Relay

Relays are hub levels where players can interact with each other, as well as do business with Syndicates and other NPCs. It was added in Update 15.5.3 for stress testing and as of Update 15.6.0 is available to all players across multiple planets.

Accessing the Relay
Relays are accessible by selecting a planet with an available relay in the Navigation Console, and then entering the relay node as one would enter a mission. The following are the list of relays currently available:

Earth, Eris, Europa and Venus once had Relays in the form of the Strata, Kuiper, Leonov and Vesper nodes respectively, until they were destroyed by Balor Fomorians during the Operation Eyes of Blight event, but it has been confirmed that there will be a possibility where relays can be rebuild, with another look and Warframe statues.

The Hangar and Main Entrance
The Hangar is the area players will spawn into. It features multiple Liset docking bays and constant Liset traffic in the background. The Main Entrance connects the Hangar to the rest of the Hub with a security station with two layers of force field installed. Going back to your docked ship will not let you leave from there, you must press if you are on PC to open up your menu, then select "Leave Relay" to go back to your Liset. However, you can still select missions in the Relay, located in the Mission Control room.

The Concourse
The Concourse is the main area of the Hub, linking the Hangar to the East, North and West wings. It features a giant Rhino sculpture, similar to one found in the Temple of Honor in Dojos, as well as numerous civilians/members of the Syndicates interacting with each other.

Void Trader

 * The Void Trader is a man known as Baro Ki'Teer, who sells various unique items in exchange for Orokin Ducats, the only currency he accepts. Players can earn Ducats by selling Prime parts on two Void Trader kiosks in the Concourse. The Void Trader himself only makes periodic appearances on the Concourse, and will only be available to sell his services for two days at a time. Countdown timers on the kiosks are available to inform players of when the Void Trader will next appear in the Concourse.

West Wing
The West Wing includes entrances to the New Loka and Perrin Sequence enclaves, as well as a small observation area at the south end. The south end of the wing contains a glass window view of space and kneeling pads similar to those in the clan dojos. Glitches have been known of people being able to be outside of the windows, and can run around freely. This is the same for the other east end.

New Loka Enclave

 * The New Loka Enclave is full of flourishing plants that have seemingly broken through the floor and the walls of the room, and a small lake where various members of New Loka are kneeling while their Leader is floating on the opposite end of the lake. There is also a giant model of Earth hanging from the ceiling. Interestingly, the design features some Orokin devices, such as lamp posts and the projector on the ceiling. In the background noise in the New Loka Enclave, you can hear water rushing and harmonious humming from the New Loka members.

Perrin Sequence Enclave

 * The Perrin Sequence Enclave follows the strict and cubic Corpus aesthetic, which is occasionally interrupted by the presence of coffee mugs and Tenno-styled banners.

North Wing
The North Wing can be entered via the West or East wings or directly from the Concourse. It has entrances to the Red Veil and Steel Meridian enclaves, Darvo's Market, and the Mission Control Room.

Red Veil Enclave

 * The Red Veil Enclave is extremely ominous, featuring a burning tree in the center of the room that the player needs to walk underneath to get the Red Veil's Leader at the far end of the room. It also features a live Grineer soldier strapped to a dissection table in front of a container full of Infested. The Grineer soldier occasionally struggles at his bonds before receiving an electric shock, while a Red Veil operative stands over him ominously wielding a Heat Dagger pair.

Steel Meridian Enclave

 * The Steel Meridian Enclave is a scrappy-looking Grineer-styled room with a huge rotary cannon hanging from the ceiling. Various resource caches can be seen throughout the room.

Mission Control

 * Mission Control is a large room with a view of space, where players can access functional Navigation Consoles identical to those found in the Liset in order to access missions. Players can also change equipment loadouts using the various consoles in the room.

Darvo's Market

 * Found on the second level of the North Wing accessible by elevator, this is where Darvo conducts business with players on the Relay, selling various items and equipment. Currently this feature is non-functional and Darvo cannot be interacted with for the time being.

East Wing
The East Wing includes another small observation area at south end and entrances to the Cephalon Suda and Arbiters of Hexis enclaves.

Cephalon Suda Enclave

 * The Cephalon Suda Enclave at first looks like a bare room with a faint hologram of Suda at the center. As the player comes closer, the room will suddenly disintegrate partially into the Void, with a manifestation of Suda (or possibly Suda herself) floating the middle. There is also a smaller Cephalon to the right of the player.

Arbiters of Hexis Enclave

 * The Arbiters of Hexis Enclave looks like a courtroom, with five Arbiters presiding at the center of the room. Present on the walls are balconies full of people.

Trivia

 * The names of the relays actually have connections to their planets in real life or mythology;
 * Larunda was a water spirit who fell in love with the Roman god Mercury. Her tongue was cut out after she revealed one of Jupiter's affairs to his wife Juno.
 * Vesper is the Roman equivalent of Hesperus, which is Ancient Greek for the planet Venus.
 * Strata is the plural form of Stratum, which refer to layers of rock or soil with characteristics that distinguishes them from other layers.
 * Kronia was an Athenian festival held in honor of the titan Cronus, whose Roman equivalent was Saturn.
 * Orcus is the name of a dwarf planet orbiting near Pluto. It is named after a god of the underworld, who was the punisher of broken oaths in Italic and Roman mythology.
 * Kuiper is most likely is a reference to the Kuiper Airborne Observatory, a heavily-modified jet transport that was used for astronomy. Among other things, it confirmed that Europa's crust is made of water and ice.
 * Alternatively, Kuiper could be a reference to the Kuiper belt, a region of space beyond the planets which is mostly composed of small rocky body and dwarves planets like Sedna and Eris.
 * Leonov may be a layered reference to the Russian-based Phobos program, which was to study both Phobos and Deimos through the use of unmanned probes.
 * In particular, a widely circulated image claimed that one of the probes picked up images of an unidentified flying object near Phobos, and that the photo first belonged to a "Cosmonaut Leonov" before it was circulated. The "UFO" has since been debunked as a digital artifact during transmission.
 * The various billboards around the Relays display a number of sentences written in Orokin language, some examples being:
 * "Welcome"
 * "A Tenno is the sworn protector of the Origin system"
 * "The Lotus is our friend, leader and guide"
 * "Energy of the Void is the lifeblood of the Tenno"
 * "A Tenno is both Shadow and Light"
 * Currently in the PS4 & Xbox One, Relays are only open to those who are Mastery Rank 10 and above. This is most likely possibly for stress testing on the consoles. It could also be a early stage glitch for the consoles.
 * As of 19/2/2015, Relays are open to all player on PC, PS4 and Xbox One.