LOS ANGELES -- Call it spring break on Mars: Spacecraft in orbit around the red planet and on the surface are taking it easy this month because of interference from the sun.

For much of April, the sun blocks the line of sight between Earth and Mars. This alignment makes it difficult for engineers to send instructions to spacecraft or hear from them.

Such communication blackouts occur every two years when Mars disappears behind the sun. No new commands are sent during this period because they can get scrambled.

Engineers have sent up commands in advance, but work will be scaled back.

Rovers Curiosity and Opportunity can't drive. Instead, they'll study their surroundings. Orbiting spacecraft will make observations, but for the most part, won't beam data back until Mars is in view again.