- CTS-1 Adventure
- CTS-2 Endeavor
- CTS-3 Intrepid
“CTS” stands for Crew Transport Shuttle“. The spacecraft are numbered in order of construction. Crew shuttles can carry a total of six Kerbals. While capable of remote piloting from Mission Control all shuttle launches are required by KSEA policy to have at least one pilot on board!
The shuttle has enough supplies for roughly one day in space, and is not intended for longer term missions. The standard mission profile is for Two Pilots to launch into orbit, deliver crew to the KSS (or other orbiting target), then return with a minimum of 1 pilot. The CTS is capable of remote flight, however it is generally not done.
With the regular use of the KSS, and the need to more regularly rotate crew, the costs began to skyrocket on crew delivery rockets. So, development began on a new crew vehicle for the KSS – the Kerbin Crew Shuttle – officially the Crew Transport Shuttle!
Initially engineers had hoped to build a single stage to orbit (or SSTO) vehicle, however no economical design could be found. Engineers and administrators also debated building a single use craft that could launch both crew and cargo. Ultimately the same problems of economics and design ruled that out.
Using aerodynamic lessons learned from the X-4 and X-5, the innovative design consists of two space planes. The first, a large launch vehicle that carries the crew shuttle to an altitude of just over 75,000.
The second vehicle is the shuttle itself, which has been designed with enough fuel to circularize its orbit, maneuver to the KSS, and return to the Space Center.
The prototype, Adventure, performed well, and led to full production of the Crew Shuttles! Before long a mission was planned to deliver the next rotation of Kerbal scientists!
KSEA has experimented off and on with developing a Supply Transport Shuttle (STS) to transport food, oxygen, water, and other supplies to the KSS with mostly negative results.
In Year 4 engineers renewed development of Supply Transport Shuttle – this time starting from scratch with a design based off the very successful Crew Shuttle, but scaled up and using new and more advanced technologies.