'Dummy' news: 'A small planet with dramatic landscapes'
6 March 2002Mars is a smallish planet, its radius is just a little over half the Earth's. Yet it boasts scenery on a scale that makes Mount Everest and the Grand Canyon seem puny by comparison.
It has the highest volcano in the solar system, Olympus Mons which stands at 26 km above the surrounding plain: Mount Everest is only a third the height. Olympus Mons lies at the western edge of another gargantuan feature, the Tharsis dome which is a 10 km high, 4000 km wide bulge in the Martian surface. Dotted in the middle of Tharsis are the Ascraeus, Pavonis and Arsia volcanoes, all of them higher than Mount Everest. And running from the eastern flanks of the rise, roughly along the equator, is Valles Marineris, a split in the Martian crust 4000 km long (about a fifth of the Martian circumference), up to 600 km wide and 7 km deep. The Grand Canyon is a mere 800 km long, up to 29 km wide and 1.6 km deep.
Then there is the Hellas Basin in the southern hemisphere, which is a massive impact crater 2300 km in diameter and more than 9 km from top to bottom. The bottom of the Hellas Basin has the lowest elevation on the planet. But perhaps most striking of all is the general difference in height and surface roughness between the northern and southern hemispheres. A quick glance at the map above shows a southern hemisphere pock marked with craters and with generally much higher terrain than the relatively smooth northern hemisphere. The map was compiled in summer 1999 from data recorded by the Mars Orbiter Laser Altimeter (MOLA) on board NASA's Mars Global Surveyor (MGS) spacecraft. MOLA is measuring the height of the Martian surface to within 13 metres of elevation on average; the heights of some parts of the Earth aren't known so accurately.
It has revealed for the first time that the slope from south to north is gradual and that the average elevation in the south is 6 km higher than in the north.
- What caused this North-South divide?
- What were the forces that created the other features in Mars' spectacular landscape?
- And when did they cease?
- Or do some of them still exist today?
- Volcanism and tectonics have clearly been important, but what was, or is, their role?
Answering these questions involves developing models of the interior and hypotheses about the planet's formation and evolution. The nature of the interior, in turn, has implications for the existence of a magnetic field. Mars has a very weak field today, but there is evidence that it had a much stronger field early in its history. What happened to turn it off?
Such questions may seem highly specialised, of interest only to planetary geologists. But the answers will throw light on the really big questions about Mars, such as the fate of the water that almost certainly existed on the planet in its early history; whether Martian life exists, has ever existed, or could have existed at some time in the past; and even whether Mars could make a hospitable venue for human exploration.
For more information please contact:
Clovis De Matos
ESA Science Programme Communication Service
Tel: +31 71 565 3460