From: yamada@yscvax.ysc.go.jp (Yoshiro Yamada)
Newsgroups: sci.space
Subject: GEOTAIL MISSION
Keywords: geotail, isas
Date: 22 Jul 92 06:45:06 GMT
Organization: Yokohama Science Center, Yokohama, JAPAN




		* GEOTAIL *


	The GEOTAIL spacecraft is Japan's largest scientific satellite to date.

	The purpose of the GEOTAIL mission is to study the mechanism of
input, transport, storage, release and conversion of energy in the magnetotail
of the Earth. Part of the energy released produces very beautiful emission of
light known as Aurora seen in the Antarctica and Arctic.

	The GEOTAIL spacecraft carries on board the following scientific 
instruments on board:


Electric field detector,

Magnetic field detector,

Low energy plasma analyzer and ion mass spectrometer,

Hot plasma analyzer and ion composition analyzer (from U.S.),

High energetic particle detector,

Energetic particles and ion composition spectrometer (from U.S.),

and Plasma wave analyzer.



	The GEOTAIL spacecraft is a spin stabilized spacecraft utilizing
a despun antennas system. The diameter of the spacecraft is approximately
2.2 meters with a height of 1.6 meters. The weight of the spacecraft 
is approximately 1,000 kg including 332 kg of hydrazine fuel. The design life
is three years.



	The GEOTAIL will be launched from KSC by making use of Delta-II rocket
into a 185 km circular parking orbit with an inclination of 28.7 degrees.
The upper stage will be ignited to boost GEOTAIL into a translunar orbit.
It is a unique point that the GEOTAIL changes its orbit by using the swingby
and maneuver technique. Following are description of the phases of the
GEOTAIL mission.


(1) Translunar Phase (until L+50 days)

	Translunar phase is defined until the first lunar swingby,
which takes place on September 8-th, 1992.


(2) Distant Tail Phase (L+50 days to 1.78 years)

	The GEOTAIL spacecraft will be first injected onto distant tail orbit
so that the orbital apsis should be aligned toward midnight side of the Earth.
The orbital plane is almost same as that of the moon.


(3) Trans-near-tail Phase (L+ 1.78 years to 1.85 years)

	This is corresponding to the period from the last swingby to the 
injection  into near tail orbit.  During this, two large amount of corrective
maneuvers are carried out. One of them is the orbital plane change maneuver 
and the other is for the reduction of the apogee. The insertion
into Near Tail Phase is scheduled in May, 1994.


(4) Near Tail Phase (L+ 1.85 years to L+ 3.3 years)

	The second half of the scientific observation will be performed
in the near tail phase, whose orbit is scheduled as 8 X 30 Re ellipse 
inclined 7.5 deg. to the ecliptic plane. The apogee is directed to antisunward
at the June solstice. This phase will last at least one and half years.



* All information is provided by the Office of External Relations; 
	The Institute of Space and Astronautical Science
	3-1-1, Yoshinodai, Sagamihara, Kanagawa 229, Japan 

-- 
-*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*---
Yoshiro Yamada                            | tel    : +81-45-832-1166
Astronomy Section                         | fax    : +81-45-832-1161
      Yokohama Science Center             | e-mail : yamada@ysc.go.jp
Newsgroups: sci.space