Reusable rockets fielded by competitive entrepreneurial companies are necessary to bring the cost of space launch down to levels that can truly open the cosmos to humanity. But they are not enough. One factor is missing: the launch rate must be radically increased.
To understand why this is so, let us consider the situation facing SpaceX, the leanest, meanest, smartest, and by far most cost-effective space launch company around. SpaceX currently has around six thousand employees. At an estimated average yearly cost per employee, including wages, benefits, and taxes of $100,000 each, that comes to a payroll bill of $600 million per year. If we assume all other company costs, including materials, rents, taxes, insurance, legal fees, and others, are at least that much again, the total gross annual bill for running the company must exceed $1.2 billion.
Now, during 2018, SpaceX performed twenty-one launches. This was an incredible feat because not only were they successful every time, but the number of launches constituted 20 percent of the entire world launch market—truly an extraordinary result for a single, relatively small company. But even so, if we take the $1.2 billion low estimate bill to run the company, divide it by twenty-one launches, and assume (rather naively) that all Elon Musk wants to do is break even, we find that SpaceX would need to charge at least $60 million per launch to stay afloat. In fact, they charge about $80 million—or about $4,000 per kilogram for a twenty-ton payload. This is less than half the price anyone else is offering, but it's no revolution in launch costs.
It's a matter of simple math. Even with full reusability, if we want to get the cost per launch down by a factor of a hundred, we are going to need a market for at least a hundred times as many launches. Can such a potential market be created?
I believe it can. It won't be led by satellite launch—that market (about one hundred launches per year globally at last count) is far too small, even if we take into account its potential tripling as a result of the massive satellite constellations that Musk and others are now planning. But there is a much larger space launch market waiting to be opened, and that is long-distance rapid passenger travel around the Earth.
A fully reusable orbital class launch system could be used to deliver passengers point to point from anywhere on the surface of the Earth to anywhere else in less than an hour. As someone who has done my share of twelve-hour-plus global air flights, I can testify that the ability to cut short their monotony could be worth a lot. With my middle-class means, I just suck it up and fly economy. But others pay up to $20,000 per ticket to make such trips less unpleasant.
So consider one such route: Los Angeles to Sydney. Currently it is serviced by many flights per day of large jets, each taking eighteen hours. If a rocket plane service provided just one flight per day each way, that single route alone would increase the world launch market by 730 flights, multiplying it eightfold. But what about Seattle to Sydney, New York to Sydney, Atlanta to Sydney, London to Sydney, London to Johannesburg, London to Rio, New York to Rio, New York to Abu Dhabi, St. Petersburg to Rio, Tokyo to Santiago, New York to Tokyo, Atlanta to Shanghai, Los Angeles to Bombay, and so on, and so on? There are dozens of worthwhile routes, collectively providing a market for tens of thousands of flights per year.
But is the technology near at hand to make such transportation systems possible? It wasn't before, but it is now. The key to global transport using rocket propulsion is a two-stage, fully reusable system in which the first stage returns to the launch site and the second makes the long-distance trip, to be sent home with the help of a first stage based at the destination. This is precisely the sort of system that is now emerging from the two-stage reusable booster development programs of SpaceX and Blue Origin.
The reason a two-stage system is necessary is a result of the basic equations of rocketry. To obtain global reach, a rocket must reach orbital velocity, which in the case of the Earth is eight kilometers per second. However, a rocket experiences velocity loss during ascent due to aerodynamic drag and gravity, and so the real velocity increment (or “delta-V,” abbreviated ∆V) that needs to be delivered by its propulsion system is closer to 9.5 km/s. This is more than twice the exhaust velocity of any practical propellant combination, which means that the amount of propellant needed will greatly outweigh the payload. (See box.)
As the amount of propellant increases, however, the vehicle needs ever-bigger tanks and engines, which eat up ever-larger fractions of the dry mass until there is nothing left for payload. In consequence, it is impossible for a single-stage rocket system to obtain the 9.5 km/s ∆V orbital velocity necessary for global reach, because its payload falls to less than zero. It could go some distance with a small but nevertheless positive payload, but when all is said and done, the potential performance is insufficient. This is shown in figure 2.1, which compares the payload and range of a single-stage rocket with that of a two-stage system of the SpaceX/Blue Origin type, where the stay-near-home first stage does the first 4 km/s of ∆V, while the passenger-carrying upper-stage vehicle does the rest. In figure 2.1, the rocket planes are all assumed to have a ground liftoff mass of 2,500 tons, roughly the takeoff mass of the Saturn V, space shuttle, or SpaceX's Starship booster system design, and employ methane/oxygen rockets for propulsion.1 (Methane/oxygen is the best propellant combination for rocket planes because it offers high performance, ease of handling, worldwide availability, and very low cost.) Their payload, in tons, is shown on the vertical axis as a function of range, in kilometers, which is displayed on the horizontal axis.
It can be seen that the payload of a single-stage rocket plane falls to zero at a range of eight thousand kilometer, or five thousand miles, while the two-stage system can deliver a one-hundred-ton payload passenger cabin over global distances. Figure 2.1 shows performance data for both ballistic flight vehicles and winged craft with lift/drag ratios of 2 (the space shuttle had a hypersonic L/D of 1, NASA's Orbital Sciences X-34 of 2.5). Such lifting configurations allow gliding after reentry, but they add dry mass to the system, so the net range extension they provide is limited. Higher L/D winged configurations are possible that could enable somewhat greater reach for each option, but the basic story remains the same.
Figure 2.1. Comparison of the payload of two-stage and one-stage reusable rocket planes as a function of range. Payload (y axis) is in tons, range (x axis) is in kilometers.
So what would this two-stage global reach rocket plane be like? Takeoff would certainly be noisy, as would landing for nonwinged options, so the pads for such systems would probably have to be platforms located some tens of kilometers offshore, or else far out in open country or desert. This suggests a brief boat, seaplane, or helicopter ride would also be part of the trip. Also, an aspect of the experience of a transglobal flight would be about forty minutes of zero gravity and the same view of space that astronauts get. This would be a big plus for sales. In fact, companies like Virgin Galactic are currently offering four minutes of zero-gravity experience for $200,000, without transporting anyone anywhere, and getting a fair number of takers.2
By my math, each flight of a one-hundred-ton passenger cabin rocket plane would consume about 2,100 tons of methane/oxygen propellant. At a cost of $120 per ton, this would entail a fuel bill of about $250,000 per trip. At 140 tons, including cabin, tanks, and engines, the long-distance flight vehicle would have a dry mass comparable to a Boeing 767, which carries about two hundred passengers. If each passenger paid the $20,000 price of current global-distance first-class tickets (getting, in addition to fast global transportation, ten times the Virgin Galactic zero-gravity fun for one-tenth the price), a gross revenue of $4 million per flight could be obtained. That leaves plenty of room for other operating costs besides propellant, even allowing for some tickets to go for less than the premium price. (At $5,000, I'm in, for at least one flight, because I want to experience zero gravity and the brilliant starry sky of space at least once before I die. Book me for New Zealand.)
TECHNICAL NOTE: FUNDAMENTALS OF ROCKETRY
Let's say you weigh fifty kilograms and are standing on roller skates. If you throw a five-kilogram brick in one direction with a velocity of 10 meters per second, that action will send you scooting the other way with a velocity of 1 m/s. This illustrates the basic principle known to physics as conservation of momentum. Split an object into two parts and send them flying in opposite directions: the momentum—or mass times velocity—of each will be the same.
Rockets work on this same principle. The more momentum a rocket vehicle can shoot out one way in the form of fast-moving propellant gases, the more it can increase its own velocity the other way. In the example above, the skater weighs more than the brick and so moves away slower. A rocket might work that way too, using a small amount of propellant to effect a tiny velocity change. If speed is called for, however, a rocket can be made to move faster than its propellant exhaust velocity by piling on the gas. But while the final kilogram of propellant used by a rocket only has to push the rocket, the next to last has to push both the rocket and the final kilogram, and the third to last must push all the above, and so forth. As a result, the amount of propellant a rocket needs to use increases exponentially with the ultimate speed desired. This leads to the famous rocket equation, which says that for any rocket with exhaust velocity C, the “mass ratio,” the ratio of its total mass (i.e., its dry mass plus propellant) to its dry mass alone increases exponentially with the factor (∆V/C). Put mathematically:
The meaning of this equation is shown in figure 2.2, below, where we see how the mass ratio of the vehicle and the payload it can deliver changes as the key factor ∆V/C, displayed on the horizontal axis, changes.
Figure 2.2. Change of mass ratio and payload of a rocket as a function of ∆V/C.
In figure 2.2, it is assumed that the vehicle has a dry mass of ten tons, including payload, tanks, and engines. If ∆V/C is zero, no tanks or engines are needed, so the ten tons of dry mass is all payload. But as ∆V/C increases, the mass ratio goes up, and more and more propellant is required. So now the vehicle needs tanks and engines, and these might typically weigh 10 percent of the propellant, which is what I assume in figure 2.2. But the vehicle only has ten tons of dry mass, so as the tanks and engines get bigger, the payload must get smaller, falling drastically when ∆V/C is greater than 2.0, until mission capability drops to zero when ∆V/C reaches 2.4.
Methane/oxygen rocket propellant has an exhaust velocity of 3.7 km/s, so for an orbital mission where ∆V is 9.5 km/s, ∆V/C is 2.6, making a single-stage-to-orbit vehicle infeasible. Hydrogen/oxygen can obtain an exhaust velocity of 4.4 km/s, so ∆V/C using it would only equal 2.16. But that propellant is not only much more expensive but bulkier, which increases the mass of the tanks, so at the end of the day, a vehicle employing H2/O2 would do no better.
(Note: Astronautical engineers frequently report the exhaust velocity of rockets not in units of km/s but in seconds of “specific impulse,” or “Isp.” Conceptually, the specific impulse of a rocket is the number of seconds it can deliver a pound of thrust using a pound of propellant. That said, you can translate Isp, given in seconds, directly to exhaust velocity, given in meters per second, simply by multiplying the Isp by 9.8. So, for example, a typical methane/oxygen rocket engine with an Isp of 378 seconds would have an exhaust velocity of 3,704 m/s or 3.7 km/s.)
If we use two stages, however, the required ∆V can be split between them, with the ∆V/C required of each being less than an easy-to-do 1.4.
This is why the two-stage reusable vehicles being developed by SpaceX and Blue Origin are the right designs for both orbital delivery and fast intercontinental travel.
More broadly, if you want any rocket vehicle to achieve a ∆V more than twice its exhaust velocity, you need to use more than one stage.
SPACE TOURISM
Since the 1990s, a number of promoters have pointed to space tourism as a clever business path to opening the final frontier. In the era of ultra-high-priced spaceflight, such concepts were impractical, with the only achievements being several flights delivering a few billionaires to either the Russian Mir or the International Space Station at prices of around $20 million each.3 However, in the relatively near future this picture could change radically, as the same intercontinental rocket plane technology enabling fast global travel could also be used to send passengers to orbit at much more affordable rates.
Why would anyone want to take a vacation on orbit? Well, for those who have had too much of the Aegean islands, Aspen, and Tahiti, a stay in a space hotel could offer something truly different. Still not convinced? How about the attractions of zero gravity, which, it has been argued, will be of special interest to honeymooners and other fun-loving couples? (There is a hilarious folk song popular in the science fiction community in which exactly the opposite proves to be the case.) This experience could well be expected to be enhanced, at least for some people, if the bedroom suite module includes a huge transparent window facing downward to give the couple a spectacular view of the blue rotating Earth (and vice versa). For those with other tastes, the module window could face out toward the endless sea of space with its myriad of unblurred stars glistening like a million jewels on black velvet. In between bouts in the bedroom, the couple could enjoy unique zero-gravity sports such as tennis, racquetball, basketball, soccer, gymnastics, or martial arts carried out in a large module suitably designed to accommodate numbers of people rapidly bouncing off the walls. For a modest extra charge, guests could take classes in extravehicular activities and become certified to wear space suits and go EVA. An astronaut certification suitable for framing would also be provided. Those with a more sedentary bent could while away the hours before bedtime engaged in astronomy or Earth studies in the hotel's observatory. To increase the variety offered by the hotel's primary attraction, a matchmaking service could also be provided. This would be especially valuable since in addition to being fun-loving and adventurous, most of the people you would meet at the hotel would undoubtedly be rich.
It's easy to see how such a business could evolve once there are orbital rocket planes engaged in fast global transportation. For example, instead of flying from New York to Sydney and landing, the rocket plane could remain in space for several orbits, turning a one-hour trip into an all-day trip, before landing back at the Big Apple. A logical evolution of such excursions might be to extend the day trips to overnights and eventually to weeklong cruises. But the cruise ship model only goes so far, because a rocket plane that could do a surface-to-surface flight every day with two hundred passengers would have to increase its rates quite a bit to maintain income when switching to weekly cruises, each necessarily accommodating fewer people.
A better plan, therefore, if multiday trips are contemplated, would be to create space hotels that remain on orbit with all the accommodations appropriate for a fun vacation and only use the rocket planes to ferry customers up and take them home.
Such hotels are already in the works. Robert Bigelow, the billionaire owner of Budget Hotels of America, has founded a company called Bigelow Aerospace to build them and has already tested habitation module technology in space.4 When Bigelow founded his company some twenty years ago, he was way ahead of his time. But now it would appear that time may soon catch up with him.
DOING RESEARCH ON ORBIT
Orbital research labs that take advantage of the unique zero-gravity and high-vacuum environments available in low Earth orbit could also be producing a profit in the relatively near future. The product of such labs is knowledge, which is massless. Thus, precious little raw material is required, at least in principle, to produce marketable products of enormous cash value. This is so forcefully the case that even the vastly overpriced space shuttle managed to produce what might be considered a kind of profit during two ten-day missions in which zero-gravity experiments helped researchers determine the structure of certain animal viruses, thereby enabling the development of veterinary vaccines worth several billions to the economy. As part of the shuttle program, a successful company called SpaceHab created and rented out the use of its lab module, which flew periodically on the shuttle. Because of the high costs and difficulty of dealing with the opaque NASA bureaucracy, commercial enterprise never signed up for this service in a big way, leaving NASA as the primary customer. The same proved true of the research facilities offered by the International Space Station. However, a dedicated orbiting research lab with a long-duration professional staff could offer much more than simply lab space. With a lower-cost launch vehicle to support the operation, prices could conceivably drop to the point where investment in such research would be competitive with the return offered by terrestrial research facilities.
On orbit, the distorting influence of gravity is nearly absent, which creates conditions enabling the production and determination of the structure of various types of crystals and other compounds. In addition, low Earth orbit provides access to very high-quality vacuum conditions that cannot be economically produced in earthbound labs. The knowledge that flows from investigations conducted in these environments can enable the development of a range of products, from disease cures to “brains” for new supercomputers so advanced that their proponents claim they would revolutionize life on Earth. Potential microgravity or high-vacuum research products with astronomical value exist in the form of vaccines, synthetic collagen (which could be used to construct corneas), targetable pharmaceuticals, structured proteins, crystal materials (for computer chips and quantum devices), ultrapure epitaxial film production, unique polymers and alloys, and electrophoresis applications. These products could lead to breakthrough applications in such high-growth areas as semiconductors, computers, instruments, biotechnology, and drug manufacturing, areas that today represent a business base of more than $240 billion per year.
Some have advanced the notion that zero-gravity research could better be done on unmanned satellites. No doubt such facilities will also be launched. But having run a research lab myself, I believe that such claims are mistaken. Yes, isolated well-planned experiments can be flown on automated spacecraft and useful data returned. But to effectively perform an investigative research program into unknown intellectual territory requires real live human experimenters with constant access to their apparatus. An automated experiment can record data that are expected; only a human investigator can respond to surprises—and most big discoveries come as surprises.
The right surprise could be worth billions.
ORBITAL INDUSTRIES
Producing patents is the best way for an orbiting lab to make money. The discovery of knowledge in space that enables industrial processes to be realized on Earth is clearly the highest payoff path for such space-based facilities. But what if that is not possible? What if the lab discovers a process that can only be replicated in the zero-gravity environment of space? Could profitable mass-production operations actually be initiated on orbit?
The answer to this question depends upon a variety of factors, chief among them the cost of space launch, which today stands at roughly $5,000 per kilogram to low Earth orbit. At such rates, creating orbital industries is out of the question. But at the $200/kg rate that now appears to be achievable, matters change radically. In order for space-based manufacturing to be profitable, the value of the goods produced per unit weight must exceed this figure. In fact, it must exceed it by a good deal, because in addition to transporting the raw materials up and the product back down, the launch system will also have to transport the orbital factory; its spares, consumables, and power system; the workforce and their consumables; and the propellants and other consumables necessary to keep the factory spacecraft functioning and stable in its proper orbit. In addition, the orbital factory business will have to support the salaries and fringe costs of the company's earthbound and spacebound staffs; its offices, advertising, insurance, taxes, interest payments, and other overhead; and the standard retail markup, and, given the high level of risk in such a business, will have to pay large dividends to investors. So if the launch cost is $200/kg, the orbital factory's product will have to boast a retail sales price of at least $2,000/kg for there to be a net payoff sufficient to motivate investment. Roughly speaking, this is about one-twentieth the price of gold or three times the price of silver ($2,000/kg works out to $57/ounce). In addition, the product produced would have to be so superior to terrestrial alternatives that it would sell well despite the fact that it might cost more. Taken together, these factors would tend to rule out almost all alloy or other materials production operations, but the production of advanced computer chips, unique pharmaceuticals, or lossless fiber-optic cables (which a company called Made in Space has demonstrated can indeed be produced under zero-gravity conditions) could certainly qualify.
Finally, the sales volume of the product must be sufficiently high. If the basic costs of running the orbital lab are $40 million per year (a number that would allow shipping about one hundred tons per year of various supplies, assuming half the budget was so dedicated), the operation will still fail if only twenty tons of its $2,000/kg wholesale-priced product can be sold. To allow for all the business's costs, at least $80 million in gross revenue would be needed, or forty tons of product. Let's say that the end use for the product was a drug or computer chip selling retail for $200 for a hundred-gram unit. In that case, four hundred thousand units would have to be sold per year. Given a sufficiently desirable and unique product, sales numbers such as these are entirely feasible.
SPACE BUSINESS PARKS
The idea of the space business park is not to define the business but to create the infrastructure to support any need. If you build it, they will come—or so the theory goes. In other words, you build a large spacecraft with a truss, a power array, attitude control systems, and some pressurized modules, and then you announce that you have space on orbit for rent. Perhaps your first customer might be an orbital research outfit. That would be logical; as we have seen, of all the orbital businesses we have discussed so far, research has the best chance of producing a big profit under near-term technological assumptions. In the course of its investigations, the research company may discover a unique product that, contrary to their initial hopes, can only be produced on orbit. In so doing, they are forced to rent additional modules from you for factory space. If necessary, you expand your space business park with additional pressurized modules to meet this demand. The operation of the orbital factory might create sufficient demand to drop the cost of providing orbital accommodations, thereby improving the economics of space tourism. At that point, the space hotel entrepreneur will find the needed funding, and you add on the deluxe bedroom modules with the reflecting mirror walls.
The space business park scheme has the advantage of being evolutionary, with an initial form of space-based activity (research) that could be viable even under current launch prices and which, moreover, will have a foundation of experience in the operation of the International Space Station, but with many advantages over that predecessor. For example, your business park would certainly eliminate the ISS's Kafkaesque process for permitting activities. Moreover, even if the ISS had subsidized its lab rental to the point where it was free, private pharmaceutical companies would generally prefer to pay premium prices for orbital research space in a place where they could keep the results of their investigations secret.
The lack of definition inherent in the concept of the mixed-use space business park is both its greatest strength and greatest weakness. It offers flexibility, which allows the business to avoid being trapped by fixed ideas of space enterprise that may prove to be crackpot. But its business plan had better be based on more than a “If we build it, they will come” philosophy. A solid set of advance commitments from well-funded orbital research projects or other initial customers will likely be required to get the business park off the ground. Fortunately, as transportation costs drop, such commitments will become increasingly obtainable.
BRINGING THE WORLD TOGETHER
For the past two decades, the volume and speed of global wireless communication has been expanding at an astonishing rate, with both increasing tenfold every five years.5 In 2000, the world's total global data traffic was four thousand terabytes (TB) per month. It is now (2019) approaching forty million TB/month and by 2030 is projected to reach four billion TB/month.
In 2000, wireless data allowed a minority of the citizens of advanced sector countries to use mobile telephones. Today, a third of the world's population has smartphones, providing access to the internet at speeds enabling television transmission. By 2030, the data grid is expected to reach nearly every person on Earth, with sufficient power to control and coordinate the movements of billions of self-driving vehicles.
The market for data delivery is already gigantic, and it's exploding. How can its enormous demand be met? And who is going to get paid to do the delivery?
Space entrepreneurs believe they have the answer. They will bring the world together with vast fleets of communications satellites. In the process, they will greatly enrich the world, while making themselves the richest people who have ever lived.
Current communication satellites operate in geosynchronous orbit, thirty-six thousand kilometers above the surface of the Earth. At this height, they orbit the Earth at exactly the same rate that it turns, thereby keeping themselves in the same place in the sky as seen from the ground. This feature, as the concept's inventor, science fiction writer Arthur C. Clarke, realized, is extremely convenient for communications purposes, as it allows ground-based antennas to be fixed in their aim, while permitting nearly the entire Earth to be covered by just three satellites spaced 120 degrees apart around the planet's equatorial plane. But to transmit from such a distance, the satellites need to be large and power hungry, and thus expensive. Moreover, it takes about 0.25 seconds for radio signals to make the seventy-two-thousand-kilometer round-trip from the Earth's surface up to geosynchronous orbit and down again. While this does not matter for applications like one-way radio or TV broadcasting, it poses serious problems for two-way communication. For long-distance telephone calls, the quarter-second signal time delay each way can be quite annoying. For systems attempting to remotely control machinery under dynamic conditions (for example, self-driving cars or aircraft), it could potentially be catastrophic.
If the satellites could orbit lower, say 1,200 kilometers, the time delay could be cut thirtyfold and the transmission power each way reduced a thousandfold. But satellites at that height orbit the Earth every two hours and can only been seen from the ground when they are relatively close by. As a result, they are constantly moving in and out of view, with each one only providing temporary coverage to a limited ground area as it travels along its orbital track. If you want to provide global communication coverage using spacecraft at such altitudes, you can't do it with three satellites; you will need thousands of them.
So that's the plan. And the race to pull it off is already on.
The first out of the box was a company called WorldVu, founded by a group of Google employees including Greg Wyler, Brian Holz, and David Bettinger.6 Subsequently renamed OneWeb, in January 2015 the group obtained backing from the Virgin Group, Google, and Qualcomm to build and deploy a constellation of 648 small satellites, each with a mass of about two hundred kilograms, orbiting at an altitude of 1,200 kilometers. This would be a very large constellation. By comparison, the total number of satellites currently orbiting the Earth is about 1,500.
But the plan only got bigger. By February 2017, OneWeb announced that it had already sold out the capacity of its 648 satellites—before a single one had been launched or even built. So, raising another billion dollars from the SoftBank Group, the company expanded its planned constellation to 2,420 satellites.7 Shortly thereafter, Samsung proclaimed it had plans for a Space Internet altitude constellation consisting of 4,600 satellites, orbiting at 1,557 kilometers altitude.8
Not to be outdone, in May 2017, Elon Musk announced that his SpaceX company would be fielding its own constellation, named Starlink, consisting of 4,425 small satellites orbiting at 1,200 kilometers, operating in eighty-three orbital planes. In turn, these craft would be supplemented with a further 7,518 satellites flying at just 340 kilometers altitude.9 Once fully deployed, the constellation would cut time delays by a factor of one hundred while increasing data rates per unit power by a factor of ten thousand relative to current geosynchronous orbit communication systems. Test satellites were launched in 2018, with the first operational satellites to be deployed in 2019 and the full system operational by 2024.
These three constellations alone comprise some nineteen thousand satellites—more than ten times all existing spacecraft put together. The spacecraft they will employ are small and probably will be launched fifty or more at a time. Launching them will therefore require four hundred medium-lift (approximately ten tons to orbit) booster flights, which over an eight-year period would amount to about fifty extra launches per year. The income these satellites promise to generate is so great that they can be profitably deployed even at current launch costs. But as launch costs collapse, the economics are going to get even better. This will no doubt lead to further generations of constellations ever more advanced in their technology and fielded by contenders from all over the world.
Where this will all lead is impossible to say. But one thing is certain: the communications revolution has just begun.
THE CUBESAT REVOLUTION
Since the dawn of the space age, the cost to get satellites into orbit has been driven by the high launch price per kilogram of expendable boosters. One solution for this problem is the lower the freight rate by making the launchers reusable. There is another way, however, to solve this problem, and that is to slash satellite launch costs by cutting their weight. Miniaturization has made great strides in computers and other areas of electronics. Indeed, a good cell phone today packs more computing power than the room-sized mainframes that enabled the Apollo program. If we can shrink computers by a factor of a thousand, why not satellites? At $5,000 per kilogram, a ten-thousand-kilogram satellite would cost $50 million to launch, but a ten-kilogram unit only $50,000. If you want to get into space on the cheap, this could be the easiest way to do it.
Such is the approach taken by professors Robert Twigg (of Stanford University) and Jordi Puig-Suari (of Cal Poly, San Luis Obispo), the inventors of the CubeSat. By the late 1990s, it had become clear to these two that it should be possible to build a minimal-capability satellite with a mass of one kilogram and a volume of one liter, or a cube about four inches on a side. Even at current high launch costs, such units would be cheap enough to get into space on the kind of budgets available to universities, allowing students to get great hands-on experience by building real spacecraft and seeing how well they functioned in orbit. But fortunately, while such educational applications were seen as the purpose of the first CubeSats, the inventors developed the concept further, planning ahead to enable more capable satellites by putting together groups of cubes. Designers were quick to take advantage of this feature, creating CubeSats composed of two, three, six, and twelve units (known as 2U, 3U, 6U, and 12U systems), whose capabilities rapidly increased as a result of the added units, continued advances in electronics, and the creation of a market for ultraminiature spacecraft instrumentation and propulsion systems. By 2005, ten CubeSats had been launched, by 2010 seventy, with the cumulative figure soaring to 420 by 2015. By the latter date, the CubeSats had become so capable that of the one hundred CubeSats launched in 2015, only five were school projects. The rest were serious spacecraft launched by NASA, the military, or commercial imaging and remote sensing companies.10
A favorite configuration is the 6U version, with dimensions of ten by twenty by thirty centimeters, or about the size of a shoebox. As of this writing, there were several companies offering to build these systems, complete with communications, attitude control, and foldout solar arrays, for less than $1 million. With a typical mass of six to ten kilograms, these little birds are very cheap to launch, yet are powerful enough to perform important scientific missions. In 2018, two of them, named MarCO-A and MarCO-B, flew along with NASA's InSight Mars lander as hitchhiker payloads and successfully fulfilled their mission of providing a real-time communication link for the primary spacecraft during its entry, descent, and landing on the Red Planet. Also, in that same year, NASA received a host of proposals from many organizations to send such vehicles to the lunar orbit to search for water ice or other resources on the surface of the moon. (My own company, Pioneer Astronautics, is one of the competitors. We are leading a team that has developed a proposed mission called RISE, for Radar Ice Satellite Explorer, which will consist of four 6U CubeSats that will go into lunar polar orbit and scan the entire moon using ground-penetrating radar as it turns beneath them, hopefully finding water ice near the poles and subsurface caverns elsewhere.) It is expected that there will be a number of winners, which will begin to take flight as soon as 2021.
Figure 2.3. The RISE mission would use four 6U CubeSats, each the size of a shoebox, to search the moon with ground-penetrating radar for polar ice and subsurface caverns. Image courtesy of the RISE team.
This is just the beginning. Once the space launch revolution is factored in, the cost of sending a highly capable ten-kilogram 6U CubeSat could drop from $50,000 to as low as $2,000, making space exploration an affordable activity not just to government, corporations, universities, and billionaires but even to private individuals of middle-class means.
Do you have a space exploration mission you would like to do yourself? Pretty soon, you may have your chance.
POWER FROM SPACE?
Many who see orbital commerce as the driving force for the development of a spacefaring civilization look to the generation of electricity for use on Earth by large solar power satellite (SPS) systems. Were it possible to generate electric power in space for terrestrial consumption at competitive rates, the market would be nearly unlimited. Vast numbers of huge SPS systems would then be built, and their construction and operation would require a huge fleet of reusable medium- and heavy-lift launch vehicles. Truly cheap access to space with booster systems of every payload capacity would be rapidly developed, and the doorway to the final frontier thrown wide open. According to advocates, such as Princeton professor Gerard O'Neill, such commerce could then provide the economic foundation for the development of large colonies, literally cities in space, in high Earth orbits, and this vision has served to motivate many space entrepreneurs, notably Blue Origin founder Jeff Bezos.
In space, solar energy is available twenty-four hours a day, not masked by the dulling effect of the Earth's atmosphere. Moreover, while most terrestrial solar arrays are fixed in orientation, an orbital solar array can track the sun. Avoiding the atmosphere increases the effective solar brightness by a factor of about 1.5, while the ability to track the sun multiplies the average power produced by the orbiting array by a factor of four. Thus, when both advantages are considered, an orbital solar array can produce a time-averaged output about six times greater per unit area than its counterpart fixed in orientation on the ground in an equatorial desert. The SPS unit beams its solar-produced power via microwaves to Earth, where it is received by a “rectenna.” The microwave energy is then converted to high-voltage alternating power for consumption on the consumer grid. About half the power would be lost in the beaming process, reducing the orbital array's advantage over its terrestrial counterpart to a factor of three. However, as a countervailing advantage, the groundside rectenna is smaller than a solar array, and cheaper, and can be put nearly anywhere in the world, including places where solar power is frequently unavailable due to weather. So, once a SPS is in operation over the appropriate hemisphere, a relatively cheap rectenna could be installed nearly anywhere in that hemisphere to obtain power. This could make enormous quantities of electricity available in remote areas of the third world and avoid the need for installing expensive power generation equipment in countries where political instability might make such installations insecure.
But what would the price of such power be? At current launch costs and solar panel weights, the business case for SPS is totally hopeless. So let's consider instead a case assuming launch costs have been reduced to $200 per kilogram and solar cells cut to one-fifth their current mass-per-unit power. Solar panels with a mass/power ratio of twenty kilograms per kilowatt when operating at the Earth's distance from the sun are currently available. Panels five times lighter than these would therefore have a mass/power ratio of about 4 kg/kW. However, half the power is lost during transmission to Earth, and the weight of the SPS spacecraft, including all supporting structure, mechanisms, and attitude control systems and the microwave transmissions system, could be expected to be at least equal to the weight of the solar panels themselves. Thus, net delivered power produced by the SPS spacecraft would be closer to 16 kg/kW.
Now, the SPS spacecraft could not be in low Earth orbit. If it were, it would zip around the Earth once every ninety minutes and be unable to provide constant, or even frequent, service to a rectenna station on Earth. Instead, the SPS would have to be in a slow-moving high orbit, with the best choice being geosynchronous (GEO), thirty-six-thousand kilometers up. At that altitude, the SPS would orbit the Earth once every twenty-four hours, and since the Earth turns at the same rate, this would allow the satellite to hover over a fixed position on the Earth's equator. While the orbit of the SPS would be equatorial, its high altitude would give it a good line of sight for transmission over most of the hemisphere. The cost of delivering payloads to GEO, however, is about four times that of LEO, running in the range of $20,000/kg today, and would still be $800/kg after the space launch revolution. Therefore, the launch cost of the SPS would be about $12,800/kW, or $12.8 billion for a one-thousand-megawatt unit suitable for providing the power needs of a city the size of Denver. But that's just the SPS launch cost. If we add in the costs of assembly (the 1,000 MW SPS would be more than five square kilometers in size and would weigh eight thousand tons); maintenance; insurance; spacecraft hardware; hardware, construction, and real estate costs for the rectenna and its power conditioning system; salaries; taxes; and so on, the price of the total SPS would undoubtedly run at least $40 billion. That's an order of magnitude more expensive than any similar output unit of any kind—natural gas, nuclear, solar, wind, you name it—built on the ground. At these installation prices, the fact that the SPS requires no fuel would make very little difference. Just the interest on $40 billion would be about $2 billion per year! If we add in maintenance and depreciation over twenty years, the cost would be at least $6 billion per year. That boils down to a user price of $0.68/kWh (assuming that nothing is added for profit), more than ten times the $0.06/kWh currently prevailing in the United States.
This suggests that for SPS to become commercially competitive as a source of baseload power, not only would the price of space lift need to drop by a factor of twenty-five (to $200/kg to LEO), but the mass of solar power systems would also need to drop by a factor of fifty. That could be quite a stretch.
The key problem with the SPS concept as a source of baseload power is that while it is technically feasible, it attempts to provide a common commodity—electricity—that can be produced much more cheaply in any number of alternative mundane ways. In that sense, it is like a business plan to provide gravel for road construction by importing it from the moon, ignoring the fact that many cheaper sources are available locally. If you are going to import something to Earth from space for sale, it needs to have unique attributes, as could be the case for zero-gravity-produced pharmaceuticals.
What is the unique attribute of SPS power that could potentially justify its higher price? Fortunately, it has one: it can be instantly projected anywhere. So rather than consider SPS as a competitor to one-thousand-megawatt municipal nuclear or natural-gas-fired power plants providing cheap bulk power, it might be better to think of it as a technology for supplying power on demand to remote locations, replacing the one-to-ten-megawatt-class diesel generators that are currently used to provide power to off-grid Arctic oil drilling sites or isolated military bases at great expense, logistical difficulty, and, in some cases, serious risk. Such customers might well be happy to pay the higher SPS price to get the power they need.
Instead of one-thousand-megawatt SPS units with a mass of eight thousand tons trying to compete with cheap grid power, SPS designs should focus on five-megawatt systems weighing forty tons, providing premium power to off-grid customers who really need it and are willing to pay the price. Small-scale power grids in isolated developing-sector locations are also a potential market. Rapid provision of emergency backup power deliverable via field-deployable rectenna systems in the wake of disasters is another possibility. In the aftermath of Hurricane Maria in 2017, much of Puerto Rico was left without power for months, with serious consequences for public health, safety, and employment. Even at $0.68/kWh, SPS-provided electricity would have been quite welcome under such conditions.
Electricity can be worth a lot if you otherwise won't have it. It can be a lifesaver. While SPS technology seems unlikely to provide humanity with any substantial fraction of its overall power needs for the foreseeable future, it could help ensure that no people, anywhere, are ever left completely powerless.
Such a niche role might seem like a rather small outcome relative to O'Neill's grand vision for solar power satellites. But all big things start out as little things, so who knows?
DETERRING WAR
The United States needs a new national security policy. For the first time in more than sixty years, we face the real possibility of a large-scale conventional war, and we are woefully unprepared.
Eastern and central Europe are now so weakly defended as to virtually invite invasion. The United States is not about to engage in nuclear war to defend any foreign country. So deterrence is dead, and with the German army cut from twelve divisions to three; the British gone from the continent; and American troops down to a thirty-thousand-person, nearly tankless remnant, the only serious and committed ground force that stands between Russia and the Rhine is the Polish army. It's not enough. Meanwhile, in Asia, the powerful growth of the Chinese economy promises that nation eventual overwhelming numerical force superiority in the region.
How can we restore the balance, creating a sufficiently powerful conventional force to deter aggressors? It won't be by matching potential adversaries tank for tank, division for division, replacement for replacement. Rather, we must seek to totally outgun them by obtaining a radical technological advantage. This can be done by achieving space supremacy.
To grasp the importance of space power some historical perspective is required. Wars are fought for control of territory. Yet for thousands of years, victory on land has frequently been determined by dominance at sea. In the twentieth century, victory on both land and sea almost invariably went to the power that controlled the air. In the twenty-first century, victory on land, sea, or in the air will go to the power that controls space.
The critical military importance of space has been obscured by the fact that, in the period since the United States has had space assets, all of our wars have been fought against minor powers that we could also have defeated without such advantages. Desert Storm has been called the first space war because the allied forces made extensive use of Global Positioning Systems (GPS). However, if we had possessed no such technology, the end result would have been just the same. This has given some the impression that space forces are just a frill to real military power—a useful and convenient frill, perhaps, but a frill nevertheless.
But consider how history might have changed had the Axis of World War II possessed reconnaissance satellites—merely one of many of today's space-based assets—without the Allies having a matching capability. The Battle of the Atlantic would have gone to the U-boats, as they would have had infallible intelligence on the location of every convoy. Cut off from oil and other supplies, Britain would have fallen. On the Eastern Front, every Soviet tank concentration would have been spotted in advance and wiped out by German air power, as would any surviving British ships or tanks in the Mediterranean and North Africa. In the Pacific, the Battle of Midway would have gone very much the other way, as the Japanese would not have wasted their first deadly air strike on the unsinkable island but sunk the American carriers instead. With these gone, the remaining cruisers and destroyers in Fletcher's fleet would have lacked air cover, and every one of them would then have been hunted down and sunk by unopposed and omniscient Japanese airpower. The same fate would have awaited any American ships that dared venture forth from the West Coast. Hawaii, Australia, and New Zealand would have subsequently fallen, and eventually China and India as well. With a monopoly of just one element of space power, the Axis would have won the war.
But modern space power involves far more than reconnaissance satellites. The use of space-based GPS can endow munitions with one hundred times greater accuracy, while space-based communications provide an unmatched capability of command and control of forces. Knock out the enemy's reconnaissance satellites, and they are effectively blind. Knock out their comsats, and they are deaf. Knock out their NAVSATs, and they lose their aim. In any serious future conventional conflict, even between opponents as mismatched as Imperial Japan was against the United States—or Poland (with one thousand tanks) currently is against Russia (with twelve thousand)—it is space power that will prove decisive.
Not only Europe but the defense of the entire free world hangs upon this matter. For the past seventy years, US Navy carrier task forces have controlled the world's oceans, first making and then keeping the Pax Americana, which has done so much to secure and advance the human condition over the postwar period. But should there ever be another major conflict, an adversary possessing the ability to locate and target those carriers from space would be able to wipe them out with the push of a button. For this reason, it is imperative that the United States possess space capabilities that are so robust as to not only assure our own ability to operate in and through space but be able to comprehensively deny this to others.
Space superiority means having better space assets than an opponent. Space supremacy means being able to assert a complete monopoly of such capabilities. The latter is what we must have. If we can gain space supremacy, then the capability of any American ally can be multiplied by orders of magnitude and, with the support of the similarly multiplied striking power of our own land- and sea-based air and missile forces, be made so formidable as to render any conventional attack unthinkable. On the other hand, should we fail to do so, we will remain so vulnerable as to increasingly invite aggression by ever-more-emboldened revanchist powers.
For this reason, both Russia and China have been developing and actively testing antisatellite (ASAT) systems. Up till now, the systems they have been testing have been ground launched, designed to orbit a few times and then collide with and destroy targets below one thousand kilometers altitude. This is sufficient to take out our reconnaissance satellites but not our GPS and communications satellites, which fly at twenty thousand and thirty-six thousand kilometers respectively. However, the means to reach these are straightforward, and, given their critical importance to us, there is every reason to believe that such development is well underway.11
The Obama administration sought to dissuade adversaries from developing ASATs by setting a good example and not working on them ourselves. This approach has failed. As a consequence, many defense policy makers are now advocating that we move aggressively to develop ASATs of our own. While more hardheaded than the previous policy, such an approach remains entirely inadequate to the situation.
The United States armed forces are far more dependent upon space assets than any potential opponent. Were both sides in a conflict able to destroy the space assets of the other, we would be the overwhelming loser by the exchange.
What we need are not ASATs but something much better: fighter satellites, fully analogous to fighter aircraft.
A fighter aircraft has two critical functions—it destroys enemy aircraft and protects our own. An ASAT, as generally conceived, only performs the first. As such, it is more analogous to an antiaircraft missile.
But the decisive weapon for achieving air supremacy has always been fighter aircraft. Only fighter aircraft can protect bombers and the rest from enemy fighters while also denying the enemy the use of the air. We need to do both in space.
We need fighter sats that can not only knock out adversarial space assets but patrol as escorts for our own reconnaissance, GPS, and communication satellites to protect them from enemy ASATs.
Such a fighter sat should be relatively small and cheap, perhaps on the order of a hundred kilograms, with an impulsive propulsion system that allows it to maneuver rapidly to intercept an approaching ASAT. It should also be armed with a standoff weapon system that allows it to destroy or deflect approaching ASATs at a distance. Perhaps a projectile weapon system firing small high-velocity rockets with limited guidance might be considered. If the fighter can maneuver well, such a short-range system might be satisfactory: even a hit that is sufficient to impact a small velocity change on an attacking ASAT could cause it to miss. Alternatively, directed energy systems or larger missiles with sophisticated guidance enabling interception at long distances could be employed. However, what is needed is a craft that transcends the ASAT's kamikaze mode of attack, because any defensive system based on such a principle could rapidly be overwhelmed.
The fighter sat's capability as an antisatellite system is also essential. After all, unless we can take out the adversary's reconnaissance satellites, the entire US Navy surface fleet will be readily visible and therefore extremely vulnerable to attack by enemy ICBMs, submarines, and other means. So, in the event of conflict, we will need to sweep enemy satellites from the skies. But this essential task cannot be trusted to mere ASATs because if the enemy creates fighter sats to protect their space assets, then our ASATs could be readily defeated.
Only American fighter sats capable of defeating the adversary's fighter sat escorts can be relied upon to get through.
Finally, it may be noted that fighter sats engaged with others will inevitably take losses. Therefore, for the defense to be effective, the ability to rapidly launch replacements must also be an essential part of the system architecture.
In the period before World War II, many airpower theorists argued that since bombers were the air assets that actually impacted operations on the ground, producing and operating large bomber fleets was the key to air superiority. This theory was wrong, and caused the Eighth Air Force, operating B-17s over Germany, to take horrendous losses while sharply limiting its effectiveness. It was only after long-range fighter escorts such as the P-51 Mustang were introduced that America was able to achieve the air supremacy necessary for victory.12
America's space power today is at risk because it is based on the same fallacy as that promoted by the prewar bomber theorists. Yes, it is true that the communications, GPS, and reconnaissance satellites comprise the business end of space power that actually influence the war below. It may not seem that they need protection because in all the years they have existed, we have not fought any wars against opponents with space power capabilities. But it is precisely against such more capable potential adversaries that they are most critically necessary.
Without our communication satellites, we would be unable to adequately coordinate our forces. Without our reconnaissance satellites, we would be nearly blind. Without our GPS system, the effective firepower of our forces would be reduced by orders of magnitude. Were we to lose such capabilities, our victory in any future conflict would be very much in doubt. Were an adversary able to eliminate our space assets while preserving their own, our defeat would be virtually guaranteed. Such an outcome is unacceptable.
We are not at war today, but the creation of the necessary systems will take some time. If we are to be sufficiently prepared to deter aggression, we need to start developing the essential capabilities now.
This battle for space supremacy is one the Western alliance can win. Because societies based on liberty are the most creative, no unfree potential adversary can match us in this area if we put our mind to it. We can and must develop ever-more-advanced satellite systems, fighter satellite systems, and truly robust space launch and logistics capabilities. Then the next time an aggressor commits an act of war against us or a country we are pledged to defend, instead of impotently threatening to limit its tourist visas, we can respond by taking out its satellites, effectively informing it in advance the certainty of defeat should it persist.
The entrepreneurial space launch revolution offers the free world the chance to obtain these critical advantages.
If Russia or China hopes to compete with such a Western military space initiative, there is only one way they could do it: they would need to also become free.
In which case, there will be no war.
THE LEAP BEYOND EARTH ORBIT
We are living on the brink of a new space age. Entrepreneurs have opened the way toward cheap access to space. As a result, all sorts of commercial activities in near-Earth space will soon become not only practical but profitable, and consequently, they will happen.
The invisible hand is unstoppable. If someone can make money doing something, it will be done, for good or ill, regardless of the wishes of kings, presidents, religions, or secret police.
That said, the invisible hand cannot be counted upon to do everything that needs to be done.
The private sector can be expected to fund the development of new and ever-more-advanced reusable launch vehicles to keep reducing the price of access to orbit and enable fast global travel. It may also finance the creation of extensive human operations on orbit, including, as we have discussed, orbital labs, manufacturing facilities, and space tourism. This is now possible because the technology, the method of operation, and a good deal of the market necessary for these launch and orbital operations have already been paid for by substantial government funding over the past four decades. There is nothing wrong with this; in fact, it follows a near-universal historical pattern of terrestrial frontiers being first opened either by governments or social groups motivated by transcendent purposes and only afterward developed by private commerce. As a result, the business case for a vast expansion of human activity in geocentric space has now been established.
But what of journeys to other worlds? People can be courageous, but money is timid; it prefers to reproduce itself in tried and proven ways. If your only fundamental goal is to make money, there are far more reliable ways to do so than to venture into the unknown. Thus, on Earth, developing new frontiers for profit has occurred only after such regions have been explored and pioneered at considerable risk and cost by individuals possessing rather different motives.
Government space initiatives over the past forty years have tamed near-Earth space to the point where it is now a potential arena for private enterprise. This is an extremely positive development. Global fast transport will provide the market for truly cheap reusable launch systems that will make orbital tourism a reality as well. Orbital labs, eventually supplemented by orbital manufacturing stations, will make available an array of products that may revolutionize medicine and computer technology. The combination of low-cost space access with orbital servicing operations will also allow the development of global communications systems whose capabilities will impact society in ways that exceed the imagination of most people today. For example, such augmented communication constellations could enable low-cost wristwatch-sized communication devices that would be able to access on a real-time interactive basis all the storehouses of human knowledge from anywhere in the world. In addition, they would enable their users to communicate very high volumes of data—including voice, video, and music—either to each other or to the system's central libraries. They will not only make possible the global coordination of billions of self-driving cars but provide the kind of previously impossible automated air traffic control that could make mass use of private aircraft (finally, flying cars!) a reality as well.
The practical value of such systems is obvious, but their implications go far beyond the practical into the social and historical. We will see nations thoroughly linked together, resulting in deep cultural fusions and a radical generalization of the dissemination of human knowledge. In a real sense, the establishment of the full range of worldwide communication and transportation services made possible by cheap space access represents the final step establishing humanity as a Type I global civilization.
That said, the fundamental problem facing the human race today—the creation of a true interplanetary spacefaring Type II civilization—will not be solved by developing orbital private enterprise in geocentric space. True, such operations will serve as a “school for sailors,” training the people and honing the skills and organizations for future space ventures in a way analogous to how coastal fisheries helped to provide the sailors to handle the ships of the great nautical explorers of the past. They will also make many of the technologies needed to venture further much cheaper. But human beings will never settle Earth orbit, because there is nothing there to settle. We need to reach beyond. The entrepreneurs’ help in providing low-cost transportation and other services to aid initial outposts growing into settlements will be vital. By creating many of the flight systems needed to go to the moon or Mars, they are sharply lowering the cost, risk, and schedule thresholds that stand in the way of a decision by political leaders to launch such a program. Ultimately, however, we need to decide as a society to take on the challenges of worlds beyond. And that is a trail to be blazed by those who live for hope and not for cash.