In its first test flight with a redesigned engine using a new, nylon-based type of solid fuel, SpaceShipTwo exploded in flight on 31 October, killing one pilot and injuring the other.

As Rand Simberg says, this is what test flights are for – not, of course, that anyone wants the vehicle to blow up, but that one very much wants it not to do so, and taking the risk that it might go badly wrong is, even in the age of computer-aided design, the only way to progress towards a more reliable craft.

And as the experience with the Space Shuttle, or indeed with any jet aircraft, shows, hundreds of test flights are very often needed to iron the bugs out of any flying vehicle design.

Note also Simberg’s point that Virgin Galactic have been stuck in a sunk cost trap for years, by virtue of having settled on a vehicle design before satisfying themselves that they had the right propulsion system. They believed that the hybrid rocket which powered SpaceShipOne could be scaled up, but they were wrong. Space tourism has not been delayed for years because toe-dipping into space is vastly more difficult than intercontinental air travel, but because of flawed management.

In an interview on the BBC website, David Whitehouse finds it worrying that SpaceShipTwo is intended for space tourist flights, and says that there is “no such thing as routine, regular, safe access to space”. He does not appear to realise that accidents such as this are inevitable, if anyone is going to change that fact.

If humanity is going to spread out into the Solar System, then mass market space tourism is an essential driver at the current stage. If that is to happen, then access to space must be made routine, regular and safe. If that is to happen, then companies like Virgin Galactic must keep flying and testing, and take the occasional accident in their stride, because engineering is not an armchair pursuit. You can only find out whether SpaceShipAnything is going to fly reliably by actually flying it.

There is some fascinating background on Virgin Galactic, and on the parallels between SpaceShipOne, Sputnik and Apollo, in a well researched essay by Doug Messier entitled “Apollo, Ansari and the Hobbling Effects of Giant Leaps”.

The quest for safe, affordable and routine access to space will continue, and rightly so, because we need that high frontier open for business, leisure, exploration and ultimately settlement beyond planet Earth.