The nose cone containing the Mars 2020 Perseverance rover sits atop a motorized payload transporter at Cape Canaveral Air Force Station in Florida on July 7, 2020. Credit: NASA/KSC

Mars 2020, the spaceship carrying NASA's new rover Perseverance to the Red Planet, is experiencing technical difficulties and is running on essential systems only, the agency said Thursday.

"Data indicate the had entered a state known as , likely because a part of the spacecraft was a little colder than expected while Mars 2020 was in Earth's shadow," NASA said.

The spaceship has left Earth's shadow and the temperatures are now normal.

When a vessel enters safe mode, it shuts down all but essential systems until it receives new commands from . "Right now, the Mars 2020 is completing a full health assessment on the spacecraft and is working to return the spacecraft to a nominal configuration for its journey to Mars," added NASA.

The spacecraft also experienced a delay in setting up its communications link with the Jet Propulsion Laboratory in Pasadena, California, its mission control.

Mars 2020 sent its first signal to ground controllers at 9:15 am (1315 GMT) but it was not until 11:30 am (1530 GMT) that it established telemetry—more detailed spacecraft data.

Matt Wallace, the mission's deputy project manager, said that the fact that the had entered safe mode was not overly concerning.

"That's perfectly fine, the spacecraft is happy there," he said.

"The team is working through that telemetry, they're going to look through the rest of the spacecraft health.

"So far, everything I've seen looks good, so we'll know more in a little bit."