It comes with Sensors-2, costs 400 points to build, and doesn't affect size. The description in-game states
Reduces the cost of the Survey Module to zero, allowing you to equip any ship to explore anomalies. |
A Survey module costs 45bc and 8 hull spaces +5% per hull size. From tiny to huge, that's 9, 10, 11, 13 and 15 hull spaces. Most weapons, defenses and engines cost 7%-10% size increase, so Survey modules actually eat up additional space slower than other equipment. (Missile weapons are an exception: They don't expand to fill the hull space, they start huge).
Anyway, the phrase "allowing you to equip any ship to explore anomalies" seems to me to suggest a hull cost reduced to zero, rather than a price reduction to zero bc. If it were a hull cost reduction, then it would be a much more useful device.
If that were the case, then it would be worthwhile earlier in the game, but Survey Modules become available with Sensors-1, and so it is used as a reason to buy Sensors-2. I only go there to get to the end and get Eyes of the Universe, a valuable tech. So it's not doing that for me. Perhaps moving it back a tech requirement to Sensors-1, or reducing the research cost of the tree to that point so it happens earlier. The 400 build point cost might also need some tweeking, if it's moved to earlier in the game, because it will represent a much larger investment.