 The closing might not be enough to stop the contamination from happening elsewhere. NASA astronauts say they're not worried about Boeing's Starliner. They say they're certain the craft will be able to bring them back to Earth safely, despite the technical problems that have extended their mission. Multiple helium leaks and failures of the capsule's thrusters have been behind the delays, and the astronauts have been docked at the space station for more than a month. Neither NASA nor Boeing has set a return date.