ИССЛЕДОВАНИЕ ВОЗМОЖНОСТЕЙ ПЕРЕЛЕТА МЕЖДУ ОРБИТАМИ ВОКРУГ ТОЧЕК ЛАГРАНЖА L2 И L1 В СИСТЕМЕ СОЛНЦЕ-ЗЕМЛЯ
A procedure has been proposed for calculating limited orbits around the L2 libration points of the Sun–Earth system. The motion of a spacecraft in the vicinity of the libration point has been considered a superposition of three components, i.e., decreasing (stable), increasing (unstable), and limited. The proposed procedure makes it possible to correct the state vector of the spacecraft so as to neutralize the unstable component of the motion. Using this procedure, the calculation of orbits around various types of libration points has been carried out and the dependence on the orbit type on the initial conditions has been studied.
International collaboration will be necessary for a viable program of exploration beyond the Moon, similar to that for the ISS, and reusable spacecraft will also be needed. High-energy Earth orbits that can be drastically modified with lunar swingbys and small propulsive maneuvers are used, especially near the collinear Sun-Earth and Earth-Moon libration points. The first human missions beyond low-Earth orbit may go to the vicinity of the translunar Earth-Moon libration point. This paper will concentrate on the next possible step, the first one into interplanetary space, that could be a one-year return mission to fly by a Near-Earth Object (NEO). Details are presented of a trajectory that leaves a halo orbit about the Earth-Moon L2 libration point, then uses three lunar swingbys and relatively small propulsive maneuvers to fly by the asteroid 1994 XL1, and return to the Earth-Moon L2 halo orbit for a ΔV of only 432 m/s. Next, rendezvous missions to some other NEO's will be presented. Finally, trajectories to reach Mars, first to Phobos or Deimos, will be outlined. The study uses highly-elliptical Earth orbits (HEOs) whose line of apsides can be rotated using lunar swingbys. The HEO provides a convenient and relatively fast location for rendezvous with crew, or to add propulsion or cargo modules, a technique that we call "Phasing Orbit Rendezvous".
Several missions are planned in Russia to launch spacecraft into the vicinity of the Solar-Terrestrial collinear libration points. The first of them is Spectr-Roentgen-Gamma intended to explore the sky in X-ray and Gamma-ray band. There are technical constraints on this project’s realization, influencing the scenario of inserting the spacecraft into the operational orbit. One of these constraints is the location of the available ground station.
Due to the high latitude of Russian stations it is impossible to have visibility of the spacecraft from them during those phases of flight when the spacecraft is well below the ecliptic plane. To avoid this phenomenon, it is necessary to decrease the orbit amplitude in the direction orthogonal to the ecliptic plane. There are several methods how to do this including one with gravity assist maneuvers near Moon or use of the rocket engine for correction maneuvers, but the simplest – the search of an appropriate option within the family of possible transfer trajectories.
In the paper all these approaches are analyzed and it is shown that for standard scenario for them some difficulties do exist leading to the decrease the reliability of mission at large. The reason is that the thrust of the spacecraft rocket engines is too low, leading to burn durations that are too long.
For more practical approach, it is proposed to use the upper stage of the launcher for the maneuvers intended to decrease the amplitude of the orbit in the ecliptic pole direction. This leads to increasing the duration of spacecraft visibility to an acceptable level for the ground stations situated on the Russian territory. But the most promising and effective option is a single impulse trajectory with an optimal choice of the initial orbital state vector.
Also the problem of reaching the maximum amplitude of the orbit normal to the ecliptic, the “Z-amplitude”, is considered. This goal is to be reached for another project -Millimetron. This project goal is to build a space interferometer with very long base consisting of two telescopes: one in space near the [Sun-Earth L2] libration point and the other on the Earth’s surface.
It is shown that it is possible to put the spacecraft into an orbit with a Z-amplitude value of more than one million kilometers, practically with the same velocity impulse as for orbits with several times less Z-amplitude. The proposed method for this is the appropriate choice of the perigee position of the transfer orbit.
The aim objective of SMMS2015 is to present the latest research and results of scientists related to Simulation, Modelling and Mathematical Statistics topics. This conference provided opportunities for the different areas delegates to exchange new ideas and application experiences face to face, to establish business or research relations and to find global partners for future collaboration.
This paper presents a study on the features and characteristics of the Lissajous orbit family around libration point L2 of the Earth-Moon system which allow optimization in terms of improving the communication between an orbiting spacecraft and the Earth.