According to a NASA press release, "Mars will be passing almost directly behind the sun [as seen from Earth]. The sun can easily disrupt radio transmissions between the two planets during the near-alignment. To prevent an impaired command from reaching an orbiter or rover, mission controllers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., are preparing to suspend sending any commands to spacecraft at Mars for weeks in April. Transmissions from Mars to Earth will also be reduced." Mars will be at its closest to the sun, a slim 0.4 degrees on April 17th.
The ongoing dance of the sun and planets is invisible to the human eye, but coronagraphs can see the show. Join SOHO for a ringside seat. www.spaceweather.com