Update November 14, 2023: The time has come again when NASA has cut off all radio contact with all of its Mars rovers and probes, including its Mars helicopter Ingenuity. NASA recently announced this. Because once again the time has come when the Earth, the Sun and Mars lie 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 this way:
The missions were suspended because hot, ionized gas emitted from the solar corona could potentially interfere with radio signals sent from Earth to NASA’s Mars probe, causing unexpected behavior.
In the opposite direction, i.e. from the Mars rovers to Earth, the transmitted data could be affected, but this would not be so tragic because the rovers and probes could send their data again at a later time. In 2023, the Mars-Solar conjunction will occur from November 11th to 25th. NASA then resumes radio contact.
Such a Mars-solar conjunction occurs every two years. This YouTube video clearly explains the phenomenon:
But the exploration continues even during the interruption
During this time, the Perseverance and Curiosity rovers will continue to collect limited data on surface changes, weather conditions on the Red Planet and radiation there. And while 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 poses a constant challenge for Mars missions, the US space agency says.
The Mars Reconnaissance Orbiter and Odyssey Orbiter probes 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 pause in communications is over, the orbiters will transmit any pending science data to Earth.
End of update, beginning of original message on the Mars-Solar conjunction of October 2021:
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 other space agencies will post October 2021 and at least until October 16 From 2021 (for some missions the interruption will last a little longer) there will no longer be commands to the numerous Mars rovers, Mars probes/landers and Mars orbiters, as NASA writes.
Commands from Earth would 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 far into space. Partial loss of radio commands that make it past the Sun to the device on Mars could cause devices on Mars to eventually receive erroneous commands. With potentially fatal consequences.
However, this does not necessarily mean a complete shutdown for Mars rovers and probes/landers and for orbiters orbiting Mars. Because before NASA breaks radio contact, all devices on Mars will be assigned tasks for the time when there is no radio contact from Earth to Mars. Then NASA sends each device a to-do list for the duration of the Mars-Solar conjunction. Typically these involve health checks and other self-assessment activities. In some cases, the devices simply continue to collect data on Mars.
This is what Perseverance, Ingenuity, Curiosity, etc. do.
The Mars rover Perseverance, for example, continues to collect weather data and continues to record data with its cameras and microphones. However, it does not drill any new drilling during the Mars-Solar conjunction. The Mars rover Curiosity, in turn, continues to measure radiation, among other things. The Mars helicopter Ingenuity, however, only sends a status report to Perseverance once a week. Otherwise, Ingenuity remains unchanged in its position 175 meters from Perseverance. And the Mars lander Insight continues to listen for earthquakes. 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 measurement work as usual.
Devices used on or near Mars can still transmit signals to Earth, but only to a limited extent. You accept that some of this data may be lost; This lost data will simply be sent again after the end of the Mars-Solar conjunction. The devices continue to collect data, but most will be transmitted back to Earth after the end of the Mars-solar conjunction. This excluded 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 also illustrates it in an animated video.