Built around the time the DHARMA Initiative arrived on the Island, the radio tower's purpose was to broadcast the core numerical values of the Valenzetti Equation (the Numbers) until such time that one of the research projects on the Island had managed to change one of the values - broadcasting to the their backers on the outside that "the one true way" had been found, and that the Equation can be changed. The tower was to broadcast the signal on a secret frequency in an encrypted format known only to the backers of the Initiative on the outside.
In 1988, two groups in the Pacific began to pick up the signal from the tower without any encryption. The first group was a listening post in the South Pacific where Sam Toomey and Leonard Simms picked up the signal. While their official purpose was to monitor longwave radio frequencies, it has not been established what part of the radio band the signal they picked up was on. The second was a French research ship at sea which included Danielle Rousseau. She claims that her ship crashed on the island. The members of the French team went to investigate the signal and found the radio tower "up by the Black Rock". Here, she claims to have shortly after changed the feed to broadcast her distress signal rather than the Numbers, hoping that someone might hear it.
What is known is that the new distress signal indicates that Rousseau was trapped inside something when she made it to the tower, and that something or someone that had "killed them all" was outside. She also mentions not having the key, adding that someone named Brennan took them. She presumably later escaped.
Since that time, little is known about what happened to the tower. Rousseau says without any further explanation that it and her signal are now under the control of the Others. Rousseau claimed that "they control it now".
The signal from the tower was blocked by jamming equipment controlled from the Looking Glass station. The survivors trekked up to the tower in "Through the Looking Glass, Part 1" in order to get a clear signal to call for rescue. Inside, Rousseau removed the CART from the player and turned off the transmission. Naomi was then able to call her ship for rescue from outside the tower. ("Through the Looking Glass, Part 1")
The radio tower area comprises of the actual mast, and a small operations room. Inside, there were multiple players in a small cabinet, as well as a speaker next to it (presumably what Rousseau used to record her message). On the door outside are the words "CAUTION - High Level Radio Frequency Energy Area", as well as the hazard symbol for dangerous non-ionising radiation.
LocationIn "The Moth", Sayid tries to triangulate the signal. Just before he is knocked out by Locke, the radio is displaying full strength. This indicates they were very close. However, it may simply be the strength of the radio.
Ben also draws a map from "pascal flats" to the tower, as well as the direction from which he anticipated the survivors would be coming from. Danielle claimed that the radio tower was close to the Black Rock, yet when the group visit it in the season 3 finale, it is far away from that location.
- According to the Sri Lanka Video, the tower broadcasts to DHARMA's headquarters. The Hanso Foundation headquarters is in Denmark. Based on the assumptions that the DHARMA headquarters is located near the Hanso headquarters , and that the Island is located at the expected crash site in the Pacific, the radio signal would need to have a very long range to be useful. While shortwave broadcasts of only a few watts ("flea power") can sometimes reach that far by reflecting off the ionosphere, longwave broadcasts such as those Sam and Leonard were meant to be monitoring would require extremely large amounts of power to cover that distance—potentially nearing 1 million watts. While such stations do exist, they generally are operated by state-owned or large commercial broadcasters, with masts around 1000 ft (308.4 m) high.
- The signal seems to be broadcast on multiple frequencies. Sayid picked it up with radio equipment and somehow Naomi's phone picked up the distress signal audio as well.
- Radio stations that broadcast a voice reciting streams of numbers, known as Number Stations and Letter Beacons, actually exist. They are thought to be broadcasting coded messages using one-time pads.
- The tape in the deck is labelled Makee Ailana, Melveen Leed. Melveen Leed is a Hawaiian country singer. The song title Makee Ailana refers to a small Hawaiian island off the shore of Kapiolani Park, and the lyrics describe romantic memories of the island.
- The map Ben draws on is shown twice @ approx. 22:53 and approx. 36:28. These two maps are not the same prop. The red lines drawn oo the two maps differ slightly.
- For fan theories about these unanswered questions, see: Radio tower/Theories
- Why did Danielle claim the Radio Tower was being controlled by The Others when, in fact, it was actually abandoned?
- Why did Danielle claim the Radio Tower was near the Black Rock when it wasn't?