Failure of key unit could have led to Chandrayaan-1 end

Last Updated: Monday, September 7, 2009 - 20:11

Bangalore: It was the failure of "heart" of
the lunar craft, the bus management unit that performed vital
control functions, which probably led to premature end of the
country`s ambitious maiden moon mission -- Chandrayaan-1.

"Bus management unit is like heart of the satellite. It
controls everything," an ISRO official said, adding its
failure might have led to snapping of radio link with the
space craft leading to its premature end.

Indian Space Research Organisation terminated the
odyssey on August 30 after it failed to re-establish contact,
lost the previous day, with the lunar craft.

But it has now emerged that the second (redundant) bus
management unit, which ISRO was using after the first one
failed within a few weeks of the mission launched on October
22 last year, stopped functioning resulting in loss of contact
with the spacecraft, officials said.

ISRO has come under criticism from some quarters over
late acknowledgement of setbacks in the mission. For example,
the failure of the first bus management unit was made public
by the space agency only in July this year, even though it
took place late last year.

And on April 26, the on board star sensor used for
determining the orientation of the spacecraft started
malfunctioning, a snag which ISRO disclosed less than two
months ago.

In May this year ISRO raised the orbit of Chandrayaan-1,
which was at a height of 100 km from the lunar surface since
November last year, to 200 km, saying the space craft in this
higher altitude would enable further studies on orbit
perturbations, gravitational field variation of the moon and
also enable imaging lunar surface with a wider swath.

It was revealed later that the main objective of the
orbit-raising move was because "environment (thermal and
radiation) encountered by Chandrayaan-1 was more severe than
anticipated by ISRO".

And also because the on board (redundant) sensors
gyroscopes, pressed into service after star sensors failed,
could be used from this orbit (unlike the 100 km orbit) to
prolong the mission without ISRO needing to control the moon
craft on a daily basis.

But, ISRO officials dismiss suggestions that the space
agency was keeping setbacks under wraps, saying in space
missions things of that sort are not uncommon and it can`t go
on giving updates when there are many instances of
malfunctioning being set right in previous missions soon after
they occurred.

Bureau Report



First Published: Monday, September 7, 2009 - 20:11

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