Filed under
atmosphere
12 milestones, in chronological order.
- c. 4.1 billion years agoFormation
The dynamo dies and the air starts leaving
Mars Global Surveyor found the oldest crust magnetised and the great impact basins blank — read as a dynamo dead inside the first half-billion years, though MAVEN data since has reopened the date.
- c. 3.7 billion years agoFormation
Tharsis rises and tips the planet over
Three hundred million cubic kilometres of magma built a bulge across a quarter of Mars, raised Olympus Mons some 22 km, and probably tipped the spin axis about 20 degrees.
- 1784The Telescope Era
Herschel gives Mars seasons, and inhabitants
Herschel put the tilt of Mars near 29 degrees, read the shrinking polar caps as seasons, and concluded its inhabitants probably lived much as we do.
- 1947Canals and Dreamers
Kuiper finds carbon dioxide, and no water
A lead-sulphide cell on the 82-inch at McDonald Observatory found the first molecule ever confirmed in the air of Mars: carbon dioxide. Water vapour stayed hidden until 1963.
- 15 July 1965First Contact
Mariner 4 photographs a cratered, near-airless Mars
Twenty-one grainy frames replaced the canals with craters, and a radio occultation put the surface pressure near one percent of Earth's.
- 21 July 1973 – 12 March 1974First Contact
The Soviet 1973 armada fails four different ways
Four spacecraft launched in 19 days. Mars 4 flew past at 1,844 km, Mars 5 leaked after nine days, Mars 6 died at touchdown, and Mars 7 missed the planet by 1,300 km.
- 12 August 1983The Rover Decades
Trapped gas proves a meteorite came from Mars
Gas sealed in shock glass inside a 7.9 kg Antarctic stone matched the air Viking had measured in 1976. Terrestrial laboratories suddenly held free samples of Mars.
- 18 February 1993The Rover Decades
Mars's tilt turns out to be chaotic
Two 1993 calculations showed the Martian axis wanders chaotically — one integration ran it from 11 to 49 degrees over 80 million years. The present 25.19 degrees is a low value, not a constant.
- 21 September 2014Follow the Water
MAVEN starts weighing the air Mars loses
The first orbiter built for the upper atmosphere measured Mars shedding roughly 100 grams of gas per second to the solar wind — and about ten times that during solar storms.
- 10 June 2018 – 13 February 2019Follow the Water
A planet-wide dust storm finishes Opportunity
A dust cloud spotted on 30 May 2018 grew to cover Mars and blacked out the sky over a rover that had driven 45 km on a 90-day warranty.
- 9 February 2021The Present Push
Hope arrives, and the Arab world reaches another planet
The UAE had no deep-space programme six years before a 27-minute burn spent half of Hope's fuel to capture the first interplanetary mission flown by any Arab nation.
- 13 November 2025The Present Push
Two small orbiters end a five-year launch drought
Nothing had left Earth for Mars since July 2020. ESCAPADE's twin orbiters broke the drought — then parked at a Lagrange point to wait a year for the transfer window.