How Are Maps of Mars Made? From Viking to HiRISE
Mars has been mapped from orbit for 50 years. Here is how cameras and lasers like Viking, MOLA, CTX and HiRISE built the maps used in Mars games and missions.
Mars is one of the best-mapped places in the Solar System, in some ways better mapped than the floor of Earth's oceans. Every map in Trawers comes from public data collected by orbiters over five decades.
Colour: the Viking mosaics
The Viking orbiters of the 1970s took tens of thousands of images that were later stitched into global mosaics. Colourised versions of those mosaics still give the familiar rust-and-brown look of the whole planet.
Height: MOLA
In the late 1990s, Mars Global Surveyor carried the Mars Orbiter Laser Altimeter (MOLA). It fired laser pulses at the surface and timed their return, measuring the height of the whole planet. MOLA's elevation maps are why we know exactly how tall Olympus Mons is and how deep Hellas goes.
Detail: THEMIS, CTX and HiRISE
- THEMIS on Mars Odyssey maps the surface in infrared at about 100 m per pixel, revealing the ground day and night.
- CTX, the Context Camera on Mars Reconnaissance Orbiter, covers almost the whole planet at about 6 m per pixel.
- HiRISE, also on Mars Reconnaissance Orbiter, can see details as small as about 30 cm, enough to spot rovers, their tracks and parachutes on the ground.
By taking two pictures of the same place from different angles, scientists turn CTX and HiRISE images into precise 3D terrain models.
How Trawers uses them
Trawers layers these datasets: a global colour mosaic and MOLA heights for the whole planet, regional mosaics for each landing area, and CTX and HiRISE terrain where rovers have driven, such as Jezero and Gale. The game is an independent project and not affiliated with NASA; it simply uses the publicly available data. Full sources are listed on the about page.