An explosion during a test of rocket engine compenents by SpaceShipTwo builder Scaled Composites claimed the lives of three Scaled employees and seriously injured three others yesterday, according to various reports.

This is sure to set back the SpaceShipTwo program, and casts a pall on the entire industry.

Those of us in and around the commercial space industry have known from day one that deaths were inevitable during the opening of the final frontier, but that doesn’t make it any easier to take.

My heart goes out to the good people at Scaled Composites and their families. I pray for a speedy recovery for those injured, and I offer that those who who died did not do so in vain. They were working to uplift all of humanity, and I very deeply appreciate their sacrifice. They are my heroes.

–Update at 2:12 p.m. ET–
We’re doing updates on the Popular Science website at as more information becomes available.