近几年来美国运载火箭和上面级多次发射失败损失了几十亿美元的重要航天资财,并且提出了有关质量控制、设计和试验方法等方面的许多问题和缺陷。过去的九个月中事故出现得异常频繁,有四次发射失败,包括德尔它一次,大力神两次和航天飞 In recent years, the United States has lost billions of dollars worth of important space assets for its launch vehicles and multiple failed launches at the top level, and has raised many problems and defects in terms of quality control, design and test methods. In the past nine months the accident occurred unusually frequently, with four failed launches, including one by Del once, twice by Hercules and astronautics