"Teknik-Teknik Penerbangan Ke Luar Angkasa Mesti Segera Kita Pelajari Bersama"
*Arip Nurahman*
- Further information: List of orbits
Transfer Orbits
Transfer orbits allow spacecraft to move from one orbit to another. Usually they require a burn at the start, a burn at the end, and sometimes one or more burns in the middle. The Hohmann transfer orbit typically requires the least delta-v, but any orbit that intersects both the origin orbit and destination orbit may be used.
Transfer orbits allow spacecraft to move from one orbit to another. Usually they require a burn at the start, a burn at the end, and sometimes one or more burns in the middle. The Hohmann transfer orbit typically requires the least delta-v, but any orbit that intersects both the origin orbit and destination orbit may be used.
Gravity assist and the Oberth effect
In a gravity assist, a spacecraft swings by a planet and leaves
in a different direction, at a different velocity. This is useful to
speed or slow a spacecraft instead of carrying more fuel.
This
maneuver can be approximated by an elastic collision at large distances, though the flyby
does not involve any physical contact. Due to Newton's Third Law (equal
and opposite reaction), any momentum gained by a spacecraft must be lost
by the planet, or vice versa. However, because the planet is much, much
more massive than the spacecraft, the effect on the planet's orbit is
negligible.
The Oberth
effect can be employed, particularly during a gravity assist
operation. This effect is that use of a propulsion system works better
at high speeds, and hence course changes are best done when close to a
gravitating body; this can multiply the effective delta-v.
Interplanetary Transport Network and Fuzzy Orbits
Interplanetary Transport Network and Fuzzy Orbits
- See also: Low energy transfers
It
is now possible to use computers to search for routes using the
nonlinearities in the gravity of the planets and moons of the solar
system. For example, it is possible to plot an orbit from high earth
orbit to Mars, passing close to one of the Earth's Trojan points.
Collectively referred to as the Interplanetary Transport Network, these highly perturbative, even chaotic, orbital trajectories in principle need no fuel (in practice keeping to the trajectory requires some course corrections). The biggest problem with them is they are usually exceedingly slow, taking many years to arrive. In addition launch windows can be very far apart.
Collectively referred to as the Interplanetary Transport Network, these highly perturbative, even chaotic, orbital trajectories in principle need no fuel (in practice keeping to the trajectory requires some course corrections). The biggest problem with them is they are usually exceedingly slow, taking many years to arrive. In addition launch windows can be very far apart.
They
have, however, been employed on projects such as Genesis. This spacecraft visited
Earth's lagrange L1 point and returned using very little propellant.
Sumber:
Wikipedia
Sumber:
Wikipedia
