Despite advances in performance and reusability, rockets like SpaceX’s Falcon Heavy share most of the same fundamental attributes, and limitations, of rockets developed decades ago. (credit: SpaceX)
by John Hollaway
The two most useful aphorisms for neophytes in the space business are the same as for any corporate environment:
- Never surprise a vice president
- Hell hath no fury like a head office scorned
For the first point, corporate vice presidents do not want their lives, so near the top of the slippery pole, suddenly disrupted by someone from somewhere lower down with unexpected bad news (or even good news when it changes matters dramatically.) And for the second point, his or her myrmidons, when also facing disruption to the even tenor of their corporate existence from an independently-minded outpost, are likely to respond with disproportionate vigor to the threat.
In 1995, the article “Disruptive Technologies: Catching the Wave,” written by Clayton M. Christensen and Joseph Bower, appeared in the Harvard Business Review. This noted how unexpected technical developments, often from outside an established business, can turn time-honored industries upside-down. On reflection the authors replaced the term “disruptive technology” by “disruptive innovation,” acknowledging that it is the exploitation of a business opportunity that has been facilitated by the technology, rather than the technology per se, that is the disruptive aspect. Whatever the phrase, it should have caused alarm among vice presidents and the occupants of head offices.
However, their counterparts in the space launch industry have been unconcerned by the threat of disruption. Despite myriad attempts, no practical, let alone economic, alternatives to its technology have yet to threaten it. We have been sending up rockets for over 90 years (taking Robert Goddard’s 1926 launch as the kickoff date), and since about 1949 we have been doing it in earnest, but always using essentially the same system as Dr. Goddard.
However, as Roger Handberg recently noted here, most successful entrepreneurs in the space access business ended up having to depend on their national militaries to get their dreams launched (see “Seeking the future: the fragility of the patron”, The Space Review, February 18, 2019). This is because these were usually the only agencies that had both the need and the resources to realize these visions at a time when the public—and hence the politicians—had little interest or understanding of these proposals.
The US was no exception, initially seeing rocketry as a military sideshow, but this all changed when Sputnik beeped into view. Thereafter space access became a national focus, culminating in the Moon landings. Everywhere—not just in the US—the industry became massive, institutionalized, and irretrievably interlocked with government.
The public exhilaration arising from those early successes then gave us the Space Shuttle and the International Space Station, but for a decade the industry has been void of major extraterrestrial achievement. NASA has been trying to fill it with its Space Launch System but now private launch initiatives have returned to center stage for the first time since Robert Goddard started the industry, a return that has brought with it some welcome innovations but no real disruption.
Why is this pervasive, sophisticated, expensive, dangerous, and grossly inefficient industry so successful in its resistance to change?
Most readers already well know the answers. First, to put anything into space takes enormous amounts of energy, about a megajoule for every kilogram just to overcome gravity. But this is negligible compared with the energy required to stay up there, which requires going into orbit. To do this means accelerating to velocities of nearly 30,000 kilometers per hour, needing about 30 megajoules a kilogram. But that is just the theoretical energy; rockets are hopelessly inefficient at low speeds, with only about five percent of the energy liberated by the combustion of the propellant is used to impart motion over the first ten kilometers or so of altitude. The overall space shuttle efficiency to orbit was about 16 percent. Why so low? Mainly because rockets haul up about 2.5 tons of oxygen for every ton of fuel they burn. There’s the rub.
Of course, like it or not, once beyond the atmosphere onboard oxygen will have to be provided anyway, either as such or through some other oxidizer. In practice it is overwhelmingly convenient to employ the same system from the start. Further, no practical (i.e. payload carrying) rockets have ever been constructed without staging. And so, we were forced, at an early date, to have rockets that rose into the air carrying all their oxygen up with them and jettisoning unwanted parts as they went.
No matter that this is grotesquely inefficient, the low cost of propellant compared with the stratospheric cost of everything else (just $1.4 million versus $450 million to launch the shuttle in 2009) meant that nobody lost any sleep over it.
Nonetheless, despite tweaking this technology to near its limit (metallic hydrogen?), what is noteworthy is how intrinsically dangerous it remains. Rockets are flying bombs, bombs carrying very expensive payloads, with a one to two percent chance of things going very badly wrong—and on almost every occasion that this has happened the vehicle has either been on the pad or still firing its first stage boosters.
Of course, all sorts of alternatives to this battering-ram approach to space launch have been proposed: skyhooks, space elevators, sled launchers, rockoons, and slingatrons, to name a few. But by far the most common proposal is for a spaceplane, usually incorporating a novel feature. As I noted here before (see “Spaceplanes: the triumph of hope over experience”, The Space Review, November 12, 2018), there have been more than 80 spaceplane proposals since World War II, none of which have been successful. But a major reason for their persistent attraction is that such a vehicle could, in theory, fly up to the top of the atmosphere using liquid fuel alone, thus making it as safe as any aircraft. (And should such a spaceplane have no moving parts in its propulsion systems it would be even safer.)
In any event, the space launch business is overdue for a disruptive technology, perhaps long overdue. Railways superseded canals after 60 years, electric locomotives superseded steam ones after 50 years, and jet turbines were powering aircraft 40 years after the propeller-driven ones took to the air. We are now entering the biggest disruptive occurrence of our lifetimes: the replacement of the internal combustion engine by battery-driven electric motors (efficiency up from about 25 to more than 90 percent.) Seventy-odd years after the V-2, there may be a comparable surprise awaiting a vice president responsible for space launch operations. For the sake of the future of the industry, let us hope so.