Here’s a brief summary of what’s known about the explosion that took place Thursday afternoon at Mojave Air and Space Port, based on reports in the Bakersfield Californian, LA Times, and LA Daily News, the most detailed accounts so far:

• Three people have been killed, two at the scene of the explosion and one later, after surgery.
• Three are injured, two in critical condition and one in serious condition.
• All of the casualties are employees of Scaled Composites, and the explosion took place at a test site operated by the company.
• The explosion took place while the workers were performing a “cold flow” test to see how nitrous oxide flowed through the system. The nitrous oxide was under pressure but there was nothing to ignite the propellant.
• Burt Rutan, at a press conference Thursday night, said that they had performed similar tests a number of times in the past without incident and believed it to be safe. He said he couldn’t speculate on the cause of the explosion.
• Rutan refused to comment on what effect this would have on the development of SpaceShipTwo, saying that the company has declined to answer questions about that development for a year and a half. “I suddenly don’t have a change for that.”

Although Virgin Galactic’s Alex Tai said Saturday that a formal announcement of Northrop Grumman’s acquisition of Scaled Composites would come on Monday, none of the companies involved made a press release or other official announcement about the deal on Monday. It is possible, though, that the announcement may come today, since Northrop will release its second quarter financial results and hold a conference call with financial analysts. Expect the deal to come up in the Q&A if the company doesn’t mention it in its earnings release.

Update: It turns out the Scaled acquisition did not come up during Tuesday’s conference call. So much for my predictive skills…

While we wait for more officials details about Northrop’s acquisition of Scaled Composites, I went back to the comments by Alex Tai of Virgin Galactic Saturday morning at the NewSpace 2007 conference. Some additional excerpts from his brief mention of the deal in his address:

We’ve spent a long time looking at this, and it’s not appropriate for a company like Virgin to own a development company. We’re an operating company. What we want to do, as we’ve said for a long time, is to be the operator of spaceships. We love the product that Burt Rutan has at Scaled Composites. But what we want to be able to do is vie this off against the next manufacturer, have other options to compete with them. So it’s not appropriate for us, really, to get involved in the development. We have a position with The Spaceship Company and, again, that creates some problems for us as well…

As far as the agreed position on this stuff, it’s all very good, we’re very, very happy with it. The headlines are that there’s no change to the management structure, no change to the operating policies of Scaled Composites, and no change to the customer base… We’re exceptionally happy…

Answering a question about how the business relationship between Scaled and Virgin will change with the acquisition:

It’s exceptionally positive. We couldn’t ask for a better partner… Northrop Grumman, I don’t think a lot of people realize, have been our partners for the last four years. They’ve had a large ownership position, up to 50 percent, they were the largest shareholder of Scaled anyway. What’s been obvious I think to them and obvious to us is that they’ve got a fantastic asset there, and if you have the opportunity to expand your ownership of that, you do. And what do you expand it to? The maximum you can possibly get; they got 100 percent. We’re really happy. There’s no change to the status quo. If anything, what it’s done is it’s taken out some of the variables, taken out some of the risk. We know now we’ve got someone who doesn’t have any financial issues and will keep the no-change policy in place. We’re very happy, very happy.

Alex Tai of Virgin Galactic gave the keynote address Saturday morning at the NewSpace 2007 conference and briefly mentioned the news that Northrop Grumman is acquiring Scaled Composites. Tai said that a formal announcement is planned for Monday, but that Virgin is “extraordinarily happy” and “extraordinarily positive” about the acquisition. He said that they couldn’t ask for a better company to work with, and that Northrop planned no changes to the status quo, including the management structure and operating plans.

Space News is reporting this afternoon that Northrop Grumman has increased its stake in Scaled Composites from 40 to 100 percent [subscription required]. A formal announcement about the deal hasn’t been made by either company, nor terms of the sale announced. Alex Tai of Virgin Galactic, who is in Washington today to attend the NewSpace 2007 conference, declined to comment about the sale in the article. This is obviously a very interesting deal, but it seems too soon right now to speculate what this means for Scaled and its suborbital spacecraft development plans.

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.

The trade publication High-Performance Composites offers this news about the development of SpaceShipTwo:

Advanced Composites Group Ltd. (ACG, Heanor, Derbyshire, U.K.) will supply a new generation of out-of-autoclave prepregs for the project, featuring MTM45-1, a variable-cure temperature, high-performance, toughened epoxy matrix developed for resin film infusion and prepreg processing. It was designed for low-pressure vacuum bag processing and, in addition to resin film and prepreg formats, is available in partially or selectively impregnated formats to reduce layup time, surface defects and internal voids. After a freestanding postcure, the system is capable of 150°C (302°F) wet Tg and reportedly exhibits good damage tolerance. Initial cure can be as low as 80°C/176°F, which ACG says allows for the use of lower cost tooling materials.

But you all knew that already.

Speaking of the Journal, the front page of today’s issue has an article about the lingering beef between Burt Rutan and Jim Benson. (Yes, subscription required. Blame the Journal, not me.) As many readers are already aware. SpaceDev, founded by Benson, built the hybrid rocket motor used by Rutan’s SpaceShipOne, but the two had a rather public falling out, which included threats of lawsuits by Rutan (which, the article states, were not followed through “to avoid the expense and distraction of litigation”.) The two now, of course, are rivals, with Rutan leading the development of SpaceShipTwo for Virgin Galactic and Benson starting a new company to help fund development of SpaceDev’s Dream Chaser concept. For those who have followed this issue over the last few years, there’s not too much new here, although reported Andy Pasztor does get comments from both Benson and Rutan.

One other item of note in the article: Benson tells the Journal that he is planning “a nationwide competition to hand out free rides aboard his spacecraft” that will be formally announced in the next few weeks.

This week’s issue of Aviation Week features an article about White Knight, the carrier aircraft for SpaceShipOne. While SS1 is now hanging from the ceiling of the National Air and Space Museum, White Knight is still flying today, serving as “an ideal testbed for large, heavy payloads,” in the words of William B. Scott, the AvWeek writer who got to fly on White Knight recently. Much of the article discusses how White Knight served as a pathfinder for key SS1 systems, ranging from the environmental control system (ECS) to the landing gear actuators on White Knight (which are the same as the feathering system actuators on SS1). Flying White Knight is a little difficult because of the unique pattern of circular portholes: “It’s like flying inside a giant ‘whiffle ball’,” said Scaled Composites’ Doug Shane. Still, he notes, “The [SS1] feather was, relatively speaking, a genius idea, but the whole idea of using this airplane to solve the problems for SpaceShipOne was equally genius. It’s the best thing we did for the program.”

SPACE.com landed an exclusive interview with Burt Rutan, published back on Friday. By and large there’s not a lot new here: many of the comments he made here are similar to comments he has made in the past, such as at the ISDC in May. He revealed that one of his biggest concerns was potential investors getting cold feet, which is why he picked Richard Branson over some alternatives to develop SpaceShipTwo, despite Branson’s outspokenness. “He was selected as an investment source because he was very early telling everybody what he was going to do, and usually I’m against that. But he’s putting his reputation on the goal of this program… doing that on day one.”

Rutan also said that being able to experience weightlessness is “a close second” to getting the view of the Earth from space. That’s why SS2 will have a large cabin so people can float about during their four minutes in weightlessness. Also, the onset of gravity will be gradual, taking more than 40 seconds to reach 1-g; enough time, he feels to get passengers strapped in before they experience stronger accelerations during reentry.

Those reading Rutan’s comments closely will also pick up on his choice of words: “I’m focusing now on going ahead and doing something that I never did with airplanes. That is, not just do research but go ahead and build something that would be certified. Produce it and sell it to spacelines and let them go out there and compete with each other to fly the public.” Also: “That’s the reason we feel we’ll easily be able to certify people floating around and getting into a seat…more of a bed to lay flat.” Notice the use of “certified” and “certify”: suborbital spacecraft are licensed, not certified (something the FAA will take great pains to point out), although Rutan rarely hides his dissatisfaction with that approach, preferring aircraft-like certification to launch vehicle licensing.