Ground magnetic survey on Mars from the Zhurong rover

Mars’ magnetic field has been measured at large scale by orbiting spacecraft and at very small scale via Martian meteorites. Here we report on a ground magnetic survey on metre to kilometre scales. The Zhurong rover made vector measurements at 16 sites along a 1,089 m track in the Utopia Basin on Mars. It recorded an extremely weak magnetic field, with an order of the average intensity less than that inferred from orbit, in contrast to the large magnetic field in Elysium Planitia measured by InSight. A spacecraft measurement samples an area with radius comparable to its altitude, while a ground measurement samples an area with radius comparable to the depth of the magnetized body. The weak magnetic field measured by Zhurong indicates no magnetization anomalies for a depth of many kilometres around and below the rover’s traverse. We suggest two possible explanations for the weak magnetic field: the entire Utopia Basin may have remained unmagnetized since its formation about 4 billion years ago or that the 5-km-radius ghost crater where Zhurong landed may have been been demagnetized by impact.

Aimin Du, Yasong Ge, Huapei Wang, Haiying Li, Ying Zhang, Hao Luo, Can Huang, Lican Shan, Fei Han, Yang Liu, Yongliao Zou, Chi Wang, Yongxin Pan, Qingsong Liu, Ross N. Mitchell, Yang Jia, Baichao Chen, Shengyi Jin, Yi Jiang, Tielong Zhang, Rixiang Zhu, David Gubbins, Keke Zhang