The Mutara Interdimensional Deep Space Array System, or MIDAS array for short, was a Federation communications array that was in service with Starfleet in the late 24th century. Starfleet worked with Vulcans in deploying this array. The array was also referred to as the Mutara Interdimensional Deep-Space-Transponder Array System by Lieutenant Reginald Barclay of the Pathfinder Project.
Located near a small gas cloud, it utilized hyper-subspace technology to greatly reduce the time it would take for a message to reach its destination. The array consisted of a hexagonal central dish, to which were attached three long arms mounting panels and three mobile emitters. When activated, the array launched a small targeting device from the center of the dish, which focused energy beams from the three emitters into a single beam.
In 2376, Deep Space 9 predicted that a pulsar would pass close to the array. By firing a tachyon beam at the pulsar, Pathfinder Project was able to create a micro-wormhole through which they made contact with USS Voyager for a brief period. (VOY: "Pathfinder")
Later, Pathfinder found a way to amplify the signal from the MIDAS array by bouncing it off a class B pulsar. This allowed a brief compressed data stream to be sent to Voyager about every thirty-two days, coinciding with the pulsar's rotation cycle. Initially Starfleet sent many letters, as well as tactical updates and stellar maps. The rotation cycle peaked for seventeen hours, giving Voyager that long after receiving the data stream to send a response. Instead of letters, Voyager sent The Doctor (a holographic program), waiting thirty-two days before they could send or receive letters again so he could treat his creator, Dr. Lewis Zimmerman, who was fatally ill. (VOY: "Life Line")
Several data streams later, Pathfinder tried to send a Reginald Barclay hologram, but it was intercepted by a Ferengi marauder which had passed within twenty meters of the array and stole the program. A month later, Pathfinder tried to send the data stream again – once again to be intercepted by the Ferengi, who took this chance to send an altered version of the first hologram with a plot to abduct Seven of Nine for her nanoprobes.
As part of the cover story, the compromised Barclay hologram claimed that the transmission of the unabridged version of his program overloaded the MIDAS array, making Pathfinder miss the transmission. (VOY: "Inside Man")
At one point Lieutenant Barclay calls it the "Mutara Inter-Dimensional Deep Space Transponder Array," and while this expanded name of the array doesn't translate easily to the acronym "MIDAS," computer panels later show the full name of the station as "Mutara Interdimensional Deep Space Array System".
The array was probably built sometime prior to 2370, as it has a TNG-style Starfleet insignia on it that was no longer used afterward. It may have some connection to the Mutara sector, although this was not confirmed. The station was probably located somewhat near Deep Space 9, however, as that station produced interstellar phenomena forecasts that affected the area near the array.
"The MIDAS array makes use of cosmic field collector and transmitter hardware also seen on the Jupiter Station. The array could be considered a "man-tended" facility, visited by Starfleet engineers for periodic maintenance or upgrades. The central faceted dish and three outer articulated antenna paddles can bore deep through subspace to pick up faint whispers of signals that might normally have been considered lost through energy dissipation over tens of thousands of light years. The longer, multi-panel collectors comprise the omnidirectional detector system, which tells the array to slew around to maximize signal energy input. Different energy levels can be focused by the dish into a mobile feed horn "cab" riding hundreds or even thousands of meters away from its docking base. The cab contains banks of subspace preprocessors running at FTL speeds and can transmit preliminary results to the array's main computers via the short-range AZUREZAHN link or directly to Starfleet by way of standard subspace radio." – Rick Sternbach,