Update November 14, 2023: The time has come for NASA to cease all radio contact with all of its rovers and probes on Mars, including its Ingenuity helicopter. NASA announced this recently. Once again the time has come when Earth, the Sun and Mars are on such an imaginary line that signals from Earth can no longer reliably reach vehicles on Mars because the Sun is in the way. This is called a Mars-solar conjunction. NASA describes the problem like this:
Missions are being paused because hot, ionized gas emitted by the Sun’s corona could potentially interfere with radio signals sent from Earth to NASA’s Mars probe, causing unexpected behavior.
In the opposite direction – that is, from Mars rovers to Earth – transmitted data could also be affected, but this would not be so tragic because the rovers and probes could send their data again later. In 2023, the Mars-Solar conjunction occurs from November 11th to 25th. NASA then resumes radio contact.
This Mars-solar conjunction occurs every two years. This YouTube video explains the phenomenon clearly:
But exploration continues even during the outage
During this period, the Perseverance and Curiosity rovers will continue to collect limited data about changes to the surface, the weather on the Red Planet and the radiation there. And although the Ingenuity Mars helicopter will remain on the ground during this period, it will use its color camera to study the movement of sand, which is a constant challenge for missions to Mars, the US space agency says.
The Mars Reconnaissance Orbiter and Odyssey Orbiter orbiting Mars will also continue to take images of the surface. And the MAVEN probe will continue to collect data on interactions between the atmosphere and the Sun.
Once the communications pause ends, the orbiters will transmit all outstanding science data to Earth.
End of update, beginning of original message about the October 2021 Mars-Solar conjunction:
There will soon be radio silence between Earth and Mars. Literally. As Mars disappears behind the Sun as seen from Earth in the first two weeks of October (this is called a Mars-solar conjunction and happens every two years), NASA, ESA and the other space agencies will send the October 2021 report and Until at least October 16, 2021 (for some missions the interruption will last a little longer) there will be no more commands for the numerous Mars rovers, Mars probes/landers and Mars orbiters, as NASA writes.
Commands from Earth would either not reach active devices on or around Mars – because the Sun directly breaks contact – or would be at least partially lost. Through the ionized gas that the sun emits into space. Partial loss of radio commands passing from the Sun to the Mars device could cause the Mars devices to receive incorrect commands. With potentially fatal consequences.
However, this does not necessarily mean a complete shutdown of Mars rovers and probes/landers and orbiters orbiting Mars. Because before NASA breaks radio contact, all Mars devices will be assigned tasks for the time when there is no radio contact from Earth to Mars. So NASA sends each device a list of tasks during the Mars-Solar conjunction. These are typically health checks and other self-assessment tasks. In some cases, the devices simply continue to collect data about Mars.
This is what Perseverance, Ingenuity, Curiosity, etc. do.
The Mars Perseverance rover, for example, continues to collect meteorological data and record data with its cameras and microphones. However, it does not perform any new drilling during the Mars-Solar conjunction. The Mars rover Curiosity, meanwhile, continues to measure radiation, among other things. The Mars Ingenuity helicopter, on the other hand, sends a status report to Perseverance only once a week. Otherwise, Ingenuity remains unchanged in its location 175 meters from Perseverance. And the Mars Insight lander continues to listen for marsquakes. The three Mars orbiters Odyssey, Mars Reconnaissance Orbiter and Maven will also transmit some data they receive from devices on Mars to Earth during the Mars-Solar conjunction and will also continue their own measurement work as usual.
Devices used on or around Mars can still transmit signals to Earth, but only to a reduced extent. It is accepted that some of this data may be lost; This lost data will simply be sent again after the Mars-Solar conjunction ends. The devices continue to collect data, but most of it will be transmitted back to Earth after the Mars-Solar conjunction ends. This left-out data for the period after the end of the Mars-solar conjunction includes, for example, all RAW image data from Perseverance, Curiosity, and InSight.
On this page, NASA not only explains the Mars-solar conjunction, but an animated video also illustrates it.