Editing Mars Express (section)

==== 2004 ====
* January 23: ESA announced the discovery of water ice in the south polar ice cap, using data collected by the OMEGA instrument.

* January 28: ''Mars Express'' orbiter reaches final science orbit altitude around Mars.

* March 17: Orbiter detects polar ice caps that contain 85% [[carbon dioxide]] (CO<sub>2</sub>) ice and 15% water ice.<ref>{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Water_at_Martian_south_pole |title=Water at Martian South Pole |publisher=[[ESA]] |date=March 17, 2004 |access-date=March 29, 2016 }}</ref>

* March 30: A press release announces that the orbiter has detected [[Methane on Mars|methane in the Martian atmosphere]]. Although the amount is small, about 10 parts in a thousand million, it has excited scientists to question its source. Since methane is removed from the Martian atmosphere very rapidly, there must be a current source that replenishes it. Because one of the possible sources could be microbial life, it is planned to verify the reliability of these data and especially watch for difference in the concentration in various places on Mars. It is hoped that the source of this gas can be discovered by finding its location of release.<ref>{{cite journal |last1=Formisano |first1=V. |last2=Atreya |first2=S. |last3=Encrenaz |first3=T. |author3-link=Thérèse Encrenaz |last4=Ignatiev |first4=N. |last5=Giuranna |first5=M. |title=Detection of Methane in the Atmosphere of Mars |journal=[[Science (journal)|Science]] |date=2004 |volume=306 |pages=1758–1761 |doi=10.1126/science.1101732 |pmid=15514118 |issue=5702 |bibcode = 2004Sci...306.1758F |s2cid=13533388 |doi-access=free }}</ref>

* April 28: ESA announced that the deployment of the boom carrying the radar-based MARSIS antenna was delayed. It described concerns with the motion of the boom during deployment, which can cause the spacecraft to be struck by elements of it. Further investigations are planned to make sure that this will not happen.

* July 15: Scientists working with the PFS instrument announced that they tentatively discovered the spectral features of the compound [[ammonia]] in the Martian atmosphere. Just like methane discovered earlier (see above), ammonia breaks down rapidly in Mars' atmosphere and needs to be constantly replenished. This points towards the existence of active life or geological activity; two contending phenomena whose presence so far have remained undetected.<ref>{{cite web|url=http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Water_and_methane_maps_overlap_on_Mars_a_new_clue|title=Water and methane maps overlap on Mars: a new clue?|publisher=[[ESA]]|date=September 20, 2004|access-date=March 29, 2016}}</ref>