When Mars is on the opposite side of the sun from earth, can NASA communicate with a probe on Mars? ?

A signal can't go thru the sun. But Mars is rarely exactly behind the sun. How close to the sun can a signal pass and still be detectable? 

quantumclaustrophobe2020-10-12T14:56:50Z

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It's actually pretty rare for the the Sun to *eclipse* Mars - but, it does happen on occasion.  But, with the immense output from the Sun, there's about a 2 to 3 week window where the sun is so close to the line of communication that they place probes on 'stand by' until the orbits carry the planets into a more favorable area for radio communication again. 

Chris Ancor2020-10-12T09:04:49Z

Only if the signal is relayed from a satellite somewhere.

wereq2020-10-12T04:54:49Z

Yes, but not with a straight shot if it's directly behind the Sun; the signal would need to be bounced, which, compared to getting things into space, or getting them to land on Mars, is hilariously simple. 

Anonymous2020-10-12T04:23:04Z

yes, but only at night, hun. 

Starrysky2020-10-12T03:57:33Z

Too many unknowns to guess that answer:
Who-what was sending
What was detecting
Activity of the sun's corona, magnetic field
Any magnetic field or other disturbances on Earth
Spacing of the sun, planets (Mars varies a lot)
Angles of the objects in line of transmission
This situation is already quite a situation for communications to Mars probes and landers and data back from them.  Look up what NASA and JPL have experienced.
I would give you the contact for my cousin's husband, but he has retired from JPL early this year.  He was a manager of the giant radio antennas system for space probe messages.  He worked on many of those probe programs for more than 40 years.