Space rendezvous
Rendezvous may or may not be followed by docking or berthing, procedures which bring the spacecraft into physical contact and create a link between them.
[3][4][5] In 1963 Buzz Aldrin submitted his doctoral thesis titled, Line-Of-Sight Guidance Techniques For Manned Orbital Rendezvous.
[6] As a NASA astronaut, Aldrin worked to "translate complex orbital mechanics into relatively simple flight plans for my colleagues.
"[7] NASA's 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.
[8] However, the Gemini 4 attempts at rendezvous were unsuccessful largely because NASA engineers had yet to learn the orbital mechanics involved in the process.
The higher altitude then increases orbital period due to Kepler's third law, putting the tracker not only above, but also behind the target.
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.Schirra used another metaphor to describe the difference between the two nations' achievements:[11] [The Russian "rendezvous"] was a passing glance—the equivalent of a male walking down a busy main street with plenty of traffic whizzing by and he spots a cute girl walking on the other side.
[16] In March 1969 Apollo 9 achieved the first internal transfer of crew members between two docked spacecraft.
[citation needed] A rendezvous takes place each time a spacecraft brings crew members or supplies to an orbiting space station.
The Japanese H-II Transfer Vehicle (HTV), SpaceX Dragon, and Orbital Sciences' Cygnus spacecraft all maneuver to a close rendezvous and maintain station-keeping, allowing the ISS Canadarm2 to grapple and move the spacecraft to a berthing port on the US segment.
However the updated version of Cargo Dragon will no longer need to berth but instead will autonomously dock directly to the space station.
The Russian segment only uses docking ports so it is not possible for HTV, Dragon and Cygnus to find a berth there.
Also, the STS-49 crew rendezvoused with and attached a rocket motor to the Intelsat VI F-3 communications satellite to allow it to make an orbital maneuver.
This technique has been used successfully for the Gemini, Apollo, Apollo/Soyuz, Salyut, Skylab, Mir, ISS, and Tiangong programs.
If the spacecraft fires thrusters and increases (or decreases) its velocity it will obtain a different orbit, one with a higher or lower altitude.
In the very final phase, the closure rate is reduced by use of the active vehicle's reaction control system.
[27] The two most common methods of approach for proximity operations are in-line with the flight path of the spacecraft (called V-bar, as it is along the velocity vector of the target) and perpendicular to the flight path along the line of the radius of the orbit (called R-bar, as it is along the radial vector, with respect to Earth, of the target).
[26][28] In the V-bar approach from behind, the chaser fires small thrusters to increase its velocity in the direction of the target.
Small rocket pulses in the orbital velocity direction are necessary to keep the chaser along the radial vector of the target.
[citation needed] Generally, the R-bar approach from below is preferable, as the chaser is in a lower (faster) orbit than the target, and thus "catches up" with it.
