Mars Solar Conjunction: NASA Explains Why It Can’t Send Commands To Mars Spacecraft In Last Week Of July

Mars will be experiencing a solar conjunction toward the end of the month, where the Red Planet will almost be directly behind the sun during the daytime. That has forced NASA to announce a moratorium on commands to its Mars spacecraft from July 22 to August 1, a temporary suspension that takes place each time these so-called conjunctions take place. Why is the space agency doing this, and why is the sun “to blame” for all of it?

In a brief statement quoted by, Chad Edwards, Mars Relay Network Office manager, explained that the Mars solar conjunction could lead to garbled communications, hence the decision to suspend the sending of commands to spacecraft on the Red Planet beginning next Saturday.

“Out of caution, we won’t talk to our Mars assets during that period because we expect significant degradation in the communication link, and we don’t want to take a chance that one of our spacecraft would act on a corrupted command.”

Edwards added that the moratorium won’t affect the flow of data from Mars to Earth, as NASA will keep on receiving telemetry each day, allowing the agency to keep tabs on the status of its Mars rovers and other spacecraft. But there may be some loss of data due to the solar conjunction, and with that in mind, the data will be retransmitted at a later date for the sake of clarity and accuracy.


In a press release, NASA’s Jet Propulsion Laboratory wrote that Mars passes near the sun every 26 months or so — this is the “Mars solar conjunction” that would sometimes see Mars going directly behind the sun. That won’t exactly happen this year, but what also stands out as interesting is the space agency’s note that people who view the August 21 total solar eclipse will learn a “visible lesson,” one that shows that Mars doesn’t have to be right behind the sun in order to garble communications between the Red Planet and ours.

According to the JPL press release, this lesson will be seen by those wearing proper eye protection while viewing the eclipse, as the sun’s corona is always visible during total eclipses — this is a feature made up of hot, ionized gas, and it can mess up radio waves that may pass through it. That’s the very reason why NASA imposes a moratorium on communications between Mars orbiters and rovers and the Earthbound teams that operate them.

Hoppy Price, NASA/JPL chief engineer of the Mars Program, confirmed in the above press release that vehicles on Mars will remain active and will perform commands that were sent in advance.

“Orbiters will be making their science observations and transmitting data. The rovers won’t be driving, but observations and measurements will continue.”

This month’s Mars solar conjunction will mark the eighth such period for the Mars Odyssey orbiter, and the seventh for the agency’s Opportunity rover. Other vehicles, including the Mars Reconnaissance Orbiter, the Curiosity Rover, and the MAVEN orbiter, were also described as “veterans” of solar conjunctions, which means NASA “knows what to expect” when this year’s conjunction finally takes place.

[Featured Image by Triff/Shutterstock]