China News Service, Shanghai, March 25th: "Zhurong" quietly "sleeps" to block sand and dust storms in the northern hemisphere of Mars
Author Zheng Yingying, Ma Shuai, Samiao Xinpei
The "Zhurong" rover is active in the northern hemisphere of Mars.
Recently, the northern hemisphere of Mars has entered autumn.
According to the analysis of previous exploration data, autumn is the season of frequent occurrence of dusty weather on Mars, and after that, Mars will enter a long and cold winter.
Sandstorm, dust accumulation, low temperature, how does the "Zhurong" rover (referred to as "Zhurong") "survive" in the harsh environment?
This has to do with its fancy "sleep skills".
The dust storm is coming, it "dormant" protective body
The Martian climate and environment are complex. Among them, the Martian dust storm will directly affect the energy acquisition of the Mars rover and affect its survival.
Historically, the Soviet Union's "Mars 3" and the American "Opportunity" were "stopped" because the solar array was covered with dust.
By observing the self-portraits sent back by the "Zhurong" rover from the surface of Mars recently, and comparing the photos taken when it just landed, people can see that a thin layer of dust has accumulated on the surface of the rover.
In the days of sandstorms, how did the "Zhurong" "survive in the sand"?
It turned out that when the huge sandstorm caused the "Zhurong" to be covered by sand and dust, the solar energy received by the "Zhurong" dropped sharply, and it would enter the "sleep" mode. wake up.
The developers judged from the telemetry information of the "Zhurong" rover that although the dust coverage has affected the power generation efficiency of its solar wings to a certain extent, its energy is still sufficient.
According to Wang Wenqiang, the solar cell designer of the Mars rover of the Eighth Institute of China Aerospace Science and Technology Corporation (abbreviation: Eighth Institute) 811, the researchers made a special coating on the surface of the solar cell glass cover of the Mars rover, so that the surface of the solar cell array is not easily contaminated with dust , even if it is contaminated with dust, it can be shaken off by vibration.
According to the on-orbit monitoring data of the Mars rover in the previous period (1 month ago), after using this coating, the current decay rate of "Zhurong" is 2% to 3%, which is far lower than that of foreign Mars rovers of 6% to 9%. decline rate.
Winter energy emergency, it "hibernates" New Year's Eve
After the northern hemisphere of Mars enters the late autumn season, the light intensity will continue to decrease.
At this time, the solar radiation intensity on the surface of Mars is only about 30% of the surface of the earth and 20% of the surface of the moon, not to mention the cold winter.
The energy acquisition of the rover will enter an "emergency state".
In this regard, the developers' response strategy is to "hibernate" the rover.
Jin Bo, a deep space exploration expert from the 811 Institute of the Eighth Academy of Sciences, revealed that its "hibernation" will last until the next spring.
Compared with the lunar rover, what is the difference between the "sleep and wake" of the Mars rover?
Jin Bo said that the "sleep and wake" of the lunar rover mainly solves the problem of how the lunar rover can survive the long and cold moon night in a low temperature environment, while the "sleep and wake" of the Mars rover is mainly aimed at the Martian dust storm and the Martian winter environment.
He said that the rover's "sleep awakening" requires human intervention.
The rover's "sleep-to-wake up" is fully autonomous.
The "sleep" of the rover depends on the power supply capability of the solar panel and the remaining capacity of the lithium-ion battery, which can be said to be anytime, anywhere; its "wake-up" depends on the output power of the solar battery and the temperature of the lithium-ion battery.
In order to enhance energy acquisition capabilities and improve the rover's survivability on Mars, China Aerospace also applied maximum power tracking (MPPT) technology in orbit for the first time.
Chen Daxing, designer of the Mars rover power controller of the 811 Institute of the Eighth Academy, said, "The tracking accuracy is as high as 98%, which improves the utilization efficiency of solar cells by 20% compared with traditional circuits." (End)