On Bonin’s ‘The case for smaller launch vehicles in human space exploration (part 1)’

Howdy All, Ken here. I just decided to weigh in a bit on an interesting article today. (and provide a bit more grist for Jon’s mill)

Over at the The Space Review, Mr. Grant Bonin visits the question “are heavy-lift launch vehicles the best technology for opening space to humankind?”. While I personally feel the question should have been something more along the lines of ‘Are HLLVs the right technology right now for opening space to all of humankind?’, I’m not going to pick nits. 😉

M. Bonin then sets out two goals:
1) to dispel the belief that HLLV is an economic necessity for human spaceflight; and
2) to demonstrate the feasibility (both technically and economically) of undertaking human space exploration beyond low Earth orbit using existing, more modest launch systems.

This is quite a chore, and he gives himself two parts to answer it, so we’ll see what unfolds next week.

In this week’s part, he jumps right in to the the ideas of Payload Fraction (payload as total % of mass of vehicle) and mass-to-orbit (where it’s generally assumed in spite of decades of miniaturization and industrial advances that it will nevertheless require hundreds of tonnes to do anything [ which is true to some extent, but…]).

In both cases the larger lifts seem to carry the day. But that’s only on a very superficial and first blush basis. Luckily, this is why we have folks like trained investment bankers, who look at things from an entirely different perspective from aerospace engineers. M. Bonin cites Ed Wright’s [not an investment banker] Ad Astra article and one of its contentions, that optimizing mass-fraction alone does not necessarily lead to a more cost effective system, as most of the lift-off weight is propellant, and fixed infrastructure and labor-hours are what really chew up the budget. It would require far more than two launches per year to even come close to making an argument that an HLLV is cost-effective. He (Mr. Bonin) also notes that the complexity of the big honkin’ rockets makes them harder to get off the ground in the first place. I’m not so sure about the analogy with the model rockets. I seem to remember an earlier post about how many Falcons, Atlases and Deltas could be flown before the first HLLV gets off the ground, and the huge amount of mass that would already be in orbit before the first Longfellow flew..

I’ve long been an advocate of high volume to orbit, but in conjunction with high frequency. Getting 100 tonnes to orbit at one time hasn’t been conclusively proven to me to be the most strategically effective way of doing it. What if the materials scientists and private consortiums need access to orbit more than twice a year? How is this thing going to serve access to the ISS?

(Answer: It’s not supposed to. It’s supposed to be a disposable means of conveying a few NASAnauts to the Moon to do a couple of practice runs for Mars. When I say a couple I do not mean a lot. Maybe 3)

M. Bonin also makes note of the learning effect. When someone does something a lot they tend to get very good at it, and figure out the thumbnail rules and shortcuts (oops, I mean procedural efficiencies…yeah, that’s it). This helps to bring overall costs down, and makes for a better overall launch experience.

While citing some economic arguments, M. Bonin fails, as so often do aerospace engineer economists, to take the economic and financial considerations deeper and start applying them to what companies actually face out in the real world. Other things than your standard cost-of-capital and value-to-shareholder buzzwords.

Look at the insurance. There’s no way to gather the risk pool sufficient to cover all of the small payloads of small companies that would be aggregated into such a behemoth. Even on larger payloads, like Bigelow’s Nautilus balloons, there’s no way anyone would launch four at the same time. This means you still need freight aggregation services to get full use out of the payload capability. Again, you run into the problem of gathering a sufficient risk pool to cover the potential losses in event of a failure.

And there will be failure. Just because a rocket is as big and complex as the Saturn V does not mean it will have the flight record of the Saturn V. It is, however, doable to get a risk pool together for a single EELV launch or some kind of RLV.

The whole point is mass production. Whether that mass number of flights is done by a boatload of cheap disposable rockets (and they will be cheap once we start using them in number) or by a whole bunch of RLV flights is something to which I’m indifferent. If the RLV guys can come up with something I’ll get behind them (and I’m more optimistic than I used to be), but I know we’ve got a bunch of 20 mt to ISS lift capability that is desperate to be used.

If NASA uses the same launch systems as everyone else, then each successive launch will be cheaper for everyone. If NASA continues to be supplied with its own private launch system, then the taxpayers will continue to have to foot the bill for inefficient and ultimately ineffective access to orbit. Besides, if NASA uses the same rockets as everyone else then when a rocket goes boom (which it will) who do you think is going to get blamed? NASA? No way, it’ll be the launch vehicle manufacturer. There’s a benefit if I ever saw one.

There’s also the question of launch risk. Is it really risk effective to put all of one’s eggs in a single basket? Business teaches us no, it’s not. It is better to spread the risk amongst a number of launches so that any individual failure does not compromise the entire investment. Business is more likely to go with the 11th launch with a 9 out of 10 success record (and only lofting 20mt of assets), than the 3rd launch of a 2 for 2 vehicle hauling 100mt of assets.

Also, I don’t understand why there seems to be an assumption that any launches to the Moon require a free-space rendezvous and direct return from Lunar orbit. This seems to have a built-in implicit assumption that the proposed ESAS HLLV will really have nothing to do with the ISS, nor the ISS anything to do with a return to our Moon. To me this is silly as we have a space platform with at least one robotic arm (I’m not sure what ever happened with the German one). With a facility in orbit you have less of a sense of urgency of getting everything together to go quick, and one can re-think the launch sequence as well as double and triple check all systems post-launch (THE single most traumatic period of any payload’s life).

We need to get lots of skilled people into space to do skilled-people things like make better products (materials science) or increase the efficiency (combustion science) of stuff here on Earth.

Hypothetical question: What if every single rotary machine on Earth used perfectly spherical, space produced ball bearings? What would be the decrease in energy required to operate each machine? What would be the aggregate of that? And the corresponding intangible benefit of less pollution from energy production?

This is of course complete fantasy, but the point is that there is so much unknown business opportunity in space it’s mind-boggling, and this is the kind of opportunity that used to excite the American spirit. Tumlinson’s “Return to the Moon” attempts to be a manifesto in this regard, but falls a bit short, I feel. It is in the right spirit, though, and this is important for our country.

Nevertheless, the idea of commerce and industry in space, fields in which the U.S. has a competitive advantage, needs wider acceptance. Investing our nation’s capital and resources in a private launch vehicle for NASA, which serves no other interests, is in my view a dead end for NASA and a dead end for the American space industry. We can’t afford this kind of investment right now, but we can afford to do it in small bite-size pieces. If we’ve got three launch vehicles and each can launch 4x per year, then we have a launch per month, and 240 mt in orbit per year. (Wait, but that’s what the HLLV is going to do 8 years from now…)

That’s not half-bad, and we know we can scale up from there. The Boeing facility is supposed to be capable of something like 40 cores per year or 14 launches just of the D-IV. The Falcon’s supposed to be cheap and easy so we should be able to launch water or expendable cargo at least once a month on that one. Give Atlas half a dozen per year and you’re talking about 30 launches per year, or 600mt to orbit per year at full speed. 2 or 3 launches per month is not a burdensome task for a smaller rocket, especially if different facilities are used.

Isakowitz doesn’t really give us any insight into the launch costs of the vehicles (prices negotiable), but I’ll assume $250Mn for the D4, $200Mn for the A5, and $25Mn for the F9. That’s (14×250)+(6×200)+(12×25)=3,500+1,200+300 = $5.0Bn for 600mt. There’s no way HLLV is going to be cheaper than that. Even at $100Mn per Falcon 9 that’s still less than $6.0Bn.

And the thing is, once you ramp up to that level of production, per-unit costs start coming down, which means that after a couple of years the D4s are down to $150Mn, A5s are $75-100Mn, and F9s are the Bic lighters of space. Okay, maybe a bit optimistic, but don’t be bamboozled by the NASA finesse. They could be applying their skills towards 20mt Moon machines, or international interface standards (now that’s useful!) for space vehicles instead of fussing over launch systems. NASA asked itself the question of whether it should be in the business of flying airplanes around. In most cases the answer was no. Should NASA be in the launch vehicle business? (Or provide engineering insight like they do with aircraft…)

Follow-up:

There has been a bit of discussion about the article on the internet (Space Politics, Transterrestrial Musings and the Space.com Uplink)

Some folks seem to be fixating on the ‘Proximity Ops’ issue as a killer for the deal, as if each and every thing that has to meet up with something else in space has to have a complete set of maneuvering devices and complicated and heavy equipment and you’re sacrificing payload on an already tight 20mt limit and…

They seem to forget that this issue has already been looked at and the answer is tugboats and robot arms. You launch something near the ISS. A tugboat runs out and fetches it. The arm attaches it to the station or something else. The tugboat can also be used for releasing/retrieving free-flyers, ferrying s/c over to the fuel depot, and so forth.

This doesn’t need to be a complicated machine. It doesn’t even need to be pretty or aerodynamic. Just capable of moving stuff around in orbit. It’s been variously called an OTV or OMV over the years. It’s also a craft that would be functional at an L-1 station as well, so it’s not just a mono-purpose or mono-location vehicle.

It’s also the kind of design challenge that would likely excite more kids than updating their grand-dad’s Apollo.

It’s been said that NASA needs a serious infusion of young talent and fresh ideas. Perhaps this project is the catharsis that will have this infusion inflicted upon them…

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21 Responses to On Bonin’s ‘The case for smaller launch vehicles in human space exploration (part 1)’

  1. Big D says:

    Is the ISS high-inclination orbit worth going to, though? Or is it better to launch a tug that has its own arm into a better orbit?

  2. Paul Dietz says:

    What if every single rotary machine on Earth used perfectly spherical, space produced ball bearings?

    Is there any evidence that space-produced ball bearings will be significantly more spherical than best grade terrestrial ball bearings? You can get ‘grade 3’ bearings now, which are spherical to within less than 100 nanometers (compare this to the grain size of steel, typically measured in microns.) Of course most applications don’t use such precise balls, since there’s no economic case for doing so.

    High performance ball bearings are now going to materials like silicon nitride (lower density, lower grain size, wears similar to steel), which can’t be cast in microgravity at all, since it doesn’t melt. The SSMEs use SiN ball bearings, IIRC (or some similar ceramic, with Al and O as well).

  3. Anonymous says:

    My biggest concern about a lot of little flights is the natural complacency that every organization suffers over time, doing the same thing over and over again. Even NASA has shown it too suffers this problem. Until there is a cure for this ill, perhaps a few flights a year is the best solution.

  4. Anonymous says:

    I don’t buy the “if we do it too much we’ll get complacent” argument. We fly thousands of commercial aircraft a day. There is no call to fly less due to complacency-caused accidents. If we flew 6 747s a year, there would be a much higher percentage of accidents.

    The comparison is not completely valid, but I believe it to be illuminating.

  5. Jon Goff says:

    Big D,
    I’m not sure. Personally, I’d rather use something in an easier to reach orbit like 23.8ish, or equatorial if we had a good near equatorial site to launch from. However, once you’re up there the cost to do a plane change on the way to the moon is actually quite minor AIUI. So it’s not an obviously broken idea. But once there’s any sort of private space station out there, it’s going to look rather silly to still use the ISS.
    ~Jon

  6. Jon Goff says:

    Paul,
    The more perfect ball bearings idea has never set particularly well with me either. However, if it would allow the equivalence of grade 3 bearings at prices not much higher than you can get a cheapo rollerblade bearing…

    But that’d only happen if there was enough space traffic for transportation costs to go way down. I think that for space manufacturing, there are other, much more profitable markets that are likely to get tapped first. But all of them depend on regular, low-hassle, reliable, and lower-cost transportation.
    ~Jon

  7. Jon Goff says:

    anonymous,
    Lots of little flights doesn’t neccessarily make a company complacent. Take a look at Southwest airlines. They fly a bunch of smaller planes, and probably fly more frequently than many of the other airlines (especially on the routes they actually fly). Yet they still have a near perfect safety record. If your company has a good safety culture, and follows good safety practices, and designs vehicles that with safety in mind (instead of with spreading as much pork around as possible in mind), you can have high flight rates with high safety.

    In most human endeavors, doing something more makes it safer, not more dangerous.

  8. mz says:

    Please use “t” or “1000 kg” or something else, your “mt” is a misunderstanding of the metric system. (meaning milliton, aka kilogram).

    This habit is spreading and it just plain wrong.

  9. Big D says:

    I’d rather have to figure out that MT doesn’t mean milliton (I’ve *never* heard a kg called that before) than to figure out whether you’re talking about ~900kg, 1000kg, or something else entirely.

    Ball bearings might not be the best example, but what about commercial crystal growth? ISTR that you get much higher quality crystals of anything in space. For that matter, does it make any molecular assembly easier? carbon nanostructures (nanotubes, etc) are likely to become as important as plastics and aluminum were in the 50s, and if you can mass-produce multi-cm ones in micro-g… well, that’s something well worth the shipping costs up there and back.

  10. Anonymous says:

    There are some problems with the Bonin piece. His analogy to commercial aviation is problematic for a number of reasons. The Airbus A380 and the Boeing 787 are not good comparisons on cost-per-seat-mile in part because they are justified according to different traffic models. Larger aircraft are indeed more cost effective per seat-mile, but other restrictions enter the equation, like the number of available airport gates. If you only have one gate and lots of customers, then you want a big airplane, and a lot of little airplanes is pointless, because they don’t fit.

    Boeing has done market analysis that indicates that the way to make money is to provide point-to-point service between smaller cities. Airbus has market analysis that is based upon the hub-and-spoke system of feeding passengers into big hubs. Put another way, flying a lot more 787s based upon Airbus’ traffic model is a recipe for failure, because you simply cannot cram more 787s into the limited number of gates at places like Heathrow. And flying A380s according to Boeing’s market analysis would make no sense, because you could not fill an A380 at a smaller airport. So the big question is which aircraft manufacturer has made the correct assumptions about the future market? We don’t know that yet. (And the reality is that they could both be right to some extent. There is no reason why one or the other of these aircraft will fail commercially. They could each succeed, but one doing better than the other.)

    Or to take the analogy further, Bonin claims that flying a lot of smaller planes is more sensible than fewer bigger airplanes. But Independence Air just closed down operations today and one of the primary reasons was because they were trying to use inefficient regional jets instead of larger jets to service their routes–something that they realized by the fall, when they decided to adopt some bigger airplanes. That model demonstrates that bigger is indeed better in some cases.

    Take these two examples together (A380 vs. 787 and the Independence Air experience) and it demonstrates a factor that Bonin apparently ignores for launch vehicles, which is that there is not a straight line or even a curved line progression for economies of scale. It is ratcheted, and there are points where the gain in efficiency might drop suddenly with only a small increase in flight rate.

    For example, he claims that flying a small rocket 10 times a year is “better” than flying a big rocket 2 times a year and will automatically be cheaper for things like ground infrastructure. However, what if the smaller vehicle has a launch pad that can only support 8 launches a year? In order to support 10 launches, you might need to build an extra pad, doubling the infrastructure costs for only a small increase in flight rate.

    As another example, Bonin’s article assumes that the same number of workers used to launch a few times can also be used to launch many times. But in reality, at some point the company will have to increase its workforce to deal with the higher flight rate, and those are the points where the cost suddenly jumps. So the progression is not going to be smooth, it will be ratcheted at various points where the rocket manufacturer is going to have to add personnel, facilities, etc. There is no automatic guarantee that more launches is “better” at all points on the curve. At some points, it might make more sense to switch to a different vehicle (for instance, if you are only going to launch 8 times a year it might make sense to use the smaller rocket, but if you need to launch 10 times, your costs might jump and it might make sense to use a different, larger rocket).

    This is where Ken makes a good point that detailed analysis of the specifics of the vehicles is important. General economic assertions, like those made by Bonin, may be missing important issues.

  11. murphydyne says:

    For big d:

    The best answer is a facility at EML-1, which gives you access to the entirety of the Moon and is relatively indifferent to the inclination of LEO orbit. This means we can get started while using the ISS, and the same LEO to EML-1 transport architecture will be applicable to future stations at other inclinations. That means we don’t have to design a special transport architecture just to make use of ISS. Are we going to use the ISS for a long time? Eh, probably not, but we could get started next year if we really wanted to.

    For Paul:
    It was a thought question. Hypothetical was the word I used in the post. The point is the unthought of possibilities and their unforeseen effects, not the ball bearings.

    For Jon:
    Yeah, as you get farther out it’ll cost less and less dV, and if you do it right at the Lagrange point you can get a serious change. Spot on with the regular, low-hassle, reliable and lower-cost transportation.

    For mz:
    millitonnes. Hadn’t seen that one, and I’ve been exposed to metric since the second grade when we moved to England. Why not just use kg? Point taken, though, and in the future I will try to use “metric tonne (m.t.)”, and then m.t. following so as to properly apply the rules of contraction (are you sure you’re not my high school English teacher? ;-).

    I will not use ‘t’ though, as the whole point is to make the distinction of a metric tonne from an English (American) ton.

    For the last anonymous:
    Good points. Though if you’re anticipating growth in the number of launches per year (something that can happen with 20 m.t.-class launchers), then it may make sense to build that second launch pad, and it’ll be easier to do so because they already know what they got wrong the first time around.

  12. Paul Dietz says:

    I found an interesting little passage about the origins of the ‘perfect ball bearing’ meme. Apparently this goes back to von Braun:

    It all started with a bad idea. In the late 1960s, Wernher von Braun, then the director of Marshall Space Flight Center, approached a group of materials scientists at the Massachusetts Institute of Technology (MIT) with an idea for processing ball bearings in space. Von Braun was concerned about the precision of guidance systems for satellites and spacecraft, which depended upon how perfectly round the ball bearings used in the systems were. Von Braun’s idea was to make the ball bearings in space, where, he reasoned, a drop of molten steel would form a perfect sphere because of the absence of gravity. The drops would be solidified in space, and all navigation systems would benefit from these perfectly spherical ball bearings.

    Von Braun sent a team of scientists to the metallurgy (now materials science) department at MIT to ask researchers there to evaluate his scheme. MIT scientists Gus Witt and Harry Gatos had to deliver some bad news. “Our reaction was very sour,” remembers Witt, “because according to basic solidification principles, the resulting solid from a drop of steel cannot be spherical; rather, it would approach the external morphology of a porcupine.”

    (from a NASA publication, ‘MICROGRAVITY 98’.)

  13. Michael Antoniewicz II says:

    A Point to remember is that the Saturn V had multiple failures thoughout it’s career.

    It reached orbit and did it’s job each launch because of 1) Robust Redundency and 2) a Launch, Analize, Fix (if needed), Next Launch throughout the program.

    We lost that somewhere in the STS-Shuttle program and that led to the loss of Chalanger and Columbia.

    This is also part of the reasoning the reason the USAF wanted TWO (2) launchers when it was looking to move into Heavy Weight payloads and the Titan IV was deminstraighting what happens when you have only one launcher that can do a payload class.

    This led to the Delta IV and Atlas V with Titan IV being phased out due to a … ‘wrong turn’ in it’s technology / building (they backed into building each Titan IV to work with each payload so each was a biiiiiiit different).

    Idealy, in the EELV program, everything should be the same from the payload interface UP. That way if there is a problem with one launcher you switch your next payload (or in a perfect world, your backup of the payload that was part of a nice fireworks show) to the other launcher and use that one until the problem is found and fixed in the one that desided to go into the entertainment industry without permission.

    But to bring this all the way back to were I was going when I started … 😉

    Whatever is used, the need to have some mass dedicated to making sure the payload gets to orbit short of a fireworks display.

    And so far only SpaceX’s F5 and F9 look like they have *any* Robust Redundency even thought of into the design and the two launch attempts for the F1 have shown a Launch (or in this case, attempt), Analize, Fix, Launch mindset.

  14. mz says:

    For people confused about SI units and SI derived units:

    m is milli, that is 1/1000
    M is mega, that is, one million

    t is ton, that is, 1000 kg
    T is tesla, that is, the unit of magnetic flux density.

    You just can not incorporate m or M in front of the t to make it “a metric ton” without destroying the whole point of the system.

    Further questions can be answered at
    http://physics.nist.gov/cuu/Units/
    I really suggest you learn SI units by heart, engineering is so much easier after that.

  15. mz says:

    sorry if I sounded so angry on lsst post, I was tired yesternight and skimmed the posts through a bit too quick.

  16. Ed says:

    Agreed, mz. “Tonne” is not actually a SI unit. The proper SI unit for the metric tonne is Mg. Either that or just write out “metric tonne”.

  17. Anonymous says:

    “And so far only SpaceX’s F5 and F9 look like they have *any* Robust Redundency even thought of into the design and the two launch attempts for the F1 have shown a Launch (or in this case, attempt), Analize, Fix, Launch mindset.”

    How many successful launches have they had?

    I am continuously amused by how hopeful space activists are about the Falcon. Before it has flown even a single time lots of people are proclaiming it to be the best thing since sliced bread. Right now there is no guarantee that it will even work. And there is also no guarantee that it will be as cheap as Elon Musk claims. And there is no guarantee that it will be financially successful. Yet lots of people are claiming that NASA should base its moon program on using lots of Falcon vehicles.

  18. Michael Antoniewicz II says:

    >>”Anonymous said…
    “And so far only SpaceX’s F5 and F9 look like they have *any* Robust Redundency even thought of into the design and the two launch attempts for the F1 have shown a Launch (or in this case, attempt), Analize, Fix, Launch mindset.”

    How many successful launches have they had?

    I am continuously amused by how hopeful space activists are about the Falcon. Before it has flown even a single time lots of people are proclaiming it to be the best thing since sliced bread. Right now there is no guarantee that it will even work. And there is also no guarantee that it will be as cheap as Elon Musk claims. And there is no guarantee that it will be financially successful. Yet lots of people are claiming that NASA should base its moon program on using lots of Falcon vehicles.

    6:36 AM”

    You will not that I was commenting on the *designs* of SpaceX’s F5 & F9?

    You will also not that I was commenting on SpaceX’s *observed* reactions to it’s first two launch attempts of it’s F1?

    You may also, perhaps, note that in my origial post that I *never* said anything about which launcher or launchers NASA should base it’s future launchings on?

    And, if you read the *whole* post, you just might have noted that what I did say about *any* future launcher was: “Whatever is used, the need to have some mass dedicated to making sure the payload gets to orbit short of a fireworks display.”?

    But to spell it out, while I have great admeration for SpaceX, it’s designs, it’s observed mindset it displaied with taking the time to test and test and test till *everyone* on the team was satisfied, and by analizing what went wrong, fixing it, and only *then* trying again. Never in the post did I ever say SpaceX was the only way NASA should go for it’s future launcher planing.

    And as for the comment you made about “How many successful launches have they had?” I will note that in two going on three years they have designed, built, two launch complexes, designed, built, tested two new rocket engines, designed, built, tested, and have two launch attempts with new problems that cropped up each time and they have fixed the problems from the first attempt and are working on the second set of problems now.

  19. Anonymous says:

    “while I have great admeration for SpaceX, it’s designs, it’s observed mindset it displaied with taking the time to test and test and test till *everyone* on the team was satisfied, and by analizing what went wrong, fixing it, and only *then* trying again.”

    And this is exactly what every rocket manufacturer does. There is nothing unique about SpaceX in this regard.

    The proof is in the launch. They have to launch and do so successfully again and again, or they will not succeed. If they do that, and they do it cheaply, then they are worth admiring.

  20. Iain McClatchie says:

    Re: A380 vs B787

    Please note that in both companies’ business models, these machine end up spending between 30 and 50% of their operating lifetimes (measured in decades) actually flying through the air and thus making revenue.

    Neither is a comparison point for the HLLV. There are no comparisons for the HLLV in aviation that I know of. Perhaps the superjumbo Antonov An-225 freighter is close, by virtue of not getting used all that much. Or maybe the B-52 fleet.

    Nobody, not even SpaceX, is talking about RLVs that spend 30% of ten years off the ground actually doing stuff. Rockets are all hangar queens.

  21. 5K0tt of datsoon says:

    what I have always wondered, is why rockets, why not modified jet engines.Every one here knows how a jet works right? well the short and simple is a rotating set of fan blades compress air and duct it into a combustion chamber where white gas
    (kerosene) is burnt. lets say it had 12 blades, the front six would get their air by pulling and their momentum to accomplish this from the
    back 6 blades being spun by the “exhaust” or pure thrust

    Now the reason the is a limit to how far we can take a jet is the air gets pretty thin and you have to use more and more fuel to get the thrust required to climb meaning lose of efficency and excess heat. why not take a step back and improve our current jet systems, they can only handle about 800 degrees F(thats when the titanium used forms an oxide and becomes useless) any one heard of glassy metals (no slip planes no crystalin grain structure) they exist i have seen it is a process of super-heating.(the aurora uses a bit of this stuff in it’s pulse jet, the pulse jet can operate well above 80,000 feet due to the way it builds up pressure before disbursing, this craft is the new stealth bomber, and can be noticed by what is called a string of pearls exhaust trail, up in the sky) brittle but STRONG very heat resistant glass metal is one more step in the right direction,up.
    also what would happen if you were to use an existing rocket fuel and use it as a supplemental air feed
    when running where theres not much air like liquid oxygen, never been done! jets have not been around that long. i don’t mean to sound like i know at all what i am talking about, but i have seen pics of the AURORA both the vessel and the jet it’s self. thats all you will hear from me, i wanna see some
    privatized moon base dammit!

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