Buzz Aldrin propellants, with an expected five and a half month journey from the Earth to Mars, and a return trip to Earth of about the same duration on a twin-cycler. Aldrin continues to research this concept with engineers from Purdue University. In December 2003, Aldrin published an opinion piece in "The New York Times" criticizing NASA's objectives. In it, he voiced concern about NASA's development of a spacecraft "limited to transporting four astronauts at a time with little or no cargo carrying capability" and declared the goal of sending astronauts back to the Moon was "more like reaching for past glory
Buzz Aldrin used a sextant and rendezvous charts he helped create to give Lovell the right information to put the spacecraft in position to dock with the target vehicle. Gemini 12 achieved the fourth docking with an Agena target vehicle. The next task was to practice undocking and docking again. On undocking, one of the three latches caught, and Lovell had to use the Gemini's thrusters to free the spacecraft. Aldrin then docked again successfully a few minutes later. The flight plan then called for the Agena main engine to be fired to take the docked spacecraft into a higher orbit, but