“Space tourism doesn’t have to be rocket science,” reads the subheading of a New Scientist article about a proposed high-altitude passenger balloon concept that would take people to the edge of space. The “bloon” concept, by Spanish company zero2infinity, features a six-person pressurized capsule carried to an altitude of 36 kilometers (118,000 feet) by a giant balloon. Four passengers, paying €110,000 (US$142,000) each, will spend two hours at that altitude, gazing down on the Earth, before gently descending to a landing.
It sounds like an interesting experience: an opportunity to gaze down on the Earth at altitudes three times higher than a commercial jetliner in what appears to be a luxurious setting (according to a brochure describing the overall experience). It may turn out to be a profitable niche for zero2infinity. However, contrary to New Scientist, it is certainly not space tourism.
And why isn’t it? For obvious reasons, the balloon is not going into space: while doesn’t have a sharp boundary like a national border, 36 kilometers is well below the altitudes commonly considered space, including the widely-accepted 100-kilometer the Kármán line. While there is some dispute about what altitude constitutes space (the US government, for example, awards astronaut wings at an altitude of 80 kilometers), the bloon flights still appear to fall far below those alternatives. Even zero2infinity markets its flights as “near-space”, using the term that emerged in the last decade for aerospace activities above altitudes commonly used by planes but below the Kármán line and other space boundary definitions.
Moreover, the bloon flights provide only part of the experience of space. While they will offer a high-altitude view of the Earth—albeit well below what suborbital and orbital space tourists would get—the bloon flights do not provide another essential aspect of spaceflight: extended weightlessness. (The company’s brochures do suggest that the bloon flights would allow “up to 25 seconds of zero, lunar and martian gravity”, comparable to a single parabola on a ZERO G or similar aircraft flight.) The New Scientist article is dismissive of the weightlessness experience: “But is the point of space travel to get funfair thrills that you could experience far more cheaply by taking a plane ride on a weightlessness-producing ‘vomit comet’?”
Well, perhaps: the “funfair thrills” of weightlessness (of much greater duration than possible on an aircraft) is widely cited as one of the primary reasons people are interested in space flight. There’s also the intangible benefits of the full experience: the view from space plus the sensation of weightlessness plus the other attributes of the flight. Suggesting one could save money by separating out the experiences (a balloon flight plus a zero-g flight, for example) is somewhat like arguing that one can save money on a trip to Hawaii or the Caribbean by staying home and going to an indoor pool and then a tanning salon. It’s not really the same.
There’s also the environmental angle: the article argues that while zero2infinity claims that its flight can be (eventually) zero-emission, suborbital vehicles flown at high flight rates could have polluting effects comparable to all of commercial aviation. However, the 2010 study cited in the article as evidence of suborbital spaceflight’s polluting effects has been questioned by some in industry, who take issue with some of the assumptions that went into that model, including the amount of propellant used on those flights and the amount of soot produced. (For what it’s worth, the New Scientist article was written by the magazine’s biology and environment features editor, and not one of its space reporters.)
There’s another important difference between suborbital spaceflight and high-altitude ballooning. The former is arguably a means to a greater end: more frequent, less expensive, and safer spaceflight for a wide range of other applications. By leveraging the large potential customer base of thousands of spaceflight participants per year versus the roughly 100 satellites launched annually, it’s possible to support development of suborbital and eventually orbital vehicles that can open up new markets and applications that would otherwise be inaccessible with current vehicles. High-altitude ballooning, on the other hand, seems unlikely to be a stepping stone to either low-cost spaceflight or even broader terrestrial applications, other than scientific research that zero2infinity mentions in its literature.
“So if you’ve always longed to travel into space but don’t want to trash the planet doing so, space ballooning is the way to go,” the New Scientist article concludes. Sadly, that conclusion is inaccurate: there’s limited, disputed evidence that commercial spaceflight will “trash the planet”, and a high-altitude balloon flight is not “travel into space”, something I’ve railed against in the past. High-altitude ballooning and suborbital (and orbital) spaceflight can coexist; the former can serve as something of an appetizer for the latter, even. But ballooning is not a substitute for spaceflight.