Spin state and deep interior structure of Mars from InSight radio tracking

Area of Science:

• Planetary Science
• Geophysics
• Astrogeology

Background:

• Understanding Mars's interior structure and atmosphere is key to its formation and evolution.
• Planetary interiors are not directly accessible, making global geophysical data difficult to interpret.
• The NASA InSight mission provided crucial seismic and radio science data.

Purpose of the Study:

• To determine fundamental properties of Mars's core, mantle, and atmosphere.
• To characterize the Martian core and mantle separately using radio science data.
• To investigate anomalies within the Martian interior and rotation rate.

Main Methods:

• Precise measurement of Martian planetary rotation.
• Detection of a resonance with a normal mode.
• Analysis of InSight's radio tracking data.

Main Results:

• Determined the liquid core radius (1,835 ± 55 km) and density (5,955–6,290 kg m⁻³).
• Characterized density increase at the core-mantle boundary (1,690–2,110 kg m⁻³).
• Argued against a solid inner core and revealed core shape, indicating mantle mass anomalies.
• Found evidence of slow acceleration in Martian rotation rate.

Conclusions:

• The InSight mission's data enabled detailed characterization of Mars's internal structure.
• Results suggest internal mass anomalies within the Martian mantle.
• Observed rotation acceleration may link to internal dynamics or atmospheric/ice cap changes.