Mars Express recent findings and future plans
Résumé
Mars Express remains one of ESA’s most scientifically productive missions whose publication record now
exceeds 1000 papers. Characterization of geological processes on a local-to-regional scale by HRSC, OMEGA
and partner experiments on NASA spacecraft has allowed constraining land-forming processes in space and time.
Recent results suggest episodic geological activity as well as the presence of large bodies of liquid water in several
provinces (e.g. Eridania Planum, Terra Chimeria) in the early and middle Amazonian epoch and formation of
vast sedimentary plains north of the Hellas basin. Mars Express observations and experimental teams provided
an essential contribution to the selection of the Mars-2020 landing sites. More than a decade-long record of
atmospheric parameters such as temperature, dust loading, water vapor and ozone abundance, water ice and CO
2
clouds distribution, collected by SPICAM, PFS and OMEGA spectrometers as well as subsequent modeling have
provided key contributions to our understanding of the martian climate. The ASPERA-3 observations of ion
escape covering a complete solar cycle have revealed important dependencies of the atmospheric erosion rate on
parameters of the solar wind and EUV flux. Structure of the ionosphere sounded by the MARSIS radar and the
MaRS radio science experiment was found to be significantly affected by the solar activity, the crustal magnetic
field, as well as by the influx of meteorite and cometary dust. MARSIS and ASPERA-3 observations suggest
that the sunlit ionosphere over the regions with strong crustal fields is denser and extends to higher altitudes as
compared to the regions with no crustal anomalies. The ionospheric plasma expands to higher altitudes where it
contacts with the solar wind plasma. Reconnection of solar magnetic field lines carried by the solar wind with
field lines of crustal origin opens channels through which the ionospheric plasma escapes to space, producing
strong and narrow cavities in the density. The situation is very different on the night side where the ionosphere has
a patchy structure. Such patchy ionizations are observed in the regions where crustal field lines have a dominant
vertical component. Through these patches the ionospheric plasma from the dayside penetrates and supplies the
nightside ionosphere.
Mars Express has fully accomplished its objectives set for 2015-2016. The mission provides unique observation
capabilities amongst the flotilla of spacecraft investigating Mars. The mission has been confirmed till the end
of 2018. The science case for the mission extension until the end of 2020 has been submitted. The observation
program proposed for 2019-2020 includes both augmenting the coverage and extending long-time series, as
well as new elements and potentially new opportunities for discoveries. It will be boosted by collaboration and
synergies with NASA’s MAVEN, ESA-Roscosmos ExoMars-2016 Trace Gas Orbiter and other missions. The talk
will give the mission status, review the recent science highlights, and outline future plans.