From Halopedia, the Halo wiki

Im pretty sure that there we 20 ODPs defending Reachedit: Not nesscessarily Earth, as there were ODPs over Reach--UNSC AI 12:02, 30 May 2007 (UTC)

Description The Oranos -class Orbital Defense Platform looks similar to the older Human-Covenant War-era orbital defense platforms. The platform is centred around the primary armament, either a Super MAC, a THOR Laser, or two ion cannons.

Category:Orbital defense platforms. From Halopedia, the Halo wiki. This category is for orbital defense platforms. Oh, and the CGI Starship Troopers films have orbital defense platforms, but like the MAC cannons of Halo, they seem to also operate as light space stations. Which I find to be silly; you don't make your orbital defense vulnerable by adding in human habitation sections.

Your correct page 283 in Fall of Reach states that 'there were 20 super MAC guns in orbit' I made the proper change

something[edit]

after reach you'd think they would reaseach a way to put generators on the guns,so they're more of a threat and are 'easier' to defend,and i'm guessing the Earth is a WHOLE lot bigger then Reach cause if 20 was in orbit around Reach and 300 around Earth Voy101

Except for the fact that the battle of Earth took place mere months after the battle of Reach. There was just no time to actually begin modifying the existing platforms. As to numbers, Reach is listed as having near-earth gravity, and actually has a bit greater, as well as having an atmosphere much like Earth. This evidence would suggest that Reach and Earth are of similar size, and the number of orbital defense platforms merely suggest the importance placed on the defense of Earth against the importance of Reach.

Except that Reach was supposed to be a military fortress, and since Earth is our home planet it would be more of a civilian center, and as for putting the giant generators into space that would be really expensive, make them harder to aim, and make the reactors more vulnerable to attack (because there would be no way to use a different reactor to power a station that had lost its original, or send extra power to a single station, giving it a higher rate of fire) Andrew-108 00:23, September 21, 2010 (UTC)

Real Life Inspiration[edit]

Does anyone else think that these platforms seem a bit like what Ronald Reagan imagined for the Stratigic Defense Initiative (SDI or 'Star Wars') program? Flag-Waving American Patriot 19:02, 21 November 2007 (UTC)

Well, if one takes point four tenths the speed of light as meaning .4c, then the energy requirement of an MAC is enormous. Using E = 1/2 MV^2, with a v = 2.99E7 and an M of 600 tons (converted to Kg of course), we get an energy usage of over 5,306 gigatons TNT! (A typical nuclear bomb is about 20 megatons).

It's not unreasonable to assume that numerous power plants and generators would be required to support the weapon, and I'm imagine that trying to generate all that power on a mobile station would be no easy feat.

--CaptainZoidberg 16:52, 2 March 2008 (UTC)

That is why they are powered by a certain amount of nuclear fusion plants on the surface. I believe that when the Covenant took Reach, they destroyed these reactors thus resulting in total orbital destruction. That's what I read, anyway.

--Cultred

Tense[edit]

Why is this written in past tense? Aren't there still MAC cannons in orbit around Earth even after the events of Halo 3? And even if most were destroyed, one would think that rebuilding them would be a top defense priority for the UNSC government.--CaptainZoidberg 18:16, 2 March 2008 (UTC)

Honestly anything but past tense sounds ridiculous.Sith-venator Wavingstrider (Commlink) 05:17, January 4, 2010 (UTC)

Size[edit]

Were the ones around Reach bigger than the ones around Earth?

Let me explain: there were 20 around Reach, and 300 around Earth. Somewhere in The Fall of Reach it says that the Super MAC barrel is three times the length of a modern cruiser. The Halcyon Class is the smallest ship ever designated a cruiser, and by looking at the barrel in Cairo Station I just can't imagine driving a warthog up that and having the trip take three times the length of the trip in the last level of Halo 1, and then some.

This also leaves the question of whether or not Earth had some of the bigger ones...

But then again, wasn't Fall of Reach written before Halo 2 came out? I think I just answered my own question.

Looking by this picture, ODP should be 1725 meters in length.

Picard578 17:41, 12 March 2011 (EST)

I'm not sure - we don't know the depth of this picture; the frigate isn't at the same distance away from us as Malta is.-- Forerunner 18:33, 12 March 2011 (EST)

Aiming?[edit]

So... since these things are attached to the orbital elevator, how exactly do they aim? Do they just depend on the Earth's rotation? And the orbital elevators would be made of a heck sturdy material to hold its own length while the Earth rotates. PX173 03:48, October 15, 2009 (UTC)

What are you talking about? ODPs are free floating installations, space stations with no connection to the planet. They likely aim through the use of retro-thrusters.

Halo Orbital Defense Platform - Video Results

Spartan 501 06:15, November 5, 2009 (UTC)

Oh, I thought they were attached, but they were just hovering above. PX173 14:14, November 30, 2009 (UTC)

that would still make it really hard to aim, given that you would have to aim the entire station, but i guess thats why they use AIs and propel the rounds to 50% of lightspeed (for range) Andrew-108 00:28, September 21, 2010 (UTC)

Geosynchronous[edit]

The person who posted the trivia claiming the Platforms might be named after the location they float above is false, Geosynchronous implies that the stations simply orbit in a way that they can be seen in the sky at the same time every day in the same spot, The word for what he thinks Geosynchronous means is Geostationary, Alternatively, it could be a mistake on Bungies part and they got the words confused too.--65.2.106.67 04:16, January 4, 2010 (UTC)Monkeychief

New full-body ODP image from Halo 2: Is it okay to add?[edit]

Hey, I found an image which seemed to be a legitimate full-body screenshot of the 'Super' MAC ODP from Halo 2. But I was wondering what others might think of it, and if it might be okay to add it to the article, in the Gallery section? --Xamikaze330 13:28, 21 June 2012 (EDT)Xamikaze330

Classes[edit]

Orbital Defense System Ulduar

Should it be added that there are multiple classes of orbital defense platforms of varying sizes and armaments? There is little to no information on the other classes, not even names, which is why I ask.--184.1.71.145 18:58, 28 June 2016 (EDT)