Doing the right thing when it’s steamboat time
by John Strickland
|The main problem with the SLS, even putting aside the cost of the horrendously inefficient development methods, is that it is expendable.|
Some in the space community are still trying to face the reality of the “Reusable Rocket Revolution,” and are finding it hard to see that it is real and should now be embraced as the best path to space. Such dilemmas between the old and the new have been faced by people for hundreds of years and they do not always come out smelling like roses. When steamboats were first invented in the late 1700s, they were the first manmade inanimate objects to move under their own power, unlike wagons, rowboats, and sailing ships. At the time, the top inventors and statesmen in the world thought steamboats were impossible. Once the commercial viability of steamboats was established in the early 1800s, there was a rush to build them, and soon there were hundreds of them operating on rivers all over the US. They gave the US a shipping advantage over Great Britain that lasted until the 1830s. Yet the first successful steamboat built by John Fitch only ran one season, since Fitch’s investors would not fund the needed repairs for the next summer season on the Delaware River. Even after the boat went thousands of miles back and forth along the Delaware, the businessmen could just not see the potential. Later investors made vast fortunes, owning entire fleets of steamboats.
In the early 1800s, keelboats were the main means of transport down the Mississippi to New Orleans. Once the cargo of cotton or lumber was unloaded, the keelboat was broken up for its lumber, since it could not go back up river. Of course, a keelboat could be built relatively cheaply and only had to last one trip. The advantages of steamboats over keelboats was very obvious to the river men of the day: they could be used for more than one trip and they could go both downriver and upriver. This awareness that it was “steamboat time” soon created one of the largest commercial fleet of boats in the entire world.
We are in a similar situation today with access to space. After over 50 years of launching payloads into space with expendable rockets, which can only make a single trip up into space before they are destroyed, several companies are quickly approaching the day when their rockets can return to Earth to be used again, just like an airliner. Reusable rockets are like the 21st century version of steamboats in the annals of transportation and the human imagination.
One of the logical fallacies that is used to support continued use of the existing expendable rockets is the idea that a large enough artificial market for launches would bring down the launch prices for the expendable to the point where space commerce could flourish. This leads to the request for a huge government-funded launch program that supposedly will bring down the cost of launches. It should be obvious that the use of thousands of large expendable rockets over nearly 60 years has not led to cheap rocket launches. The very deliberate push by Elon Musk and others to develop reusable rockets has finally produced the technological innovation that will soon give us that critical capability.
Another historical analogy may explain why the “large enough” market fallacy is false for transportation in many cases. Before the Erie Canal was built, there was no practical way for goods such as grain to be shipped from the new agricultural lands in Ohio and Pennsylvania to Eastern cities. It could take weeks for a single wagon load of grain to reach Albany from Buffalo, along horribly muddy and dangerous roads. A large, expensive team of horses was needed to pull the single heavy wagon over the roads, up and down hill after hill, and out of mud holes.
Assume that the New York State government had hired thousands of teams of horses and wagons, and set them to haul freight from Buffalo to Albany for a very low cost, in an attempt to reduce the commercial cost of transporting such goods. The makers of freight wagons would make a fortune, but the roads would deteriorate, and when the program was over, the freight cost would still be very high. There was no effort to improve roads between cities until much later.
Instead, forward thinking men like DeWitt Clinton got the state to put teams of horses and men busy building the Erie Canal. When the canal opened in 1825, the cost of freight between Buffalo and Albany went down by a factor of about 100, according to many historians and economists. The reason was the technological innovation that let a single horse and two people move a very large boatload of goods along the canal. The friction of boat with water was so low that only a single horse was needed to keep it moving along the level canal, and the steady, slow movement of the canal boats added up mileage quickly. This quickly made the US a grain exporting country, since farmers in the Midwest could now ship their grain, cotton, and other goods not only to New York City, but from there to any country. Once rail locomotives and tracks were improved, the moving friction of freight was reduced still further, and with steel wheels on steel tracks and no water to cause increased friction at high speed, rail speeds were able to far exceed canal speeds. This reduced transport costs and time still further.
|The very deliberate push by Elon Musk and others to develop reusable rockets has finally produced the technological innovation that will soon give us that critical capability.|
The most visible current disagreement between proponents of reusable and expendable rockets is the controversy over the SLS, paradoxically a rocket that does not actually yet exist. Sometimes hard numbers will finally get people to look at the real world situation. So to compare apples to apples, we can set up a comparison between the expendable SLS, which Congress is forcing NASA to fund, and a reusable Falcon XX (or whatever SpaceX will call their HLV when it is finally unveiled.)
Let us assume for the moment that both rockets can deliver about the same 130 metric tons of payload to low Earth orbit (LEO), and that the Falcon XX is fully reusable, with a first stage that lands like the Grasshopper and an upper stage that can drop itself out of orbit and survive reentry with thermal protection, just like a large Dragon capsule. All stages of the SLS are expendable, which means they either smash into the ocean at high speed and are destroyed by the impact, or burn up during reentry.
Let us also assume that somehow NASA has the money to fund eight SLS launches a year, instead of the currently planned one every two to four years, even though no payloads or missions currently are funded for such a large number of launches. This would mean an SLS production rate increase of 16 to 32 times. It would also mean adding four times more equipment to produce the SLS rocket stages than currently is planned. The larger launch rate would mean that the roughly $30 billion development cost of the SLS (up to the year 2030), and the annual pad maintenance and launch crew costs, could be pro-rated among a larger number of launches. We will also assume a period of two decades of launches of eight per year for each rocket, or 160 launches.
We will assume that the SpaceX development cost for the Falcon XX is $5 billion based on the estimated development cost for the Falcon 9 and the $2.5 billion cost stated for an expendable version by Elon Musk in 2011, and will assume that each rocket will cost about $250 million to build, based on the stated launch price for the same expendable rocket of $300 million. The fuel costs are assumed to be the same, while the higher SLS pad cost reflects the innovations that SpaceX has created to reduce pad and launch operational costs. No official cost per SLS has yet been published by NASA, but the value of $1 billion is about three times that of the Delta IV Heavy, even though the projected SLS payload is five times greater. We assume the annual facilities maintenance and launch team costs are $1 billion per year for the SLS and $80 million per year for the Falcon XX, based upon the very lean pad facilities used by SpaceX. We will also assume that the Falcon XX can be used at least 25 times.
This table lets us compare the launch costs, per launch and per pound. The SpaceX rocket values are educated guesses with upper limits partly constrained by the posted launch prices of existing SpaceX launchers. No official launch cost estimates have ever been released by NASA. Note that the launch costs do not include the cost of the payloads.
|Vehicle:||SLS (low estimate)||Falcon XX|
|Construction cost per rocket||$1,000,000,000||$10,000,000 (share)|
|Pro-rated development cost share||$187,000,000||$31,000,000|
|Pro-rated annual facility maintenance||$125,000,000||$10,000,000|
|Fuel cost per launch (roughly)||$1,000,000||$1,000,000|
|Pad operations per launch||$5,000,000||$1,000,000|
|Total cost per launch||$1,318,000,000||$53,000,000|
An SLS launch thus costs about 25 times more than a Falcon XX launch if eight are launched each year. Cost for the SLS at eight launches per year is $10.1 million per metric ton and $4,580 per pound, comparable to most current commercial launch rates. A high launch rate without technological improvement does not cut costs. Cost for the Falcon XX is about $400,000 per metric ton and $185 per pound, which is again about 1/25 of the cost of current commercial launches other than the SpaceX Falcon 9. Cost for 8 launches per year would be $10.5 billion for the SLS and $424 million for the Falcon XX. One year’s worth of launches would place 1040 metric tons of payload in LEO. We anticipate that the SpaceX launch costs will continue to decline after reusability is achieved, as the program of continuous improvement at SpaceX continues.
A more realistic scenario came from a recent online discussion of Garver’s radio show appearance. That discussion cited a 2011 article about HLV development costs. That articles suggests that the cost of each SLS rocket will be closer to $2.5 billion, and then only if they are purchased in bulk – 18 at a time.
Here is a table based on this logic that ignores the planned gaps in launches for the next decade and also does not include the cost of the payload:
|Vehicle:||SLS (high estimate)|
|Construction cost per rocket||$2,500,000,000|
|Pro-rated development cost share||$187,000,000|
|Pro-rated annual facility maintenance||$125,000,000|
|Fuel cost per launch (roughly)||$1,000,000|
|Pad operations per launch||$5,000,000|
|Total cost per launch||$2,818,000,000|
Now the cost for the SLS is $21.7 million per metric ton and $8,831 per pound, close to the estimated cost of a Delta IV Heavy launch, and its cost is now 48 times more than the Falcon XX.
|Without adopting the reusable rockets, NASA will be left in the Apollo era, able to do little more than stunt missions with human crews, due to the continuing high expense of moving mass into orbit.|
Assume that the US wanted to build logistics bases both in LEO and the Earth-Moon L1 point to create a cislunar transport system. We will assume that this effort would require 5,000 tons of equipment and space vehicles taken to LEO and half of that also delivered to the L1 point. We will allocate 1,000 tons for the LEO base, 2,500 tons for the larger L1 logistics base, and 1,500 tons of propellant to reach L1 from LEO. Once this base is set up, it could support the creation of a lunar polar propellant plant since it is only 12 hours flight time from any point on the Moon. To launch 1,000 tons per year requires 7.7 launches a year at 130 tons per launch, close to the eight launches specified earlier.
Which rocket can make such a plan affordable? The cost of launching this much mass in to LEO over a roughly five-year period starting after 2020 would be:
SLS (low est) $1.3 billion each: $50.5 billion dollars or $10.1 billion each year.
SLS (high est) $2.8 billion each: $108.5 billion dollars or $21.7 billion each year.
Falcon XX: $2.0 billion dollars or $400 million per year.
Notice that the Falcon XX launch cost for this operation is comparable to the current cost of paying the Russians to ferry our crews to the space station each year, while the low SLS cost is almost two-thirds of NASA’s entire annual budget, and the high estimate exceeds its budget by over $4 billion. We cannot know the actual cost of an SLS operation since no launch cost has been posted. The only comparable costs would be if we were using a fleet of expendable cargo aircraft, which were thrown away after each cargo flight to a distant shore due to lack of aviation fuel at the destination.
These calculations make it clear that using an expendable SLS is not affordable, and that using the reusable Falcon XX is easily affordable. Without adopting the reusable rockets, NASA will be left in the Apollo era, able to do little more than stunt missions with human crews, due to the continuing high expense of moving mass into orbit. The reusable rocket solves that problem, and allows us to conduct high mass missions that will allow real space development. We should rejoice that a solution to this long standing barrier to space is not just on the horizon, but is now close at hand. Let’s get on the steamboat and ride. The “bandwagon” for the reusable rocket is on its way.