To hear Richard Branson tell it, your next vacation will be in space. On Friday, Branson, the swashbuckling CEO of Virgin Airlines and the newer Virgin Galactic, cut the ribbon on a 2-mi. (3.2 km) runway in La Cruces, N.M., which will be used in as little as 18 months, he promises, to begin carrying paying tourists into suborbital space. “This is the beginning of the second space age,” he said.
Sounds like fun! But there are a few small problems, not the least being that the technology is unproven, even a small malfunction could kill you and in the event that you do come back in one piece, your 15-minute vacation would have cost you a minimum of $200,000. Now, on the very day of Branson’s grand unveiling, add one more reason not to get too carried away by the talk of a coming boom in space tourism: according to a new study by the American Geophysical Union (AGU) all the rocketing around could make the atmospheric an even bigger mess than it is today.
Launching rockets can be either a very, very dirty business or a pretty clean one, depending on the kind of fuel you use. The shuttle’s solid boosters are filled with a rubbery mix made up of ammonium perchlorate, aluminum, iron oxide, epoxy and a polymer bonding agent. If you think setting all that on fire would produce some nasty exhaust, you’re right. The Saturn V moon rockets used a mix of kerosene and liquid oxygen in their first stages, which produced it’s own air-fouling smoke. The second and third stages, however, were fueled with liquid oxygen and liquid hydrogen, releasing mostly flame and steam. The rockets that would be used for launching tourists on suborbital missions would be filled with some kind of hydrocarbon fuel which, like the kerosene in the Saturn V, would act as a pollutant. (See photos of the labor of space exploration)
To conduct its calculations on the atmospheric impact of recreational rocketry, the AGU proceeded on the assumption that the space tourism industry is correct when it projects that it will be launching about 1,000 vacation rockets per year by 2020. That’s not an entirely unreasonable prediction since Branson is by no means the only entrepreneur in the game. If that ambitious goal is met, the first and biggest concern would be the amount of soot the engines would produce. One thousand commercial launches would produce 10 times the soot emitted by government and private rockets today—and that presents serious problems.
Since particles of soot are black, they absorb rather than reflect away heat and light. Soot from rockets poses a special danger since it is emitted far higher in the atmosphere than 0ther sources of air pollution. “Rockets are the only direct source of human-produced compounds above 14 miles [22.5 km],” said the paper’s chief author Martin Ross in a statement.
In the case of vacation rockets, this would mean a layer of accumulated soot in the stratosphere about 25 miles (40 km) high, or three times the altitude at which commercial airlines fly. The AGU’s computer models showed that by blocking sunlight, the soot could actually cool much of the surface of the planet by 1.2ºF (.7ºC), which seems like a good thing in the face of global warming. However, it would warm Antarctica by 1.5ºF (.7ºC), which is exactly what the rapidly melting southern ice does not need. Worse, soot that’s been deposited 25 miles high can hang around in the atmosphere for years, unlike soot from factories, coal-fired power plants and airliners, which precipitates out in as little as a few days or as much as a few weeks, depending on quantities and circulation patterns. (See photos of the Hubble telescope’s latest hits)
“The response of the climate system to a relatively small input of black soot is surprising,” said study co-author Michael Mills. “Our results show particular climate system sensitivity to the type of particles that rockets emit.”
Soot is not the only problem. Commercial rockets would release CO2 as well, which would exert its own, smaller, warming effect. Ozone levels would also be affected worldwide, with the poles experiencing a 10% increase and equatorial areas a 1% decline. Averaged out planet-wide, this too would nudge temperatures upward.
Certainly, these ghosts of pollutants future do not have to come to pass and the AGU acknowledges that just because the rocketeers predict such a robust launch schedule within the decade does not mean it will occur. There’s a reason for the idiomatic meaning the term “rocket science” has acquired. It’s an extraordinarily tricky technology—and one that exacts an extraordinarily high price for errors. It’s hard to sell seats on vehicles that explode, and if the long history of rocketry proves anything it’s that somewhere along the way, something always blows up. NASA and the space agencies of other nations have taken decades to master the business of extraterrestrial travel. The commercial sector enters the field at their passengers’—and the planet’s—peril.
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