@suddenlyjon Marsipedia Field encyclopedia

Datum areoid Sol 24 h 39 m 35 s Year 686.98 d Moons 2

Index

Atlas

Every article on this sheet, grouped the way a survey groups a planet. Search is in the header. Random picks one article.

Planet

Mars as a world: orbit, size, day, and the reason the ground is red.

  • Mars The fourth planet from the Sun: a cold desert world with a thin carbon-dioxide atmosphere and two small moons.
  • Seasons of Mars A 687-day year, a 25-degree tilt, and seasons made unequal by an eccentric orbit.
  • Timekeeping on Mars A tested Mars24 clock: solar longitude, season, and mean solar time from a UTC instant and an east longitude.

Geography

Lowlands, highlands, basins, and the places missions actually land.

  • Geography of Mars Northern lowlands, southern highlands, and the great named landforms between them.
  • Olympus Mons The largest shield volcano on Mars, about 22 km above the datum, with a still broader relief from the plains.
  • Valles Marineris The canyon system east of Tharsis, thousands of kilometers long and the largest of its kind known.
  • Hellas Planitia The largest clear impact basin on Mars, about 2,300 km across, with a floor more than 7 km below the datum.
  • Tharsis The great volcanic bulge of Mars, home of the Tharsis Montes and the neighbor of Olympus Mons.
  • Polar caps of Mars Seasonal carbon-dioxide frost over residual water ice, plus stacked layers that record climate.
  • Jezero crater A 45 km crater with a fossil delta, and the workplace of the Perseverance rover since 2021.
  • Gale crater A 154 km crater with a 5 km mountain of layers, climbed by Curiosity since 2012.
  • Site dossiers Six places on one table. Columns are evidence. Nothing on the table is a winner.

Geology

Volcanoes, canyons, and the impact basins cut into the crust.

  • Olympus Mons The largest shield volcano on Mars, about 22 km above the datum, with a still broader relief from the plains.
  • Valles Marineris The canyon system east of Tharsis, thousands of kilometers long and the largest of its kind known.
  • Hellas Planitia The largest clear impact basin on Mars, about 2,300 km across, with a floor more than 7 km below the datum.
  • Tharsis The great volcanic bulge of Mars, home of the Tharsis Montes and the neighbor of Olympus Mons.

Climate

Thin air, long seasons, migrating ice, and the dust.

  • Atmosphere of Mars A thin, cold envelope of carbon dioxide, nitrogen, and argon, with pressure under one percent of Earth's.
  • Water on Mars Ice at the poles and underground, and a rock record of rivers, lakes, and deltas from an earlier Mars.
  • Polar caps of Mars Seasonal carbon-dioxide frost over residual water ice, plus stacked layers that record climate.
  • Dust storms on Mars Local, regional, and planet-encircling storms that veil the surface and can end a solar-powered mission.
  • Seasons of Mars A 687-day year, a 25-degree tilt, and seasons made unequal by an eccentric orbit.
  • Timekeeping on Mars A tested Mars24 clock: solar longitude, season, and mean solar time from a UTC instant and an east longitude.
  • Pressure and the areoid A Class B screen: surface pressure falls exponentially with height above the areoid, using the fact-sheet datum and an 11 km scale height.
  • Design envelope Index of the screening instruments. They share one constant file and they are not for flight.
  • Solar resource A Class D sunlight screen. The fact-sheet irradiance is 586.2 W/m2. Optical depth is yours. There is no clear-sky preset and no storm preset.
  • Subsurface ice Ice on this sheet is an evidence class: radar, geomorphology, neutrons, or thermal data. It is not a tonnage.

Moons

The two small satellites, Phobos and Deimos.

  • Phobos The inner and larger moon of Mars, a dark irregular body that orbits in 7 hours 39 minutes.
  • Deimos The outer and smaller moon of Mars, smoother than Phobos, with a 30-hour orbit.

Exploration

Flybys, orbiters, landers, and the rovers still at work.

  • Exploration of Mars From Mariner 4's first close pictures to the rovers still driving in 2026, and the sample cache still on the surface.
  • Jezero crater A 45 km crater with a fossil delta, and the workplace of the Perseverance rover since 2021.
  • Gale crater A 154 km crater with a 5 km mountain of layers, climbed by Curiosity since 2012.
  • Mission instruments The flights that earned a number on this sheet, and the measurements that are named but not stored.
  • Landed mass The rolled mass of Curiosity and Perseverance, from NASA. The entry craft was heavier. This is not a design for a crewed lander.

Astrobiology

Ancient water, habitability, and what has not been proved.

  • Water on Mars Ice at the poles and underground, and a rock record of rivers, lakes, and deltas from an earlier Mars.
  • Jezero crater A 45 km crater with a fossil delta, and the workplace of the Perseverance rover since 2021.
  • Life on Mars No confirmed life. The strongest current case is a potential biosignature in a Jezero mudstone, still on Mars.
  • Perchlorates Phoenix leached 0.4 to 0.6 percent perchlorate by mass from northern-plains soil. That is one site, not a recipe, and not a drinking limit.

History

How Mars was drawn before spacecraft arrived.

  • Canals of Mars A nineteenth-century map of straight lines that spacecraft showed were not there.

Engineering

Screening instruments for pressure, cabins, crew mass, oxygen, propellant, regolith columns, sunlight, light time, and passes. Not for flight.

  • Pressure and the areoid A Class B screen: surface pressure falls exponentially with height above the areoid, using the fact-sheet datum and an 11 km scale height.
  • Cabin gas Class A ideal-gas mass, dry-gas oxygen partial pressure, and inspired oxygen for a cabin you describe.
  • Crew budget Class A open-loop mass from the 2018 life-support baseline: oxygen, food, potable water, and the separate hygiene lines.
  • Design envelope Index of the screening instruments. They share one constant file and they are not for flight.
  • Oxygen from air Integer-mass screen of CO2 -> CO + 1/2 O2. The MOXIE record is a flight instrument, not a crew plant.
  • Propellant from air Integer-mass screen of the net methane reaction. Imported hydrogen is 4/16 of the methane, carbon dioxide is 44/16, and oxygen is twice the methane.
  • Regolith shield A column of soil is a thickness times a density you supply. The Gale and cruise dose rates are context. This page does not turn the column into a dose.
  • Solar resource A Class D sunlight screen. The fact-sheet irradiance is 586.2 W/m2. Optical depth is yours. There is no clear-sky preset and no storm preset.
  • Site dossiers Six places on one table. Columns are evidence. Nothing on the table is a winner.
  • Perchlorates Phoenix leached 0.4 to 0.6 percent perchlorate by mass from northern-plains soil. That is one site, not a recipe, and not a drinking limit.
  • Subsurface ice Ice on this sheet is an evidence class: radar, geomorphology, neutrons, or thermal data. It is not a tonnage.
  • Mission instruments The flights that earned a number on this sheet, and the measurements that are named but not stored.
  • Methods How a number gets onto this sheet, what the trust classes mean, and what the sheet refuses to do.
  • Light time Vacuum light time for a distance you type. The long Earth-Mars envelope on the example missions is about 22 minutes. This page does not look up today.
  • Landed mass The rolled mass of Curiosity and Perseverance, from NASA. The entry craft was heavier. This is not a design for a crewed lander.
  • Dust and wheels Curiosity's wheels were already torn by 2013, with a dated odometer and a dated grouser count. Energy per kilometer is not invented here.
  • Ice to water Heat and water mass from ice, using heat capacities you type. Empty fields refuse. The result is not a drinking liter.
  • Pass volume How many sols of a daily product fit in one pass, if you type both amounts in the same units.