<P> The first attempt at rendezvous was made on June 3, 1965, when US astronaut Jim McDivitt tried to maneuver his Gemini 4 craft to meet its spent Titan II launch vehicle's upper stage . McDivitt was unable to get close enough to achieve station - keeping, due to depth - perception problems, and stage propellant venting which kept moving it around . However, the Gemini 4 attempts at rendezvous were unsuccessful largely because NASA engineers had yet to learn the orbital mechanics involved in the process . Simply pointing the active vehicle's nose at the target and thrusting was unsuccessful . If the target is ahead in the orbit and the tracking vehicle increases speed, its altitude also increases, actually moving it away from the target . The higher altitude then increases orbital period due to Kepler's third law, putting the tracker not only above, but also behind the target . The proper technique requires changing the tracking vehicle's orbit to allow the rendezvous target to either catch up or be caught up with, and then at the correct moment changing to the same orbit as the target with no relative motion between the vehicles (for example, putting the tracker into a lower orbit, which has a shorter orbital period allowing it to catch up, then executing a Hohmann transfer back to the original orbital height). </P> <P> As GPO engineer André Meyer later remarked, "There is a good explanation for what went wrong with rendezvous ." The crew, like everyone else at MSC, "just didn't understand or reason out the orbital mechanics involved . As a result, we all got a whole lot smarter and really perfected rendezvous maneuvers, which Apollo now uses ." </P> <P> Rendezvous was first successfully accomplished by US astronaut Wally Schirra on December 15, 1965 . Schirra maneuvered the Gemini 6 spacecraft within 1 foot (30 cm) of its sister craft Gemini 7 . The spacecraft were not equipped to dock with each other, but maintained station - keeping for more than 20 minutes . Schirra later commented: </P> <P> Somebody said...when you come to within three miles (5 km), you've rendezvoused . If anybody thinks they've pulled a rendezvous off at three miles (5 km), have fun! This is when we started doing our work . I don't think rendezvous is over until you are stopped--completely stopped--with no relative motion between the two vehicles, at a range of approximately 120 feet (37 m). That's rendezvous! From there on, it's stationkeeping . That's when you can go back and play the game of driving a car or driving an airplane or pushing a skateboard--it's about that simple . </P>

When did gemini 6 and 7 complete 1st space rendezvous