KAGUYA lunar explorer (aka SELENE) Options

[Rakhir]

SELENE has now a nickname : KAGUYA.
http://www.jaxa.jp/topics/2007/06_e.html

Edit :
And Emily searched for the origin of the name
http://www.planetary.org/blog/article/00000996/

[SpaceListener]

A new update from Kaguya. It has already performed the 3rd LOI.
The First LOI:
Injected orbit
Apogee altitude 11,741 km
Perigee altitude 101 km
Period 16 hours 42 minutes

The second LOI:
Apogee altitude 5,694 km
Perigee altitude 108 km
Period 7 hours 53 minutes

The third LOI: has already conducted. There are still three more.

More details KAGUYA (SELENE) Lunar Orbit Adjustment Maneuver (LOIx)

Just a curiosity, how does the spacecraft able to lower the Apogee?
Trying to understand it, it is done by firing the rocket when the spacecraft is reaching the apogee so that the next loop will go slower and thus reducing its next apogee altitude and continues until reaching the desired altitude?

[jabe]

Just a curiosity, how does the spacecraft able to lower the Apogee?
Trying to understand it, it is done by firing the rocket when the spacecraft is reaching the apogee so that the next loop will go slower and thus reducing its next apogee altitude and continues until reaching the desired altitude?

Simple Really,
The simplest way to raise or lower the perigee or apogee is to do a rocket firing at opposite position you want to change.
ie. to lower apogee you decrease speed at perigee. or to raise apogee you increase speed when at perigee. etc...
so the burn doesn't change the current position..it affects the opposite side of the orbit.
Efficiency issues using fuel resources sometimes has multiple perigee burns to increase the apogee to the required size..which is why I believe the probe did several orbits around the Earth. (I may be wrongabout why multiple burns though )
cheers
jb

[rlorenz]

Efficiency issues using fuel resources sometimes has multiple perigee burns to increase the apogee to the required size..which is why I believe the probe did several orbits around the Earth. (I may be wrongabout why multiple burns though )

A couple of factors play in. One, ideally the delta-V should be impulsive (i.e. instantaneous, with infinite thrust)
But that means infinite structural loads, and a big engine. With a real engine, the thrusting must be conducted
over a finite time, i.e. a finite orbital arc. If the vehicle is spin-stabilized, and the arc is long, then the
engine suffers a cosine loss in useful thrust at the ends of the arc, and so it can be more efficient to split the
burn up into smaller ones (each with lower losses). There can also be issues of orbit determination or safety
(e.g. that should a burn fail part way through, you arent left in some catastrophic orbit - sometimes splitting
it up can avoid danger zones) but that is less likely here.