No Conflict of Interest Here

Did you hear who just got selected as the new head of Exploration Systems Mission Directorate at NASA? None other than your friendly Shaft-shill, Scott Horowitz. Though I'm not entirely sure how the heirarchy at NASA is currently organized, the fact that Centennial Challenges is run out of ESMD doesn't seem to bode well. I'm sure Scott will make sure that the Innovative Programs NASA has been talking about will get plenty of money and attention. After all, since those alt.space commercial projects like commercial ISS resupply aren't on the critical path, their funding can't possibly be considered expendable when the Shaft goes over budget, right? I mean, I'm sure that Scott would rather see his company's vehicle only used for VSE. No interest whatsoever in those ISS resupply and crew transfer missions.

No conflict of interest here. Nope, none at all. Nothing to see people. These aren't the noids you were looking for. Move along.

Book Review: The Rocket Company

Now that I'm done venting on Mark, I think I'm done kvetching about the ESAS plan for now. I'm still home sick with this stupid cold, but I'm most of the way back out of the woods, and will probably be going in to work this afternoon. While we've been recuperating, Tiff and I finished reading The Rocket Company, and since I promised Patrick I'd write a review, I'd like to take the time to do so now.

The Rocket Company is a fairly interesting semi-fictional book about one company's attempts to open space up for commercial development. If you're looking for a good work of fiction with excellent plot, character development, page turning action...this isn't it. In fact, it is about as dry as The Goal, but at least it was intellectually fascinating. Don't get me wrong, I enjoyed this book quite a bit, and it's an excellent book if you're a rocket nerd, but I wouldn't suggest inflicting it on your significant other unless they are almost as nerdy as you are (or at least very patient). Also, if you're anywhere near as hoity-toity about literature as my coworker Pierce.....

Anyhow, the book covers a variety of topics from general business, to management, to technical issues, marketting, public relations, regulatory work, etc. It's a fairly good introduction to how most of those various topic relate to actually making a profitable space launch business. The technical chapters were for the most part quite interesting, even though I would quibble fairly strongly with a few of the design approaches. All in all, the book provides a very good way to develop a rocket manufacturing company...if you happen to have a couple of true-believer billionaire angel investors with Dirksens burning holes in their pockets, itching for the chance to open space to the masses.

Business and Financing Stuff:
Which brings me to my main qualm with the book--the assumption that developing and fielding even a small reusable vehicle has to take billions of dollars. Note, I didn't call this a flaw--the authors may very well be right, and if they are right, most of the other conclusions in the book more or less naturally flow from that assumption. It just kinda made me wonder after the author introduced yet another "team of experts" in the book if all that was really neccessary for a first-generation commercial reusable vehicle.

At least part of this stems from the design philosophy they chose for their vehicle. Admittedly, there are many subtle problems facing low-operational-cost RLVs that they do a very good job of addressing. Basically, once you realize that SSTOs are really pushing it, the challenge of how do you handle getting both stages back to the launch site so you can prep them and fly them again is rather interesting. Their approach of doing a VTVL straight-up first stage is rather interesting, and IMO one of several potential solutions to the problem. However once that decision has been made, the requirement of near SSTO performance on the upper stage tends to really drive up the development/engineering costs of that stage. Shaving weight becomes a must. I wouldn't really be surprised if such a vehicle really took that much to develop. Not that there are any obviously superior alternatives--there are alternatives, just no obviously perfect design (that's how engineering usually goes).

I've always been a fan of doing the build-a-little, test-a-little, incremental approach where you try to target intermediate markets to build up capital and experience as you work your way towards your goal. I think such a method would be able to bring a spacecraft with similar performance and operating costs to what they're suggesting at a much lower price, and without requring billions of up-front investment. But I may well be wrong.

All that said, one of the most interesting ideas presented in the book is a ramification of these assumed high development costs (but may actually be applicable even for lower development cost vehicles). Basically almost every commercial space startup I've heard of over the past several years has assumed that they would not just be building their vehicle, but that they'd be operating it, and that they would make money by selling rides. The book however makes the case that the only way to get large amounts of revenue quickly is by selling vehicles instead of rides. I personally think there's a lot of merit to this idea. After all, it will take a long time for the general market to adapt to the idea of low-cost, high flight-rate vehicles, even after they are in existance. It should be stressed that most of the customers for these low-cost reusable launch vehicles aren't even in the market yet, and may not even realize themselves that they'll be in the market for them!

The basic idea is one I've been pondering for a long time. There seems to be a lot to it. One of the key challenges with space businesses is that there's a huge amount of unknowns with the market, the capital cost to get into the business is high, and the time to revenue is often high. By selling your rockets to flight operators, you can create at least some buffer between yourself and the first and third problem. Say it takes three years to go from concept to a full orbital flight prototype, another two years from there to when you have your first production vehicle, and another two to three years after that until the market has ramped up enough that you can at least be cashflow positive on your launch vehicle operations. That's 7-8 years from initial capital to cashflow positive. Now, imagine if instead you have two companies, a launch vehicle provider and a launch vehicle operator. The provider can now start having serious revenue, and probably be cashflow positive after only 5 years, while the operator can be cashflow positive within 2-3 years of initial investment. It may take the operator years to become fully profitable (and many of them will likely never make it to profitability), but the launch vehicle provider will likely be profitable much sooner. All in all something like this seems to make pretty good business sense, even for low-development cost projects.

One of the results that followed this idea in the book was the suggestion to try and sell these as "prestige" items to various national governments who don't yet have manned spaceflight capabilities. Tickling the ITAR dragon (or at least having your business plan staked on getting the State Department to act sensibly) seems pretty darned scary to me, but if you can make it work, there are some real benefits. Those other countries (say Europe, Japan, Taiwan, South Korea, etc) would probably be a lot more willing to actually buy vehicles than to buy flights. US Legislators aren't the only ones who prefer to fund programs that employ people in their own countries than to just buy services from whoever can provide them cheapest. Giving people the option of buying a vehicle that they can then operate themselves seems to strike a happier middle ground. These prestige vehicle buys are therefore not really taking away from the commercial launch service market, because they probably wouldn't be in the market just for rides.

I'm not so much a fan of governments spending a bunch of money on national prestige bull, but if it's cheap, and if they could actually use it for useful purposes, I think I'd be willing to take their money if they wanted to buy some vehicles.

Anyhow, the whole concept of selling vehicles instead of flights is one that anyone involved in commercial space launch world should give serious thought to. It might not make sense in all cases, but it has some real potential to bring in substantial amounts of revenue early on.

Technical Nerdlichkeit:
Ok, that's enough for now about their business ideas, now back to the technical goodies! I really strongly suggest reading their chapter on balloon tanks and fracture mechanics. I've been working on the design for the propellant tanks for our demo vehicle for the past week or two, and although I had previously learned about fracture mechanics in college, that was a long time ago. While I definitely would never want to have to design a vehicle to as demanding of standards as what is portrayed in the rocket company, it does provide a useful reminder of that key point. Ironically, after my initial materials selection analysis, we almost ended up going with (and might still end up reverting to if the alternative I'm looking at doesn't pan out) the exact same aluminum alloy suggested in the book.

The section on GN&C was fascinating. I'm definitely going to have to read up a bit on fluidic controls, but that's probably something expensive enough to be out of reach for most alt.space vehicle designers.

I also liked the discussion about using turbojets on the first stage for extra landing cross-range (and possibly self-ferrying capabilities). Making sure you can land back at the launch site is a big deal. [As an aside, if John Hare is reading this, I'd suggest he keep working on proving out his high T/W ratio airbreathing idea he presented at Space Access '04. If he gets something working, I'll try and twist Dave's arm into trying it out on one of our flight test vehicles.]

Oh, and the chapter about spacesuits was pretty darned cool, particularly the discussion of hard suits and Webb suits. Definitely worth reading, and definitely thought provoking.

Conclusions:
There were a lot of other fun chapters discussing potential future markets, lunar and martian transportation systems, and a whole bunch more. If you're interested in space access, this is definitely a book worth buying. If you're working for a space access company, this book should be on your bookshelf at work. If you're a billionaire true-believer with Dirksens burning a hole in your pocket just chomping at the bit to become the next major "space angel", you can contact Michael about investment opportunities at Masten Sp....just kidding (I wouldn't know what to do with a Dirksen if I got one), seriously, if you're an investor looking for some interesting insight into this market, I'd suggest buying the book. If on the other hand, you're looking for an excellent work of literary genius, you're probably reading the wrong blog anyway.

NASA needs a garage sale.

Howdy all, Ken again.

I was thinking of ways that NASA might be able to raise money for the brilliant ESAS architecture they've contrived. Well, okay, actually I was just wondering what's going to happen to all of the ISS-related stuff here on the ground once NASA completes and promptly writes off the U.S. portion of the station. I'm thinking of the kinds of equipment used in prep work for a particular component that's no longer needed and kind of sitting around. Why not put it into the hands of the American people?

Unfortunately, NASA likely has no idea what it has stashed in its closets. The summer I worked at the NASA Academy at Goddard SFC I always hated the drive up to the building we worked in, because in a big pile off to the side of the parking lot were the unassembled components of a satellite dish in rotting crates.

Recently were found some spy suits long locked in a closet at JSC. The MMUs are probably in another locked closet there somewhere.

Now don't get me wrong, some examples do belong in museums, but there's also a lot of junk that will never make an interesting exhibit no matter how much you try to dress it up.

So on the NASA-side we have the value-added of cleaning out unused stuff that they don't have to pay to store and getting a bit of cash in return. $104Bn? No, but some fun money for more Centennial Challenges, or perhaps an offset that NASA very publicly returns to the nation's coffers to show that they are serious about doing this return to our Moon thing in a cost-effective manner.

On the taxpayer side, you suddenly put a whole-lot of high-tech and unique aerospace equipment in the hands of American entrepreneurs. Some kinds of restrictions would have to be put in place, such as export embargos for X years, only U.S. purchasers, some stuff can only go to universities, and so forth, but it is a do-able concept.

The value-added on the taxpayer side is the unlocking of a lot of assets that are put into the hands of people that can do unique things with them.

I wonder if that old satellite dish is salvageable...

Reply to Mark Whittington

Since I'm still sick at home today, I figured I'd take some time to blog a bit. I don't want to waste too much time getting into a jousting match with Mark, but I figured there were a couple of useful points worth making. [Ed: This turned into a rather long and excessively snarky fisking, so I decided to pare it back a bit to the important points]

I think that by Jon's definition any plan to return to the Moon, whether it was done by NASA, the Chinese, or by Elon Musk would be considered Apollo Part 2. It could be done any number of ways, but the end result is that people will be back on the Moon.

Well, this is rather missing my point. I was using movie sequels and TV sequels as an analogy for what was going on with the ESAS plan. The key point was that although a few of the technical details are slightly different, the plan is going to be executed in a very similar way, doing very similar stuff, and will for very similar reasons not be economically sustainable. NASA could do things substantially different, by choosing a technical architecture and management approach that was more amenable to real development. Just because Star Trek the Next Generation was just a 80s/90s rehash of the old socialist misadventures of the original, doesn't mean that all sci-fi movies have to be the same. It's quite possible for example to do a Firefly or something else entirely.

In other words, it's quite possible to do lunar exploration in vastly different and more effective manners than NASA is choosing to do, and those methods would therefore be very justifiably not considered just an Apollo 2.0.

Now, it could be that Jon is suggesting that any return to the Moon would be "boring" and therefore to be avoided. By that criteria, would it mean that he would support going directly to Mars? It's a differnt place, after all. One can't be sure.

Nope. I don't think NASA should be wasting money on doing and Apollo to Mars either. I think going back to the moon, and this time developing it and settling it, and opening it up for normal non-government employees to visit and live on is a very good goal. I wouldn't be involved in the Moon Society if I thought the moon itself is a waste. What I was merely concerned with was that the method being proposed was not conducive towards the ends that really matter.

Now we get closer to the meat of Jon's argument. A government financed, government operated return to the moon is "socialistic" and therefore, evil. Now, it seems to me that if we define any activity that a government might undertake to be socialistic, then there seems to be only two real forms of organizing a society: socialism and anarchy.

Well, I wouldn't go entirely that far. I'm a Bastiat style minarchist. So long as government isn't stealing from one person to give to another, or using force or coersion, I'm perfectly willing to put up with it. I think that government has some role in society. I just think that involuntarily taking billions from the nation to feed the dreams of a few is morally repugnant. That said, I also realize that I'm in the minority on this, and that NASA isn't going away anytime soon. Since NASA isn't going away, I'd at least like to see it try and operate in the least damaging way possible. "First do no harm" should be the motto of the day, or at least "first try to do as little harm as physically possible, please" would be better than what we have now.

I'd like to see NASA acting more as a customer. I'd like to see them buying off-the shelf systems for off-the shelf problems, instead of constantly trying to operate their own launchers. I'd like to see them using more firm-fixed fee contracts for services, and less cost-plus contracting. Commercial launchers have been available for years now. Better ones are coming on line all the time. There is a glut in this industry. If NASA has to exist, at least it could buy from them instead of trying to create their own redundant operational systems.

If NASA were planning on doing something more along those lines (as it could if it wanted to), instead of just trying to preserve jobs and do everything in-house, I'd be more supportive of it.

Now, I like the idea of space going tankers. I used the concept for Children of Apollo. But, it's new technology, the development of which has certain pit falls that have a greater chance of increasing the cost and expanding the schedule of the program than NASA's idea of going with the tried and true. I think it's a worthy idea to develop in the view of enhancing the infrastructure once people start going to the Moon on a regular basis.

The big problem is that by not developing the technology up front, and designing it in from the start, it will be very difficult to retrofit it in later--basically require substantial redesign of the whole system.

Developing the capability to do on-orbit transfer of cryogens is no more difficult for NASA now than developing rendezvous capabilities was for NASA back in the 60s. If they're going to be blowing a 100 Billion dollars on going back to the moon, they sure as heck ought to at least put $200-500M into trying to make sure it's done right. If NASA insists on doing things exactly the same as Apollo did it, then why the heck do they deserve to get the same amount of money up front? Do you really think that wasting $15B on uncertain technology development projects for the two new launches is really money better spent than trying to demonstrate on-orbit refueling so you don't need new launchers?

[D]oes Jon suggest that using five or nine or whatever number of EELVs is going to be cheaper than using two larger launch vehicles?

Heck. Yes. Does Mark Whittington suggest that with the $15B development costs, and $3B+ per year fixed cost that somehow NASA's launchers will be cheaper? Seriously, for the amount they want to design and field the Stick and the Longfellow, they could buy 60 Delta IVH flights, 150 Atlas V flights, or nearly 540 (!) Falcon IX flights (if those become available). How on earth is NASA going to be cheaper, unless you ignore the $15B development cost and the $3B/year fixed costs?

Not to mention the cost of man rating the launchers, which I'm told is very expensive and very time consumning.

Ah, the man rating red herring. All you need for man-rating above and beyond what is already needed for a commercial launch on a Delta or Atlas is a reliable abort system and a way for detecting when it needs to be initiated. The Stick already requires the former anyway, and the latter really isn't that expensive or difficult. Most of the required sensors are probably already there. Sure, it might require a half dozen engineers a few months to work out the rest of the details, but we're not talking about anything on the same scale as a $15B vehicle development program.

For comparison, DC-X and DC-XA had all the require sensors that would be needed for "man-rating" a EELV (in fact what they had was probably overkill) and DAQ for much much less than $100M in non-recurring engineering costs, and probably less than $5M in per unit recurring costs.

Heck, even Mike Griffin himself knew this argument was a load of crap as is evident from his quote on the Space Review that I quoted here previously:

In other testimony, Griffin has made it clear that he is not opposed to using EELV vehicles effectively unmodified from their current versions to launch crewed vehicles. In a May 2003 hearing by the House Science Committee’s space subcommittee on NASA’s Orbital Space Plane (OSP) program—a short-lived effort to develop a manned spacecraft that was superseded by the CEV—Griffin noted that the term “man rating” dated back to efforts in the 1950s and 1960s to modify ICBMs to carry capsules. “This involved a number of factors such as pogo suppression, structural stiffening, and other details not particularly germane to today’s expendable vehicles. The concept of ‘man rating’ in this sense is, I believe, no longer very relevant.”

The Atlas 5 and Delta 4 EELVs, he noted, have a specified design reliability of 98 percent, in line with experience with the premier expendable vehicles to date. If such a vehicle was used to launch a crewed spacecraft equipped with an escape system of just 90 percent reliability, he noted, the combined system would have a 1-in-500 chance of a fatal accident, “substantially better than for the Shuttle.”

In other words, this whole "we'd have to man-rate them and that would be so expensive" bit is just a rash of bull, especially compared to the expense of developing two new launch vehicles. It's the same sort of jiggering of the requirements to force the results you want that I pointed out in one of my recent posts. If they were willing to use off-the shelf commercial launchers (which are far safer and more reliable than the converted ICBMs that NASA used for Mercury and Gemini), they could get them man-rated for a rather marginal extra cost, probably round-off error compared to the current cost per flight, let alone compared to a $15B new vehicle development.

But since there are no launch vehicles in existence or likely to be in existence in the near future that will meet NASA's requirements, then--sadly--returning to the Moon, at least initally, has to be done the old fashioned way.

No it doesn't have to be done the NASA way. There is a better way, but NASA doesn't want to do it that way because if would force NASA to actually change, to actually show some backbone. NASA doesn't have to give in to all the whining porkbarrel politics. If they came up with a clear vision that was cost effective and promoted commerce, they could get enough supporters in Congress to get it passed. They didn't even try. That's sad.

A Healthy Take on NASA

Just read Dan Schmelzer's take on this whole NASA business:

To my mind, the manned spaceflight portion of NASA is a parasite on the American people. It's now a jobs program for rocketeers. I look at it rather benignly, though. It's a waste of money, but no more than that. NASA doesn't stop anybody from doing what they want to do. No small, innovative companies -- those who will form the backbone of future space activity -- are going broke because of NASA. On the other hand, I discount heavily the potential good that NASA can do for the industry.
...
Because of this view, to my mind the best thing to do is to ignore NASA's manned spaceflight activities. It would be boring to follow it anyway.

Amen. As someone on one of the MSM websites put it "its the yawn of a new era".

It's more fun to follow SpaceX and Bigelow Aerospace, and potentially Scaled Composites and Armadillo Aerospace once their orbital programs come into sharper focus.

It'll be nice once we at MSS actually get something flying so people can start speculating about our future plans too. :-)

LH2, Love It or Hate It?

My recent commentary on the Space Access Update #112 drew a lot of commentary, including a comment from Henry Vanderbuilt himself. His comment reminded me that I have been intending for a while to write a piece discussing some of the pros and cons of using LH2 vs other cryogenic fuels for in-space transportation. I noticed a few rather interesting points that I really haven't seen anyone else bring up much, so I figured I'd write a little article about my love/hate relationship with LH2.

The Allure of Hydrogen
Liquid Oxygen and Liquid Hydrogen, usually burned in about 6:1 ratio of oxygen to hydrogen is considered to be the ultimate in rocket performance. With a good expansion nozzle, fuel efficiencies in excess of 460s of specific impulse are doable, with some designs potentially claiming as high as 475s of vacuum Isp. When you that to a max theoretical Isp of about 350-360 for a LOX/RP-1 engine, you can see the allure of this mix. NASA in particular has been very fond of this mixture. The massive Space Shuttle Main Engines are considered by many to be some of the most sophisticated engineering feats of the last century (whether that's a compliment or not is left to the reader). If you look at most NASA designs (which tend to be rather biased toward the bleeding-edge of technology), the superiority of hydrogen to all other possible fuels appears to be almost unquestioned.

Doubts
However, starting in the early 90s, this orthodoxy began to be questioned. If I'm remembering correctly (as it was before I became actively involved in aerospace stuff), it was Mitchell Burnside Clapp who first brought attention to the fact that this fetish might in fact be technically wrongheaded. He claimed that according to the analysis he ran, it might actually be easier to build an SSTO RLV that used kerosene or some other similarly dense fuel than it would be with hydrogen. Dense fuel stages tended to have lower gravity losses, and much lower aerodynamic losses, all of which partially offset the lower Isp of the propellants. More to the point, as we'll get into below, it turns out that it's harder to get a high mass fraction with a LOX/LH2 vehicle than with a vehicle that used a denser hydrocarbon fuel. [Ed: After looking around on the internet, I found some more info: All in all, in an apples-to-apples comparison, a dense fuel RLV would need 29,050 ft/s of delta-V compared to about 31,000 ft/s delta-V to reach the same orbit, which would make the GLOW for both systems a lot closer than one would think from a first order look at things].

Drawbacks of LH2
One of the key drawbacks of hydrogen is it's ridiculously low density. Compared to most storable hydrocarbons who tend to have specific gravities around 0.7-0.8, hydrogen's specific gravity is a measly 0.07! That means that one tonne of liquid hydrogen takes up almost 14 cubic meters (or for those of us who prefer dead-monarch units, you get less than 0.5lb of the stuff per gallon). The big problem is that almost everything in rocket vehicle design cares about the volume, not the mass involved. Tanks mass scales almost linearly with volume. Pumps pump volume, not mass. Feedlines have to be sized for the volumetric flow rate of the fluid. As Henry brings up in his comment:

By my hasty back-of-the-envelope numbers, the ET LOX tank masses less than 1% of the LOX it carries, the ET LH2 tank masses greater than 12% of its LH2 content.

Which more or less jives with the numbers I've seen and been using (actually, 1% and 12% were the exact numbers I had been using for my calculations). Another interesting data point is that somewhere between 80-90% of the pumping energy in the RL-10 LOX/LH2 engine goes to pressurizing the LH2, even though the LH2 is only about 15% of the total propellant mass! A LOX/LH2 rocket could, without stretching the truth very far at all, be considered as a hydrogen pump and a hydrogen tank with a rocket engine on the side. Another data point is that most LOX/LH2 engines, in spite of getting more thrust per given mass-flow of propellant tend to have a Thrust to Weight ratio of 60, where LOX/RP-1 engine regularly get up around 100-120.

There's another annoying problem with LH2--the stuff is so darn cold. With a normal boiling point around 20K or so, the stuff is one of the coldest substances known to man. Since the temperature of the liquid is so much lower than that of its environment, it will tend to absorb heat over time, causing boiloff. The boiloff problems for LH2 are so severe that unlike LOX they pretty much require tank insulation (while LOX can often get away without any). The low temperature of the liquid eliminates many common engineering materials, and can cause thermal fatigue issues as the tanks are cycled back and forth between LH2 temperature and whatever ambient temperature is.

Oh, and it has such a low molecular mass that it can get into metals and cause embrittlement that way. Oh, and it makes sealing tougher. Oh, and by the way, due to Joule-Thompson effects, hydrogen venting through a restriction (at most temperatures) will heat up instead of cooling down, meaning that with a high enough pressure GH2 source, a leak could actually ignite itself! Oh, and it burns with a nearly invisible flame that is several thousand K...

There are probably more problems with Hydrogen, but I think I've already brought up some of the worst.

So What are the Alternatives?
Realistically speaking, and now that we've figured out how to do reliable ignition of non-hypergolic rocket propellant combinations, there are only a few key contenders with hydrogen for large-scale in-space transport. Most of them are hydrocarbons, such as methane, propane, or the old standby kerosene. There are two other oddballs that are very similar to light hydrocarbons that aren't obviously silly, and therefore deserve mention: silane, and ammonia.

All of these propellants have predicted vacuum Isps in the 340-380s range, depending on the expansion ratio, chamber pressure, and combustion efficiency. All of them have bulk propellant densities much better than LOX/LH2. Ranging from a bulk density of about 1.03 for LOK/RP-1, down to 0.83 or so for LOX/Methane, as compared to 0.33 or so for LOX/LH2. That means you can get somewhere near 2.5-3x as much propellant into the same volume when compared to LH2. This is important for two things: drylaunch, and tank mass.

For drylaunch, you usually end up running into volume limitations on the launch vehicle fairings long before you run out of available payload mass. For example, the Atlas V, 4.5m PLF has about 180 cubic meters of space in its cylindrical section. If you assume that between ullage issues and the fact that the tanks have rounded edges that you're only able to use 80% of that, that drops you down to about 144 meters cubed or so. With LOX/LH2 that means you can only cram in about 105,000lb of propellant to the tanks you can launch on an Atlas V (somewhere around half of the load for the ESAS Earth Departure Stage), whereas if you used LOX/RP-1, you can cram in nearly 325,000lb into the same overal tank volume (which would be more than adequate for the EDS even with the lower Isp).

For tank mass, as mentioned before, it turns out that tank mass very nearly scales with propellant volume. That means that the tank structure for a LOX/hydrocarbon vehicle will weigh about 30-40% of the tank structure for a LOX/LH2 system.

Another important thing is boiloff. Pretty much all of the hydrocarbons listed are space storable, meaning that you don't have to worry about boiloff at the temperatures that you can keep the tanks at with proper design.

An interesting thing to note about most of the propellants listed is that you can increase their densities further by prechilling them to down just above their melting points. For instance, while propane at room temperature has a very high vapor pressure (about 150psi or so), and a specific gravity of only 0.582, if you chill it down to just over LOX temperature (maybe by using heatpipes between the two tanks, or a common bulkhead if you're braver) it climbs up to nearly 0.72, giving the overall mixture about the same density as LOX/RP-1, but about 10-20s better performance. [Ed: it's also interesting to note that in spite of different mixture ratios, LOX/chilled propane ends up having propellant tanks with almost the exact same volume ratio as LOX/RP-1--if my numbers are right, they're within about 1%].

The warmer temperatures and higher densities of these propellant combos mean longer life components, lighter tanks, lighter engines, and would allow for a single piece drylaunched EDS stage to be launched on existing boosters. Not to mention cheaper to design, easier to handle, etc.

Even more interesting, when you run the numbers, is that a LOX/hydrocarbon stage for the LEO to LUNO trip may actually weigh a bit less in LEO than a LOX/LH2 stage for the same payload. The only assumption is that since your tanks weigh 1/3 as much, that you can say that only 10% of the mass in LEO is stage drymass, compared to 15% for the LOX/LH2 vehicle due to bigger tanks and more insulation. Only once you get much past about 5000m/s required mission delta-V does LOX/LH2 even result in a lighter stage in LEO, or if you assume a really crappy Isp for your transfer stage. [Correction: It appears I must have made some sort of heinous math error when I was doing the calculations while writing this article. Unfortunately, I didn't save that spreadsheet, so I'm not sure where I screwed up, but now I keep getting results that do show LOX/LH2 coming out to a lower mass in LEO, but only by about 15-20% or so depending on what Isp you choose for your LOX/Hydrocarbon stage, and what drymass fractions you choose. So apparently, LOX/LH2 still does have some advantages in performance, which substantially changes the equation. Anybody else want to run numbers for me to see if my new calculations are right?]

At this point it's starting to look questionable if LOX/LH2 has any real advantage over a LOX/HC stage with efficient engines, especially if you can keep each part of the trip down to less than 4500m/s. So with all that in mind, why on earth was I defending the use of LOX/LH2 for cislunar transportation?

LH2: What's there to Love?
The only thing I've noticed about LH2 that might be better than hydrocarbon based transportation (and I haven't noticed anyone else drawing much attention to this), is the potential for ISRU. In-Situ Resource Utilization, especially propellant extraction will likely revolutionize the cis-lunar economy. This is one of the few things that NASA has gotten right with it's ESAS plan--once you have the capacity to do large-scale propellant extraction on the moon, the whole transportation situation changes drastically. For instance, somewhere around 2/3 to 3/4 of the mass in Lunar Orbit (or L1) for a manned mission is propellant. Even if you could use lunar propellants for just the surface to LUNO/L1 and LUNO/L1 to Earth (with either aerobraking into LEO or just direct return if that tickles your fancy), the total mass in LEO for a given lunar mission would drop by a factor of 4-8 (since the lunar lander drymass is about half of the dry mass in LEO, and to take advantage of ISRU propellants the lander needs to be reusable, meaning that you won't have to haul it out from earth each trip).

There's one big problem. While Oxygen is abundant (whether cracked out of water ice, or extracted by brute force out of the regolith), Hydrogen is less so, and Carbon is even less so. Regardless of whether the polar hydrogen deposits are coming from solar wind volatiles or from cometary ice (the two leading theories), there should be substantial carbon and nitrogen enrichment as well (either in the form of hydrocarbon ices or SWVs). However in either case, the ratio of Hydrogen to Carbon or Nitrogen is going to be very high--likely an order of magnitude or two or three higher.

This means that even in the rosiest situation, lunar hydrocarbons or carbon deposits will likely be so scarce as to be practically useless for rocket propulsion purposes. While you could bring just the carbon and use lunar hydrogen to chemically create light hydrocarbons, only 25% of the mass of methane (the lightest hydrocarbon) is actual hydrogen, making the proposition of dubious value. Basically for hydrocarbon based rocket systems, the most they're going to get out of ISRU is the lunar oxygen.

And that is the second problem. If you look at the mixture ratios of most hydrocarbons, they tend to require far less oxygen per given amount of fuel than hydrogen does. For LOX/LH2, the ratio is usually 6:1, whereas for LOX/Methane it is only 3.4:1, 3.1:1 for LOX/propane, and only 2.7:1 for LOX/RP-1. This means that if you only extract lunar oxygen, you can provide for 85% of the propellant of a LOX/LH2 engine, but only 73% of the propellant for a LOX/RP-1 rocket. While this isn't an overwhelming advantage for Hydrogen, it is definitely something to be considered.

Ramifications?
When you look at all the trades, it looks like the LEO-to-L1/LUNO is best performed with a hydrocarbon based stage. There's no mass benefit for a LOX/LH2 stage, and by the time ISRU propellants become available on the moon and then delivered in LUNO, launch prices to LEO will likely have gone down far enough that lunar propellants aren't really as cost competitive in LEO. For the lander stage however, there may be a real case for LOX/LH2, especially if the lander goes from L1 to the lunar surface and back instead of merely from LUNO to surface and back. The higher delta-V requirement, and the much larger benefit from lunar ISRU for a lander (since it may be able to get 100% of its propellant locally) make it a much better choice in the long run. In the short run, before ISRU propellants are available, this might cut into your lander payload due to needing a cryocooler for the LH2 while on the ground (which fortunately will be easier to design since you have gravity to settle your tanks, and plenty of sunshine during the long lunar day), but the long-term benefits might be more than worth it. Ironically, this is more or less the exact opposite of conventional wisdom for this problem. [Ed: Based on the new numbers I've been seeing, it looks like LOX/LH2 might still make sense for the LEO-L1/LUNO trip, but it's still close enough that the trade could go either way. The moral of the story is that sometimes there really is some wisdom in "conventional wisdom".]

Thoughts, comments, flames?

Apollo 2.0?

Since I'm sick at home today, I figured I'd finally get around to taking Mark to task for some of the stuff he said over at Curmudgeon's Corner. Mark decided to take Henry Vanderbuilt and Rand Simberg to task for their response to the announced plan:

Both gentlemen, incorrectly, think that the VSE is "Apollo 2.0", the ultimate calumny one can offer to a proposed space project, at least in certain quarters. That's wrong because the plan does not so much retrace Apollo's steps as it picks up where it leaves off.

I've heard a lot of people justify this plan by using similar arguments. "We're not just doing what we did last time! This time we'll put FOUR government employees down on the moon, maybe even for a week or two at a time." Yawn. And how does this prove that calling it Apollo 2.0 is incorrect? When you see a Part Two to a movie, do you assume that it is an exact repeat of the earlier movie? No, what Henry and Rand were saying is that this ESAS plan is like an Apollo:The Next Generation. Sleeker ship, cooler destinations, neater costumes, but more or less the same old socialist misadventures of a starship misnamed "Enterprise". It's like the old Back to the Future movies. By the time number three rolled out, you already knew what some of the key plot elements were going to be, even if the sets were different, the stunts and visuals a bit higher quality, and several characters were entirely new.

That's one of the problems with this plan. Sure, the "Longfellow" isn't exactly the Saturn V, and the Stick isn't exactly the Saturn IB. Sure, the LSAM isn't exactly a LEM either, and their capabilities are a little bit better than the old Apollo system. They have newer electronics, and might even reuse part of the capsule. However it's once again the bumbling socialist misadventures of our dear Space Agency. With steely eyed rocket men (and maybe some women too this time) boldly going where...you get the idea. I mean, do these guys really have that much desparation to have the program go the way of Apollo? Do they really want to put some bootprints on the moon for a couple of months only to have the whole thing eventually killed off by Congress for costing so much?

Anyhow, moving along:

Vanderbilt goes on with an argument that NASA ought to assemble its moon ship from much smaller pieces using existing (or proposed to soon exist) launchers. There is certainly some validity for that approach. But Vanderbilt airily dismisses the counter argument that with more launches required per mission, the greater the risk that a single launch failure will delay or even scrub the mission entirely.

How exactly will a single launch failure scrub the mission entirely? Almost all of the additional launches for such a technique would be propellant launches. We're talking at most a slight delay as you have another propellant delivery launched. There are about a half dozen or more potential launch vehicles out there, so it's not like you can't have multiple suppliers. The whole fact that your program isn't beholden to a single launch vehicle makes it more robust. If you have a launch failure with the Stick or the Longfellow (man, can these guys come up with less lampoonable names? I mean seriously, this sounds like something I would see as a header for some perverted spam message--possibly with at least one word slightly mispelled or with some other character in place of a letter), your entire program gets stood down for a year or two or three while they figure out what went wrong.

He also, I think incorrectly, suggests that the return to the Moon infrastructure will shoulder the same personel costs as running the shuttle fleet. That runs contrary to what NASA itself has been saying and the common sense fact that a great deal of the personel costs of running the shuttle consists of turning around the orbiters, which of course would go away when the shuttle fleet is retired.

Except for the fact that NASA's also touting this plan as one to "keep the team together". Mark himself uses the argument elsewhere that this plan is more "politically" feasible because it doesn't eliminate a lot of jobs at KSC. So which is it? Does it eliminate enough jobs to actually free up enough money to actually develop the hardware to go back to the moon, or does it keep enough jobs intact so that it is easier to get political approvals? You can't have it both ways.

Then even more silliness:

Vanderbilt makes a number of other questionable assumptions, in my opinion. For instance, NASA's building a launch system in house rather than waiting for commercial launchers to come on line which may or may not be available is the wrong approach. Now, if the Falcon series and others now being contemplated were actually flying, it would be another matter. I can understand NASA's decision to go with the tried and true (i.e. a couple of rockets with existing technology) rather than count on the commercial space sector which may or may not deliver. Mind, I might have made a different decision (at the very least keeping some options open.) But that's not a deal breaker for me.

I wonder how well Mr Whittington has been paying attention to the industry if he's completely unaware of the existance of Atlas V, Delta IV, Sea Launch, Proton, Soyuz, Ariane V, and other existing launchers. NASA doesn't need to "wait for commercial launchers to come on line that may or may not be available". Just by designing the individual pieces to be launchable on current vehicles would at least keep the door open for future cheaper vehicles. Especially if NASA keeps a common interface design so that they can switch between launch providers (or possibly use multiple different providers) as prices change. Once again, we see an interesting world where the Stick and the paper Longfellow are treated as real, existing, proven vehicles, while other vehicles like the Atlas V and Delta IV that have actually flown to space are denegrated. Sure, I can understand not designing the whole thing to work only with a Falcon V or Falcon IX, in case they don't get developed. But ignoring existing current boosters and developing what are in effect brand new, unproven vehicles inhouse is just wasteful. For the $15B NASA wants to develop their own rockets, they could buy 60-150 launches on existing boosters that would be just as safe and cheaper per launch than the vehicles NASA wants to fly. Not only that, but by developing in-space vehicles that are capable of being assembled from smaller pieces and refueled on-orbit NASA would actually allow themselves to take advantage of advances in lower cost orbital flight, thereby allowing them to do more exploration. But it appears that keeping ATK fat and happy, and keeping KSC fully staffed is more important than actual exploration. I can see why politicians might be happy with that, but why are pundits like Mark standing up for this Don Young's Way to the moon?

Griffin

I realize that over the past several months, ever since I started this blog, I've been pretty darn hard on Mike Griffin for the approach he's been taking with NASA. I usually don't like ripping on people that much. Griffin is a smart, talented guy. His heart is in the right place even if his actions aren't. I guess the reason why I'm ripping so hard on his decisions is because I expect more out of him. Here's a guy who at least knows something about the commercial world. Here's a smart, creative person. here's a guy who really feels that it's important to help promote commercial space--because unlike some of the pundits and fanboys out there, he realizes that without commerce there will be no real space development. Griffin is probably the NASA administrator most likely to be able to help promote the commercial development of space.

As I said, I think the reason I'm so hard on him, is because I expect more out of him. The Innovative Programs idea that was pitched at the Return to the Moon Conference was rather good. Of all the NASA programs I've seen in years, if funded and not botched, this one has the most potential of really helping a commercial cislunar economy become a reality instead of just a dream. Unfortunately instead of focusing on it, and giving it the emphasis he ought to, he's almost acting as though he's embarassed. Like as though he realizes its a good idea, but is afraid of what the Congresscritters will think. Instead he's been playing up reuse of a little shuttle hardware and building Apollo 2.0, expecting that we'd be impressed. Unfortunately, after having spent so long since Apollo with no access to the moon, some of the pundits really are impressed. I'm still not.

I tend to be just about as self-critical in real life as I am critical of others. One of my gifts or curses is the ability to see potential. I can often see what could be done if people acted competently. I see what I could do if I didn't waste so much time on the internet. I see what NASA could do if it stopped trying to play pork politics. I see what the US could do as a nation if it weren't content to merely be the best in the world. With that in mind, I'm not very happy with excuses. Merely being the freest nation in the world doesn't mean much compared to how free we can and ought to be. When I hear pundits justifying our bumbling in Iraq with crap like "things are much better now than they were under Saddam", I get disgusted. They darn well should be better than they were under a tyrant. I'm supposed to be impressed that our nation is at least not as bad as a thug like that?

Instead of comparing ourselves against others to excuse ourselves, we ought to compare ourselves against what we can and ought to become. Instead of saying "well this architecture is better than what we used to have", we really ought to be thinking more about what the architecture ought to be. At least if we had the cajones to stand up to porkers, pundits, and ATK lobbyists.

Anyhow, as I said, I do think that Griffin's heart is in the right place. Maybe he really will fight tooth-and-nail to make sure that Innovative Programs gets the funding it needs, and is run wisely. Maybe if some of those projects turn out as well as is possible, he (or whoever replaces him down the road) might actually be willing to change the architecture to something more sustainable, affordable, and commercial. We'll see. There is still hope.

Lies, Darn Lies, and Trade Studies

Before I get into pointing out the flaws I saw on Mark Whittington's blog the other day, I need to lay a little groundwork. A few weeks ago, I got an email from one of the coauthors of an interesting new book, The Rocket Company. Some of the chapters from the book were initially released on Hobbyspace.com about a year ago as a serial. I read some of them at the time, and it definitely had some interesting ideas. Anyhow, one of the coauthors wrote me asking if I'd like to review a copy of the finished book. Twisting my own arm, I agreed, and have been reading it with Tiffany ever since (whenever we have time we'll sneak a chapter in). Tiffany is taking it like a trooper (her nerdiness only goes so far), but I've been rather enjoying it. I'll do a further review once we actually get done.

Anyhow, one of the profound pieces in the book had to do with the title of this post. Basically, as one of the characters was explaining about the history of aerospace projects, one of the biggest hurdles most engineering companies (and government agencies) faced was figuring out how to keep Congress or NASA or other government agencies from constantly second guessing them in all their decisions. In order to deal with this challenge a set of psuedoscientific tools was crafted to give the veneer of absolute certainty to what is in reality a rather uncertain field--product design. One of those tools was the trade study (emphasis and spelling errors mine):

It worked like this: the systems engineers, working with the design engineers, came up with an approach that, based on their experience and investigations, they thought was most likely to work. They then engaged in an imaginative game of listing every possible design approach they could think of, no matter how far-fetched. The preferred approach and all of the alternatives were then analyzed according to a complicated equation involving many parametric constants and weighting factors for the requirements. This analysis generated so-called figures of merit for each option. The constants and the equation were then tinkered with until the chosen design approach came out as clearly superior.

When the design concept was presented to the top brass or congressional committees, it was presented as the best solution out of all possible solutions, arrived at by a purely scientific process. This made it essentially impossible for the design decision to be questioned. If there was any questioning of the design, the program managers would launch into interminable explanations and arguments concerning all of the many different design concepts, the figures of merit, and the trade table, until the questioner was exhasuted. Thus any attempt to interfere with the decision that the engineers had already made could be blocked.

Having worked in engineering, I can vouch for the fact that at some level this is pretty much true for all trade studies. Even when you haven't completely made up your mind in advance, when your favorite approach(es) don't do as well, it must be because you didn't assign the right weighting factors, or didn't take the right factors into consideration. After all, you're a really smart person, and your initial hunch has got to be right for some reason!

As an example, about two-and-a-half years ago or so, I went to watch a static test firing of a 2000lbf Nitrous/Rubber hybrid that BYU and USU had been working on. Due to igniter problems, they had several misfires, and it ended up taking all day to get two or three good short firings (which were tres cool when they actually did go however). Having just read about some of John Carmack's work with catalysts, and how flowing hydrogen over a catalyst in the presence of air caused catalytic ignition, I got the idea that maybe a catalyst igniter would solve all their problems. I started a project with the BYU Space Development Club trying to investigate that (finding along the way that there had actually been significant previous work by other smart people like myself--geniuses, geniuses I tell you!). When I started doing some work with MSS, I was still pushing this idea. It seemed so simple. Just open GOX, open GH2, and hot flamey stuff must surely come out the thruster thingo!

After getting more involved with the project, and finding some cleverly hidden challenges of this sort of gas-gas igniter, I decided it was time to document my work, so the others could all be on the same page as I was. As part of the documentation, I decided to put in a little trade study. You know, to show why this was such a good idea that we should keep throwing money at the problem. After all, we were getting pretty close. So, I thought up a couple different styles of igniters: GOX/IPA spark, GOX/IPA resonance, TEA/TAB, a few others far-out ones to make my idea look better, and I took all those and crammed them into a table. I then tried to figure out what the key figures of merit should be (particularly making sure I chose ones that catalyst ignition did well, as well as a few that it didn't do quite as well in just to be honest), and assigned what I figured were reasonable scores for each design in each category. I then figured out what reasonable weighting factors would be and.....stupid trade table! You're not supposed to say that resonance and spark ignition are better than catalyst work! I'm smart. I know what's the best way to do things! I'll show you! So, I start tweaking with the numbers. "You know, resonance ignition is probably really, really tough to develop, so I'll drop its 'development cost score a bit'"...."Hrm...the simplicity of not having a spark isn't enough to counteract the fact that spark igniters are proven....better add an 'low EMI category'"....

Anyhow, after several minutes of rationalization, I finally realized I was being a schmuck. The ammount of torture I was having to put the data to (because after all, while data never lies, if you torture it, it will confess) in order to justify my idea was just absurd. That evening I suggested to MSS that we shelve the catalyst igniter project, and ramp up the spark igniter project (which Pierce had fortunately been stubborn enough to insist on starting in parallel). The result is that we now have a pretty darn reliable spark igniter. The resonance igniter came out a little ahead in most categories, so maybe I'll try dabbling with that in the future, but I learned a valuable lesson. Trade studies can be dangerous tools of rationalization and self-justification if you aren't careful.

[Warning, this post is close captioned for the snark impaired. Excessive sarcasm and lampoonage coming up. Stop reading now if you're drinking soda through a straw--that could be rather messy!]

And that's one of the big issues I see with the whole ESAS report. Here we get blinded by the science. The fact that this "scientific" trade study was carried out by tons of really smart guys at NASA over the course of months and months, that painstakingly analyzed all the possible booster combinations in every way possible means that what they came up with must be the absolutely 100% super best uber-Rocket design that is physically possible! Yay! Ve can now shut off our brains and vatch as our nation builds very very big rockets und our brave astronauts return to the moon! After all, if these NASA super geniuses did a trade study (pay no attention to the fact that almost none of those engineers have actually designed anything that's been built and succesfully flown to space in oh, say 30 years, unlike the engineers at Boeing and Lockmart and several of the other contractors who've actually at least designed, built, and flown stuff within the past 10).....(oh, and also pay no attention to the fact that in spite of being the obviously best possible approach that is humanly possible for thus sayeth the trade study, Amen! The trade studies done by smart people at Boeing, Lockheed, t/Space, and other groups came up with substantially different approaches like--*gasp* dry launch, reusable lunar landers, etc. Those engineers must not be as wise as them NASA engineers. After all, what have they done over the past several years other than design, build, and fly space hardware! Heck, they haven't even published any major acedemic papers on hypersonic scramjets or SSTO VTHL RLVs! The noive, the noive of those people)

[We now return you to your regularly scheduled, desnarkified blogging. In all seriousness.]

Seriously though, before anyone accuses me of conspiracy theories (Mark?), I'm just pointing out a real phenomenon common in engineering design projects. I've seen it even when the engineers had no malicious intent whatsoever, no larceny, no conspiracy. Just ego. And come on, if you don't realize that engineers are some of the most egotistical people on the planet, you must not know too many.

Even more seriously though, it is also important to realize that even if your engineers are perfectly self-honest, perfectly unbiased, and perfectly humble, trade studies are still a Garbage-in-garbage-out process. If you start with the wrong requirements, it will lead you to the wrong approaches. If one of your key goals is how best to "keep the team together", and how best to "use current capabilities", you will end up picking stuff that looks pretty darned similar to what you've been doing already. James Womack in his excellent intro to Lean Manufacturing called "Lean Thinking" made a very important point. Value lies in meeting people's needs at a price they want and where and when they want it. Value doesn't lie in maximizing the utilization of existing resources. A customer doesn't give a darn about the fact that you built your new product keeping most of your old team together and facilities used if that product doesn't meet their needs, costs too much, or is delivered too-late. Getting the maximum utility out of previously sunk costs is not the way to deliver real value.

Anyhow, that's enough of a rant for this morning. I think I've said enough to lay the groundwork for the points I want to make about Mark's posts tomorrow.

Various Thoughts about the ESAS report

I stumbled across a witty poem today at Crooked Timber that more or less reflects my mood about the ESAS report:

If something can get worse it will
Is a phrase I’ve often sardonically used
But here’s some grist for Mr Murphy’s mill
I used to be disgusted
Now I’m just amused

I've been thinking about what to say and how to say it about this report for the past two days. I was putting it off hoping to come up with something very clever and insightful (and also waiting for more time to do such a writeup), but I've got some time on my hands now as I wait for my computer to spit out pretty FEA pictures telling me how screwed up my tank sump design is, so I may as well make the most of it.

Before I am too tempted to point out all the glaring fallacies that Mark's been churning out over at Curmudgeon's Corner, I want to start by commenting on an analysis that I mostly agree with. Henry Vanderbuilt over at the Space Access Society is one of my favorite space commentators. The fact that his views often are fairly similar to mine, and that he's seen as being a rather smart person in the alt.space crowd thus making me look smart too has absolutely nothing to do with it. Anyhow, in previous Space Access Updates, Henry had been taking a cautiously optimistic tone toward the whole VSE. There was originally hope for it to actually be done in a non-stupid way, and there was even hope for it helping catalyze the development of a true and thriving cis-lunar economy. It was a long-shot, but sometimes long-shots are worth it. As part of this gamble, the SAS had joined a coalition supporting funding increases for NASA for carrying out the VSE. However, as NASA's plan has been rolled out over the past several months, Henry has changed his mind. As he put it:

To be blunt, we have big problems with this plan. It's the same basic approach as Apollo, disposable (mostly) spacecraft, on big NASA-proprietary boosters, flown a few times a year, by a standing army of NASA and contractor employees. This is Apollo 2.0, with somewhat more delivered exploration, at moderately higher cost, on a significantly slower schedule.

We have to ask, after forty years of stunning technological progress, shouldn't we be able to improve on Apollo's cost-to-exploration ratio a bit more than this? US taxpayers will get little more Buck Rogers for their inflation-adjusted buck than they did in the 1960's

Henry then goes on to hit on many of the same points I've been hitting on over the past few months. One of his good points is the danger in putting too much faith in commercial ISS resupply contracts and the other "Innovative Programs" that Griffin has been touting in order to gain the support of the alt.space crowd (emphasis mine):

[T[here are potentially useful bits in ESAS, not least of them the plan's flirtation with Station resupply being put out to commercial bid. Mind, with all due respect to various of our colleagues who pin large hopes on this, we have to say we see a strong liklihood that it, along with all sorts of other useful NASA non-manned-space functions (what does that first "A" stand for again?) will end up defunded to pay for ESAS's big upfront vehicle developments.

We also see considerable danger that commercial Station resupply will turn into (despite the best will in the world by those at HQ conceiving it) a tarbaby (a glue-trap for you kids never taught the old folk tales) as the people actually administering Station set impossible standards for would-be vendors, until they go broke and go away. (Last we heard, not even Shuttle and Soyuz meet the official "prox ops" Station docking rules; both had to be grandfathered in.) Our hypothetical turf-jealous Station managers could then go to Congress saying "see, those damned
amateurs couldn't hack it, now fund us pros to do the job!"

The only part of ESAS that is even worth funding is the Innovative Programs office, but precisely because it is seen as being "off the critical path", it is the most vulnerable to cost overruns and budget cuts. As it is, it's looking as though Congress is trying to zero-out Centennial Challenges and the ISS commercial contracts already. Without the Innovative Programs work, there really isn't anything in the ESAS architecture worth supporting, as the rest of it is pretty much welfare for space nerds.

Henry's suggestions were more or less what I've been saying here, so I agree with them 100%. Quoting Henry (emphasis again mine):

- NASA should let go of controlling their own space transportation from start to finish. They should make an exploration plan based on a variety of existing commercially available boosters, then put the entire ground-to-orbit leg of their new deep space missions out to bid.

- NASA should lay off and/or BRAC large parts of their Shuttle/Station establishment as Shuttle is shut down and Station completed, rather than again compulsively trying to "keep the team together". It's been a long time since this team had a winning season, the payroll is crippling, and the game has changed. Rebuild from the ground up.

- NASA should let go of numerous arbitrary and/or dated "this is best" prejudices the organization has accumulated over the years. Old NASA (as someone once said of a notoriously inbred european royal house) forgets nothing, and it learns nothing.

Henry then went a little into what he saw as being the ramifications of a commercially launched Earth Orbit Rendezvous-type system. Here's where I have to pick on quick nit. Henry mentions that due to the fact that hydrogen is "hard to store for long", if you insist on using only the fastest transfer orbits, the launch windows are short, and that can be a big problem. This is a more intelligent (but still slightly flawed, IMO) variant on a commonly heard complaint that if you go with on-orbit assembly or refueling, that if a single launch fails, you lose your entire mission. If you look at the real numbers, the problem just isn't as big as most people assume. Borrowing from Bruce Dunn's analysis, a properly insulated tank in the size range we're looking at will probably have less than 1lb/hr of LH2 boiloff, and about 3/4 that of LOX boiloff. That's not a lot. Over a full month we're talking about less than 4% of the LH2 boiling off, and less than 0.5% of the LOX. That ends up coming out to only about 1% of the total propellants after a full month of delay. Even if you assume the worst case numbers they were showing (that required less insulation), you're still only talking about something like 4% of the total propellant boiling off. And if you use a heat exchanger like Bruce suggested to use some of the LH2 boiloff to cool the LOX tanks, you can get those numbers back down to 2% or so of the total propellant volume over a full month worth of delays. Extra tankage isn't free, but most propellant tanks weigh about 1lb for every 10-100lbs of propellant (depending on the density of the propellant).

What that all means is that even if you insist on using LH2 (which isn't neccessarily as stupid of an idea as Henry makes it seem to be--I'll probably write a future blog entry about the pros and cons of LH2 for cislunar flight), the boiloff issue just isn't that rough. It isn't a real argument for not doing on-orbit refueling. A trivial design expense up-front can more than handle making sure the tanks have sufficient margin. Doing slower multi-burn trajectories to open up more launch windows, or going with a more space storable fuel like propane or methane make the problem even smaller, but even if you insist on the fast flights, and the LH2....you get the point.

Anyhow, that's enough for now. Henry's article is a good take on the whole situation. What a bloody waste.

XP Cup Expo

I hate bumping one of Ken's posts off the top of the blog, especially right after he posted it, but I figured I needed to mention this.

Basically, it looks like I won't be at the XP Cup Expo after all. This is unfortunate because I had been hoping to meet some of you in person, and I might have had the chance to meet Elon Musk and a few other major players in this industry, and it would have been cool showing off some of the stuff we've been working on. But alas.

I had noticed a week or two ago that the main day for the expo was going to be a Sunday. This poses a bit of dillema for me personally, because I've always believed in the importance of keeping the Sabbath day holy. I was thinking that maybe I could come down, man the MSS booth on Thursday through Saturday, then duck out on Sunday. But that would be kinda weird and pointless--driving halfway across the nation just to not go to the thing you were going to. My coworkers Pierce and Ian couldn't make it at all due to the few college classes they're taking at the moment (so they can graduate next summer), and we wanted one of the engineering team to be there in case people had technical questions about the projects we were working on. Anyhow, I was kinda concerned about what on earth I was going to do, so I finally brought it up with Dave and Michael (since Michael was in town this week to work with Dave on some financial stuff for the company--and also to see our remote test site).

That's when Dave mentioned that the only day that our stand would really need manning was going to be Sunday. He knew my standards as well as I do, so we decided that it didn't make sense for me to come this time. It's nice having a boss who helps you stick to your guns. Anyhow, he'll be there, and he can probably answer most of the technical questions better than I could anyway (and he's less likely to blab on and on about stuff that we should be talking about...) He's been the one doing the big picture design, trajectory analysis, aerodynamics and reentry analysis stuff for XA-1, and can also discuss most of the rest of the subsystems, since he's managing the whole project.

Hopefully someone can take some good videos of the flights for those of us who won't be there this time. Also, hopefully next year they'll have more of the events on other days so I can participate. As for those of you who were hoping to meet me there, hopefully we can find another opportunity to meet in person. I might not be able to make it to Space Frontiers conference, but I will most definitely be at the Space Access conference next spring.

I guess that's all I have to say about that.

On Space Priorities: NASA and its funders

Howdy all, Ken here.

I'm just sitting here on a quiet Sunday morning thinking about all of the recent and upcoming activities that the National Space Society of North Texas (NSS-NT) has undertaken.

Our chapter activities are geared towards talking with people, not just to people. We don't address auditoriums full of students, but rather talk with families that visit museums and other public events. Our displays are very interactive and hands on, and it gives us a lot of opportunity to discover what it is that the "average joe" thinks about space, and what some of their priorities are.

NASA's priorities, in a nutshell, are to realize the goal of the VSE by going to Mars, and to continue to study the farthest reaches of our Universe.

The priorities of the public? Asteroids. It is the one topic that consistently everyone has an interest in. People have heard about 2004 MN4, and know something about some pass in 2029, they've seen Deep Impact or Armageddon, it's one of the aspects of space that has reached a common level of awareness, and it's a topic that people think is important.

The ISS is kind of "eh, whatever". Its utility hasn't been sold to the public very well. The idea of using it as a staging point to points beyond is an idea that does seem to make sense to people, but strictly as a science lab or "humans as guinea pigs" place isn't as compelling for them, and it comes across as an expensive endeavor.

I'm an unabashed Moon guy, and command a significant amount of Moon-related materials. I don't exclude Mars, but I don't emphasize it either. Typically, I don't get too many questions about Mars (nowhere near as many as about asteroids). My personal belief is that it is too far below the radar in the quotidien lives of most folks, and so by pursuing it as a goal and realization of a 70+ year-old Von Braunian dream NASA is heading in a direction that increasingly removes it from the priorities of the public.

There is a lot of interest in space in general, but it's hard for people to put their fingers on what it is specifically that interests them. For the parents it's easy, they'd like for there to be some sort of job possibility in space should their child choose to work there, but doing what they have no idea. They don't want to be wiped out by a nasty asteroid impact. (As an aside, the TV movie "Asteroid" was set here in Dallas. Scenes of destruction include the Reunion Tower globe, a DART train, and downtown being turned into a crater a mile wide). One notable demographic trend that I'm seeing is that first generation hispanic American families are strongly encouraging their children to pursue engineering and other technical fields in order to step up from the trades to the professions.

Using materials from the Moon for space activities is sensible. Being able to fix our space assets is sensible. Getting energy from space and tapping a 4.5Bn year power supply is sensible. Using the ISS as a staging point and space base of operations is sensible. Voyaging to the asteroids and negating their menace is sensible. Studying the Sun and watching it for flares is sensible. Creating a permanent space-faring capability is sensible.

How about a job building Solar Power Sats at GEO?
How about a job building Solar Power Towers at the Lunar poles?
How about a job fixing robots at a Moonbase?
How about a job fixing satellites in GEO?
How about a job piloting the ISS-EML-1-ISS route?
How about a job tending far side radio scopes?
How about a job growing plants in a Lunar greenhouse module?
How about a job prospecting Near-Earth asteroids?
How about a job upgrading L-point probes?
How about a job tending the Moonbase ECLSS? (i.e. cleaning the toilets)
How about a job in space?

Perhaps NASA needs to slow down a bit and actually try to see what it is that the nation wants it to do. After all, NASA administers space for the nation. Perhaps by pursuing goals and agendas that more closely align with those folks who pay the bills, NASA can better assure itself of the kind of funding levels it really needs. And if it does it right, NASA is going to be directly paying for very little of the above.

This may well mean that NASA's realization of the dreams of Von Braun and other "stale, pale males" (as Dan Goldin might put it, ;-) might have to wait a while. It's not like Mars is going anywhere. But in creating a permanent and "sustainable" (as the VSE puts it) space infrastructure, NASA can help carry the U.S. into space for good. That, to me, is a worthy dispensation of the tax dollars that I, as a Libertarian, am loath to give to our government.

SpaceX Test Problems Confirmation

Well, it looks like there is more information about what happened, and what SpaceX is intending on doing here at space.com. I was kinda bugged with some of the attitudes expressed on sci.space.policy about the whole situation. I guess I'm not in much of a position to talk, seeing as how I was the one who blogged it in the first place....

SpaceX reported this problem just about as quickly as they did their previous problems. They are a rocket engineering company, not a rocket nerd entertainment company. They make money by designing, testing and flying hardware, not be wasting their time explaining all of their decisions to monday morning quarterback style engineers and engineer wannabes. Companies tend to like to release information about snags after they've had a chance to analyze and fix the problem. Problems happen, but solving problems show competence.

Anyway, it's interesting to note that Elon's reply mentions that the failures occured during tests that were intentionally testing severely off-nominal situations. In other words, they were trying to test the bolts off the thing. The fact that they had a failure in such a situation isn't too suprising at all.

Anyway, I needed to vent a little spleen. Back to work now.

Better Sourced SpaceX Post

This one isn't as speculative, anonymously sourced, or even controversial, just interesting.

Clark linked to an interesting article in Flight International about SpaceX's plans for the Falcon 9. After mentioning the two heavy versions (ie the ones with strapons), they stated that:

However, development work for these will not start until a customer places an order.

“There is not a great amount of further development to be done [for the heavy versions],” says SpaceX chairman and chief executive Elon Musk. “We won’t spend that money until we have a customer. Then we will do aerodynamic analysis, separation systems, a few things like that.”

He adds that development of the medium versions would include the attachment points for the heavy’s two strap-on stages and the analysis for the loading expected for heavy Falcon 9s.

Seems like a rather intelligent way of going about it. That way if nobody really wants that capability, SpaceX doesn't have to waste money providing it, but if someone does, it can become quickly and readily available. If they get the three main Falcon designs (1, 5, and 9) flying reliably, and have done all the structural design work to make a Falcon 9 core, the amount of remaining technical risk for the Falcon 9 S5 or S9 is pretty minimal. Small enough that the risk of being the first customer isn't that bad. Not only that, but SpaceX probably won't even charge a premium for that development work--probably just the launch price.

The further mention that:

SpaceX will conduct a hold-down fire test of the Falcon 9’s first stage in the second quarter of 2006 and a fairing separation test in the fourth quarter.

SpaceX bought a 3Mlbf vertical test stand (the thing looks like a ten-story tall milk stool) from Beal Aerospace down near their other test facilities, and they could probably do a full duration test with all 27 engines. There are some weird aerodynamic effects that could happen due to the large number of engines interacting that couldn't be effectively tested on the ground, but a full duration ground firing with all 27 engines lit could go a long way toward proving the reliability of the F9 S9 vehicle.

Armadillo Tethered Test

While we're still working on getting into engine testing and designing our first demo vehicle, Armadillo did some hover tests of their biprop VTVL vehicle over the weekend (Warning: very big file ~13MB, they also have a shorter 3MB file of the last of their four tests). They've still got quite a bit to go before they can show off their vehicle at the X-Prize Cup next month, but it looks like they may make it on time.

I've really enjoyed following the Armadillo team's progress over the past few years. John Carmack has a nice group put together, and they've moved pretty far up the learning curve. John's also a genuinely nice guy. He provided me with some free catalyst materials back when we were trying out GOX/GH2 catalytic ignition, and has always been willing to freely discuss rocket hardware related questions. That's one of the things I like about the industry--with very few exceptions, the big players are genuinely nice human beings in addition to being good rocket engineers and businesspeople.

At MSS, we're still working our way up the learning curve ourselves, and we're taking some different technical approaches on engine development and testing from what Armadillo is doing, but it's always cool to see other groups doing well. It makes it all that much easier to convince others that you really don't need to be NASA or the government to do sophisticated rocket flight projects.

SpaceX Merlin Test Failure?

I just saw a report on a usenet group about a test-stand failure of a SpaceX Merlin engine. [Update: the original message appears to be missing, and none of the other replies contain much of the original message. I don't know if this means that the initial report was bogus, or if it means that the person sharing it didn't have the right to be doing so, and took it down to avoid legal problems for himself or his source.] Now, it is important to mention that the report didn't mention which Merlin version this is. As I understand it, they have both the Merlin-1 and the Merlin-2 in development, and since the report doesn't mention which Merlin variant the problem was with, it isn't yet clear if this will affect the Falcon I launch planned for the end of this month. The current timeframe for the first flight was stated as being sometime between September 30th and mid-October, but if this was a failure of the exact same version of engine as is on the Falcon I that is being shipped out to Kwaj, that date might very well slip.

Here's some excerpts from the report:

SpaceX attempted a full Mission Duty Cycle (MDC) test of the Merlin S/N 003 engine on Wednesday, 7 Sep 05 with catastrophic results.

At T+158 seconds the chamber and nozzle separated from the engine, breaking several mounts including one of the pitch/yaw actuators and one of two struts which attach to the TPA. Joints in the fuel lines from the TPA to the engine injector and the gas generator were separated causing fuel to be sprayed around the test stand for just a
short time (probably less than 1-2 seconds) but sufficient to burn for 10-15 minutes.

...

It looks like when the chamber started to come off that the side forces generated were sufficient to break the strut and pitch/yaw actuator attach points and the engine swiveled into the TPA causing fuel lines to break, damaging the TPA, and tearing apart the turbine exhaust and roll control nozzle.

Technicians are evaluating now the damage done to facility wiring, tank insulation, and valves. It may take two weeks to repair the damage and get the stand back in shape to test a Merlin. The next Merlin engine is in El Segundo waiting for an engine computer to complete acceptance testing and might ship as early as next Monday. In the meantime SpaceX intends to press with Kestrel testing which should be largely unaffected by the Merlin problems.

Anyhow, if anyone else can verify this report, or clarify which version of the Merlin had this failure, I'd be interested to hear. The SpaceX crew has a lot of sharp engineers in their group, and I hope they're able to figure out this bug and get things back on track for a succesful Falcon I first flight in the next month or so.

[Update 9/13/05: It appears that the original usenet post had some proprietary information in it that wasn't supposed to be released publicly, so SpaceX has requested that the original poster remove the report. I was kinda suspicious since the person posting was an ATK employee. Anyhow, SpaceX has had test problems in the past, and they've been actually surprisingly forthright about most of them in Elon's updates, as well as in other places. I'm sure there's a good chance that we'll hear more about the problem (sans proprietary details) and the solution to the problem in the near future.]

More Jonny Bloggin

Now that we have this newfangled digital camera of ours...I figured it might be fun to put some more pictures up. Once again, most of them are of little Jon.


[Update: Tiff wanted me to add the following picture]

Straight from the Source

Well, after a bunch of posts about SpaceX that were mostly based on speculation and single-source anonymous rumors, it is nice to be able to report something right from the source. In comments to my previous question about why the Falcon V's payload capacity was being lowered back to its original numbers, Elon Musk himself replied:

Falcon 5 has lower payload for two reasons:

1. SpaceX originally planned to upgrade the Merlin 1 to 100klbf sea level. Instead, the upgrade is only to 85klbf and resources are being focused on the Merlin 2.

2. The Falcon 5 is carrying a lot of extra tankage on the first stage.

The first reason explains about two thirds of the difference and the second reason one third.

Falcon 1 paylod dropped by 100kg due to no reliable Al-Li source.

So there you have it.

[Note to self--be careful what you write, you'd be amazed who might actually read what you're saying...]

Falcon V Downgrade?

Hey all,
Am I the only one that noticed the fact that the new stats and prices announced by SpaceX for their vehicles shows Falcon V as having a much lower payload than previously quoted, while costing nearly $2M more?


The most recent previously quoted price for the Falcon V was $16M, though that didn't include 3rd party insurance and range fees like the new prices, so the total fly-away price is actually more or less identical. However, the old Falcon V specs were 6020kg to a 200km Low-Earth Orbit, but now it's back down to only 4100kg. I can see a few possible reasons for this:

• The 4100kg is nearly identical to their previous early estimates for payload. It could be that they accidentally put the old payload numbers in when making the chart. Unlikely though that they'd make a screwup like that.


• It could be that they're going back to more conservative numbers for the Falcon V payload until they have the vehicle further refined, since they appear to be going back and changing the design so that the Falcon V/IX first stages share common tankage and engine mounts. This means that they may upgrade both payload numbers as they get closer to production (as they did with Falcon I).


• It could be that the upgraded Merlin-1B engines they wanted to use for Falcon V aren't doing as well in development as they had expected.


• It could be that the added weight of being able to be interchangeable with a Falcon IX (ie extra engine attachment points, excess tankage) is enough to drop the payload that much.

All that said, if those numbers end up being how things turn out, the Falcon V is no longer anywhere near as good of a deal, but the Falcon IX ends up being quite good. The cost per pound of the Falcon IX is about the same as the previous Falcon V numbers ($1320/lb vs ~$1200-1300/lb), and the payload is big enough that you can do a lot of things with it. If they don't end up bringing the Falcon V payload back up to the 6000kg it was previously quoted at, I expect the Falcon IX will be their workhorse vehicle. Ironically or not, its also their vehicle that probably has the highest profit margin. The marginal cost of four extra first stage engines, and possibly 1-2 upper stage engines, plus a couple thousand bucks worth of extra fuel is nothing compared to the $9M price difference. If they can actually get the Falcon IX to fly like reliably at that price point, they'll make money. A LOT of money.

But I wonder what the final fate of the Falcon V will be. Pity, I really liked that design.

[Update: Hrmm...it looks like the Falcon I has been downgraded from 670kg to 570kg too. The price increase makes sense, since it now includes range and insurnace costs, so the total fly-away price tag may actually be about $100k lower than previously quoted.]

[Update: Another interesting suggestion was from the comments was that due to a shortage of (or fabrication difficulties with) Al-Li alloys, the Falcon I and V had to be built with heavier, but more common Al alloys--2219 if the memory serves right. That would definitely explain all of the hit on the Falcon I, and between that and having to carry a bunch of empty tankage each flight, it might account for the payload drop in the Falcon V....I wonder if someone could twist Musk's arm into building a Falcon V first stage that had only as many straight tank segments as it actually needs, if there was enough demand? That could possibly get back some of that lost performance and bring F5 back into the ring.]

SpaceX and Reusability

While I'm waiting for the FEA solver to paint me some pretty pictures for a part I'm working on, I figured I'd write a quick blog post. Yesterday I wrote a little about SpaceX's Falcon IX announcement, and I asked if anyone had any details about how SpaceX intends to recover its upper stage for the Falcon V and IX vehicles. I had been confused about this because I had just asked them last month if they intended to reuse the upper stage of Falcon V, and they said that they weren't intending to, but now they're saying that they are.

Earlier today, I received some information about how SpaceX intends to go about recovering their upper stage. Apparently, if this source is right, SpaceX is looking into having the upper stage reenter with the engine nosecone facing forward. Apparently they've done some analysis that shows that the upper stage should be stable in this configuration, and the upper stage nozzle will have a high temperature extension that should supposedly be able to take the heat. The source I had expressed a bit of healthy skepticism about if this would work, but was at least interested in seeing how the attempt actually goes. It is a kind of weird approach, but one that isn't obviously stupid. If they can insure that the vehicle is aerodynamically stable in this configuration (possibly by adding some sort of flaps to drag the center of pressure back), it might just work. The shock wave would be far away from most of the vehicle, with only the bottom ring of the nozzle being very close to most of the heating. A brief search on Matweb shows that some of the refractory metals have at least semi-decent thermoconductivities, ranging from as low as Stainless Steel for some all the way up to almost as good as Aluminum for others--Not bad. That means that with the right metal, that very high temperature zone at the tip of the nozzle can transfer some heat via conduction to the rest of the nozzle, which can then radiate a lot of that away, due to its high temperature capabilities.......as I said, not obviously stupid at all.

I think that the approach that SpaceX is taking for developing first stage recovery systems for the Falcon family of vehicles may also be indicative of how they will go about the development of their upper stage recovery systems. Falcon I is almost as much a test vehicle as it is an operational vehicle. They took their best guess at a design that they think can withstand a water-based recovery, and soon they'll flight test the concept. Any issues that come up, any components that just don't cut it, will likely be modified and tweaked, possibly with some changes in conceptual design. Then they'll try it again, until they eventually have a decent system. During this time, they'll also be building up experience with recovery, getting economic data on how cost-effective it is (and where they can improve the process to make it more cost effective), and building up a store of knowledge that should allow them to do a better job the first time with Falcon V and IX first stage recovery.

I imagine they'll probably go about the upper stage recovery development the same way. They've probably taken a decent amount of time to try and design the system as well as they can for recovery, then they'll fly it. If it comes even close to working, they'll keep tweaking and iterating till they have a workable, recoverable upper stage. They may need to change recovery concepts at some point if the nozzle-first approach doesn't work, but I have decent confidence that if it is possible to recover and reuse an upper stage like theirs, that they'll eventually find a way to do it, and make it economical. It'll take time, and it probably won't work very well right off the block, but I think from the approach we've been seeing them take, we can have good confidence that they will get it right eventually.

[Update: It just occured to me that if they wanted to do so, they could probably get some preliminary data on this kind of recovery method using Falcon I. Falcon I also has a radiatively cooled nozzle, so maybe they could just instrument/RocketCam the heck out of the thing, and take some data. After all, their first 2-3 Falcon I payloads only use up an tiny portion of their vehicle's launch capacity.]

New Additions to the Blogroll

Just wanted to draw some attention to the new additions to my blogroll. One is the Space Transport News blog run by Clark Lindsey (formerly the Hobbyspace RLV News page). The other is Carried Away by Dan Schmelzer. Dan's is mostly space focused, with a lot of good commentary about SpaceX and other commercial groups. Clark's is probably the single best place on the net to read about what's going on in the industry. If you don't already have the old Hobbyspace url in your bookmarks, or the new one, hopefully you'll take the time to fix that mistake. Apparently his new format allows for RSS feeds too. [Update: Just added Iain McClatchie's blog, the Ambivalent Engineer as well.]