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Ion engines aboard Hayabusa have worked well.
21st Monday is a national holiday in Japan and this status update becomes late.
From this week, the orbit information is shown in magnified figures as below.
They may need some explanation.
When the reentry capsule is made plunge into atmosphere, it must fly in the direction
compliant with the Earth rotation direction so that the entry speed can be lowered.
It means the incoming trajectory needs to approach from the night of the Earth,
while current approach is from theday side of the Earth. And the trajectory must traverse
to the oppositeside from present flight path. The resulted outgoing path after the
virtual swingby will leave Earth in opposite direction when thistraverse completes.
When move to the other side, an unintended interruption of the ionengine propulsion has
to be taken into account and even an instantaneoustrajectory shall not run cross
the Earth disk. And the sophisticated orbitmaneuver is devised to fly over the Antarctica
on the way.
The continuous ion engine propulsion lasts until the end of March, whenHayabusa will be
guided to a tentative target point with respect to theEarth.
It is intentionally set very far from the Earth taking the enoughguidance error into account,
when Hayabusa reaches the point avoiding inadvertent entry to the atmosphere.
Hayabusa's attitude controllability is well operable, but the orbitcorrection direction is not
arbitrary and restricted. Hayabusa is awkward in exhibiting thrust in Sun or anti-Sun
direction. In order thatthe orbit correction can be performed mostly in the tangential
direction to the orbital motion around the Sun in a series of orbit corrections from April,
the target point should be tactically prescribed and defined.
As of March 20th, an instantaneous closest distance to Earth this Junewill be 46 thousand
kilometers. Hayabusa soon reaches the orbit thatpasses through within a geosynchronous
orbit.



Fig.1: Closest distance to Earth when Hayabusa flies ballistically from the moment designated.

Fig.2: The plane is normal to the approach velocity to Earth, and the horizontal axis corresponds to a crossing line with the equatorial plane. Sun is in the left hand side. Plots show the points where Hayabusa flies through this plane.

Fig.3: Trajectories relative to Earth in inertial frame. The plane corresponds to the ecliptic plane.

Notes: Dates designated in the left figure do not indicate the return dates.

 

Hayabusa completed the correction TCM-2
Jun 8, 2010 Up!!

Hayabusa completed the correction TCM-2
Jun 1, 2010 Up!!

Hayabusa Caotured its Home Earth
May 17, 2010 Up!!

Hayabusa completed the correction TCM-1
May 10, 2010 Up!!

Hayabusa successfully completed its initial correction(TCM-0)
May 6, 2010 Up!!

Hayabusa about to enter into Earth's gravity sphere
Apr121, 2010 Up!!

Hayabusa about to enter into Earth's gravity sphere
Apr 1, 2010 Up!!

Hayabusa traversed over south pole and will fly-by at night side of Earth
Mar 26, 2010 Up!!

Hayabusa will skim the geosynchronous orbit
Mar 23, 2010 Up!!

Hayabusa now at the Final Guidance Phase
Mar 12, 2010 Up!!

Hayabusa, passes within half of the Moon's distance
Mar 8, 2010 Up!!

Hayabusa, now will pass within Moon's distance
Feb 26, 2010 Up!!

Hayabusa is skimming the Moon
Feb 18, 2010 Up!!

Hayabusa, Right on the Course
Feb 15, 2010 Up!!

Hayabusa will will pass at two times as far distance as to the Moon
Feb 9, 2010 Up!!

Hayabusa will approach within 1 million km from Earth
Feb 1, 2010 Up!!

Hayabusa Approach in Order with Two More Months of Ion Engines Burn Left
Jan 21, 2010 Up!!

Hayabusa on a path passing through Earth's gravity sphere
Jan 14, 2010 Up!!

Hayabusa about to enter into Earth's gravity sphere
Jan 8, 2010 Up!!

Hayabusa about to enter into Earth's gravity sphere
Jan 4, 2010 Up!!

more detail

 
 
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