiped at and sniped at.
It is certainly an opinion, and the authors are entitled to it. However, to pretend that this book is not anything but heavily judgmental and biased is, frankly, laughable. A more accurate title for it would have been “Goldin Bad, O’Keefe Good.” I am sure Sean O’Keefe loves every word in this book, but even he would not pretend it is impartial and must cringe at some of the more venomous attacks on his predecessor
…
One of the authors, Keith Cowing, ran a website for many years called ‘[redacted]’ which did a very important, in fact a vital job in pointing out many of the sillier bureaucratic decisions during the Goldin era. It appears that, with a change of administration, any critical thinking skills he had vanished, and he has now become the kind of apologist he once criticized. The book supports many of O’Keefe’s decisions – such as the writing off of the Space Station when it was almost complete and finally ready to begin what it was designed for, and the ludicrous decision to abandon the Hubble space telescope – decisions that I suspect this book would have spent whole chapters criticizing if another administrator had taken such weak backward steps.
…
http://www.amazon.com/gp/product/customer-reviews/1894959124/ref=cm_rev_next/103-3677579-2318258?%5Fencoding=UTF8&customer-reviews.sort%5Fby=-SubmissionDate&n=283155&s=books&customer-reviews.start=11
I sincerely do not know much about geology.
I have a question: Does the Moon’s soil significantly lack nitogen, compared to Earth?
David, why are you wasting space on Jeff’s site reposting all this (off topic) stuff? – indeed you posted a large chunk of text *twice*. A link would suffice. Grow up.
Karen: “green land is a special case.”
Only in the sense that it was one of the first really long-distance arctic ocean journeys. I believe they used their standard ships for the journey.
“I am certain though the last thing [Congress wants] is to loose any more americans in space”
In that case, we should stop right here and save ourselves a lot of money and heartache. Because, if we are not willing to lose people on the way, we have no chance whatsoever of settling any part of the Solar System or even establishing scientific bases (including in unsettled parts of Earth). If we return to Earth’s moon, no matter what launch vehicles we use and how much we spend on safety, we _will_ lose people and, as Greg has pointed out in a different context, probably a significant percentage of those we send.
If you are right, if we are not going to balance practicality and reasonable cost against risk and accept that there will be casualties, and probably a lot of them, we do not have the gumption to carry this through.
If we don’t have that gumption, why waste money futzing around with technology we’re never going to use? Let’s just shut down the whole Exploration mission and admit that we’re never going to do anything but send clockwork robots.
The one good thing to come out of Challenger and Columbia is quantitative evidence that you are wrong. We spent way too much trying to make the Orbiters safer than they can be, but even after the loss of fourteen people I don’t think much of anyone from any political party has argued we fully retreat from human spaceflight. Human spaceflight appears to be on more secure political ground now than it has been at any time since Apollo.
“And I am almost certain that is what will happen with in the first ten missions with either an EELV or SDHL.”
I don’t dispute this, though I doubt it will be much safer with any other vehicles. The journey itself is dangerous. Again, as Greg pointed out, we were very lucky with Apollo; we could easily have had serious losses. (Maybe we’d still be flying to the moon if we had. . . .)
Out of scientific curiosity, I’d be interested in what vehicle you would use if money were no object and you could develop anything from scratch.
Thanks!
— Donald
Ooh, I want to answer that one…
My dream design is called the caplet. It’s sort of like a capsule, but long and skinny like a caplet. It’s sole function is to keep a fixed number of people alive for a fixed period of time in space (and very limited maneuvering). Everything else is ancillary.
You want to come back to Earth? Bolt on a heatshield and parachute.
Want to go to EML-1? Strap on some engines and tanks. (4 km/s dV class, IIRC)
Want to drop to the Moon from EML-1? Strap on the 6 km/s dV propulsion assembly and some landing legs.
Want to rove around on the Moon? Drop the caplet in a wheeled or tracked cradle and away you go.
Want to go to a NEO? Dock a caplet or two, with propulsion, and a couple of Bigelow Balloons to a Universal Docking Node and away you go.
It’s the perfect modular approach, and allows for infinite variation. It also avoids such silliness as sending lifting body or ablative heatshield mass beyond LEO.
Stage from ISS to EML-1 (and from future inclined stations as well for about the same dV). Stage from EML-1 to pretty much anywhere you would want to go. Do what you gotta do anywhere on the Moon, or out at the asteroids, or back down in GEO, or even launch a mission to Mars that half the planet can watch leave.
That’s why the caplet is my vehicle of choice.
I have a question: Does the Moon’s soil significantly lack nitogen, compared to Earth?
Terrestrial soils don’t have all that much nitrogen either, typically — it gets recycled back to plants or the atmosphere fairly quickly. There are exceptions, particularly nitrate-rich soils in Chile, guano, and minor amounts of nitrogen in fossil organic matter.
Lunar nitrogen seems to be from the solar wind; the high temperature formation of the moon is thought to have baked out most volatiles. There’s probably some nitrogen compounds in the lunar polar volatiles, but no evidence of that as yet.
The shuttle and any system derived from it will be dangerous because we still do not have the technolgy to build what was promised in the late 1960’s, this created dangerous compromises and a culture which avoids looking at or for possible problems because they know if they do the will never be able to fly.
Any system which requires multiple launches for a mission will be significantly more dangerous than single launch missions.
What I would like to see is a shorter, fatter modernized Saturn 5.
Karen: “Any system which requires multiple launches for a mission will be significantly more dangerous than single launch missions.”
While I admit proving it is beyond my abilities, I don’t believe that this is autoatically true. Say we do two lunar missions a year and launch them complete on a large launch vehicle.
First, this does limit your mass on the lunar surface, possibly to a great degree. If you stage with smaller vehicles, you can launch as many as you need for the particular mission. With one giant vehicle, you’re limited to what that vehicle can carry.
Second, it does not allow for emergencies or quick fixes. Say something goes wrong on the moon. If you’ve got a relatively small vehicle, you can afford to keep it on standby and launch whatever is needed when it is needed. With a Saturn-V, you either have to wait until the next scheduled mission or you launch a standby Saturn with a largely empty payload.
Larger payloads reduce flexibility as well as complexity.
Third, the human crew only launches on one rocket. Therefore, the human crew is at no more risk during launch than they would be on a Saturn-V. In fact, they are probably safer since smaller rockets have less to go wrong and are easier to escape.
Since docking can be done before the crew is launched, and certainly before TLI, it is not clear to me that the crew is at greater danger on the way to the moon.
Nor is it clear that a large number of small, semi-independent modules on the moon is inherently more dangerous than one or two giant modules containing everything — rather the reverse.
Admittedly, these are intuitive rather than quantitative arguments, but I think your case is not without its own problems.
I like Ken’s ideas. They’re an extreme version of what I think O’Keef had in mind in the first place. I think that something like them is the most flexible, and probably the cheapest, way to go, at least in the near term.
— Donald
There are two reasons why multiple launch missions are inherently more dangerous than single launch missions; multiplication of failure rate over the number of launches and launch pressure.
1. All launch vehicles used have close to the same failure rate, between just above zero and 2%. If a vehicle fails more than 2% of the time it tends to get taken out of service. A failure rate is never really zero even if it hasn’t failed yet, any vehicle will fail eventually.
Since there is no significant difference between failure rates of launch vehicles, the failure rate of a mission is a multiple of the number of launches required.
2. Launch pressure. The pressure to launch will increase with the number of other launches required to successfully complete a mission. So, launching the humans last may actually increase danger since so many other assets are waiting in orbit, launch workers will tend to down play any problems, simply because of the psychological pressure caused by the other assets. If on the other hand all assets are together so there is no architecture pressure workers will feel freer to express concerns knowing that the mission can always go later. Going later may not be an option for a multi launch mission as fuel is boiling off in orbit.
Both your points accept all the benefits of large launchers and none of the costs.
1. So, if you launch your entire mission on a Saturn-V, a la Apollo, you have that less-than two percent chance of losing your entire mission.
If you launch on multiple flights, you have the same chance of losing your crew. You also have the same chance of losing each element, true, but you also have a chance to recover the mission by re-flying the lost element. Maybe this is somewhat riskier than the Saturn-V approach, but the difference is less than you and others imply and it is also less flexible.
2. Other than the fuel-burnoff, I think most of your point two is bogus. It seems to me that launch pressure would be higher on teh Saturn-V approach because the entire mission is staked on a single launch and every element must work perfectly the first time. If several elements are launched separately, pressure is lower because you know you can recover. Keep the vehicles simple, launch them high enough to give yourself time, and make sure you have a stock of payloads on hand.
The boiloff issue is fixed by using storable fuel or by launching the fuel last, after the crew is already in orbit.
— Donald
Donald: “First, this does limit your mass on the lunar surface, possibly to a great degree. If you stage with smaller vehicles, you can launch as many as you need for the particular mission. With one giant vehicle, you’re limited to what that vehicle can carry.”
HUH? We can launch just as many small vehicles we like? Someone is giving them away??
Launch one Saturn-V with full mission, that’s the mass you have. You need to launch another Saturn-V to add _any_ additional payload.
Launch four EELVs, sure, you’ve spent more in launch costs, but to fly an additional payload you only need the incremental cost and effort of one more EELV. No, it’s not free, but it is more flexible.
— Donald
It isn’t as simple as that. But generally speaking a larger vehicle places fewer design restraints on what sort of payload you can loft. But there is nothing to say that EELV’s can’t be used to supplement HLV launched missions.
I’m going to expound a bit on the design restraints that smaller vehicles place on spacecraft design.
For an example let’s say we want to launch Apollo hardware using smaller vehicles. I don’t know all the Apollo craft weights offhand so for this example I’ll just say that it require an EELV each for: the LM decent stage, the LM ascent stage, command module, service module, and a stage to push all this to the moon since there won’t be a Saturn 2nd stage to do so.
Now I know it may be an exaggeration to say that each of these pieces of hardware are heavy enough to require its own launch vehicle but I’m trying to demonstrate a point I think is overlooked too often.
If you launched all this Apollo hardware in this manner each vehicle would need to be modified such that it could be assembled remotely on orbit.
Say we launch the LM descent stage first and then the ascent stage. They have to “find” one another and dock in space, something they were not design to do in the Apollo program. This will require weighty and expensive modifications, RCS, Radars etc. plus extra electrical capacity to operate these things and keep the craft alive while being assembled and waiting on the remainder of the vehicle “stack”.
The same applies to launching the command module, service module and the trans-lunar injection stage.
My point in this admittedly fictional example is that when you design for on orbit rendezvous, docking and build up of a orbital complex you have to build in things that add weight and expense that are only useful to you during that stage of the mission. After the assembly process all those extra RCS assemblies, rendezvous radars, docking rings, airlocks, etc. are just dead weight.
Having a launch vehicle that is large enough to launch bigger “chunks” at a time minimizes the amount of dead weight rendezvous equipment you need.
While I still think you way over-emphasize the disadvantages of multiple launched missions, and under-emphasize the advantages, I’m not going to dispute any of that. Make your whole plan fit under circa $8 billion a year and I’ll buy it.
It doesn’t matter what you “need.” In our time and place, all that matters is the money available, and $8 billion is the money the nation has decided human spaceflight is worth. If it doesn’t fit in that constraint, it literally won’t fly.
So, rather than continue _this_ debate, how would you make developing and maintaining the CEV; trans-lunar vehicle; lunar lander; return vehicle; lunar surface module; lunar surface equipment; the HLV; an additional medium-class vehicle; an orderly shut-down of the the Shuttle program; finishing the Space Station or at least maintaining it as is; and anything I haven’t thought of all fit within $8 billion a year? If you can’t, what would you cut?
I’ve given you my solution: strip it down to modify the EELV; build “light” CEV; light lunar vehicles; lunar base and equipment; Shuttle shutdown and maintain Station; plus probably signficantly higher operations costs than your model. I think there’s just a chance you could fit all that into $8 billion a year, especially if you move Shuttle shutdown forward and commercialized Space Station maintenance.
How do you fit your model into the resources available?
— Donald
Well as I understand it the NASA plan is to spend that 8 billion a year on developing CEV/its launch vehicle/shuttle over the next 5 years. And in the 8 years from 2010-2018 the 8 billion per year will be spent on HLV/lander/trnasfer stage.
That plan sounds as if it might be cutting things a bit close but I am in no position to argue that it is impossible, I don’t have enough hard information to make that call. It boils down to my trusting Griffin. Which at this point I do.
I do have to say that I kinda trust Griffin, too, but that trust is wearing thin. I’m still willing to give him the benefit of the doubt, but I increasingly fear he’s looking at it through the NASA-colored glasses of “what we need” rather than “what we can afford.” If NASA’s demonstrated nothing else in the last thirty years, its that the former view will always get you into trouble.
However, I sincerely hope that I will never have the opportunity to say, “I told you so.”
— Donald
Cecil,
The sequential approach you reference won’t work. Assuming NASA could indeed develop a CEV & launcher in 5 years is questionable given their past performance on large dollar programs. But granting they perform this miracle, the next 8 years leaves the CEV waiting for someplace to go or something to do. That just isn;t realistic. Griffin has selected the configuration to maximize existing infrastructure, etc. It also means he inherits the standing army behind that infrastructure that still needs to be fed. At $2-$3B per year, the developmnet schedule for the rest of the architecture is stretched another 30-40%. We’ll end up with the same situation we are in now, the CEV flying to a meaningless outpost at LEO just to maintain critical skills and hopefully public interest so that funding streams can be maintained. Better to get to the destination as soon as possible and demonstrate that there is something worthwhile there to whet the appetite for more.
GW: “the next 8 years leaves the CEV waiting for someplace to go or something to do.”
It’s called ISS.
It looks like this argument is lost, but I still think GuessWho has it closer to the truth.
— Donald