Watch a video replay of NASA’s exoplanet announcement

Blaming a slew of technical snags and “avoidable errors,” NASA officials said Tuesday that the launch of the James Webb Space Telescope, already years behind schedule, will be delayed to 2020, potentially pushing the mission’s development cost above an $8 billion cap mandated by Congress.

After years of analyses and debate, NASA announced Monday that the agency’s next Mars rover will land on or near an ancient river delta where water once flowed into a 30-mile-wide, 1,600-foot-deep crater to search for signs of ancient microbial life and to continue ongoing studies of the red planet’s history and evolution.

Technical problems discovered during ground testing of U.S.-built detectors for the European Space Agency’s Euclid astronomy mission will delay the completion of the telescope’s scientific payload, jeopardizing the observatory’s 2020 launch target, the head of NASA’s astrophysics division said last week.