Cosmos Bird 2

Credit: The spacecraft was designed for use in deepfriedfrenchtoast's Solar System. All screenshots in this post were captured using this system.

Cosmos Bird 2 carries enough fuel to complete a single shuttle between a 300 km circular orbit around Mars and the Martian surface. With refueling, it can also return from Mars to Earth. The following description is based on this mission profile, though the spacecraft is capable of supporting a variety of other missions as well.

Crew capacity: 12

Launch: The most convenient way is to place the spacecraft directly in orbit around Mars. When fully fueled, its TWR on Mars is near 1, making liftoff from the Martian surface difficult. If you want to launch it with a rocket using a fairing, the fairing must be set to nearly the maximum diameter allowed in the stock game, and some lateral offset will be necessary to fit the spacecraft properly.

Power: Landing on Mars from a 300 km circular orbit may consume more than half of the available power, so it is recommended to perform this operation only when the power is at 100%. After landing, recharging via solar panels could take over a dozen Martian days. Charging with fuel cells (AG 2) is much faster, but ensure that the spacecraft’s delta-v is sufficient for the return journey.

Mars Landing: Before entering the denser regions of the Martian atmosphere, the spacecraft's speed must be reduced to a level that prevents heat damage. In the final stage of landing, the deviation between the spacecraft’s orientation at the time of ignition and its locked direction may become significant. At that point, the locked direction must be compensated for to ensure that the rocket is aligned with its intended trajectory.

Mars Ascent: A pitch angle of 60 degrees with 100% throttle is suitable for liftoff. At lower altitudes, launching with a pitch angle that is too shallow (for example, 45 degrees) may cause parts to suffer from heat damage.

Returning to Earth: Before re-entry into Earth's atmosphere, the periapsis must be lowered to a region of lower atmospheric density (for example, around 30 km) to avoid excessive thermal damage to the heat shield. Then activate AG 5,the remainder of the reentry process will complete automatically. The current program is intended for Earth return; if you have other requirements, feel free to modify it as needed. AG 5 is a one-time-use action group, so please confirm that the spacecraft is on a safe return trajectory before activating it. If AG 5 is activated by mistake, the crew module can still dock with another spacecraft via its top docking port to rescue the passengers. You can also avoid unintended crew drift by saving your game in advance and reloading if necessary. Note: An asymmetric crew arrangement during re-entry may cause overheating damage.