Page 27 - test

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

DFH 4 Series Spacecraft Date : 28 Sept 2014
Page 25 of 38

CHINASAT 16 Observation Comment /Assessment Cri
 In this spacecraft there are many new units which
can reserve some surprises.
 At this stage it is difficult to apprehend the risk, but
for sure there some risks attached to these new
developments.

 The categorization between C and B can be
challenged, because a qualification on a LEO
spacecraft cannot be directly extrapolated to a
GEO

 Onboard software qualification, there are many  Is there enough resources allocated to these new
items categorized as S1 (new software). Due to developments?
new devices to be used (battery management,  What is the strategy to spec, develop and test new /
Ion thrusters...) modified software (incremental validation or other
techniques)
 The FDIR implementation is not presented.
 Any flight experience?
 Why they are making use of both single junction for
some of their satellite and a triple junction for other
while their reference to the qualify is always the
Platform DFH 4 satellite/development
overview  Page 97.Solar array triple Junction cells

 U heat pipe  Is it new?

 There is no mention of PFM levels, for design  Surprising for a first spacecraft.
or testing (unit and system level)
Thermal  Nothing is said on the predicted temperature  Hopefully there will be more details in the future
control for each equipment and how they are  Use of U type of Heat pipe is critical as it will be
compatible with the one used to qualify each difficult to test them in the Tvac chamber due to
Subsystem equipment. What is the in orbit experience gravity (there will be always a part of the HP which
when using radiative collector. How they will will be vertical). Moreover the length of the HP will
cool down the satellite during AIT. What is the
process that they proposed to verify the proper be long therefore with less heat transfer capability...
integration and operation of the Heat Pipe
 Classical subsystem. 16 thrusters in two semi
system  To report on corrective action and implementation
 Page 108 it appears that they experienced some on spacecraft under development..
in orbit anomalies (helium leakage, 10 N
thrusters..)
 The Pyro valves on the LAE are not in  This is a risk item.
UPS redundancy (the other pyro valves are in
Subsystem redundancy) .In case of a pyro valve failure the
entire mission is lost
 Page 87. For the thrusters, 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 thrusters fails they will
be loosing all thrusters in one branch. If they
add latch valve on each 10 N thruster, they can

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