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Planet View
Orbital Distance 1.2 AU
Orbital Period 1.5 Earth Years
Keplerian Ratio 0.768
Radius 5,522 km
Day Length 44.4 Earth Hours
Atm. Pressure 0.84 atm
Surface Temp −15 °C
Surface Gravity 0.87 g
Mass 0.647 Earth Masses
Satellites N/A

Location: Milky WayCrescent NebulaZelene System Second planet

Prerequisite: Horizon (mission) (Mass Effect 2)


Helyme is a "post-garden" world that once enjoyed an Earth-like oxygen-nitrogen atmosphere. It is still blessed with plentiful water, but a generally cold climate (and extreme seasonal shifts, courtesy of a 38-degree axial tilt).

Helyme is thought to be the homeworld of the arthenn, a spacefaring species that disappeared approximately 300,000 years ago. Precisely what happened to Helyme is still under debate. It appears a global extinction occurred, wiping out all native animal life forms more complex than zooplankton. Plant forms were not affected, but the lack of oxygen-breathing life caused oxygenation of the atmosphere. Plant life was reduced after lighting storms ignited global wildfires.

The leading theory for Helyme's devastation is an out-of-control biological weapon. For this reason, landing is strictly prohibited. The corporations of Illium have emplaced a network of quarantine satellites to dissuade would-be looters from landing in the crumbling cities.


Mineral DepositsEdit

Initial Scanner Result: Moderate

Mineral Amount Approximate Value
Palladium Medium 6,400
Platinum Medium 7,000
Iridium Medium 7,300
Element Zero Low 4,800

Lifeforms Edit

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