Hayabusa's Ion Engines Achieve 20,000 Hours of Operation

http://www.isas.ac.jp/e/snews/2004/1209.shtml

HAYABUSA's ion engines achieved 20,000 hour Space Operation
Hitoshi Kuninaka
Japan Aerospace Exploration Agency
December 9, 2004

The microwave discharge ion engines onboard HAYABUSA asteroid
explorer have marked space operation of twenty thousands hour and unit
as the accumulated operational time on December 9th.

HAYABUSA spacecraft, which was launched on May 2003, succeeded the
Earth
swing-by on May this year and continues to transfer into the asteroid
using the acceleration by the ion engines.

They generated 1,300m/s delta-V consuming 20kg propellant up to now.
After September the space maneuver using three ion engines was
throttled
down in order to adapt power reduction of the solar array panels due to
enlargement of solar distance.

Furthermore one of three engines was turned off in the middle of
October.
The spacecraft stays in deep space 1.3 astronautical unit apart from
Earth.
The communication time lag exceeds twenty minutes, which is the time
duration between sending commands and confirming answers on Earth.
The telemetry bit rate is also gradually falling, so that the operation
team feels helpless.

HAYABUSA spacecraft, which is executing the maneuver operation
diligently and automatically in the lonely deep space, is sturdy and
dependable rather than us.