As far as I know, Mars has no inner dynamo to create a major global magnetic field. However, crustal magnetic fields exist on Mars. I would like to know how the property of this field changes with time? Is it possible to detect and map the global crustal magnetic fields?
Zheng-shi,
> Is it possible to detect and map the global crustal magnetic fields?
Yes.
http://mgs-mager.gsfc.nasa.gov/
I do not know of any datasets analyses that have looked for a time-varying component of the fields that can be uniquely associated with the crustal magnetism. The magnetospheric variation would make any search from orbit very hard.
As far as I know there is no data on how Mars’s crustal magnetic field changes in time. The map of the present crustal magnetism is performed (based on data of missions to Mars). In addition some theories exist which explain why the modern field is weak.
Thank you all for your answers!!
If the crustal magnetic field of Mars is time invariant (or changes very little) and is unique at different position on Mars, maybe it can be used to navigate the spacecraft at EDL phase just like the navigation by map-matching on the Earth. Is it possible? Perhaps I am so ideal.
Thank you!
Zheng-shi,
An interesting idea.
Generally the combined data from star-trackers and camera imagery pins the location of the craft inside a roughly ellipsoidal shape a few km in size.
(I'm arm-waving here: probably not of order 100m, and probably a bit better than 100km)
Knowing where the craft is with finer accuracy could be useful if the craft had some significant aerodynamic command authority, and that's currently not built into most craft.
To be able to sense the magnetic field requires some rather sensitive equipment deployed on long spindly arms poking away from everything ferrous and electronic. Such 'booms' would not last long in the entry phase - which generally takes place over a relatively small distance as measured on the ground - a few 10 of km at most (as I recall), so even an armoured magnetometer wouldn't really see much variation during EDL.
Still, an interesting idea!
Thank you!
@Garry
Thank you very much for your quick reply. At present, the position error at Mars entry point is about several km, this error may be increased in the entry phase because only IMU can be used for navigation. Finding other potential navigation sources is really a tough job. Although the navigation based on radio measurements to orbiters has been proposed, maybe using the natural sources has lower cost.
Thank you again!
The actual size of the magnetic field of Mars is not known yet but its strength is probably much less than one ten thousandths of that of the Earth and like Venus the intrinsic magnetic field is not significant for the solar wind interaction. The Martian magnetosphere has been studied by the Mariner 4 flyby mission and the Mars 2, 3, 5 and Phobos orbiters. The ionosphere is thought to be magnetized because the solar wind dynamic pressure exceeds the thermal pressure of the ionosphere but no measurements have been made to confirm this hypothesis.
Hi Adebesin. Thanks a lot for your answer. Maybe much more investigations are needed to understand the magnetic field of Mars.
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