Here’s the link.

As I said, very well worth the read, since it’s only 3pgs.  I think he may be working on a more detailed paper as part of a Master’s Thesis or PhD dissertation, though I could be misremembering.

And now back to continued light blogging.

May 25th, 2010, Mojave, CA, USA: XCOR Aerospace and Masten Space Systems, two of the leaders in the New Space sector, have announced a strategic business and technology relationship to pursue jointly the anticipated NASA sponsored unmanned lander projects. These automated lander programs are expected to serve as robotic test beds on Earth, on the lunar surface, Mars, near Earth objects and other interplanetary locales, helping NASA push the boundaries of technology and opening the solar system for future human exploration.

Masten’s award winning automated vertical take off, vertical landing (VTVL) flight vehicles combined with XCOR’s strong experience in liquid oxygen (LOX) / methane powered propulsion systems and nonflammable cryogenically compatible composite tanks, brings to NASA a powerful and competitive combination of innovative talent with a proven record of producing exceptional results quickly and affordably.

Last October, Masten won the $1 million first prize for Level II of NASA’s Lunar Lander Challenge, beating out a host of New Space rivals, and demonstrating they are the leading VTVL development group in the country. In 2007 XCOR Aerospace’s LOX/methane engine, developed for NASA, was named by Time Magazine as one of the “Inventions of the Year”, recognizing XCOR’s successive advancement in the state of the art of both pump and pressure fed reusable, throttle-able rocket propulsion systems. XCOR and Masten have also demonstrated the ability to rapidly take from concept to live fire, new propulsion and control system designs using innovative rapid prototyping techniques that surpass client requirements in much shorter periods of time than traditional aerospace methods.

Dave Masten, founder and President of Masten Space Systems commented “Masten Space and XCOR are next door neighbors here in Mojave. We’ve worked together on many tactical problems over the years and our corporate cultures mesh well. Working together on something like this simply made too much sense. We can’t wait to start working with Jeff, Dan, and the XCOR team to help NASA build affordable and responsive landing platforms.”

“Our company work ethic and styles are very compatible, and with XCOR propulsion and Masten VTVL technology, we can solve problems of national interest, and I am excited about the possibilities,” said Jeff Greason, CEO and Founder of XCOR.
Andrew Nelson, Chief Operating Officer of XCOR added, “It’s a no brainer, Dave’s team is the absolute best New Space company when it comes to VTVL and autopilot unmanned operations – they demonstrated that in October by winning NASA’s lander challenge. And we feel our LOX/methane engines are unsurpassed in the trade space today by anyone. We should bring this tandem set of best in class capabilities to NASA, it just makes sense for them and for us.”

XCOR and Masten will be jointly marketing their skill sets and services to the NASA community as prime contractors, and as joint teaming partners for larger systems integrators and prime contractors servicing the NASA community.

# # # # #

Masten Space Systems is a Mojave, CA based aerospace company developing fully reusable vertical takeoff, vertical landing (VTVL) launch vehicles, rocket-related products, and engineering services. The company’s 6000 square foot production facility and 200,000 square foot testing facility is located on the Mojave Air and Space Port. The company designs and builds aerospace solutions that focus on durability, long operational lifetimes, and minimal per-flight maintenance. For more information on the company see http://masten-space.com

XCOR Aerospace is a California corporation located in Mojave, California. The company is in the business of developing and producing safe, reliable and reusable rocket powered vehicles, propulsion systems, advanced non-flammable composites and other enabling technologies for responsive private space flight, scientific missions, upper atmospheric research, and small satellite launch to low earth orbit. The Lynx is a piloted, two seat, fully reusable, liquid rocket powered vehicle that takes off and lands horizontally. The Lynx production models (designated Lynx Mark II) are designed to be robust, multi-commercial mission vehicles capable of flying to 100+ km in altitude up to four times per day. XCOR’s web address is: www.xcor.com.

Contact:
Michael Mealling
Masten Space Systems
Phone: +1-888-488-8455 x102
Email: mmealling@masten-space.com

Mike Massee
XCOR Aerospace
Phone +1-661-824-4714 x127
Email: press@xcor.com

I can’t speak for the company, but personally I’m really glad we were able to find a way to make this partnership work. I’ve got nothing but respect for the XCOR team, and have been trying to find a way to work with them for years. As Jeff said at Space Access, it’s deals like this that show that the industry is starting to grow up.

This author, being intimately familiar with the forecast, can shed some light on that forecast. A common misconception about the study is that it forecasts the number of people who will actually fly. Instead, it forecasts the demand for space tourism based on the level of interest among the population of people with the means to pay for such flights. Realizing that demand is a separate issue (as can be seen in the delays in opening the even-larger market for suborbital space tourism.) The supply of vehicles that could serve the orbital space tourism market was dramatically affected by the Columbia accident and the concomitant policy changes. At the time the study was released the ISS was scheduled for completion by mid-decade, with an increase in the number of Soyuz flights, all of which could accommodate at least one commercial passenger. Delays in assembling the station and the planned retirement of the shuttle have all affected the number of seats available, and have kept prices high.

His next paragraphs also make the point that Space Tourism isn’t the only commercial human spaceflight market.

I’m not opposed to other markets, and in some ways have become a much bigger fan of propellants as an early RLV market, but I think the “case” against the commercial spaceflight market has always been a rather weak one.

Here is the humor slide I started out with:

We Don’t Need No Steeking Propellant Depots!

My actual presentation:

RLV Friendly Depots

Bernard Kutter’s presentation for ULA:

Near Term Depots

and Dallas Bienhoff’s presentation for Boeing:

Space Transportation Impedance Matching

I haven’t been given a copy of Rand’s presentation yet.

[Edit, here it is, Rand says he'll probably get some annotations up later]

Anyhow, a few quick random thoughts that I don’t think anyone else has really hit upon on the intarwebs:

• One of the concepts out of Dallas’s presentation I liked was the idea of having a space transfer tug that takes landers from EML1 (L2 would also work) to some perilune trajectory, and then returns to EML1.  I’ve been toying with variants of this idea for some time.  With a Centaur-sized trasnsfer tug, fully-tanked-up in EML-1/2, you can actually bring pretty darned big landers most of the way to the lunar surface (ie leaving 1000m/s or less of delta-V for the descent), while still having enough propellant to return to lunar orbit and from there to the L-point station.  That segment is probably one of the easiest in-space segments to start doing reusable stages, since you don’t need an aerobrake, and don’t have to deal with lunar dust, just propellant transfer, and lots of engine relights.
• In a conversation with Jeff Greason late one night at the conference, we got off onto the topic of RLVs and propellant depots.  One of Jeff’s opinions is that in order to really have an industry for some service, you need enough demand to allow for 2-3 healthy competitors.  With only one provider, you get monopolies, three is ideal.  But for RLVs you probably want a small fleet (~3 vehicles) of RLVs so that you can provide dependable service even if you either have a mishap or have to pull one of the vehicles for maintenance or repair.  Having a single vehicle may work during the development phase where you’re transitioning into operations, but once you’re in full operations, you want enough demand for 2-3 companies with probably 2-3 vehicles per year.  And for each of those vehicles, in order to get the per flight price in a really good range, you need to fly often–Jeff says 100 times per year, but I’ve heard numbers as low as 30-50 (but any way you slice it, it’s a lot of flights).  That comes out to somewhere in the 120-900 flights per year range.  The interesting thing that Jeff mentioned was that if you postulated very small RLVs to start with (say 300-500lb to LEO net payload capacity), just one lunar mission per year would be enough to provide enough demand for an entire healthy industry by itself.  Towards the lower ends of that scale, you’d only need one “soyuz around the moon” flight, or 1-3 GEO flights that used a propellant tank-up in LEO (say using a Falcon 1 with a mini-Raptor type LOX/LH2 upper stage?) to provide enough demand for at least the starting of an industry.
  • While 300-500lb to orbit sounds tiny, that’s actually a pretty reasonable size for a first-generation RLV.  The first stage doesn’t end up being that much bigger than existing or planned suborbital vehicles, doesn’t have to have much more capability either.  The upper stage ends up down in the middle of the size range for proposed suborbital vehicles.  While it has a much higher performance requirement, and much nastier reentry environment, it’s on a size that you can realistically work with a lot easier.  Also, a lot of the TPS work can be refined by flying “expendable” upper stages on these first generation commercial suborbital launchers.
  • This would definitely require the sort of RLV-friendly depot setup I described in my presentations–you’d have to have tugs that carry all the rendezvous/docking smarts, and keep the RLV-side of the propellant system as dumb as possible
  • Propellants are a much less demanding payload than people.  Not only does this keep up-front development costs down, but it also reduces the business risk if you happen to lose a vehicle occasionally.  While high flight-rate RLVs should be capable of high reliability, we’re also talking about 1st or 2nd generation systems here, where we’re still learning a lot–and learning can be painful.
• I also liked Bernard Kutter’s graphic of the simple, single-launch, dual-fluid depot concept.  This is a simpler version of the ideas Frank Z and I came up with last year (it uses a stock Centaur-sized tank for the LH2 side of the depot), but is still quite capable–on the order of 30mT capacity is nothing to sneeze at.  With one of those in LEO and one in L2, that’s actually enough to do an ESAS-capacity lunar transportation system without Heavy Lift.
  • One of the really interesting possibilities is that if something like this demonstrator depot were chosen as a part of the money Obama has proposed for orbital refueling technology demonstration (it wouldn’t need anywhere near the full $400M-1B that Obama mentioned per technology area), if the demo system worked, it would actually be operationally useful.  Sure, you’d want to replace it and/or upgrade it down the road with lessons learned, but I’m a fan of pressing technology demos into operational service, as that’s a good way to get a lot more data out of the deal.
• I also liked how Bernard explained a lot of the cryo storage issues.  A lot of this stuff still needs to be proven in space, but they (ULA, LM, and Boeing) have a lot more experience doing related tasks than most people realize.

I probably have some more thoughts on the matter, but I’m home at sick with a cold today, so I’ll leave it at that.

If it fails, commercial space people will switch back to “it was only a test” mode while to Ares-huggers, it will prove, prove, prove that all commercial vehicles (including those with existing proven track records) are all death traps. After all, imagine the national security risk of flying our astronauts on private launch vehicles! I mean, if we’re going to turn LEO crew transportation over to the private sector, we might as well all start learning Chinese and reading the little Red Book, cause them Commies are going to come and sap and impurify our precious bodily fluids.

Michael Mealling once quipped that it was far easier to take a business guy and get him interested in space, than it was to take an aerospace engineer, and somehow get him to understand business. I’ll admit to being firmly in the “aerospace engineer that’s trying to understand business” category myself, so I think having blogs like Colin’s out there is a trend I hope to see increasing over the years.

Oh, and welcome to the blogroll, Colin!

As far as implementing this idea, the technology isn’t the hard part. Technologically, this is something that could’ve been done in the 70s. Modern technology and modern launch services make it a whole lot easier and more feasible, but the technology isn’t the key obstacle. Money is and always has been the biggest obstacle. But I think I have an idea, and it’s just crazy enough that I want to share it.

Any business plan whose first step is “first we convince a billionaire to give us lots of money” usually deserves to be laughed off the stage. But this isn’t a business plan competition entry, or some pitch before VCs that I’m demanding to be taken seriously, so I’m going to suggest just that. Even with a wealthy philantrocapitalist, I think you’d still want a concept that both gives you a reasonable chance of making the money back if things go well as well as minimizing your losses if it doesn’t work out.

Anyhow, this is a bit of a long-shot, and definitely not fully-baked, but here’s what I have so far. The business case revolves around a few core concepts:

• A privately developed simple lander and an ITAR approved method for launching it on both US and domestic launchers.
• Using barter with various space agencies with domestic medium-lift vehicles to provide both the startup launches and the sustaining launches
• Making revenue off of selling remaining space to corporations, research institutions, and smaller countries that are interested in lunar experiments, but lack indigenous launch capabilities
• Possibly offsetting initial lander development by selling rover delivery services to NASA or other large space agencies.

Some of these sound a bit crazy, so why don’t I explain them in turn.

Private Landers
The key technology piece in the project is obviously the lander. As discussed before, I’m thinking of something in the 10-20klb IMLEO range, with a payload in the 4-6klb range. The propellant combination for the lander doesn’t hugely matter. It could use storables like Martijn likes, it could use space storables like LOX/Methane or LOX/Propane. Heck, it could even use LOX/LH2. While the state of the VTVL industry isn’t quite mature enough where you could just order one of these custom and have it delivered to your launch pad 6 months ARO, a lander in these capability ranges isn’t a huge stretch for the commercial space industry, especially if they can partner wisely with some of the more traditional space companies or work with NASA via Space Acts. DC-X was actually a much bigger, probably more complicated system, and was done by a traditional aerospace company for around $100M in current dollars. A bare-bones lander, developed leveraging the emerging capabilities in the entrepreneurial community could probably be fielded for less than that. Possibly in the $50M range. You don’t need to push too hard on mass fractions or engine performance (you need to push a bit, but it isn’t as weight critical as some of the Apollo LM systems), and the technology is a lot more mature than it was in the 60s.

An important part of this process is not just developing the lander, but also working from the start with ITAR to make sure a process is in place that will allow you to launch on as many international launch vehicles as is feasible. This may not be fun, but is probably doable with appropriate precautions.

International Horse-Trading
Most space agencies prefer to spend money within their own borders, and interact with other agencies on a barter basis as much as possible. While this can sometimes lead to suboptimal solutions, it might just work in this situation. On the launch side, the barter would go something like this–the private entity would provide a lander, all lander ops, and physical launch integration work, and the space agency (NASA, ESA, RSA, JAXA, ISRO, or CNSA) would provide the lifter and upper stage for the mission. The launching country would get a certain share of the lander’s cargo space for their own experiments, a certain portion would be reserved for consumables and spare parts, and the remainder would be owned by the private entity to resell to other countries without launch capabilities (say a 40/40/20 split). In addition to transportation of the space hardware, the launching country would also get a share of the astronaut’s time on the surface. So basically you’re providing them with transportation and manned experimentation on the lunar surface in exchange for them providing a launch done by their own people. If one of the countries is willing to take some additional risks, they could even “buy” one of the two initial astronaut slots, in exchange say for a commitment to a certain higher share of the logistics launches per year. In exchange they’d get both the prestige of having one of the initial lunar crew, as well as a higher share in the available time. Over time, as the risk decreases, the initial crew could also be expanded (once again on barter terms that would have the agency in question shouldering a larger share of the required launches).

It should be mentioned how crazy of a bargain this really is for them in comparison to the typical lunar mission approach. Look at Constellation. It will be a lot more capable, but ultimately, somewhere around $10B/yr (and about $150B up-front), you get 4-person years/yr (2x 4-man crew rotations) and about 75klb of cargo (2x 17mT landings) on the moon once you have a base setup. Calling it a 60/40 split on costs (for manned vs cargo flights), that comes out to $1.5B per person-year, and about $53k/lb on the lunar surface–ignoring development costs. With a program like this, say you gave a country 1/4 of a man-year per launch, and about 1800lb, at a cost to them of call it a $200M launcher plus extra upper stage for the transfer. Splitting that $200M the same way (60/40), that gives you $480M per person year, and about $45k/lb on the surface. You don’t save a huge amount per pound of cargo on the surface, but your cost per person hour is about 1/4 as much (which is once again not too surprising–you’re not rotating crews, and not having to carry enough propellant to get them home–which takes about 4x as much mass per mission compared to a one-way manned landing). And you don’t have to spend tens of billions up-front, and you can buy your lunar program “by-the-slice”. Paying for an extra launch every year (and some lunar systems costs) is well within the budget capabilities of many of these agencies. While they might not be willing to take the risk of flying their own astronauts, or of “owning” the program, they are a lot more likely to be interested in a program like this, where someone else is shouldering the key risks, and they’re just getting a cheap deal. Even if they have their own lunar ambitions down the road, using a service like this would allow them to drastically reduce their technological risk moving forward, and might allow them to get a lot more benefit out of their investment when they eventually get that capability themselves.

“Sovereign Customers”
One of the key markets Bigelow is looking at for his inflatable space habitats is providing smaller countries with a way to participate in space for much cheaper than trying to do everything in-house themselves. By lowering the cost to participate, it makes it a lot more feasible for smaller countries, and even some corporations or research institutions to participate. This may be a country like South Korea wanting to send a rover that can get maintained by the astronauts over time. It may be a country wanting to do its own sample return mission–with the ability to have a human on the ground helping to presort/preprocess samples to maximize the bang for the buck. It could be a company like Catepillar that wants to get involved in lunar surface systems for future exploration programs sending a bunch of bearing concepts to test exposed to the lunar environment. It could be some small startup that has a crazy idea for lunar dust mitigation that it wants to try selling to future government programs, but needs testing and debugging first. There are many possibilities. The key here is that since the launch is already paid for, the private entity running all this can price the payloads however makes the most sense. You do need to cover lander costs, ground-ops costs, and the time of the scientists, but it might be possible to offer these slots at a price that is lower than they could buy commercially to try and stimulate demand, or if there is enough demand already you could price it high enough to make a decent profit. If there’s enough demand, you might even be able to justify paying for an additional “purely commercial” flight or two per year. You would want to save up some of the money to cover contingencies–like if something breaks down and you have to fly an emergency resupply flight on short notice, or if you decide for one reason or another to throw-in-the-towel after a few years, you can send enough propellant to get the settlers home. But depending on the interest level, this could easily be a business that has revenues in the low hundreds of millions per year.

Minimizing the Initial Risk
One additional market for the lander, and one that could allow the initial investment to be recovered a lot faster, would be to see if you could sell it to one of the space agencies for landing a rover or some other scientific package. The key here is that the lander is getting developed, on the philantrocapitalist’s own dime regardless of if he can presell any lander slots. This makes it easier to sell it as a commercially available service instead of a government funded development program. Using a light Atlas vehicle for instance (maybe with one or two strapons) you could probably short-load the vehicle enough to put a couple hundred pounds of useable payload onto the lunar surface. For a bundled price of say $200-250M for the launcher and lander, it would still be a steal transportation-wise for your customer, but could possibly pay off the initial costs of the project in one shot, even before the initial landings. The good news is that while its great if you can presell the landers for other applications, it isn’t the end of the world if you can’t.

One other way of minimizing the downside may be to see if you can prearrange the initial several launches. If you can line up enough international partners, it may be possible to get the initial setup done without having to actually buy any of the launches yourself. You’d still have to pay for the landers, but this way your total capital at risk for the startup is only the cost of 3-4 landers.

Anyhow, comments? thoughts? attempts to send nice young men in their clean white jackets to cart a certain space blogger away?

Let’s turn to the Augustine Report itself for some information. On pages 83 and 84 they discuss implementing the Program of Record on entirely unconstrained budgets–ie if we gave the program the full funding it needs to execute, and allot it to move at the full pace it can realistically move at, what do we get?

• A $145B pricetag over the 2010-2020 timeframe, which doesn’t even get us to the point of having Ares V and the LSAM ready for operations, much less a moonbase.  This would require almost $5B extra per year–ie a 25% increase in NASA’s topline budget.
• An international space station deorbited within 5 years of its completion, during which time the only method of access would be by paying the Russian government for flights.
• A crew launch vehicle that becomes available two years after its first destination is deorbited, and whose operational costs have to be carried for over half a decade until we have any of the tools that would be necessary to actually use it for anything.  But don’t worry, we can spend $2B+ per year to send even fewer astronauts flying in even more useless circles.
• A seven plus year manned orbital spaceflight gap in the US.
• Almost no investment in long-term technology development (not much more than the current SBIR budget, and entirely focused on short-term Constellation needs, not on making future missions safer, more affordable, and more valuable).
• No stimulation of commercial industry beyond the CRS contracts which wouldn’t be extended since the ISS would be gone by 2016.  No investment or early market for commercial crew delivery
• No money to actually develop hardware for actually doing anything on the Moon, since almost all of the money will go to figuring out how to go there while maximizing employment in Shelbyville.
• No more robotic orbiters or landers for years to follow-up on the work LCROSS did.

But hey, at least if we do it this way, sometime 15+ years from now, we’ll have the ability to send 8 people to the moon every year at the cost of an “exploration” program that costs almost as much per year as NASA’s entire current budget!

If you assume that there are parts of NASA outside of Huntsville that actually matter (ie that NASA != Northern Alabama Space Administration), the situation gets even worse.  In order to fund Constellation at full speed without splashing the space station almost as soon as it’s completed, you would need $159B over that timeframe, which constitutes a $7B per year increase for NASA.  That increase still:

• Gets you a space station you can’t access without the Russians for most of its operational lifetime (why does Congress trust Russian commercial space more than American commercial space, btw?).
• Gets you no real investment in long-term technologies, ensuring that the cost, safety, and efficiency of manned spaceflight will be stagnant for another couple decades.
• Gets you no real investment or encouragement of the commercial industry (in direct contravention of the laws of the land and NASA’s charter I might mention).
• Gets you no more robotic follow-ons for LRO and LCROSS for over 15 years.

Compare this with the Flexible Path option that Mark likes to mock so much.  For less than half as much of an increase per year, you get:

• Robust ISS utilization through 2020, with multiple methods of providing crew and cargo delivery that aren’t all dependent on Russia
• Investments in commercial space that can help keep the US in the forefront of space technology and utilization
• Robust investments in high-payoff medium-term technologies like propellant depots, space radiation, space nuclear power, aerocapture and other EDL techniques, ISRU, and other high-payoff technologies that can vastly lower the cost of future exploration missions, allowing us to accomplish more for less and at lower risk.
• A manned lunar landing program that at most is only 3-4 years behind the current PoR, but when it gets there, it provides a much more affordable, more commercially and internationally interesting program, and has much greater capabilities once you get there.
• A manned spaceflight program that is much more capable of exploring the whole inner solar system, and not just doing a few flags and footprints landing on the Moon.
• A manned spaceflight program that builds on and leverages our impressive achievements in robotic space exploration.
• A program that in spite of doing a lot more looking, also allows a lot more touching of new destinations like NEOs and Phobos/Deimos, all on about the same timeframe that the PoR would at best be going for its first lunar landings.

Where I come from, we tend to think that getting a heck of a lot less while paying a heck of a lot more is usually the sign of a sucker.  I just wish that a few space pundits and public figures didn’t keep enabling Senator Shelby and his ilk from hijacking NASA’s budget to enrich his campaign contributors at the rest of our expense.

[Note: As an aside, am I the only one who finds Shelby's latest childish tantrum accusing the Augustine Committee of being compromised by biased by evil commercial lobbyists to be richly and hilariously ironic?  When it comes to lecturing people about the evils of lobbyists corrupting the political process for their own personal gain, Senator Shelby has about as much moral standing as Tiger Woods does when it comes to lecturing people about marital fidelity.]

To me one of the more interesting points is found at the top of page 11.  There were several misleading statements made by several people today about the relative safety of Ares-I compared to commercial crew vehicles.  As Brett put it (my emphasis added):

Second, some have claimed that NASA’s Exploration Systems Architecture Study (ESAS) shows that the current exploration vehicles are safer than commercial crew vehicles. In actuality, commercial crew vehicles were never even analyzed in the ESAS report – the ESAS report only looked at vehicles large enough to carry Orion, such as Ares I and variants of the triple-core Delta IV Heavy, and did not examine the smaller, simple, single-core vehicles, such as Atlas V Medium and Falcon 9 Medium that are sufficiently sized for commercial crew missions.  Moreover, even if ESAS had compared exploration vehicles to commercial crew-sized vehicles, the comparisons would be “apples vs. oranges,” because of the dramatically different tasks of these two types of vehicles.

When Jeff Hanley talks about how the Great Oz and supercomputers at NASA show that Ares-I is 3x safer than commercial launch vehicles, I wonder if he’s ever going to release their analyses for actually commercial crew vehicles, or if he’s being accidentally or intentionally dishonest. Because so far we haven’t been shown any data about the safety of actual commercial crew launchers. So far we have lots of data shown for the risks of using existing or modified commercial launch vehicles for launching a massive spacecraft designed to go to and return from the moon, including significant plane change maneuvers to allow anytime returns (ie Orion). It’s interesting to note that over half of the mass on Orion is the oversized launch escape system needed to get away from an SRB you can’t shutoff, and enough propellant for about 1500m/s of maneuvering to reach orbit and then to do in-space ops. That’s above and beyond the RCS propellant on the CM itself.

Most of the stuff that make Orion so massive are flat-out completely unnecessary for an earth-to-LEO crew capsule. You don’t need those kinds of delta-V capabilities. You don’t need as roomy of facilities, since by definition the flight times should be a lot shorter. Etc. There’s a reason why almost all of the proposed commercial crew systems are able to utilize single-stick launchers like Atlas V or Falcon 9–for an actual earth-to-LEO capsule you really don’t need anything bigger.

This realization that earth to LEO capsules can be much smaller than Orion leads to at least two important corollaries that I can think of:

1. Smaller capsules mean higher structural margins.  One of the existing vehicles most often suggested for commercial crew, Atlas V, was designed for the worst-case loading environment of any of its configurations (in this case I believe that would be the Atlas V 551 or 552).  The Atlas V 552 sees much higher max-Q’s than the 401/402 do, and has a much heavier payload on top, which exerts much larger structural loads on the Centaur stage than are seen in the 401/402 configuration.  While the Centaur structures may not meet the 1.4 magic number NASA likes in some of the bigger configurations, as I understand it, it actually exceeds that number in the 401/402 config most likely used for commercial applications.  The Falcon 9 was designed from the start to meet NASA structural margin specs.
2. No need for strapons.  Only one of the commercial crew ideas I’ve seen so far used a vehicle with strapons for crew launch (Dreamchaser).  This alone should make a huge difference in launcher reliability, since there are less things that can go wrong, less staging events, etc.  Most of the commercial launcher ideas they mentioned in ESAS assumed multi-core configurations.

There’s also the possiblity on the Atlas-V of using a dual-engine Centaur configuration to allow for some upper stage engine-out capability, or running the RL-10 at a derated performance level (not sure if that’s something it can do automatically, or if you’d have to make modifications–if you have to modify it it probably isn’t worth it).  With the much lower max-Q, and the ability to shut off the booster engine in case of an abort, I have a hard time believing that Ares-I is really that much more reliable than an actual commercial crew capsule launched on a commercial launch vehicle that has dozens of flights under its belt.

Food for thought.

Drop Tanks to Enable SSTO?
I don’t like drop tanks. While they do definitely make the rest of the SSTO easier, they come with several significant drawbacks:

1. Large expendable hardware on an otherwise RLV somewhat misses the point.  While rocket tanks are relative cheap compared to the rest of the stage, they’re still pretty expensive compared to the propellant cost, or even the likely maintenance cost of the rest of the vehicle.
2. Dropping stuff on people is usually considered somewhat anti-social.  That means you’re stuck launching over water like the ELVs (there might be one or two over land paths where the drop zone would be in a safely unpopulated area that isn’t a national park, but it’s unlikely).  Launching overwater means aborts have a much higher chance of costing you the launch vehicle.  It also likely limits you to existing ranges, and ties you in with their practices that may not be very conducive to RLV operations.
3. You still get some of the drawbacks of TSTOs.  You still have to design and analyze two vehicles instead of one.  You still have to design and analyze a separation system.  You still have to integrate two stages together at the pad instead of dealing with just one.  You still have to figure out how you handle aborts (if possible) while the drop tank is on.
4. Drop tanks reduce the “fluffiness” of the orbiter stage, which may complicate reentry TPS considerations (though maybe not enough to matter).
5. The dry weight to orbit savings might not be as much as you think.  Propellant tanks are pretty lightweight for pump-fed vehicles.  Mechanical connections, separation systems, plumbing, pressurization systems, quick disconnects all add quite a bit of mass.   How much mass do you really save compared to just building slightly bigger tanks on the SSTO side?
6. Drop tanks probably complicate the aerodynamics.  If you have one drop tank, you now have something like a Biamese vehicle (I’ll get to those in a minute), which has much more complicated aerodynamics, harder abort environments, etc.  If you go with a lot of smaller tanks, the aerodynamics becomes easier, but your scar weight to structures, plumbing, etc becomes a lot heavier.

That’s not saying they don’t have some advantages.  Any reduction in dry mass can go a long way towards making an SSTO shift from marginally infeasible to marginally feasible.  Expendable tanks can be designed to lower safety factors since they don’t need to consider fatigue issues like RLV tanks do.  Less dry mass means a lighter landing weight, which decreases the amount of landing propellants required and the weight of landing gear (or the wing and landing gear weight if you’re doing an HTHL design).

It’s not that they don’t have advantages, but the disadvantages are enough that I’m not convinced it pays for itself.

Biamese or Parallel Staged TSTOs
Even though my boss Dave is fan of Biamese approaches, I’ve never been.  He gives me crap about far-out stuff like FLOC, I give him crap about Biamese.

While once again there are enough benefits for Biamese vehicles to make them sound interesting, I think the drawbacks once again win out:

1. The engines have to be able to operate from launch altitude all the way to vacuum.  While altitude compensation can often help TSTO RLV designs, and while there are some techniques like TAN and Flow Separation Control that might make it easier to have an engine operating over that wide of a regime, you’re still making some pretty big compromises to both stages (or you’re making compromises to the biamese concept and losing some of the benefits).  The upper stage now has to have far more thrust than it would’ve wanted anyway.  That means more weight that the upper stage didn’t need.  It also needs some way of operating its space-rated engines at low altitudes.  This means altitude compensation (which tends to be heavy and complicated), high pressures (which makes the engine harder to develop and more complicated, or something like TAN or Flow Separation Control, which it might not have otherwise needed.  If the booster and upper stage engines are the same (as they would be in a purist Biamese design), the booster engines now have to have a much higher expansion ratio than they would have otherwise.  Once again this leads to higher pressures or other complications that they might not have needed otherwise.
2. A nearly 50/50 mass split is not very optimal for staging.  Especially when you figure in that the first stage wants to get back to the launch site.  It isn’t heinously bad, but it does mean you end up having moderately high delta-V requirements on both stages (since the first stage is likely going to be far enough downrange that you’ll need to do some sort of boostback).
3. TPS requirements for the two stages are vastly different.  For a purist Biamese vehicle this means the booster is lugging around a lot of weight and complexity it really doesn’t need.
4. If you don’t do a purist Biamese design (where the two stages are really identical and interchangeable), you’re back to designing two separate stages, but now with all sorts of unneccessary constraints.  The more divergences you make to simplify things (like going with a lower expansion ratio on the booster stage, or going with a lighter TPS on the booster stage), the more the two designs become different, and the more and more you start losing any real benefit from the process.
5. Parallel staged vehicles have uglier aerodynamics.  Aerodynamic design and analysis for supersonic vehicles can be very complicated and expensive.  I’ve never seen a TSTO Biamese design that didn’t look like it would be a bear to analyze and design the control system for.
6. Biamese RLVs tend to lead to compromised structural design.  Rocket vehicles are most weight efficient (and easiest to design and fabricate) when they are bodies of revolution.  In order to get good mechanical connections, most Biamese vehicles I’ve seen end up being lifting bodies, which starts driving either really weird propellant tank shapes (with added weight and fabrication complexity) or really inefficient structures (where the propellant tanks fit inside a more complicated shell.
7. Because of the different operating modes of the stages, you’re really stuck still designing and analyzing three different vehicles (the two together, the first stage independently and the upper stage), not just one stage.
8. You do potentially reduce the number of engines you need to make, and may allow you to design some subsystems only once, but now they’re being designed to meet more constraints.  Many times it’s easier to design two slightly different subsystems with 10 constraints each than one with 15.  You can still reuse a lot of the design and analysis work if you do things right, but each of the two designs are easier.

I guess to me it boils down to the fact that jacks of all trades really tend to be compromised kludges by the time they make it into operations.  In a Biamese system, both stages are carrying stuff they don’t need, and are being designed to more constraints than were necessary.  I really don’t see how that will lead to a cheaper system than one that has the two stages scaled the way that performance and operations want them to scale, and that can be more custom-suited for the task they’re being asked to perform.  Hybrids tend to give you the worst of both worlds.

Sea Dragon
For those of you not familiar with this concept, the Sea Dragon was an old Aerojet design by Bob Truax for putting 1,000,000lb of payload into orbit on a single TSTO launch vehicle (whose first stage might be recoverable). The design was a Big Dumb Booster, with pressure fed tanks made of maraging steels, built more like a submarine than a rocket vehicle. The first stage engine would’ve been something like 70x higher thrust than the F-1 engine on the Saturn-V. You can get more details here.

I’m a tiny bit more torn on this one than the others, but I still think it makes sense in today’s world.  It might make sense at some future date, but not right now.

Here’s my big concerns:

1. Where’s the demand?  I don’t think we currently as a species launch a million lb or payload into orbit in a year.  Until other systems like RLVs get the cost down and the flight rate up there’s never going to be enough demand for more than one or maybe two of these per year.  While the marginal cost of one of these would be pretty low, the fixed costs and development costs aren’t going to be trivial, and they have to be amortized over those flights, cutting into any cost advantage the design might have.  Now, if RLVs do get the cost down to the point where you start having enough demand where Sea Dragon could make sense, you run into a different problem–the Sea Dragon is no longer competing against expensive existing ELVs, it would be competing against RLVs.  Sea Dragon may get stuck only launching payloads where the integration costs of launching them separately and putting them together in orbit outweigh the cost diffrence between the two.  Now, we live in a world where even though most stuff gets shipped in tiny intermodal containers, there are still Super Guppies and Belugas that get used occasionally.  In an RLV centric world, there may still be situations where a Super Heavy Launch Vehicle might be useful enough frequent enough to justify its existence.  But we’re nowhere near that point in time.
2. What’s it going to be like developing and testing a 70 Mlbf rocket engine?  Pintles are a pretty cool, pretty scalable combustion system, but will they really scale up to something 70x bigger than has ever been built before?  We have no idea what unknowns lurk between here and there.  Maybe pintles will turn out to work fine without any problems, but we’re pushing far past what has ever been done in the past.   But pintles tend to get worse c* as they scale up, will they still have adequate performance at those scales?  Nobody knows, and nobody will know until they start.  That’s scary.
3. Testing an engine this big is going to be mindbogglingly expensive as well.  Every second the engine would be going through about 5 Falcon-1’s worth of propellant.  That’s only $110k/s of propellant (the upper stage uses much more expensive propellants, so even though it’s only 8Mlbf, it’s still likely going to cost a lot), but that’s not counting anything else.  You’re talking about $25M per full-duration burn test.  With how expensive the payloads would likely be for a vehicle this big (see below), you’re likely going to need to do a lot of tests.  Just the injector testing alone for something like this would likely run you into the $1B+ range.  If you did even a fraction of the number of runs typically done in a rocket engine project, you’d be talking about billions of dollars up front.  And where are you going to test a monster that big?  You’d pretty much have to do it out at sea a long ways.  How are you going to vacuum test an engine the size of the upper stage engine?  I guess you can get away with not doing the full nozzle extension tests, but that’s still putting a lot of risk into the first few flights.
4. Development costs would be insane.   Between testing the huge engines, and doing at least one or two flight tests, you’re likely talking several billion dollars to develop–if it’s done on a commercial basis!  The marginal cost of one of these things in 2009 dollars is likely going to be in the $1B range, so that starts adding up fast.  It’ll be a long time before there’s enough demand to justify putting up that kind of money.
5. Payload costs per launch would likely be very high.  While I full-heartedly agree that relaxing mass constraints can reduce the cost of space payloads, it’s only one part of the cost involved.  Being able to go with welded steel and an FOS of 3 may reduce some design and fabrication costs a lot, you’ve still got the fact that unless you’re launching bulk commodities, you’re designing hardware that has to operate in a very harsh environment, that still needs to be fairly complex, and which very few will be built.  People talk about stuff like being able to launch an ISS in a single launch.  While avoiding all of the EVAs and integration stuff would take a lot of work out of ISS, you’d still be talking about a several billion dollar payload.  How would you get launch insurance?  How often can you afford to fly a vehicle that costs $500M-1B to launch and has payloads that will tend to cost several times more?

Unlike the other two ideas, I’m not convinced that super heavy launch vehicles will never have a place in the rocket world.  I’m just not convinced we’re even within visual range of such a time where they make sense.  We’re still back not too far past the Wright Flyer stage of launch vehicle design.  We’re nowhere near the point where a Beluga or Super Guppy makes sense.