On June 21, 2004, a single event sent the hopes of mankind soaring, along with confident predictions of dreams soon to come true: The first private flight of SpaceShipOne (SS1) past the generally recognized boundary of space (100 km), into the record books, and into the imaginations of millions. When the second such flight won the $ 20 million Ansari X Prize, those hopes seemed to become tangible, and the realization of human potential imminent. We are now less than a month from 2010, and nary a single commercial* manned spacecraft is presently in commercial operation.
After the 2004 flights, optimists originally projected that not only would there be commercial crewed spaceflights within two years (by late 2006 / early 2007), but that there might even be several firms offering it. Those pessimists who chose to offer timelines might have solemnly observed that there is many a slip 'twixt a cup and a lip, and suggested that 2008 might be more realistic. It is very nearly 2010, and the one and only firm anywhere near to offering a commercial manned space vehicle is set to unveil its product, SpaceShipTwo, next Monday.
But that milestone, while encouraging, merely begins a long and potentially bumpy program of flight testing early in the coming year: A process that is likely to take more than a year even if no significant modifications are found necessary, and if the FAA/AST - the regulatory body governing commercial spaceflight - is extraordinarily accommodating and internally versatile in its own tasks.
It should be noted that this agency will be creating the rules governing manned commercial suborbital spaceflight on the fly, as Virgin Galactic single-handedly creates the industry, and commercial operations cannot begin - indeed, not even flight tests can begin - until they have their regulatory ducks in a row with respect to each step in the process involving actual flights. In addition, their instinct will be to clamp down hard if any dramatic hiccups occur during flight testing.
Another complication is that, as a combined system of two vehicles - the White Knight Two (WK2) carrier aircraft and SS2 suborbital crew vehicle - the flight testing regimen of the latter will also include the later-stage flight testing of the former. WK2 has undergone many successful flights so far, so it is known that it is a viable aircraft by itself, but the manufacturers (Scaled Composites) will be testing it under conditions closer to operational before they even begin testing SS2.
That probably means the system attaching the SS2 to WK2 and release mechanism, and then an unknown number of carry-and-drop flights of the actual SS2 vehicle, omitting the space launch. Then - and I would say the FAA/AST will probably take its sweet damn time permitting this step - my guess is that what will follow would be a series of drops with graduated rocket burns by the SS2 up to higher and higher altitudes, culminating in a large number of full-operational-profile space launches.
I expect a long delay between the conclusion of the SS2 testing program, however drawn out it is, and the final granting of permit to carry paying passengers to space - and that's even if nothing of note goes wrong. Current estimates (always by third parties - VG wisely avoids firm commitments to timeline) place the first commercial flight of SS2 in 2012, and that is of course the standard refrain of the optimistic space commentariat: 18 months to 2 years. So long as any tangible progress whatsoever is being made, that is the distance to the horizon: The Space Tourism Friedman Unit, or "STFU."
This is a modification of the Friedman Unit - a unit coined in mockery of Thomas Friedman's continuous, years-long assertions that the outcome of the Iraq war would be determined "in the next six months." The space tourism equivalent is that "flights will begin in (current year + 1.5 to 2)".
There are thus only three domains in the realm of space tourism prediction: Never, STFU, and "We're Here, Oh Awesome" (WHOA). In the vast majority of cases, Never means Never - the firms in question don't know what they're doing, or are trying to execute fundamentally flawed plans that will simply not converge no matter how brilliant they are. This includes quixotic engineering teams with 7-figure budgets trying to pursue 10-figure vehicles (e.g., SSTO spaceplanes), bullshit artists selling rides on paper spaceships (like the now-essentially-defunct Rocketplane Kistler, and major aerospace firms (*cough* EADS Astrium cough) indulging their engineers in make-believe for PR purposes.
However, there are also cases where Never actually means Could Be: There is promise in the idea and in the people pursuing it, but there has been very little significant, tangible progress toward it, or what progress has been made has occurred with such aching slowness that they are unlikely to realize their objectives. JP Aerospace, for instance, has a concept called Dark Sky Station that I find intriguing, and their ability to make tangible advances despite being extremely resource-poor highly promising, but I think they will need to attract a big-time angel investor to get much further than they already are.
STFU, or Space Tourism Friedman Unit, means that tangible progress is being made on a regular basis, but the endpoint of the process has not yet crested the horizon - and therefore anyone stating confidently that operational flights will begin in 20XX (provided the present year is not 20XX), is merely citing a STFU, and should follow his own advice in that respect. Firms that have entered the STFU prediction-blackout horizon are, or at least appear to be: SpaceX**, Virgin Galactic, XCOR, Blue Origin, Bigelow Aerospace, Armadillo Aerospace, and Masten Space Systems.
Now, STFU doesn't mean the firms themselves should be secretive or uncommunicative (as Blue Origin has infamously been), but rather that commentators of progress in the field may need to exercise some restraint to avoid gushing out over-optimistic predictions every time a significant milestone is reached. I myself have been guilty of this on occasion. It also doesn't mean that the actual endpoint is within the 2-year horizon, just that it has passed a point where the time to the objective can substantively be called finite. The actual time it takes may be a decade or more - STFU is just the distance to the horizon, not the distance that must be traveled to reach the destination.
In other words, STFU means ultimate success is reasonably plausible - the idea and business plan are sound, the technical plans credible, the resources sufficiently available, the team capable, and tangible progress is consistently made - but there remain too many ifs for the margin of error in a prediction to be within the horizon. When a firm enters the STFU horizon, commentators should STFU and stop jinxing them with unrealistic expectations.
Then there is WHOA: I define this condition to mean that the vehicle is in its final operational configuration, the testing regimen is complete, all regulatory processes have concluded, all necessary permits granted, the ground operations are well-characterized and ready to go, the company operating the vehicle has set a firm date for first commercial flight with paying passengers, and that date is within 12 months of the present.
I would very much like to believe that Virgin Galactic will achieve WHOA status before the decadal anniversary of the X Prize flights that set this all in motion, but the current STFU horizon (2012) is 8 years after those flights, so I can't discount the possibility that it won't. If we are to be perfectly masochistic, the list of possible sources of delay is so vast - and multiplicative when chained in series - that it's easy to despair.
Still, I remain confident of ultimate success, and don't hold with certain bellicose ignoramuses calling it a "hoax." Nor do I hold generally with people who dismiss real, tangible progress by talking about everything that hasn't been done yet - as if it would make sense to dismiss the Wright Brothers because their aircraft were slower than trains, or belittle someone who swims the English Channel because they didn't swim the Atlantic Ocean. There is a kind of madness to such an attitude, and yet it seems dishearteningly commonplace.
Even so, I can both be confident and realistic at the same time: I recognize the basic truth of Hofstadter's Law: Everything takes longer than you expect, even when you take Hofstadter's Law into account. Delays are not caused by problems in linear fashion, but by the recursive of chain of problems, solutions, problems caused by the solutions, solutions to the 2nd set of problems, and so on, and so on. Entering STFU territory means that, barring a radical catastrophe, this recursion appears to converge on a finite and manageable number of problem/solution cycles in the real world.
We are going to get there - mankind will expand into space - but I think the process is going to ooze and congeal rather than explode in starbursts of creation like we've experienced with information technology. There will probably come a day when progress is radical, but that hope, at least, is nowhere near being within a Space Tourism Friedman Unit.
*Space Adventures doesn't count as commercial, because they are merely functioning as sales agents for a Russian government infrastructure that occasionally, grudgingly, allows a single ultra-wealthy individual to hop along on Soyuz flights to ISS at an ever-increasing price.
**SpaceX has announced a flight window for its first Dragon cargo flight to ISS that is within a year of today, barring likely delays, but their horizon for manned flights is still well outside this boundary.