ESA UNCLASSIFIED – For Official Use
Meeting Date
13/03/2014
Ref
HSO-IF/14.2014/ACES PO
Meeting Place
Spectratime/Neuchatel
Chairman
L. Cacciapuoti, R. Much
Minute’s Date
14/03/2014
Participants
D. Goujon (Spectratime)
X. Stehlin (Spectratime)
P. Mosset (Spectratime)
M. P. Hess (Airbus DS)
G. Smolik (Airbus DS)
D. Piester (IWG - PTB)
I. Prochazka (IWG - TU Prague)
L. Cacciapuoti (ESA)
R. Much (ESA)
part time per telecon:
C. Salomon (IWG - LKB)
P. Wolf (IWG - Syrte)
L. De Parolis (ESA)
S. Carli (ESA)
Subject
Minutes of SHM Meeting
with IWG
Copy
Description
Action
SHM status presentation was given by Spectratime (cf. annex).
Spectratime
The magn. sensitivity measurements are summarized in the table below.
Model
Date
B-sensitivity
C-field
Shield configuration
4.5E-14/G
112uG
0.5/0.5/0.5/0.5/0.5
4.5E-14/G
700uG
1.0/1.0/0.5/0.5/0.5
1
EM1
2
EM2A
3
Several manipulations took place in order to optimize performance.
Demagnetization was performed.
A measurement just before the replacement of the shields was performed.
SpT to provide results.
EM2A
Feb/14
~4.5E-14/G
280uG
1.0/1.0/0.5/0.5/1.0
4
June/13
The difference between 1st and 2nd measurement can qualitatively be
explained by the change in shielding factor and C-field. The magn.
sensitivity measurements presented in the EM2A test report was made
early on in the test programme. In order to compare the last measurement
(measurement 4), a test result (magn. sensitivity and C-field) is required
just before the swop of the outer magnetic shield (cf action 04).
Page 1/3
Due
Date
20/03/14
11/04/14
ADS
IWG
20/03/14
Spectratime
20/03/14
ADS
20/03/14
Spectratime
21/03/14
Spectratime
21/03/14
ESA UNCLASSIFIED – For Official Use
Description
Action
IWG
A very high magn. field was measured around the SHM ion pump (up to
70G). The implementation of a design change is under way which
improves the magn. shielding around the ion pump. The shielding factor of
the improved design will be measured (cf. action 06, 07).
SpT explained that the maximum space available was used for the
shielding around the ion pump. No more additional shielding can added.
It was explained, that the ACT does not react to any changes in the
magnetic field sensitivity measurements, as the frequency shifts induced
by the magn. field changes are too small for the ACT to react.
Airbus gave a summary of the SHM performance as seen within the ACES
system perspective (cf. annex). It was stated, that in the thermal analysis
the orbital period is only seen at very rare occasions, i.e. in a few days
over the two year mission. This need to be confirmed by applying a
Fourier analysis to the simulated thermal behaviour (cf. action 02).
In the magnetic analysis the amplitude of the magn. field seems to be
underestimated. Airbus will check this (cf. action 05) and correct the
analysis if required.
IWG members explained, that there is the theoretical possibility to correct
for frequency shift induced by thermal or magnetic environment changes.
PHARAO corrects the frequency based on the PHARAO-magnetometer
measurements. (cf. Action 01,03, 08, 09).
Overview of the SHM schedule was provided. SHM is on the critical path of
the ACES schedule. At the moment the SHM schedule is driven by the
availability of the PFM electronic package.
An initial assessment of the SHM performance for the ACES mission was
given by IWG members (cf. annex). The current SHM performance is very
disappointing and not sufficient. All science objectives are either directly
or indirectly negatively impacted. Some science will no longer be possible.
IWG will assess the SHM performance in more detail. An initial feedback is
required by ESA in week 12. (cf. action 10, 11)
Summary of actions:
Action 01: Provide the correlation df vs. dT of SHM sensors (spt) (period of
5400sec)
Action 02: FFT of the simulated Temperatures need to be applied, (ADS)
(1st week of april)
Action 03: IWG will propose in their assessment the possibility of onboard
s/w correction dT vs. df
Action 04: Extract magn. sensitivity measurement data with EM2A just
before outer shield was replaced with thicker shield (Spt) (20/3/14)
Page 2/3
Date 14/03/2014 Ref HSO-IF/14.2014/ACES PO
Due
Date
21/03/14
ESA
IWG
Week 12
IWG
13/04/14
ESA UNCLASSIFIED – For Official Use
Description
Action 05: ADS to check correctness of assumed B-field in system level
assessment (ADS) (20/3/14)
Action 06: Report on change of ion pump shield (soft iron shielding),
strength of improved ion pump shielding
Action 07: Measurement of the shielding factor of 4th and 5th magn. shield
in presence of ion pump (21-3) (under AC field with 0.01 Hz)
Action 08: IWG will propose in their assessment an implement of a
frequency correction as function of the B-field measured by a magn.
sensor inside SHM.
Action 09: ESA ACES project with ADS to assess feasibility (technical,
schedule, cost) of implementing a frequency correction to SHM DDS to
correct for frequency variations induced by magnetic field and
temperature variations.
Action 10: IWG provide initial feedback on affected science objectives in
telecon
Action 11: IWG to provide final assessment report (13/04/2014)
Page 3/3
Date 14/03/2014 Ref HSO-IF/14.2014/ACES PO
Action
Due
Date