More on Mars > MARSIS Update with Giovanni Picardi

MARSIS, a multi-frequency Synthetic Radar Altimeter with around penetration capabilities, one of the seven instruments onboard Mars Express has, a primary scientific objectives, the mapping of distribution of water, both liquid and solid, in the upper portion of the crust of Mars.
The instrument is also able to perform geologic probing of Mars subsurface and to characterize it by using large scale altimetry.
Mars ionosphere sounding is another secondary scientific goal by globally measuring the ionosphere electron density and investigating sun and the solar wind on the electron density.
Since the mission start, MARSIS has retrieved precious information, giving us a new insight of Mars, revealing a new look towards the past of the Red Planet, finding evidence for large aquifers on early Mars or discovering a new layer in Martian ionosphere just to use two examples.

While its tantalizing data keep on being acquired, Giovanni Picardi, MARSIS Principal Investigator, from the University of Rome ‘La Sapienza’, in spite of the workload, shared some of its time to answer some questions.

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Dr. Picardi, what activities is, currently, MARSIS performing?

MARSIS is currently taking data for subsurface sounding as well for ionosphere sounding.


According to the latest buried crater findings might the finding of bodies of water become harder to achieve in the North hemisphere?

Presently INFOCOM is working on MARSIS data inversion process to determine the dielectric constant of the subsurface detected interface. The first results have been obtained on flat surface to avoid the clutter presence as well the surface and subsurface behaviour that can jeopardize the accuracy on the estimated dielectric constant. In the north hemisphere few areas exhibit suitable characteristics for the data inversion.


Is it possible to say that the North was similar to the South in the past? More heavily cratered? Is there a way to know if this might of cyclical nature?
Will the Southern Hemisphere become smoother?

This is a question whose answer should be stated by the geologist expertises. By the radar point of view the south pole surface is smoother than north pole area.


Regarding latest fresh gullies finding by NASA's MGS did MARSIS performed localized observations? Any results so far?

Not yet MARSIS data have been inverted on these areas.

Is it possible for MARSIS to "see" what lies beneath Elysium's frozen ocean or does the thickness of this one surpasses the capabilities of the instrument?

There is not any technical reason for limiting the MARSIS capabilities excluding the depth of the interface and its dielectric constant. Stated in other words depends from the first layer attenuation and from the reflectivity of the subsurface.


Elysium was a major finding, were there large concentrations of water founded?

The inversion has not be yet performed on this area.


And liquid water? Do we have answers to where it might be?

MARSIS data inversion on the south pole has found compatibility with water dielectric constant. According to the geologist opinion in many areas at medium latitude could be possible to find subsurface water traces.


One of the objectives is to provide a 3D topographic map of the poles, was this already performed? What might we earn from it?

Actually has not yet been performed.


And about solar wind interaction. Are there already answers?

The solar wind interacts with Mars ionosphere and MARSIS is able to recover the distortion due to the ionosphere interaction with the electromagnetic pulses by contrast technique.


And on one of the parameters for the ionospheric sounding data processing, temperatures, any conclusions so far?

By the radar point of view the ionosphere parameters have been estimated by the surface signal and compared with the active ionosphere sounding data.


What will MARSIS provide us in the current year?

More wide area investigation in order to determine the subsurface dielectric constant to help the geologist on the interpretation of the Mars geological history.

More on Mars Express at ESA.int