As a followup to Benson Space’s announcement of its “low-G” reentry plan, Brian Binnie of Scaled Composites talked a bit about the planned reentry experience for SpaceShipTwo during a talk Saturday at the Heinlein Centennial in Kansas City. According to Binnie, the peak G forces on reentry will be about 7 Gs. However, in a later discussion, he said that the G-force profile during reentry will be shaped like a bell curve, with about 20 seconds where the forces are in excess of 4 Gs. (Taking 7 Gs lying flat, as passengers on SS2 will be doing, is equivalent to taking 3-4 Gs sitting up, he noted.) He added that while Benson Space’s approach could be a way to mitigate G forces, the approach Scaled and Virgin are taking has the advantage of being simpler and thus less prone to failures.

Saturday’s issue of the Nashua (N.H.) Telegraph has an editorial raising questions about the environmental impact of suborbital spaceflight. The article is based on a recent AP article about the growth of the suborbital space tourism field, specifically mentioning the recent investment in XCOR Aerospace. (You can tell that the editorial is not going to be that positive when it refers to Boston Harbor Angels, the group of angel investors that made the investment into XCOR, as “fat cats with money to spare”.)

The Telegraph editorial’s key section is:

While these ventures have a futuristic outlook, what no one questions is whether the planet, already inundated with harmful emissions, needs yet more of them from space vehicles that serve no other purpose that to give rides for people with money to burn for a brief personal adventure.

Planes provide needed transportation and scientific rockets hopefully will benefit humankind. But do we really need to unload more fuel emissions into the skies with tourist rockets while we haven’t yet brought the Earth’s present overload of toxic gases under control? Just wondering.

This is not the first time this issue has come up; Richard Branson and Virgin Galactic tried to head this issue off at the pass last year at the SpaceShipTwo cabin mockup unveiling in New York by claiming that each SpaceShipTwo flight would have one ten-thousandth the environmental impact of a space shuttle launch, or about the same carbon dioxide emission as a single Virgin Atlantic business-class passenger on a New York-to-London flight. Other suborbital vehicles under development will probably have environmental impacts of roughly the same order as SS2, given the relatively short duration of the powered portion of their flights (a few minutes of rocket power, and in some cases additional time under jet power.)

Even in the most robust market scenarios the number of flights will only be in the hundreds or low thousands per year for years to come, which means that the total environmental impact of suborbital spaceflight will be an almost infinitesimal fraction of the overall commercial aviation industry. Couldn’t the Telegraph’s editors reached that same conclusion with just a modest amount of research? Just wondering.