Page 16 - test

Ref : CM-DFH4-2014-1
BEAZLEY Issue : 1

DFH 4 Series Spacecraft Date : 28 Sept 2014
Page 14 of 38

Loasat-1 Observation Comment /Assessment Cri

Subsystem in orbit anaomalies (helium leakage, 10 N development.
thruster..)
 The Pyro valves on the LAE are not in  This is a risk item.
redundancy (the other pyro valves are in
redundabcy) .In case of a pyro valve failure the
nentire mission is lost
 Page 87. For the thusters, There is only one  This is a risk item
latch valve for each branch. If one thruster is
leaking, the entire branch need to be isolated,
that means for a single thuster faile they will be
loosing all thusters in one branch. If they add
latch valve on each 10 N thruster, they can
isolate the defective thuster. Or they could use
double seat thrusters
 Page 88.In case of LAE failure, the backup  See comment on the left.
mode using the 10N thuster is questionable.
 Page 90.Usage of star tracker and fiber optic  What is the experience and in-orbit experience?
gyros. What is the experience and implication on the
Software (emergency mode, FDIR, on station).
 Who is the supplier of these items (FOG, and
AOCS STS)
Subsystem  Page 92, subsystem configuration, i twill be See comment on the left.
good to have a descriotion of the power
distribution to all units (DC/DC converters) and
explain the fusing.
 Operations mode and algorithm.  Explain the difference with The ECM mode and
the FDIR.
 Page 102, It will be good to have on block  See comment on the left.
diagram, all redundancies (cold, hot) and the
power distribution.
 Page 106. It seems that the AOCS is similar to  With all the changes in the subsystem, it is
previous design with removing of the IPS. difficult to assess the real heritage.
Avionic  Is the AOCS computer in cold redundancy or is  Difficult to comprehend with the information
Subsystem the second one in standby mode (with all the provided.
context and patches stored in case of a need to
use the redundant). Same question for the
CMU processor.
 Is there an EDAC protection to correct soft  See comment on the left.
errors and prevent SEU effects?
 Page 109-113. If we trust all the good wording  To substantiate the heritage, it will be interesting
on these pages, one can conclude that the solar to get feedback for the in-orbit satellites
array is in good shape. (operational performances versus predictions)
Solar Array  Coherence between predicted performances
between all the programs to be demonstrated.


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