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There is more information available on this subject at Mars on the English Wikipedia.
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Sol system[1]



Orbital position:

Fourth planet[1]


Two; Phobos, Deimos[1]



6,792 kilometres (4,220 mi)[1]


0.376 G[1]

Length of day:

24 hours, 39 minutes, 35 seconds[1]

Length of year:

668.6 days[1]


0.7 (CO2, N2, O2)[1]

Surface temperature:

-84°C to 26°C (-120°F to 80°F)[1]









Unified Earth Government

"Time on Mars tends to give a man... perspective."
Edward Buck, referring to Taylor H. Miles.[2]

Mars, also known as Sol IV,[3] known as Edom in the Forerunner era,[4] is the fourth planet of the Sol system, and one of four terrestrial worlds. One of the first human interplanetary colonies,[5] Mars is a major industrial center and one of the largest in the Sol system.[1] Mars is home to the UNSC Navy's primary shipyards[6] and the Orbital Drop Shock Troopers' headquarters in the city of Kenosha, Tanais.[1]


Forerunner era[edit]

Circa 97,445 BCE, ten thousand years after the human-Forerunner wars, Forerunner Miners worked on Mars. Bornstellar Makes Eternal Lasting was sent to work into a step family of Miners as punishment for his rebellious ways. Inspired by his ancilla's tales of Precursor treasure, Bornstellar eventually escaped and made his way to Earth aboard an automated transport. During his stay on Mars, Bornstellar climbed the planet's highest volcano, Olympus Mons.[4]

Following the firing of the Halo Array, an automated Juridical listening post remained hidden on Mars for over a hundred millennia.[7]

Human colonization[edit]

In 2080, Mars was the first planet colonized by humanity[1] in the first wave of interplanetary colonization in the late 21st century.[8] Following its colonization—largely driven by corporations eager to break free from the restrictions of Earth's gravity and international law—Mars quickly became a hub of industry and state-of-the-art scientific research. Advancements were made particularly in the areas of nano- and biotechnologies; largely robotics-driven industrial manufacturing and spacecraft construction flourished, the latter most notably in the Argyre Planitia.[5] Even before the planet was terraformed, Mars was one of the largest industrial hubs in the Sol system.[1] With the advances in terraforming technology that accompanied this boom of technological development, Mars was transformed into a planet with near-Earth conditions, becoming home to many.[5]

Interplanetary War[edit]

Main article: Mars Campaign

During the Interplanetary War, Mars became the first colony to rebel from Earth's control. During the events that led up to the war, Mars was home to numerous activists and anti-Earth insurgents. When the first shots of the war were fired, many Martians aligned themselves with the neo-communist Koslovics.[1]

Mars was the site of a decisive battle during the events surrounding the formation of the United Nations Space Command. The Koslovics attempted to seize control of the shipbuilding plants in the Argyre Planitia, but were repelled by a series of blitzkrieg attacks by the newly-organized UNSC Marines in a series of brutal battles in 2163. This victory marked a significant boost in the morale of the United Nations forces, and the nascent UNSC subsequently moved on to destroy the Koslovic and Frieden movements throughout the Solar System.[5] After the war ended in 2170 with the signing of the Callisto Treaty, remaining rebels on Mars were put down in a series of harsh crackdowns on the planet.[1]

Human-Covenant War[edit]

Main article: Human-Covenant War

On January 18, 2524, a telescope located on or orbiting Mars spotted an anomalous, evidently artificial object while observing the stellar cluster NGC 2244; while unknown to humans at the time, this was actually the Covenant planetoid station High Charity.[9][note 1]

On April 2, 2526, UNSC forces working with ONI agents prevented an attack on New Harmony. Two Insurrectionists, Christina Rice and James McCann, were disguised as Army specialists and were stealing nuclear weapons for a possible attack.[10] Throughout the war, the UEG kept plans for an evacuation of industrial facilities away from Mars and Earth, which were eventually put into action following the Fall of Reach and the believed compromised location of the human homeworld.[11]

During the Covenant's assault in the Sol system in late 2552, Mars was attacked by the Covenant following the arrival of the High Prophet of Truth's fleet.[1] Mars was the site of a large-scale engagement called the Battle of Mare Erythraeum, set on the fields of Mare Erythraeum. There, Colonel James Ackerson and his UNSC Army forces combated against the Fleet of Furious Redemption's ground forces, commanded by Jiralhanae Chieftain Lepidus. The UNSC lost the battle and Ackerson was taken prisoner.[12] While the UNSC resistance was crushed, the human population centers on Mars survived the Covenant assault relatively intact.[13] The Martian defense on the planet is credited for delaying Covenant forces from pressing their invasion on Earth.[1]

On November 18, 2552, at 15:45 pm, High Charity arrived near Mars and made a Slipspace jump to Installation 00. This event was recorded by the local Juridical terminal.[7]


After the Human-Covenant War, an ONI surgical and research facility and a UNSC Spartan base were established on Mars, which augmented and housed the SPARTAN-IV supersoldiers.[14][15] As the UNSC continued to rebuild in the years following the war, the orbital shipyards located on and around Mars remained its primary shipyards.[6]


Terraforming has transformed the surface of Mars from a former barren and uninhabitable environment into an Earth-like world.[16][17]


Forerunner locations[edit]

Orbital installations[edit]


Martians produce a type of Whiskey, one that is enjoyed by Michael Stanforth.[18] Misriah Armory, the largest military weapons and equipment manufacturer in human history, is based on Mars.[19]


Olympus Mons has been made suitable for snowboarding, with one Marine suggesting that they rode it during their youth.[20]

Known residents[edit]


  • Despite being terraformed its still depicted as having a red-orange color when seen from space in Halo: Uprising. The Halo Encyclopedia contradicts this, saying that Mars is now "as blue and green as Earth."
  • In Halo: Arms Race, the sun is erroneously depicted as several times larger than it appears from Earth. The sun would actually appear far smaller when viewed from Mars.
  • Edom is the Hebrew word for Red, and the name of an ancient Semitic Kingdom.
  • One of Mars' moons, Phobos, is the location of a penal colony.[17]


List of appearances[edit]


  1. ^ NGC 2244 is 5200 light-years away from Sol, meaning that the light from the cluster would have taken 5200 years to reach the telescope. High Charity was commissioned in 648 BCE, which implies that the holy city must have been significantly closer to Sol than NGC 2244, which the telescope was observing. This is also apparent by High Charity's silhouette being recognizable from the image, as it would otherwise be impossible to discern on the scale involved.


  1. ^ a b c d e f g h i j k l m n o p q r s t Halo Waypoint: Mars
  2. ^ Halo 3: ODST, ViDoc, Desperate Measures
  3. ^ Halo Channel: Encyclopedia
  4. ^ a b Halo: Cryptum, Chapter 1
  5. ^ a b c d Halo Encyclopedia, p. 42 (2011)
  6. ^ a b Halo Waypoint: Canon Fodder - Have S'moa
  7. ^ a b Halo Waypoint - Query: Catalog
  8. ^ Halo Encyclopedia, p. 44
  9. ^ Dr. Halsey's personal journal, "A new threat?" image
  10. ^ Halo 4: Forward Unto Dawn, Part 1
  11. ^, Jason Jones Interviewed By You (Archive)
  12. ^ Halo: Uprising, Issue #1
  13. ^ Halo Waypoint: Humans
  14. ^ Halo: New Blood, Chapter 14
  15. ^ Halo: New Blood, Chapter 18
  16. ^ Halo: Arms Race
  17. ^ a b Halo Encyclopedia, p. 294
  18. ^ Halo: Fleet Battles - Fall of Reach Campaign Guide, p. 29
  19. ^ Halo Waypoint - Canon Fodder: Outpost Discoveries
  20. ^ Type-51 Carbine