The heat shield for NASA's Mars 2020 mission cracked during a test. Pictured, an artist's concept of the Mars Science Laboratory, which landed Curiosity in 2012, entry into the Martian atmosphere. NASA/JPL-Caltech

In an unexpected turn of events, the heat shield designed to protect NASA’s 2020 Mars rover developed a crack, prompting the space agency to start working on a new one.

The fracture, which occurred during the most recent set of structural tests, appeared on the outer-edge of the shield and covered the entire circumference of the whole thing. Officials at NASA are already working with those at Lockheed Martin Space, the developer of the component, in order to gain more insight into how the crack appeared and see if any design is needed to prevent such damage in the future.

“After a recent Mars 2020 rover heat shield test, teams identified a fracture in the structure,” tweeted Thomas Zurbuchen, head of NASA’s science directorate. “I’m happy that our standard test procedures revealed the issue & allow the team to build a replacement without impacting the launch readiness date.”

Despite this setback and the additional amount of effort going towards the development and testing of the new-shield, the agency has assured that it will not push back the launch of the $2 billion mission, which is scheduled to lift-off in July 2020. The cost of replacing the shield with a new one was also not revealed.

A heat shield is a curved structure that forms a critical part of the thermal protection system and aeroshell designed to protect the rover and its landing tech from heat and all other forces that come into play while making an atmospheric entry into the Red Planet. It is made from phenolic-impregnated carbon ablator or PICA, a material which is extremely light, but can bear temperatures going up to a whopping 4000 degrees Fahrenheit (2200 degrees Celsius), according to an NPR report.

The heat shield that got damaged was developed way back as part of a set of two. The first shield was used for the Mars Science Laboratory mission, which landed the Curiosity rover in 2012, while the second — originally tested in 2008 — was being aimed for the 2020 mission. However, during the week-long stress-test at Lockheed Martin’s facility in Denver, it cracked open.

NASA said in a statement, the 15-foot-wide shield was subjected to forces 20% greater than those expected during entry into the atmosphere of Mars. By the time a replacement shield is prepped, this one will be repaired to support the agency’s pre-launch testing efforts. Once the new shield is ready, all components of the aeroshell will be shipped to NASA’s Kennedy Space Center, Florida, to get on with the final processing before lift-off.

After reaching the Red Planet, the souped-up, six-wheeled successor of Curiosity will explore the Martian surface in search of microbial life. In addition, it will collect and store necessary samples so that they could be flown back to Earth via subsequent missions. The robotic car-like rover appears a lot like Curiosity but will carry as many as seven new scientific instruments, with more autonomy and super-strong wheels.