A post-test inspection of the composite structure for a heat shield to be used on the Mars 2020 mission revealed that a fracture occurred during structural testing. The fracture, which occurred near the shield’s outer edge and spans the circumference of the component, was discovered on April 12, after the shield completed a week-long test at the Lockheed Martin Space facility. The heat shield is designed to protect the rover as it enters the Martian atmosphere and was subjected to forces up to 20 percent greater than those expected during entry into the Martian atmosphere, NASA said in a statement. NASA and is working with contractor Lockheed Martin Space, Denver, to understand the cause of the fracture and determine whether any design changes need to be incorporated into a replacement.