China's Tianwen 1 orbiter and Zhurong rover are once again active at Mars following a communications blackout caused by the sun interfering with radio signals sent from Earth.
Tianwen 1 and Zhurong had been in standby mode for about a month, since mid-September. With the Earth and Mars orbiting at opposite sides of the sun and all three bodies almost perfectly aligned, communications with the Red Planet were effectively blocked by interference from our star's charged particles.
The China Lunar Exploration announced (Chinese) on Thursday (Oct. 21) that the orbiter and rover had reestablished communications and resumed science and exploration activities.
Both Tianwen 1 and Zhurong are active sooner than first anticipated, as the spacecraft were expected to be beyond the reach of communications until the end of October. This estimate was likely conservative as this was the first time China has operated Mars spacecraft during a once-every-26-month solar conjunction. (Tianwen 1 is China's first Red Planet mission.)
Zhurong had covered a total of 3,878 feet (1,182 meters) before going on standby for the solar conjunction, Sun Zezhou, Tianwen 1 chief designer with the China Academy of Space Technology (CAST), told Chinese media earlier this month. Zhurong landed in Utopia Planitia on May 14 and rolled onto the surface a week later, having remained in orbit since February after Tianwen 1 arrived at Mars.
Zhurong also returned a panoramic view of its surroundings ahead of going on standby, showing the area it will be exploring.
Things will be changing for both Tianwen 1 and Zhurong in the coming weeks. In early November, the orbiter will end its role as a dedicated relay satellite for Zhurong, since the rover has completed its primary mission. Tianwen 1 has been passing over Zhurong's position once every Martian day, or sol, to relay data from the rover to Earth, but it will now shift its orbit to begin global mapping and analysis of the Martian surface and subsurface with its suite of seven science instruments.
While Tianwen 1 will still provide relay services, a European satellite could also step in to help transmit Zhurong's data across hundreds of millions of miles of space. The European Space Agency's (ESA) Mars Express, which launched in 2003, is planning to perform a set of five tests with Zhurong in November.
Mars Express will attempt to receive data from Zhurong and then retransmit the information to Earth, James Godfrey, Mars Express spacecraft operations manager at ESA, told Space.com. However, Mars Express won't be able to send commands to Zhurong, as the rover's message-sending capabilities are limited to channels that Mars Express can't monitor.
In the meantime, Zhurong will continue its journey south from the landing platform that safely delivered it to the surface.
A new paper published in Earth and Planetary Science Letters on geomorphologic exploration targets led by Ye Binlong of the University of Hong Kong) and Qian Yuqi of the China University of Geosciences identifies fascinating targets for analysis by Zhurong. These include mud volcanoes and features that may have been formed by movements of subsurface water and ice.
Zhurong's ground-penetrating radar is expected to provide "fundamentally new perspectives" on potential subsurface Martian water ice, the authors claim. Underground water would not only have implications for potential life, but would also be a strategic natural resource for future crewed Mars exploration. NASA's Perseverance rover is also looking for water reserves under the Martian surface using its own ground-penetrating radar.
A preprint science paper about Zhurong's progress so far reveals that the rover has been covering covering on average about 33 ft (10 meters) and up to 66 ft (20 meters) per sol for the first 60 sols, depending on terrain and science tasks, also detailing the route planning and autonomous drive aspects of Zhurong's operations.
The paper also reveals some of the features in the landing area and rocks showing evidence of being weathered. Expect Zhurong to continue returning new images, findings and science data as it makes quick progress south.