Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.kiam1.rssi.ru/pubs/20121219_L2_Halo_abstract.doc Дата изменения: Tue Dec 25 12:29:09 2012 Дата индексирования: Sat Feb 2 22:09:12 2013 Кодировка: Поисковые слова: р п р п р п п р п

«Spectr-RG» mission. Ballistics, navigation and flight control of the
spacecraft, going to the L2 point of Sun-Earth system.

I.S. Ilin, G.S. Zaslavsky, S.M. Lavrenov, V.V. Sazonov, V.A. Stepanyants,
A.G. Tuchin, D.A. Tuchin, V.S. Yaroshevsky.

«Spectr-RG» mission presupposes a flight to the vicinity of the Sun-
Earth system L2 point and halo orbit motion in L2 point vicinity. The
following methods and calculation algorithms have been developed:
- an algorithm, building nominal trajectories for one impulse flights to
the L2 point of Sun-Earth system, including a Moon swingby maneuver or
not.
- an algorithm, calculating corrections of spacecraft trajectory needed
for the flight from Earth to halo orbit and for stationkeeping of the
spacecraft moving in halo orbit.
- an algorithm, evaluating the determination accuracy of parameters of
spacecraft motion in halo orbit with the help of ground stations,
providing trajectory measurements and the accuracy of spacecraft
motion parameters prognosis.
The calculation of trajectories for one impulse flight from Earth to
halo orbit uses initial approximations building algorithms. Initial
approximations for the trajectory of one impulse flight are built with the
isoline method both for the case of using Moon swingby maneuver and for the
case of direct flight. For searching the time span, allowing to perform a
gravitational maneuver in the vicinity of Moon to fly to the halo orbit,
there is an angle limit for Earth -Sun and Earth - Moon vectors.
Halo orbit design requirements, providing spacecraft . and radio
visibility from Russian tracking stations, situated in the northern
hemisphere, are following:
- if the spacecraft is near the ecliptic plane, it can enter the
penumbra area
- if the spacecraft gets too far from the ecliptic plane, there are
long periods of time with no radio visibility.
The problem of obtaining given values of halo orbit parameters,
determining orbit geometry in the ecliptic plane and in the plane
orthogonal to it is solved. Characteristic speed costs, needed for
stationkeeping during the halo orbit motion of the spacecraft have been
evaluated. Evaluations of determination and prognosis accuracy of
parameters of spacecraft motion in halo orbit have been obtained.