f2014 wrote:Ćao raja.
Imam jedno pitanje za sve Vas, pa ko je upućen u domen fizike da mi objasni.
Pretpostavite da se nalazite u svemirskom brodu koji se kreće po kružnoj orbiti oko Zemlje. Po istoj kružnoj orbiti se kreće svemirska stanica koja je nekoliko kilometara ispred vas. Da li treba povećati ili smanjiti brzinu broda da bi stigao svemirsku stanicu? Obrazložiti odgovor.
Hvala unaprijed. lp
neznam kakav si engleskim ali evo
The standard technique for rendezvous and docking is to dock an active vehicle, the "chaser", with a passive "target". This technique has been used successfully for the Gemini, Apollo, Apollo/Soyuz, Salyut, Skylab, Mir, ISS, and Tiāngōng programs.[citation needed]
To properly understand spacecraft rendezvous it is essential to understand the relation between spacecraft velocity and orbit. A spacecraft in a certain orbit cannot arbitrarily alter its velocity. Each orbit correlates to a certain orbital velocity. If the spacecraft fires thrusters and increases (decreases) its velocity it will obtain a different orbit, one that correlates to the higher (lower) velocity. For circular orbits, higher orbits have a lower orbital velocity. Lower orbits have a higher orbital velocity. This might seem counter-intuitive, but an orbit is nothing else but a state of equilibrium between the force of the gravitational body (the Earth) and the force due to circular motion. At higher orbits the force of the gravity becomes weaker, therefore the balancing force of the circular motion can be lower, corresponding to a lower velocity.[citation needed]
For orbital rendezvous to occur, both spacecraft must be in the same orbital plane, and the phase of the orbit (the position of the spacecraft in the orbit) must be matched. The "chaser" is placed in a slightly lower orbit than the target. The lower the orbit, the higher the orbital velocity. The difference in orbital velocities of chaser and target is therefore such that the chaser is faster than the target, and catches up with it.[citation needed]
Once the two spacecraft are sufficiently close, the chaser's orbit is synchronized with the target's orbit. That is, the chaser will be accelerated. This increase in velocity carries the chaser to a higher orbit. The increase in velocity is chosen such that the chaser approximately assumes the orbit of the target. Stepwise, the chaser closes in on the target, until proximity operations (see below) can be started. In the very final phase, the closure rate is reduced by use of the active vehicle's reaction control system. Docking typically occurs at a rate of 0.1 ft/s (0.030 m/s) to 0.2 ft/s (0.061 m/s).