Starfleet first began to look at developing a full-sized science cruiser right after its inception in 2161. The Daedalus class was originally going to be a fully-fledged exploratory science ship with minimal armaments and tactical staff. However, the nature of the astro-political climate after the incorporation of the Federation the initial confrontations with the Klingons and the Earth-Romulan War to name but two events squelched this original configuration at the early design meetings. A more versatile layout was finally adopted that incorporated capabilities for all mission roles the ship could be expected to perform as the new flagship class of the recently-born Federation. This is a tradition that continues to this day, and Starfleet cruiser-type starships are the most capable and versatile in service in Known Space.
As such, however, pure science vessels evolved into small, specialised ships as demonstrated in the early T’Pina and current Oberth classes. A small crew of scientists would embark upon a small vessel that could be easily and quickly constructed at civilian-grade ship yards, and then packed with the most advanced sensors and computers that were available or could be afforded. This allowed many civilian institutions such as universities and private research groups to put together their own teams to investigate and research their own pet projects, then allowed the ships used to be switched to a different specialisation with a short period in a shipyard.
Starfleet too followed this trend for planetary surveys, in which a planet discovered and assessed by exploratory cruisers would be visited by a dedicated science vessel that would over many weeks or months exhaustively study and catalogue each lifeform animal, plant, bacteria, microbe, etc. and their lifecycles and habitats. This added extensively to the Federation's early store of knowledge about the universe, and this data would allow the Bureau of Exploration to determine how a newly discovered planet should be treated. Frequently exercised recommendations were:
This latter option required a "Guarantee of Suitability", and in the early days of the Federation when extra-solar colonies were still a rarity and homeworld overcrowding was still very high, the U.F.P. BurEx often found itself under heavy pressure to provide one regardless of outside considerations if a planet's natural resources were plentiful or the enviromnent apparently suitable.
Starfleet also followed this pattern of "discover then study" for surveys and investigations of stellar phenomena, but it was found that the specialised science vessels were too small for extended analysis with no chance of getting off-ship. It was quickly discovered that there were too many people crowded aboard these ships, which strained the small ships’ environmental systems to the limits and further reduced the time they could spend on-station. Further, laboratory and computer time had to be either conducted in larger groups or on a very regulated schedule for personal/individual team access.
While the single-mindedness of scientists in pursuit of their research to the exclusion of home comforts is well documented, it is equally well documented that a scientist can regard their own work as more important than everyone else's. The spirit of scientific cooperation helped to defuse many pending ego-fuelled tirades, but enough occurred that multi-discipline co-operative or joint scientific missions soon became a thing of the past. In their place came single-discipline missions on specifically-configured science vessels, leading to further specialisation of this already specialised class.
A case study on the specific example of the Oberth class' layout found that, while nominally being 150m long and containing five (5) decks, there is actually very little habitable and work space abord the vessel.
Most of the length of the Oberth class is actually the huge secondary hull, which is in fact just the housing for a massive array of sensors. This housing also holds the purported and so-called "Deck 5" of the ship, but that is really just a walkway which gives physical access for repairs, maintenance, and physical reconfiguring or component removal of the myriad sensor packages mounted there.
The forward end of Deck 5 houses the ship's probe launcher which performs double duty as the ship's only photon torpedo tube and a massive magazine of various classes of probe.
In a highly unusual design decision, Deck 5 is only accessible by Jeffries Crawl Tubes down the pylons, or by short-range transporter. There is no turbolift or standard stairwell access to the secondary hull. It was implemented this way as it was envisioned that there would be very little use made of “Deck 5”.
With this secondary hull containing no habitable or work spaces, the burden for housing the Oberth class' entire ship operations, mission spaces, and crew support facilities falls on the primary hull. This saucer section is a bare 60m in diameter and contains a mere three (3) decks. In addition to this is the Engineering deck which directly mounts the saucer section, warp nacelles, and support pylons for the secondary hull. Within the Engineering deck there are no scientific or crew-related facilities.
Within the Saucer section, three (3) small bay cutouts are visible around the saucer circumference. At the forward position is the tiny shuttlebay, holding a single shuttlecraft. The two bays to port and starboard are access doors for two small cargo bays. Each holds a single workbee, but no more shuttles. Further to that are the bridge module, escape pods, crew quarters, sickbay, laboratories, and some very limited recreational facilities, all vying for space within the confines of the saucer’s three (3) decks.
The study came to the conclusion that a far bigger habitable section would be greatly desirable in a ship assigned to an extended duration mission with broad scientific appeal. The additional volume could be used for increased laboratory space, recreational facilities, life support machinery spaces, and allow the embarking of a far larger complement of scientists. The crew complement would increase only slightly.
With the data from their Oberth Class Case Study, Starfleet R&D quickly came up with the ideal solution. Since the only problem was a lack of habitable/usable space, they would attach the superb Oberth-class sensor pallet to a standard-sized Class 1-B starship saucer.
Since this vessel was also intended for longer endurance missions it was obvious that longer endurance should also mean greater range, to allow for deep space investigations. Fuel efficiency and increased time between component failure (T.B.C.F.) were thus deemed as priorities, so the Oberth's specially designed small nacelles and the escort-class' single nacelle arrangement were dispensed with in favour of the typical cruiser "tuning fork" arrangement of full-size warp nacelles.
The Creator's Observation: As an interesting note, had I chosen the single nacelle option the T`Lani would have ended up looking like a modern iteration of the U.S.S. Kelvin NCC-0512 from the first JJ Abrams Trek movie.
The internal arrangement of the saucer was reconfigured to give private cabins with built-in workstations for a maximum of 200 scientists as well as extensive recreational and “downtime” facilities on Decks 5 & 6. Private cabins for a maximum of 50 crew were sited on Deck 4, and Decks 2 & 3 were configured as the crew’s administrative centre, with two (2) extra docking ports for personnel transfers. Decks 7 through 14 are almost exclusively dedicated to scientific facilities such as sensor arrays, laboratories, library computer rooms, real-time data uplinks to other institutions and facilities, and probe control rooms.
Engineering consists of most of the aft section of Deck 6, where a modified escort-type warp reactor is mounted flush with the upper surface of the saucer forward of the impulse deflection crystal.
For the coupling of the Oberth class sensor pallet to the saucer section, a few variations were tried. The original plan to use the Oberth pylons was quickly discarded and it was agreed upon to use a standard dorsal neck to counter the critisism in the Oberth Class Case Study:
With the use of a dorsal neck stairwell and turbolift access was provided, as were additional conference rooms and viewing galleries.
It was decided fairly late on to add a full-sized shuttle bay to the design, but it was realised that a science cruiser should have the ability to carry a scientific shuttle or two as well. A fully equipped bay with a four (4) shuttle capacity was mounted at the top of the dorsal neck under the saucer at the rear edge, and allowed the storage of several more travel pods.
One of the more obvious visual differences between the T`Lani class and her Starfleet stablemates is the complete lack of tactical sensor packages, as visible on their ventral saucer surface. It is this difference that distinguishes her as a primarily SciFleet vessel, much like the Tikopai-class large exploratory cruisers, the Jenshahn-class exploratory carriers, and the primarily logistical (LogFleet) Amchitka-class light cruisers.
For defence, the standard saucer phaser complement of six (6) banks of twin emitters is included, though they are downgraded to Type-V defensive units. The standard Oberth-class photon torpedo arrangement and complement is included, with ten (10) torpedoes firing from the probe launcher in the sensor pallet. A standard escort-level shield grid is fitted.
With an escort-level warp reactor and the more fuel-efficient "tuning fork" arrangement of her twin warp nacelles this class is capable of a two-year independent mission endurance. The increased power available to the Structural Integrity Field (S.I.F.) coupled with her full-size nacelles allows her extended warp 6 cruising and warp 8 emergency speeds.
With the extra power available to this class its sensor range is increased 200% over that of the standard Oberth even utilising the same sensor packages, though maximum resolution is the same.
The U.S.S. T`Lani NX-3941 was commissioned into experimental Starfleet duty in 2275. After a year of trials & testing and proof-of-concept missions, the T`Lani had proven herself as a successful large science vessel and authorisation was granted and appropriations given for up to a class of twenty (20) ships with the option for twenty (20) more should the need be demonstrated for them.
The T`Lani herself was recommissioned as NCC-3941 in 2276 and the first of her sister-ships began entering service in 2278.
To be detailed.