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starship-design: A Rocket a Day Keeps the High Costs Away




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               A Rocket a Day Keeps the High Costs Away

               ========================================



                            by John Walker

                          September 27, 1993



There's a pretty general consensus that one of the greatest barriers

to the exploration and development of space is the cost of launch to

low earth orbit.  The incessant and acrimonious arguments among

partisans of the Shuttle, DC-*, NASP, TSTO, Big Dumb Boosters,

bringing back the Saturn V, buying launches from the Russians and/or

Chinese, or of developing exotic launch technologies (laser,

electromagnetic, skyhook, etc.) conceal the common premise of all

those who argue--that if we could launch payloads for a fraction of

today's cost, perhaps at a tenth to a thousandth of today's rates of

thousands of US$ per kilogram, then the frontier would open as the

great railway to orbit supplanted the first generation wagon trains.

The dispute is merely over which launch technology best achieves this

goal.



Conventional wisdom as to why industry and government choose not to

invest in this or that promising launch technology is that there

aren't enough payloads to generate the volume to recoup the

development cost and, in all likelihood, there never will be.



How much would it cost to find out if this is true?



What we pay today

-----------------



Could we take a moment's pause from debating which is the best

successor to the outrageously expensive way we launch now and, as

engineers, ask ourselves just why it is that rockets have to cost tens

or hundreds of million of US$ per shot.  Space FAQ space/launchers

gives approximate per-launch costs of representative systems on which

commercial launches can be purchased as:



    Vehicle         Mission cost, US$ millions

    -------         --------------------------

    Scout G1                    12

    Pegasus                     13.5

    Soyuz                       15

    Long March 3                33

    Titan II                    43

    Delta                    45 -  50

    Proton                   35 -  70

    Zenit                       65

    Atlas                    45 -  85

    Ariane 4                 65 - 115

    Energia                    110

    H-2                        110

    Titan III                  158

    Titan IV                315 - 360



I've deliberately not included data on performance, reliability, or

anything else because that would distract us from the most striking

observation about these vehicles; each and every one of them, whatever

the technology, country of origin, original design intent, launch

history, fuel and oxidiser, success or failure in the commercial

launch market, have mission costs in ranging from tens to hundreds of

millions of US$.



Why is this?  Why do rockets cost so much?



What's in a launcher?

---------------------



Let's simplify the problem by focusing entirely on expendable boosters

built with current technologies--those used in the existing launchers

named above.  Further, let's consider only pure liquid-fueled

launchers (with the exception of Scout and Pegasus, the core stages of

each of the above launchers are liquid rockets).  From an engineering

standpoint, then, what is a rocket?



Well, it consists of a collection, often vertically stacked, of:



    Cylindrical fuel and oxidiser tanks

    Rocket engines (including turbopumps, gas generators, etc.)

    Guidance mechanisms (gimbal joints, hydraulic actuators, APUs)

    Guidance and navigation system (IMU, GPS, radio command receiver)



plus other ancillary details like range safety receivers and telemetry

sensors and transmitters and the like, and that's about it, isn't it?



Now the question that comes to mind is this: why should something like

that cost tens to hundreds of millions of US$?



Cylindrical fuel tanks aren't that expensive, and they make up most of

the rocket.  (Sure, if you're striving for every last gram of

throw-weight in an ICBM, you can push the tankage cost as high as you

like, but in a commercial launcher?)  And rocket engines are finicky,

complicated, and intolerant of defects.  Well, yes...but so is a DOHC

4 valve per cylinder turbocharged, intercooled V-8 internal combustion

engine, and nonetheless one can purchase such an engine, integrated

into a ground transportation vehicle, from a number of manufacturers

at a cost three orders of magnitude less than that charged for the

rocket, and expect it to function without catastrophic failures or

extensive maintenance, for five years, tens of thousands of

kilometers, and thousands of mission cycles.  Guidance?  Again, as

long as we aren't gram-shaving, this is pretty mundane stuff--the

hydraulics can mostly be adapted from airliners, and the electronics

from a PC--"mem'ry for nothin', chips for free".  (For an LEO launcher

we don't need radiation-hardened electronics.)



The first mass-produced launcher

--------------------------------



We've seen from the "standing army" argument for launchers requiring

minimal (airline-scale) ground mission support the impact of fixed

costs on per-mission costs when the number of missions is limited.

But the presence or absence of a "standing army", and the frequency of

flights over which fixed costs are spread, isn't fundamentally linked

to whether the launcher is reusable or expendable.  Consider the

following mass-produced expendable rocket.



    Number manufactured:        6,240



    Number launched:            3,590

        Successes:                        2,890  (81%)

        Failures:                           700  (19%)

    In inventory:               2,100

    Work in progress:             250

    Expended in development:      300



    Development program cost:               US$ 2 billion

    Development cost per launcher:          US$ 350,512

    Total manufacturing cost per launcher:  US$  43,750

    Marginal cost, launchers 5000+:         US$  13,000  (Yes, 13K!)



These are actual figures for the first mass-produced rocket vehicle,

the V2 (A4)--fifty years ago.  Prices are in US wartime dollars.



Stating the obvious....  The V2 was a suborbital vehicle, intended to

lob high explosive over relatively short distances.  Quantity

production of the V2 at Mittelwerk was accomplished with unpaid slave

labour under the brutal rule of the SS.  And the failure rate was

unacceptable by current standards.



And yet...consider that this was the very first space-capable rocket

ever built.  That it was manufactured under the constraints of a war

that Germany was losing, subject to aerial bombardment by night and by

day, with continual supply shortages.  That, as a consequence of Nazi

slave-labour, the desperate war situation, and the state of current

technology, no significant automation was applied to its manufacture.

In February 1945 the underground Mittelwerk V2 factory delivered 800

ready-to-launch V2s; after the war U.S. intelligence expert T. P.

Wright estimated that at full production, unconstrained by wartime

shortages, the Mittelwerk plant could have produced 900 to 1000 V2s

per month.



One thousand rockets per month...fifty years ago.  Think about that.



A Rocket a Day

--------------



Suppose we translate these figures, almost incomprehensible by modern

standards (*three hundred* launch vehicles expended in the development

program!) into quasi-modern terms.  Consider an orbital launch vehicle

two-stage, say, clean and green thanks to LH2/LOX propulsion in all

stages.  Engines: J2 or RL10s or follow-on uprated versions (we'll

have plenty of opportunity to develop them and phase them in).  A

simple two stage cylindrical stack like Titan II, with GPS or

ground-commanded navigation.  Payload interface is a big ring with

bolt-holes and a standard fairing with plenty of volume inside.



Sounds a lot like NLS/SpaceLifter, doesn't it?  STMEs may have

marginal advantages over sea-level-optimised derivatives of RL10 or

J2, but otherwise what's the difference?



What if we launch one every day?



Three hundred and sixty-five a year.



That would be less than one twenty-fifth the production rate of the V2

under concentrated Allied bombardment in 1945.



How much would each one cost?



Assume we expense the development cost or amortise it over a

sufficiently large number of vehicles that it can be ignored.

Further, assume that our bigger, more complicated (two-stage), and

higher tech (LH2/LOX instead of Ethanol/LOX), launcher costs ten times

as much as the V2, and that 1945 wartime dollars convert into current

dollars at 10 to 1.  Then, starting with the US$13,000 marginal cost

of a V2, we arrive at a cost of US$1.3 million per launch vehicle.  If

we launch one a day our total vehicle budget will be US$475 million

per year--comparable to a single shuttle flight (no, I don't want to

re-open *that* debate again; let's just say it's the same order of

magnitude, OK?).  If our mass produced LH2/LOX launcher equals the

performance of the Delta 6925 by placing 3900 kg in LEO, the cost to

LEO is US$333/kg; if we achieve better throw-weight, this figure goes

down accordingly.  If we build the thing so cheap, dumb, and heavy

that its payload is only 1000 kg--one metric ton--the cost rises to

US$1300/kg, which is still a factor of ten lower than the comparable

cost to LEO for Ariane, Atlas, Delta, and Titan.



Logistics and Ground Support

----------------------------



Okay, you say, suppose mass production in these absurd quantities

could actually drive the hardware cost down to less than a million and

half per bird, we still haven't accounted for the standing army that

launch operations require.  If it takes thousands or tens of thousands

of people to launch tens of vehicles per year, won't it take hundreds

of thousands to launch one every day?



Well, why should it?  Again consider the V2.  In the two weeks from

September 18-30 1944, a total of 127 V2s were launched from five

different launch sites.  That's an average of almost ten a day.  This

was accomplished by two mobile groups totaling about 6,300 men and

1600 vehicles, forced to relocate frequently due to the Allied

advance, and subjected to frequent aerial bombardment.  It was

estimated that, given adequate supply, one hundred V2s could be

launched per day in a "maximum effort" by the mobile units, and that a

rate of half that, 350 per week, was sustainable.



Parkinson's law notwithstanding, why, after fifty years of

technological progress and experience in launch operations, should it

take tens of thousands of people and hundreds of millions of dollars

to achieve a launch rate one fiftieth that of a V2 group launching the

very first operational ballistic missile from a launch site with tanks

and infantry advancing toward it and airplanes flying over dropping

bombs on them?



Yes, LH2 is trickier to handle; a multistage rocket requires a more

complicated launch and service facility, and so on.  But if we design

up-front for a sustained launch rate of one per day, can we not find

ways around these problems?  Perhaps a mobile transporter / erector /

launcher like SS24 or Pershing II, with fuel and oxidiser delivered by

underground pipes that attach to the launch truck.  Or something....

Let's tell the engineers to go figure it out and see if they come up

with something that works.



It can't be impossible; the Soviet R-7 series launchers (Vostok /

Voskhod / Soyuz) almost furnish an existence proof.  These launchers,

despite their mechanical complexity (4 liquid boosters and 20 first

stage engines), are typically launched one to two days after

horizontal delivery to the pad.  On several occasions beginning in

1962, two manned launches were made from the same pad less than 24

hours apart.  On October 11-13 1969, three manned missions (Soyuz 6,

7, and 8) were launched from the same pad within 48 hours.



If we use contemporary sensors and computers to automate the fueling

and checkout, why does the "launch team" need to be huge?  Bob drives

the launcher out to the middle of the circle of concrete, hooks up the

hoses, then goes back to the blockhouse and presses the green "Start"

button.  An hour later, or so, the "Ready" light comes on, and at High

Noon he pushes the red "Go" button.  Sitting immediately to his right

Fred, in the blue suit, follows the proceedings on a laptop computer

with his index finger on the orange "Oops" button.



Assuming things go OK, ten minutes after the ship lifts, Bob goes out

and drives the launch truck back to the garage where it's reloaded

with the next rocket (assume we have ten trucks, or so, to pipeline

the setup process and account for attrition).  Then it's off the

cafeteria for lunch.



Excess Capacity

---------------



Every proposal, prosaic or exotic, for a high-capacity,

fast-turnaround launch system immediately runs into the objection,

"There just aren't enough payloads to make the system pay.  Other than

a few established markets for satellites, there just aren't that many

profitable, useful, or interesting things to do in space right now,

and we already have too many launchers chasing too few launch

customers."



This is the heart of the chicken-and-egg problem that is blocking the

development and exploration of space.



As long as launches cost tens or hundreds of millions of US$ each,

only governments and the very largest corporations will be able to

afford them, and only for the most obvious and essential purposes,

such as communication, earth resource, navigation, and reconnaissance

satellites.  And as long as the number of such payloads is less than a

hundred per year, who is realistically going to pay to develop a

launcher capable of sustained rates many times as great, however cheap

it ends up being?  You'd just end up with a huge pile of rockets

gathering dust waiting for payloads, wouldn't you?



Would you?



Consider the following scenario.  The Agency announces a procurement

in which bidders are invited to provide launches, one per day, of 2000

kg or more to a standard Low Earth Orbit, mating with a specified

payload and shroud interface and to a prescribed set of services on a

flat concrete pad.  A suitably derated payload is specified for polar

orbit.  Bids of more than US$1.25 million per successful launch will

be returned unread.  The winner of the bid will be awarded a

fixed-price contract for 1000 launches at the agreed price.  The first

100 launches will be considered development flights and will be

purchased at the bid price regardless of success or failure; afterward

only successful launches will be purchased.  The procurement will be

re-competed every 1000 launches; if a new vendor wins with a

substantially lower cost per launch, they will be granted the same

development period for the first 100 flights.  The vendor retains all

rights to the launcher design and is free to offer it on the open

market independent of the Agency.



Immediately the launch contract awarded, the Agency announces the

availability of daily flights of 2000 kg to LEO or 1500 kg to polar

orbit.  Commercial enterprises may purchase launches for whatever

purpose they wish at a price equal to the Agency's cost per launch

plus 25%.  Unsold flights are offered on a first-come, first-served

basis to researchers, government agencies, and individuals.  In the

event of excess demand, non-commercial proposals will be selected by a

peer review process similar to that used to allocate telescope time at

astronomical observatories.  All risks of launch failure are borne by

the provider of the payload; clients should note historical failure

rates and build appropriate spares.  Provider of the payload assumes

all liability for it once it separates from Agency's rocket.  Payloads

shall be delivered by truck to the loading dock of the Agency's Rocket

Garage.  All payloads must be supplied with adequate documentation to

verify their content and safety.  The payload interface specification

handbook is available for US$5 from the Agency's toll-free order line;

payload test and integration jigs are available in the Agency's

regional centres and many major universities around the world.  Plans

for building your own are available for US$5.



Payloads delivered to the Rocket Garage are inspected to ensure they

are not nuclear bombs, sacks of gravel, or otherwise unacceptable.

Payloads containing propulsion hardware are reviewed especially

closely.  Assuming no big no-nos, the payload is bolted to the top of

the next free rocket, the requested orbit inclination is dialed into

the rocket's guidance system, and it moves down the queue toward the

pad.



The adventurous will recall that the Project Mercury capsule had a

launch weight of 1935 kg.



If fewer than one payload a day arrives at the Rocket Garage (as is

certain at the outset), the Agency will store the excess rockets in

the Rocket Warehouse out back, while continuing to launch at least one

per week with an inert concrete payload (in a rapidly decaying orbit)

to maintain launch team proficiency and verify the continuing quality

of rockets supplied by the vendor.



This procurement and offering of launch services is explicitly

intended to punch through the chicken-and-egg problem.  In essence,

the Agency would be spending US$475 million a year on a flock of 365

hens, then waiting to see if eggs started to show up.  This runs the

risk, of course, of ending up with egg all over one's face.



Suppose it isn't possible to build a rocket that will orbit half the

payload of a Delta, launched 50 times less frequently than the V2, at

a cost ten times greater than that primitive fifty year old missile.

In that case nobody responds seriously to the Agency's bid, and the

Agency goes and blows the money on something else, vowing to try again

in ten years.



Now suppose the rockets do start showing up one a day, and departing

on schedule with a success rate that makes the supplier's profit

margin juicy enough to fund further R&D, but the payloads don't

appear.  The Agency rapidly becomes the butt of every stand-up comic

and a motion is introduced in the Legislature to re-name it the

"Orbital Ready-Mix Delivery Agency".  Well, if that's how it plays

out, I guess we all ought to pack up and go home then, shouldn't we?

Because that would demonstrate, in a real-world test, than there

really aren't very many useful things to do in space, after all.  That

even if we push the marginal cost of launches down to zero, nobody

will be able to think of anything to use them for, not for Venus probe

science fair projects, personal spysats, hypersonic surfing

demonstration/validation flights, nor microgravity research, material

processing, life sciences, remote sensing, VLBI radio astronomy,

optical astronomy, or anything else.  That other than the existing

big-market space applications, there's no earthly reason to leave the

Earth, that much of the "space age" was based on faulty premises, that

the "final frontier" isn't worth exploring.



Is this likely to be the case?



Loose Ends

----------



Naturally, things aren't as easy to accomplish in the real world as

they are to bandy about on paper.  Special relativity limits the

velocity with which one can wave one's arms, and the UNDO button

doesn't remove a hole you've just bored the wrong place into an

expensive piece of metal.  Many things might go wrong in an attempt to

jump-start the exploitation of space this way.  The two real biggies

are discussed above: "it won't work", or "space isn't worth it".  Here

are some others I'm concerned about as well.



Range Capacity.  Given current low launch rates, configuring a range

is complicated and takes a long time which couldn't accommodate daily

launches, especially to a variety of inclinations.  And most existing

spaceports can't handle both equatorial and polar launches.  Maybe we

should plan on Hawaii or Cape York from the outset and get the

paperwork started to declare an appropriate air and sea exclusion zone

(for two hours per day around the scheduled launch time).  Any rocket

that meets the launch rate and cost criteria cannot require complex or

expensive ground infrastructure.



Environmental Issues.  One reason for insisting on LH2/LOX rather than

Kerosene/LOX, hypergolics, or solids/hybrids is that it's clean.  We

could launch one every minute and contribute less to global warming,

ozone layer depletion, and other varieties of atmospheric pollution

than 747s crossing the Atlantic every day.  Also, exhaust and/or

fluffy white clouds resulting from the occasional really bad day

aren't harmful to anybody who happens to be downwind.  On the solid

waste issue, clearly dropping big chunks of aluminum and steel into

the ocean every day isn't a particularly elegant way to break the

bonds of gravity, not compared to all those sleek paper spaceplanes on

the magazine covers.  But I suspect if one were to compare the total

mass wasted in expended stages to that of non-recycled aluminum cans

and automobile engines, it would be an insignificant percentage.  It's

worth noting that what we're throwing away every day consists

basically of aluminum and iron with a dash of silicon, and that these

are three of the four most abundant elements in the Earth's crust.

Besides, outside the two-hour launch period, salvage boats are welcome

to recover the expended stages and sell them for scrap.



Space Junk.  So many launches may run the risk of unacceptably

polluting the near-Earth environment.  Clearly, as noted above, care

will be required not to launch payloads likely to explode or otherwise

misbehave in orbit.  Payloads will probably have to be released in

orbits which guarantee the timely decay and burn-up of expended upper

stages.  We need to make sure the upper stage always burns up

completely, leaving no chunks to go "thump" in the night.  Payloads

intended for high-traffic or high-risk final orbits will require

special certification that they will dispose of themselves in a

responsible manner.



Fuel cost.  It may be that if we succeed in pushing the hardware cost

down, we'll end up with an airline-like situation where fuel cost

becomes a major component of the expense.  I don't know how much

liquid hydrogen goes for today, and I haven't tried to predict what

it would cost when purchased in the quantities a launch a day would

require.  This needs to be worked out.  Even daily launches should be

a minor consumer in the market for liquid oxygen.



Payload pyrotechnic servicing.  In the discussion of payload delivery

and integration, I confess to glossing over the issue of pre-launch

payload servicing.  You can't just take a satellite with a solid kick

motor and a hundred kilograms of hydrazine on board down to the DHL

counter and ship it to the spaceport.  The hazardous aspects of

payload processing must be done in a thoroughly professional manner at

a facility close to the launch site, and the design of these aspects

of payloads must be subjected to design reviews comparable to those

currently used for commercial launches.  This increases the payload

cost, but not the launch cost.  It will probably promote the emergence

of standard spacecraft buses which provide these components of the

payload, which can be serviced for launch for a flat fee by their

vendors.



Tracking and control.  The daily launch rate envisioned here would

overwhelm existing ground control facilities.  Yet the experience of

AMSAT and UOSAT proves that sophisticated and expensive gear isn't

required to manage a satellite, at least in LEO. Without access to

TDRSS or a global tracking network, most satellites are going to have

be very autonomous, communicating with their makers in occasional

high-bandwidth gabfests as they pop above the horizon.  Since it's

very likely that one or more manufacturers will offer a standard

satellite bus compatible with the launcher, providing power,

communications, etc., perhaps they will also market access to an

uplink and downlink as a value-added service.  From your nearest ISDN

jack or Internet site, you could send and receive packets to your

satellite and let the bus vendor worry about how and when they were

delivered.  Deep space missions are a problem; those who propose them

are going to have to obtain time on a big dish as part of their grant

proposal.  One hopes that if many missions with clear scientific merit

are proposed, money might be forthcoming to expand the existing deep

space communication facilities.



NASA/Congress will never do it.  Who said anything about NASA or the

U.S. Congress?  A total budget of US$475 million per year is within

the reach of many industrialised nations, especially at a time when

defence spending is being curtailed, aerospace companies are suffering

from excess capacity, engineering and manufacturing people are

suffering lay-offs, and policy makers worry about how to convert

defence industries without harming readiness by eroding the industrial

base.  US$475 million per year represents the following percentage of

the early 1990's defence budgets (CIA World Factbook 1992) of the

following countries:



    Country        % Defence Budget

    ---------      ----------------

    South Africa       13.6%

    Switzerland        10.3%

    Sweden              7.7%

    Australia           6.3%

    Israel              6.3%

    Spain               5.5%

    China               4.0% (approx)

    Italy               2.1%

    France              1.4%

    Japan               1.3%

    Germany             1.2%

    United Kingdom      1.1%

    United States       0.15%



Any country whose government became convinced that a scheme like this

might give it a long-term (literal) leg up in the world and beyond,

eventually, could implement it by reprogramming a small percentage of

its existing military spending, much of which would flow right back

into its own industries and economy and might be seen to have military

value it its own right.  For that matter, US$475 million is just about

what Microsoft will spend on R&D in fiscal year 1993 and a third of

their pre-tax profit, and it's less than 3% of Motorola's sales for

the same year, so well-heeled and forward-looking companies (or

consortium of such) could play as well.



Conclusion

----------



The near-term development of space is constrained by excessive costs

of launching payloads to low Earth orbit.  The development of

innovative launch technologies is discouraged by an apparent over

capacity of existing launchers, "where will the payloads come from?",

while development of payloads for new space applications isn't

affordable given current launch costs.



Rocketry was originally developed as a branch of artillery.

Proponents of various reusable launch technologies argue that as long

as an artillery-like model is maintained, affordable launches will

never be possible.  But to be effective, artillery must not only have

adequate throw-weight, it must also provide a rapid rate of fire while

minimising the cost of expended rounds.  Today's space launch

"artillery" costs tens to hundreds of millions of US$ per shot and

fires at intervals measured in weeks or months.  Yes, expendable

launchers are artillery, and the ones we have today are, as artillery

pieces, extremely overpriced and under-performing.



The last time liquid rockets were truly treated as artillery was the

very first time they were used in war, the A4/V2, fifty years ago.

Despite an increasingly desperate war situation, constant supply

problems, and aerial bombardment, V2s were manufactured at rates of up

to 800 per month, launched at a comparable pace, and produced at a

marginal cost of US$13,000 (1945 dollars) for each additional rocket

after the first 5000.



Making allowances for all the differences between Nazi Germany and the

modern world, between a not very militarily useful nor reliable weapon

and a viable space launcher, between a one-stage Ethanol/LOX missile

and a multistage LH2/LOX launcher, between 1945 wartime dollars and

current currency, still one must ask why, after 50 years of

technological progress and rocket experience, our current rockets cost

not five, not ten, not twenty times as much as a V2, but between one

hundred (Pegasus) and two thousand four hundred (Titan III/SRM) times

as much.  Is what a Delta 6925 does, lobbing 3900 kg into LEO,

fundamentally three hundred times more expensive than what a V2 did

fifty years ago?



It is interesting to observe that current launchers are bought and

launched in quantities about a thousand times less than those of the

V2 at peak production.  In no sense are they mass-produced, and

therefore they do not benefit from either the means of mass production

(investment in highly-automated manufacturing), nor from the learning

curve that results when one builds hundreds and thousands of an

identical product.  Could it be that a large component of the present

unacceptably high launch cost is both cause and effect of the present

low rate of launches?





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Kelly Starks                       Internet: kgstar@most.fw.hac.com

Sr. Systems Engineer

Magnavox Electronic Systems Company

(Magnavox URL: http://www.fw.hac.com/external.html)



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