Three of the five planets that are easily visible to the unaided eye are in decent view now, with one more just starting to join them. Brilliant Jupiter, the largest planet in the solar system, is in the east at nightfall. Saturn, the second-largest, is in the southwest at the same time, well to the upper left of the Moon. Venus, the “morning star,” is in the southeast at dawn. And little Mercury is about to climb into the western sky during evening twilight.

Only one planet is missing: Mars. It’s passing directly behind the Sun today. It won’t return to view, in the morning sky, until next year.

That’s an inconvenience not just for skywatchers. It’s also a problem for the scientists and engineers who operate Mars landers, rovers, and orbiters.

When Mars is within two degrees of the Sun — the width of your finger held at arm’s length — the Sun can interfere with radio transmissions. This year, that period spans November 11th through the 25th.

Scientists beamed up two weeks’ of commands before the blackout period. Some instruments were shut down. Others will record their observations for playback later on. And if anything goes wrong, the craft can go into “safe mode” — they shut down most operations and wait to hear from Earth.

So flight controllers are anxiously waiting for Mars to move away from the Sun a couple of days after Thanksgiving — allowing their charges to get back to work.
 

Script by Damond Benningfield

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