HOUSTON (AP) — Officials of a Houston company trying to crack the space barrier say they plan to launch a rocket on a suborbital flight next week and believe “‘it’s going to work like a charm.” Donald K. Slayton, a former astronaut who is mission director for Space Services Inc., said the rocket is on a launch pad at Matagorda Island on the Texas Gulf Coast and will be ready to blast off at 10 a.m. on Sept. 8. He said he was “about 99.4 per cent” sure the rocket would fly as planned. ““We’re confident it’s going to work up a charm,” Slayton said Wednes day. Named Conestoga I, the rocket is a solid-fueled second stage of a Minuteman I missile. In a 10- minute flight, the rocket will carry a dummy payload far above the Earth and spew out a shower of ice crystals. I will then fall into the Gulf of Mex co. Space Services Inc. paid the Na tional Aeronautics and Space Ad ministration $365,000 for the rocket. The total cost for the launch is about $2.5 million, company officials said. ‘David Hannah, chairman of Space Services, said the success of the launch is critical for the company because of a fiery failure last year. “We've got to see whether we can do it,’’ he said.