Memento Mori

Memento Mori is a newly built particle beam cannon that was installed onto the lower orbital ring of the solar satellite system in Gundam 00. The cannon has the destructive yield of nukes (how many Hiroshimas is unclear) to instantly vaporize an entire country off the map. It draws power from the solar collection grid.

Memento mori is a Latin phrase that may be translated as "Remember that you are mortal," "Remember you will die," "Remember that you must die," or "Remember your death". It names a genre of artistic creations that vary widely from one another, but which all share the same purpose, which is to remind people of their own mortality.

Development
It's unknown when the Memento Mori was designed or built, but Innovator's Ribbons Almark forwarded the technology to the Federation for development. Wang Liu Mei was Ribbon's sponsor for the project in their mutual beliefs to Aeolia Schenberg's plan for planetary unification and preparing humanity into space.

Destroying Seel
To accelerate the unification of the world, Ribbons decided to activate Memento Mori to test its capabilities and wipe out the Seel Kingdom (last country(s) left to oppose the Federation) at the same time. A-Laws successfully vaporized the Seel Kingdom instantly with a single blast, nearly taking several nearby Federation Army units as well.

Assault on Memento Mori
The A-Laws had plans to eradicate any Katharon base they can find. At the same time, Katharon deployed their entire fleet to destroy the weapon. However during this time the Memento Mori showed that it was not only capable to fire on Earth but also into space. It used this ability to destroy several ships of the Katharon fleet.

The remainder of the Katharon forces were decimated by the A-Laws mobile suits defending Memento Mori, until Setsuna F. Seiei arrived in the 00 Raiser. While Setsuna diverted the defending mobile suits, including Healing Care's Gadessa, the Ptolemaios 2 moved into position to attack. After using Arios's Trans-Am to dodge Memento Mori's beam, Tieria Erde uses Seravee GN Bazooka II to blast a hole in the weapon's outer bulkhead, allowing Lockon Stratos to snipe its light resonance chamber with Cherudim's GN Sniper Rifle II. This caused a chain reaction that destroyed Memento Mori.