Bigelow Shoots for the Moon

I'll add some more commentary later, but for now a fascinating scoop by Alan Boyle.

More on The Path Not Taken

I'm still not trying to claim omniscience by saying that had NASA taken this alternative route (building a set of very small RLV demonstrators/X-Vehicles first instead of Shuttle) that everything would have been perfect. But I figured it would be worth thinking a bit about some of the potential implications.

What if the public's first impression of the difficulty of reusing rocket engines was the RL-10 instead of the SSME? Instead of hundreds of engineers tearing the engine down after each and every flight (as was the case at first with the SSME), there'd have been a little bit of post flight inspection (with the engine still fully assembled), with overhauls only once every 20-50 flights.

What if the public's first impression of TPS wasn't the brittle ceramic tiles on our high cross-range, high ballistic coefficient shuttle, but was a more robust metallic TPS or ceramic cloth TPS on a low ballistic coefficient vehicle?

What if the public's first impression of an orbital RLV was a vehicle that could be launched from any airport in the world that could handle a 747, instead of something that required thousands of workers, massive crawlers and launch towers, and was only considered safe to launch over the open ocean?

What if the public's first impression of an RLV being serviced between flights was in a standard aircraft hangar, and if their first impression of RLV stages being stacked was a simple overhead gantry crane in said hangar, instead of the massive Vertical Assembly Building?

What if the public's first impression of the manufacturing of an orbital RLVs was that they cost about the same as a medium sized passenger jet, and were expected to fly hundreds of times before being retired, instead of costing an order of magnitude more, and only flying just barely over once per year per airframe?

What if the public's first impression of the economics of an RLV was that they were cheap enough that private firms like FedEx and PanAm could buy and operate multiple tail numbers for intercontinental package and personnel delivery, instead of being so expensive that only NASA could afford to own and operate them?

What if rocket vehicles were actually flying enough that maintenance costs, and hardware lifetime started becoming as important as the same for early jet engines? What improvements to robustness and reusability would we have seen over the past 30 years?

What if a smaller, simpler vehicle had been ready in time to refuel Skylab so it wouldn't have been allowed to deorbit? What if people's first experience with a space station were based on vehicles that could fly once per day per vehicle, instead of once per year per vehicle? A station where new crew or scientists or tourists could visit every day, with new experiments coming up and down just like on a ground based lab?

What would have happened to the orbital launch market if all of the sudden Boeing or McDonnell Douglas, or whoever was selling launch vehicles as fast as they could make them? How much money and how many competing designs would've sprung up in short order? Especially if developing an orbital RLV was seen as being not vastly more difficult than designing a commercial passenger jet?

It's an interesting thought, isn't it?

The other interesting thought is the realization that such small RLVs are still doable today, and in fact can probably be developed for less thanks to all the advances over a lifetime. Just a thought.

A Path Not Taken

I have to admit that last post was kind of weak. Most of the good points had already been made, and I'm not sure I actually added anything relevant to the discussion. So, as penance, and since the antibiotics I just took say not to lie down for 30 minutes after taking them, I'm going to try and actually put out some original thought on a topic that I've been thinking about for a while.

Monte Davis got me thinking about things again, and lessons from the Shuttle program. One of his big points (if I'm not mangling it unduly) was that the problem with Shuttle wasn't just that it mixed expendable parts with reusable parts. He pointed out that the fully reusable TSTO designs that had been studied were so challenging that they might have been just as big of a mess (or even worse if that's imaginable!). The problem was that the Shuttle was just a bridge too far. NASA bit off far more than it was ready to chew. The requirements were too high. They were suffering from the conceit that they could somehow jump straight to a large, high-flight rate reusable space transportation right from the very first generation.

I full-heartedly agree that there's no way NASA could have developed the monster sized TSTO fully-RLV designs that were dropped in favor of the current Frankensteinian amalgam of expendable and "refurbishable" rocket hardware. What I wonder is if there was a different path that could've been taken. One that would've allowed for more incremental development. One that would've allowed for a truly reusable launch vehicle (albeit of much more modest capabilities). One that wouldn't have become the mess we have in today's Shuttle.

I'm not conceited enough to state that I know the following would definitely have been better. But I wanted to toss the idea out for discussion. See what you all think.

One of the big not commonly discussed problems with the Shuttle was that NASA was trying to keep as much of the Saturn team together as possible. They were shutting down both Saturn lines, and wanted to keep as many of the engineers and technicians as they possibly could in a time of tight budgets. Keeping as many Saturn engineers around as possible required a big budget development project. However, money was a lot tighter in the post-Apollo days. In order to get the money for Shuttle, as I understand it, they had to scrap both Saturns, and go snuggling up with the Air Force. They had to make their Shuttle design be everything to everybody. Keeping as many of the Saturn engineers as possible involved in the development of the Shuttle implied very large development costs. Those costs were high enough that they had to get the Air Force on board as well in order to get the funding they needed. In order to do that, they had to bloat the requirements even worse than the original Shuttle concepts. However, the requirements grew quicker than the additional money, and in the end they ended up having to make all sorts of compromises.

What if they had intentionally bitten off a smaller task at first. What if they had retired the Saturn V, and slimmed down the staff for the Saturn IB (or better yet, auctioned it off or allowed the companies involved to commercialize it), and then done a much smaller first generation "shuttle"? This shuttle might have only been capable of putting a couple thousand pounds into orbit, and might not have gone straight to an operation vehicle. This wouldn't have been a program trying to keep as much of the Saturn team together as possible, or an attempt to replace all existing rockets in one fell-swoop. It would've been an X-vehicle in reality.

About a month ago, on NASASpaceFlight.com's L2 section, there was discussion of some conceptual design work done by Dan DeLong (of XCOR) back in the mid 80s that might have been a good way of doing things. The concepts ("Space Plane" and "Frequent Flyer") that he developed while working for Teledyne Brown were air-launched HTHL style RLVs. They used a modified 747 carrier plane as the first stage, and a LOX/LH2 powered reusable upper stage. While the bigger "Space Plane" design baselined an SSME and 6 RL-10s for the orbiter, and would've been barely launchable on a heavily modified 747, I realized that by dropping the cargo capacity a bit, you could both eliminate the SSME and probably cut the modifications on the 747 substantially.

It's just an idea, and LOX/LH2 isn't necessarily the right propellant combination for things, but imagine if a vehicle like that had been built. It wouldn't have required any new propulsion development, since RL-10s were on-the-shelf technology by then. The system would've been a lot more reusable, simple, and safe. The engines were a lot easier to maintain and reuse than the SSME. Since the stage had the tanks inside, it would've had a much "fluffier" reentry, which when combined with the lower cross-range design, would've allowed for a much more robust TPS system to be used--no need for ceramic tiles. Doing an extensive flight test involving dozens of test flights would've been perfectly reasonable. You probably wouldn't have even needed much better of an escape system than a standard aircraft ejector seat, since most of the failure modes would've been a lot more benign than for most typical rockets.

Let's be honest though, the performance would've sucked rocks. You would likely have been lucky to get 3000lbs of useful cargo out of the vehicle (in the unmanned version), or possibly 2-4 people on board. This wouldn't have been everything for everybody. But it would've been an extraordinarily good starting point for learning how to design and operate reusable vehicles.

Anyhow, my half-hour is up, but what do you guys think?

Thoughts on the NASA Budget

I figured that if I'm going to be considered a space pundit, I may as well share a few of my thoughts about the recent NASA budget situation. I would have put my two cents in earlier, if it wasn't for the fact that "anonymous" over on Jeff Foust's Space Politics blog beat me to the punch on most of my thoughts (as well as bringing up several I hadn't thought about). Heck, if I knew how to contact him offline, I'd like to invite to join Ken as a guest blogger here on Selenian Boondocks.

But here are a few of my thoughts on the matter:

1. A lot of discussion over the past year has centered on how ESAS was so clever for dealing with "political realities" regarding the Shuttle workforce. And that because this big workforce meant so many jobs in several congressional districts, it meant that the ESAS approach to implementing the VSE was politically impossible to kill. The whole idea that you could somehow make a program so pork-o-licious that it couldn't possibly be canceled flies in the face of history. If jobs and inertia was all that was needed to keep a program funded, we'd still have the Saturn V. It provided tons of jobs after all. What it didn't provide was a benefit even close to commensurate with the cost of keeping it around. Not to mention the fact that with the results of the 2006 midterm elections, I highly doubt that Utah jobs matter quite as much to Congress any more.
2. The ESAS approach was also touted as a "go as you pay" type program. Basically claiming that it was perfectly capable of adapting to budgetary ups and downs. However, even Griffin himself recently more or less admitted this was a crock. Without large increases in the Exploration budget, Ares I/Orion are not going to fly in time. And the longer that program gets stretched out, the higher a percentage of the program funding is going to be tied up just in keeping the team together and paying fixed overhead. How are they going to retain all those Shuttle employees when the gap between Shuttle operations and Ares I operations starts getting bigger and bigger? While NASA is being forced to "go as you pay", it isbecoming increasingly obvious that the ESAS approach is a really lousy fit for that funding method. It is front loaded with a lot of development cost filling a "badly needed gap in US launch capabilities".
3. If the Ares I launch manifest from LaunchSpace.com is to believed (and there are some who are skeptical that their launch manifest really is official), they're now looking at cutting out unmanned test flights in order to avoid having the first manned Ares I flight shoved out too far into the future. But don't worry boys and girls. In spite of MSFC's complete and utter lack of recent successful launch vehicle design experience, their top men guarantee us (to four significant figures mind you!) that Ares I will be the safest launch vehicle ever, by a factor of about 8x. I mean, with top men like that working on the problem, who needs test flights? Why not just design it perfectly in the first place? What could possibly go wrong?
4. Regardless of which manifest is correct, most of the scheduled Ares I flights between first flight and when Ares V, EDS, and LSAM are ready are crew/cargo flights to ISS. If COTS is successful however, and if NASA actually obeys the law and buys commercial, what exactly will Ares I do for all that time (other than soak up fixed operating expenses)? Without Ares V, EDS, or LSAM, Orion is pretty much stuck in LEO or thereabouts. They might be able to do a bit of a burn and try and simulate a lunar reentry, but other than that, Ares I is going to be mostly sitting around gathering dust for 4 years or more. All while burning through somewhere around a billion dollars a year in fixed expenses, to keep the team around for lunar operations. The sad thing is that this reality alone makes Ares I a severe threat to COTS. It'll be very easy to argue that "we've got this national asset sitting around here that we're paying for even if it isn't used, and we have this space station. Why are we buying commercial services when we're having to pay for Ares I anyway?"
5. With the current NASA budget being so far below the budget request for last year, it will make it all the harder for NASA to actually get this year's budget request. As some have pointed out, the FY 2008 budget for NASA represents a nearly 6% increase over the budget that just got passed, all the while almost all other discretionary spending is increasing at a much slower rate. Being realistic, there's a good chance that NASA isn't going to see big Exploration Systems budgetary increases any time soon. Which means even more delays, cost overruns, etc. Now I'm not saying that NASA couldn't somehow stick with Ares I and Orion, and somehow keep slogging away at them till they get completed. I'm just saying that whatever technical "victory" that would be would be Pyrrhic at best.
6. Most of the shuttle workforce that gets talked about is technicians, not engineers. You can't just transfer a guy from tightening bolts on an SSME to designing the EDS. If you "retain" these people, it means that you're having to pay for them while at the same time also paying for the engineering work that needs to be done to get Ares I/V built and flying. Now, some of these people have relevant skills that will be useful during the test programs for Ares I/V, but many of them aren't really needed until Ares I and Ares V start flying. And some of these people can or will have to be retrained (at additional expense) for new tasks since their old expertise is obsolete.
   
7. The argument often gets made that no Congressman is going to vote to end the US manned space program. But the question is, if in 2014 the Atlas V team (and/or SpaceX or RpK) are flying people into orbit and Ares I isn't, how much water will this argument hold? If the ability to put people and cargo into orbit on domestic commercial launch vehicles becomes a reality before Ares I, why are Congressmen really going to care that much about continuing to fund an overpriced government competitor?

I could go on, but the main thing I take away from this is that the so-called "political realities" we heard about weren't. And that by spending so much time and money trying to reduplicate existing commercial earth-to-orbit launch capabilities, NASA has likely blown its chance at a return to the moon. If NASA had gone with their original (pre-ESAS) plan, and built a "CEV" that could be flown on either of the existing EELVs (and consequentially on SpaceX's Falcon IX if that ever flies), we would likely be in much better shape.

Space Access "Pundit Panel"

Just thought I'd let you all know that I've been invited to speak on a "Pundit Panel" at this year's Space Access conference, along with Henry Spencer, Rand Simberg, and Jeff Foust. I've never participated in a conference panel like that before, so it should be...interesting.

I do have to admit though, when Henry asked me if I'd like to participate in that, my first thought was "I'm a pundit?"

Blogger's Cramp

Sorry the posting has been so light lately. I had a whole list of topics I wanted to cover back in January, but I've just had an impossible time getting up the time, desire, and mental energy to blog lately. Part of it has been due to tooth problems--I have a tooth that needs a root canal, and I had been putting it off for a while since it hadn't been hurting. The pain flared up all of the sudden this last week, and even with the antibiotics helping with the inflammation, I've been feeling lousy for most of the past week.

Another part of it has been how busy I've been at work, with my cub scout den, and with my thesis.

Work is going pretty well. We've been doing a series of fixes/upgrades on our vehicle based on some of the things we learned from the first hold-down tests. We'll probably blog some results later next week.

Scouts is going fairly well. We studied first aid this last month (including having a nurse from the local hospital come with some CPR dummies to demonstrate rescue breathing and the Heimlich maneuver), and are starting Engineering this month. One of our projects we're working on this week is building catapults. My coworker Ian was helping us, but his design was gnarly enough that it was too big to fit in his station wagon afterwards, so I'm working on some scaled down models. In spite of what he thinks, while it's a good idea to build something a little bit manlier than those pansy popsicle stick catapults in the scout books, 10 year olds really don't need to build a catapult that could lob a bowling ball 100 yards...

My thesis has also been moving forward a bit. I got a blog comment from Carl Feynman with a link to an online book discussing closed-form solutions my particular question about Bessel Functions. I also figured out a better, more tidy way for doing the math in that model than the approach I had been taking. More importantly, I found a good paper discussing fluid flow in a tube with pulsating walls. The math is a bit hairy (Bessel functions, Fourier Expansions, and Complex Numbers, oh my!), but I'm slowly working my way through it. With luck by sometime next month I'll have that all tied together into an integrated model.

Which brings up a question. Would any of you be interested if I published at least the modeling portion of my thesis on the blog? Kind of like a serial novel, but with ugly math instead? Or is that more pain than most of you are interested in?

Lastly, I've been enjoying watching our two little boys grow up. James is still our cute little Mr Wide-Eyed Wobbly-Neck, but he's getting some neck muscles. Jonny can now open all the doors in the house, figured out the "child-proof" doorknob covers, and likes "sharing his toys" with his little brother. Which means that we walk into his room, and James is half-way buried in toys with this very consternated look on his face, while Jonny is giggling uncontrollably. I'll have to post some pictures sometime.

Jonny's also really into trains, which he calls "Hoo-Hoos". We went to a model train shop in town today, and boy was he was so excited. You should've seen the look in his eyes when the store owner turned on their little train track for Jonny to watch. He was stoked.

I asked him afterward "Do you know how to say train?"
He emphatically replied "Yeah."
So I said "Ok, say it then."
He said "Hoo-Hoo!"

Cute.

Anyway, I'm not sure if I'm going to get the time or the mental energy to post much space related stuff this next week, but I figured I'd let everyone know what I'm up to.

Some thoughts on "Just how full of..."

By guest blogger Ken.

(Who hopes that Jon is getting his thesis knocked out...)

One of the usual Monday morning rituals for a lot of folks is to stop by The Space Review to see what kind of new and interesting space commentary is being offered up. This week, per the usual, was a varied affair, but of course my attention was immediately drawn to the Moon story served up by Mr. Donald Beattie, "Just how full of opportunity is the Moon?". I printed it out and read it. Then I read it again, trying to figure out just what point exactly Mr. Beattie was trying to make. The rhetorical structure was very difficult, and it wasn't until I took out a pen and started trying to underline his important points that it became clear. He was opening with the very vogue rhetorical device of mistating someone's position, reframing it to the point they want to argue, then running with it.

So I dropped by the Curmudgeon's Corner to see what comments Mark W. might have made, and it turns out he had some issues (unstated) with it as well, or as he said, "Donald Beattie make[s] some remarkable and unsupported claims about the usefulness of returning to the Moon in particular and sending humans into space in general." I have to agree about 98% with what he says. (Full agreement with Mark? C'mon, then y'all wouldn't have any fun ;-) In a further altering of the planets in their trajectories, I may even make some of Mark's points during my discourse.

Let us dive right in. I assume the premise is that Mr. Beattie will address the extent ("just how") to which there is or is not opportunity on the Moon. He opens his case by noting the recent article by noted Lunar advocate Paul Spudis entitled "A Moon full of opportunity", and quoting from that article's first paragraph as "Paul Spudis asserts that '…some complain that the reason for going to the Moon is still unclear.'"

The full comment was "The 2nd Space Exploration Conference held December 2006 in Houston outlined several reasons for a human return to the Moon. Remarkably, some complain that the reason for going to the Moon is still unclear." This is a reasonable statement. I know I hear it all the time when I do NSS outreach. It's why we have things like ISU's "Why the Moon?" Symposium later this month. Perhaps such compaints were why NASA spent the money to produce a "Why the Moon?" poster. It's certainly why I invested the time to put together "25 Good Reasons to Go to the Moon" here at the Selenian Boondocks. Because people don't know.

Mr. Beattie, however, seems to take it personally, contending that "That is, unfortunately, an incorrect understanding of why there are objections to returning to the Moon with an emphasis on human settlement and exploration." This is an interesting statement. I've generally found that when people object to returning to the Moon, they usually say things like "I don't think we should go back to the Moon, I think we should [insert prefered rationale here]", not "So I'm not really clear on this, Why the Moon again?". However, this is where Mr. Beattie offers up the rationale for this commentary, to object to returning to the Moon with an emphasis on human settlement and exploration. He then goes on to accuse Dr. Spudis of both trying to stifle debate and dismissing as whiners "those who have expressed concerns that NASA is pursuing the wrong goal.

So I went back to see what Dr. Spudis said. Which was "The alt-space community whined about it being another big government boondoggle. The Mars Society whined about the focus on the Moon. The scientific community just whined." Which I found rather funny, because if you look back at all the sturm und drang back after the VSE was released there was a lot of what was in effect whining, but for the very legitimate purpose of each organization making sure that their agenda was being heard. There wasn't a lot of public and open debate at the government level, so people did it where they could - in the strident arena of the internet. I certainly contributed my fair share of whining about the government plans not sufficiently addressing the commercial aspects of what was presented. So did I think Dr. Spudis was doing a "disservice to legitmate debate"? Oh, please. I think it was a funny characterization of what actually happened. Do I think Dr. Spudis thinks I'm a whiner? No.

Mr. Beattie remarks that "These concerns are well founded based on disagreements about the benefit and attainability of the goal." Presumably the wrong goal that NASA is pursuing? Not sure. He does give the two main points he wants to make:

1) We can "...do everything else that we want to do in space" without detouring to the Moon.
2) All indications are that such a detour will inhibit everything else we "should" do in space with the limited resources available.

Now I've seen that 'detour' language somewhere before. Hmm... He does have a good point with number 2. It does look like ESAS is going to consume all budget potentially available to it. However, ESAS is not the VSE, and nor should the two be confused. VSE is a strategic framework for making the US a space-faring society, one that includes the Solar system in its economic sphere of influence, as Marburger noted. ESAS is a transportation architecture. The fact that ESAS might be bad as an implementation of VSE does not make the VSE bad.

He then outlines his key disagreements, presumably with the wrong goal that NASA is pursuing:

1) The six themes that are the foundation underlying the rationale to return humans and robots to the Moon were predicated in many false assumptions. This is shown by the fact that Nixon & Congress nixed Moon base plans in the late 1960s, and Congress quashed the SEI back in '89. If Congress wouldn't fund the plans with which they were presented then, then there can clearly not now be a compelling reason for Congress to fund a return to the Moon, irrespective of the plans presented.

2) Human missions to Mars, if and when they might occur, are so far in the future that lessons learned on the Moon will have little relevance. Apparently the technology used in vacuum, dust, and heightened radiation levels will be capped on the Moon at 2025. He denies that there will be any technology applicability whatsoever from Moon equipment to Mars equipment. I would contend that by providing a spectrum (1 atmosphere, 0 atmosphere) you have a deeper knowledge base to apply to situations lying in between. Remember also that Moon equipment is also foreseen as being potentially applicable to asteroidal operations. This would also hold true to gravity operations. We have a spectrum (1 gravity, .000001 gravity), which .16 gravity operations on the Moon will help to fill in. Most of the NEOs will be closer to the ISS, gravity reference-wise, but what about Ceres?

3) The only reason to pursue the recent National Research Council report "The Scientific Context for Exploration of the Moon" is to add detail that is "only of interest to those who have spent most or all of their professional lives studying the Moon" because "[i]t is unlikely that any new information collected during detailed lunar exploration will resolve fundamental questions being asked regarding the origin and evolution of the solar system." I think this is in reference to crater counting, sizing, and dating which some are calling for as a means of documenting the impact flux of asteroids in near-Earth space over time. There is no other place in the Solar system to do this than the Moon. Fickle and ever-changing Earth is okay, but... There is apparently no benefit in this.

4) "There are no lunar resources that, when processed, would have any economic value if utilized on the Moon or returned to Earth." Now or ever? How does he know? Well, because the correct analyses showed no positive cost benefit, while the incorrect enthusiasts use questionable and optimistic projections. I am advised to "reopen [my] chemistry and physics textbooks and spend some time with real-world mining and drilling operations." Fine, I'll go back and revisit "The Lunar Sourcebook", and read some of the earlier chapters of "New Views of the Moon". Though I would note that it seems by Mr. Beattie's argumentation that Earth-based mining can teach us nothing about Moon mining in the same way that Moon mining can teach us nothing about Mars mining.

Mr. Beattie uses the example of water ice at the poles, referencing an earlier article by Dr. Spudis "Ice on the Moon". Mr. Beattie states definitively that only high-latitude comet impacts could have conveyed water into the craters, so the amount that might be present is highly speculative and building a base on such a flimsy pretext should not be considered. Dr. Spudis' conclusions were that "No single piece of evidence for lunar ice is decisive, but I think the preponderance of evidence indicates that water ice exists in permanently dark areas near the poles. However, its origin and the processes associated with its deposition are unclear. The ice could be of cometary, meteoritic, or solar wind origin".

My views are a little different from most about the polar "ice". I for one make no assumption for water. I do assume for hydrogen, which has pretty convincingly been shown to be present. I think that what we're going to find in the craters will be effectively 'lunacrete' - mixed hydrates and regolith at about 40 K. I'm thinking that the likeliest way to process the stuff will be to carefully heat the soil to create facturing. I seriously doubt that we're going to have much luck with drills and dozers. Anyone that's played out in the back yard in deep winter knows how hard the soil gets. My guess is lasers and solar mirrors will be the solution at the everdark craters to get the stuff to a grindable state.

Even if there is not a single drop of water, there is still hydrogen. The Moon's soil is about 40-45% oxygen by chemical composition. From what I understand, water can be produced from fuel cells. Irrespective of the polar craters, the Sun has been depositing hydrogen throughout the regolith all over the Moon for aeons. It's not much, but it is there. No one ever said this was going to be easy.

5) International cooperation doesn't seem to be there for the Moon, and everyone is leapfrogging for "the indisputable scientific prize". (What is, the moons of Jupiter? Bzzt. What is, the Solar system? Ehh. Mars, ladies and gentlemen, Mars is the indisputable scientific prize). Besides, those other guys sending stuff to the Moon are just catching up to us forty years ago.

I'm sorry, but I find that kind of assertion to be groundlessly arrogant. I'll leave it at that.

6) Polls show the general public to be generally clueless about all of this.

So, Mr. Beattie asks, "Should a large percentage of NASA’s budget be spent on a single objective—returning to the Moon—that has little scientific value and no real economic benefits other than job creation?"

I would contend that Mr. Beattie is not asking the right question, which should be "Should a large percentage of NASA's budget be spent on the ESAS architecture as a means of implementing the VSE which includes Lunar activities?" My analysis has led me to conclude no, it shouldn't. A lot of people disagree with me, but that's okay, that's what reasoned debate is all about. In that context I have to answer No to the question he poses. That should not be read, however, as my being against a return to the Moon, even though that's how the question is couched.

He clearly, though indirectly, answers his titular question, "Just how full of opportunity is the Moon?" with a resounding Not At All! Now to be fair, Mr. Beattie did write a book about Lunar Science, "Taking Science to the Moon", so he must know a thing or three, and he has a solid background with NASA, ERDA, NSF, DoE, and consulting. I thought that I had read his book, but apparently only made it to chapter two, 'Early theories and questions about the Moon'. It was Stuart Taylor's "Planetary Science: A Lunar Perspective" that I was thinking of.

My conclusion is that this was a weak counter-attack to Dr. Spudis, NSF, NASA and others being excited about going to the Moon. To be clear, I AM A (relatively young) BANKER AND I AM STOKED THAT THE U.S. WILL GO TO THE MOON. (Again!) I am looking forward to the data from the probes. I hope the Chinese will share the Chang'e-1 results to the same extent the Europeans did the SMART-1 results. I hope that ISRO is also open with the Chandrayaan-1 results.

My sense of this weakness in the article was fueled by a strong undercurrent of Mars Society bullet points in much of his argumentation. The very awkward start seems to have to pirouette to get into the position that the author wants. He makes authoritative statements without qualifications, which I always find tough to swallow when they're not backed up with some good fiber supporting what's asserted. He also seems to be arguing against NASA's six themes for returning to the Moon by way of Dr. Spudis' prior articles at The Space Review. Ultimately, it seems to be a plea not to cut the unmanned science portions of NASA's budget.

Don't get me wrong. I think that Mr. Beattie is entirely entitled to argue his points, and I'm going to contact Peter Kokh over at the Moon Society who is co-supervising with me the "Moon & Cislunar Space Development" track for the ISDC 2007 to see about possibly asking Mr. Beattie to participate in a panel. I just think that this particular article was insufficient to sway my thinking in any way, and I don't think it argued the title of his article.

SpaceX Website Update

With SpaceX's second Falcon I launch attempt on hold again (supposedly due to some people in the Kwajalein range safety group not being there during their launch window), I figured it would be worth mentioning a few short things I noticed from their website upgrade.

• Apparently starting in 2009, Falcon I is switching to the regen version of the Merlin engine. Also according to their site, this version has about 30% higher thrust, coming in at ~102klbf. The CAD picture they have on their website for the regen Merlin looks really darned cool. And I hate to admit it, but their regen cooled pintle engine does look sexier than ours.
  
• It looks as though they may have sorted out their supplier issues for Al-Li materials, because they are back to being listed as standard on the Falcon I upper stage, though it appears that Falcon IX is still planned to be Al 2219 for both stages. Between the higher thrust for Falcon I, and the lighter Al-Li tanks for the upper stage, predicted payload is back up into the 1500lb range, with price still in the $6.7M range.
• On their launch manifest, their first flight (back in Q1 2006) is amusingly listed as "completed"...Though they did include lots of info at the bottom of the section about the mishap. So not a snowjob, but definitely an interesting spin.
• They're claiming about 250 employees, which actually isn't a huge change from last time I heard numbers from them. They don't seem to be ramping up employment quite as quickly as I had figured would be the case after winning one of the two COTS awards.

All in all, a rather cool new look for the site, with a little new information. Whoever they paid to do the site definitely knows how to pimp their rockets. Here's to hoping that they can pull off a successful flight in the coming months, and that they can start matching their advertising (and website snazziness) with a solid and reliable track record.

Oh, and here's to also hoping that at some point they can get a launch site that doesn't jerk them around quite so much. If my previous articles are right, Wallops might be an option worth looking into.

Good luck guys!

Sundancer Orbital Trajectory Implications (Part Three)

Sundancer Orbital Trajectory Implications (Part One)
Sundancer Orbital Trajectory Implications (Part Two)

Henry Spencer was kind enough to send me some feedback on the first two posts in this series, and it appears that I forgot to highlight what both of us see as the key benefit of such repeating ground track orbits: first orbit rendezvous.

First Orbit Rendezvous
Orbital Mechanics isn't my strongest suit, but I'll try to explain. For optimal launches you want the destination plane to cross through your launch site. For typical, non-repeating orbits like that of ISS, a given launch window won't actually have the station itself passing directly overhead, just the plane. So what you do is you launch into what's called a "phasing orbit". Basically orbits at different altitudes will complete a revolution in a different amount of time, with lower orbits being faster. So, basically you go around a bunch of times before things actually line up for the transfer out to the final orbit. That's probably a painfully oversimplified explanation, but gives the general idea.

The problem is that orbit phasing like this typically requires as much as 3 days between launch and rendezvous. That's a long time. When you think about it, that's actually about the same time it would take for a vehicle to travel from LEO to a lunar orbital station! Imagine how much fun that must be in something cramped like Soyuz. Long phasing time requirements like that drive up the design complexity and cost of a transfer vehicle, while also typically making it less comfortable. Basically, instead of being just a simple LEO equivalence of a Toyota Corolla, it ends up being an orbital RV, just more cramped.

On the other hand, if both the plane of the station and the station itself cross over the launch site daily, you can do a "first orbit rendezvous". Ie you don't have to do phasing orbits first, and could be done with rendezvous and docking in as little as 90 minutes, possibly less with practice. This allows you to go with a much more spartan, lightweight, simple, and inexpensive transfer vehicle. It also makes the trip to orbit a lot shorter, so you get to spend more of your time at an actual station or transfer vehicle which can afford to have nicer...er facilities. Being able to avoid the need for the "diapers" is probably well worth it.

The other nice thing is that once things have gotten going well enough that you have a steady flow of vehicles up and down from the station, the stay-time of any individual vehicle can be kept relatively short, allowing you to turn things around more frequently. This is at least part of the reason why multi-hundred million dollar airplanes can keep costs low enough that Joe Schmoe can buy a ticket from LA to New York for a price that is actually not much more expensive than driving (and possibly cheaper).

Other Repeating Ground Track Orbits
Another thing worth mentioning is that just about every inclination you can imagine has these repeating ground track orbits. It's just a case of matching things like the time it takes to complete an orbit, and how fast the earth is rotating underneath you. It's substantially more complicated then that in detail (as usual in engineering), but this 41 degree orbit isn't the only resonant orbit out there. There exist repeating ground track orbits in 51.6 degrees for instance. I do believe the one which repeats every 24 hours ends up being not much more than 100km higher than ISS is currently located. A friend of mine actually suggested boosting ISS into such an orbit to make it easier to access for multiple users. If ISS weren't being run partially by NASA (ie if they say auctioned off their stake in things), that might not be a bad approach to things.

[Note: Hopefully sometime next week I'll have a global ground track to discuss.]

100k Site Visits!

Just wanted to mention that as of sometime in the next few hours, my site will have logged 100,000 visitors since the time I put up my sitemeter! Now, that may only come out to several hundred or a couple of thousand of unique visitors, but it's still a milestone worth mentioning!

Thesis Bleg: Bessel Functions and Complex Numbers Question

A couple months ago, I posted about endurance, and when it is best to stay the course vs when it's best to cut bait. One of the examples I gave was my thesis. I wasn't sure if staying the course made sense, or if I should change topics. After a lot of deliberation, last month I determined that staying the course was the best route, and have been slogging away at the thing (which is a big part of why blogging has skimped out lately). I'm starting to get some real traction in several areas, having found some very useful papers, and making some progress on the modeling side of things.

So I have a question for any hardcore math nerds.

In my model for radial vibration of a piezoelectric crystal, I get an equation for the radial displacement as a function of the radial location (at rest), and time:

ur(r,t) = [A * J0 (k * r) + B * Y0 (k *r)] * cos (omega * t)

Where J0 and Y0 are Bessel functions of the first and second kind (0th order) respectively, k is omega/vp, omega is the driving frequency for the piezoelectric crystal, and vp is the speed of sound of the crystal in I think the thickness direction. Vp = sqrt (c11/rho), where c11 is the stiffness in the thickness direction, and rho is density. The problem is that in order to model losses, c11 is really a complex number, with the real part being analogous to the static stiffness, and the imaginary part being the "loss modulus".

Anyhow, the problem I have is that the complex number is inside the Bessel Function, and I was having a hard time figuring out how to handle that for my model. I've came up with an idea, but wanted to run it past some more eyes.

Ok, so since the stiffness, c11, is complex, the velocity is also complex, so you can sub in vp = vr - i * vi, where vr is the real component of velocity, and vi is the imaginary component. So the term inside the Bessel function becomes:

(omega * r) / (vr - i * vi)

My thought was, what happens if you multiply the top and bottom by (vr + i * vi)? If I'm doing the math right, I get:

(omega * r * (vr + i * vi))/(vr^2 + vi^2)

The bottom term is just the square of the magnitude of the complex velocity, ie |vp|^2. Splitting things up a bit, and subbing in term |k| = omega/|vp| you get:

|k| * r * vr/|vp| + i * |k| * r * vi/|vp|

Basically, the left hand side looks just like the "k * r" term in the original formula multiplied by a term that is just the magnitude of the real over the magnitude of the complex velocities. The right hand side is just the imaginary version of the same. Now, |k|, vr, vi, and |vp| are all just constants based on the density, the static stiffness, the quality factor of the material, and the driving frequency of the system.

So, the Bessel functions appear to be in a form like this:

J0 ((A + i * B) *r)

The two big questions I have (other than have I made any obvious math errors so far?) are:

1. Are Bessel Functions distributive?

Ie, does J0 ((A + i * B) *r) = J0 (A*r) + J0 (i*B*r)?

2. Since the Modified Bessel Function (I), is represented as In(x)=(-1)^n * Jn(ix), can I then rewrite this all as: J0((A+i*B) * r) = J0 (A*r) + I0(B*r)?

If both of those are true, I may finally have figured this out. Can anyone shed any light on that?