Things are about to get a little quiet between NASA and its fleet of robotic Mars explorers. That's because an expected communication breakdown is about to happen, all thanks to the sun.
The Mars solar conjunction takes place between Oct. 2 and 16, and this lapse of check-ins between Earth and Mars occurs for a couple of weeks every two years, when both planets are on opposite sides of the sun.
The NASA teams that manage Mars missions stop sending commands to the orbiters and rovers on the Martian surface until mid-October, but that doesn't mean all exploration on the red planet will grind to a halt.
"Though our Mars missions won't be as active these next few weeks, they'll still let us know their state of health," said Roy Gladden, manager of the Mars Relay Network at NASA's Jet Propulsion Laboratory in Pasadena, California, in a statement. "Each mission has been given some homework to do until they hear from us again."
The sun is like a giant roadblock to communications, spewing out hot, energized gas from its outer atmosphere across space. When Mars and Earth are on opposite sides of the sun, this solar gas can interfere with the radio signals that NASA uses to communicate with its Martian robotic explorers.
If engineers attempt to send commands to any of the Martian spacecraft during this time, the messages may get mixed up — and that gamble isn't worth the risk of rovers or orbiters receiving corrupted communication that could endanger them.
Instead, the robots are getting lists of simple commands ahead of the solar event that will keep them plenty busy. This way, they can cruise on autopilot without the need to await more instructions during the communication blackout. But don't expect the rovers to go for a joyride or for the Ingenuity helicopter to take to the Martian skies.
The two rovers, Perseverance and Curiosity, have found some comfortable places to park. The Ingenuity helicopter is sitting 575 feet away from Perseverance and will send updates on how it's doing to the rover each week. The two can keep each other company on Mars since they won't be talking to their teams on Earth.
Perseverance will use its MEDA instrument, or Mars Environmental Dynamics Analyzer, to keep tabs on Martian weather, run its RIMFAX radar instrument, listen for sounds with its microphones and use its cameras to look for dust devils. However, the rover won't even be moving its mast — which is like turning your head — to do any of these things. Curiosity has a similar set of homework assignments, using slightly different instruments.
The InSight lander, which is already stationary by nature, will use its seismometer to listen out for marsquakes. The three NASA orbiters at Mars, including Odyssey, MAVEN and Mars Reconnaissance Orbiter, will continue collecting observations of the planet from above while collecting data from the surface missions that can later be sent back to Earth.
The agency expects that a small amount of data will come back to Earth during solar conjunction, but distribution of most data will be saved until after the event is over. So if you enjoy watching the steady stream of raw images that come in from the rovers or InSight each week, you'll need to wait until the sun isn't hanging out between Earth and Mars.
Teams will analyze the information sent back by the Martian spacecraft to Earth using NASA's Deep Space Network of radio antennas before the missions resume their normal operations after the event. This ensures that if any data was corrupted, it can be resent.
"We've already sent Perseverance a set of commands so it can perform science activities without having 'ground in the loop,' meaning that they pose no risk to the rover's safety, and the team won't need to check that they successfully completed each day," wrote Melissa Rice, associate professor of planetary science at Western Washington University and long-term planner for the rover's science team, in an update.
"Solar conjunction is also an opportunity for us [to] step back and reflect. In our day-to-day operations, it's easy to stay deep into the weeds of mission technicalities, and to lose sight of the profundity of operating a robot on an alien world."
Perseverance is currently in the South Séítah region of Jezero Crater, where it will likely make its next sample collection attempt after the conjunction.
The conjunction will give the Ingenuity helicopter a much-needed break. What began as a technology demonstration has turned into an aerial workhorse, completing 13 flights since April — when it was only designed to fly five times.
The Ingenuity team is trying to prepare the helicopter to fly with a higher rotor speed as the seasons change on Mars, causing decreasing atmospheric density. The little chopper successfully performed a high-speed spin test on Sept. 15, but the helicopter aborted its test flight attempt on Sept. 18.
The team is still trying to work out why this occurred, but it could be due to the wear and tear of Ingenuity's active flight schedule since April.
"We have a number of tools available for working through the anomaly and we're optimistic that we'll get past it and back to flying again soon," wrote Jaakko Karras, Ingenuity Mars Helicopter deputy operations lead at JPL, in an update.
The team will check on Ingenuity after the conjunction to start planning for its 14th flight and see how the helicopter handled two weeks of downtime.
In the meantime, here's wishing the mission teams on Earth some rest and fun, unsupervised but responsible vacation time on Mars for the robots.