Notes by Matthew Whyndham
Present: Watanabe [chair], Kosugi, Hara, Sakao (day 1), Ohyama (day 1), Culhane, Bentley, Whyndham,
- we followed the 3rd edition outline :
Solar-B Status
from the Japanese view
EIS Status
schedule, milestones
management plan
System & System Interfaces
MDP
coordinated actions among the
scientific instruments
interface; observational sequence
data rate control
data recorder, compression/packetisation
(+item brought in from EIS design section)
EIS DPU electronics & software issues
architecture
observing modes
observations controls
PCU (voltage selection)
++ Alignment etc.
EIS Design
System Requirements
science requirements
wavelength range
TRACE results
science scenarios
Opto-mechanical issues
structural tradeoffs
optical modelling
tolerances
gratings
pre-filter, hood
filters, shutter
done before: DPU electronics &
software issues
architecture
observing modes
observations
controls
CCD camera issues
architecture
cooling
baking
Preparation for US proposals
Tradeoffs & criteria
Review of Actions from June
Meeting
from the Japanese view : (Kosugi) Solar-B to be officially (J. gov't public spending cttee) v. soon, this hopefully a formality. AO process schedule (Len has these dates too) referred to. 3 Aug. p. due date. (Q: when will copies come out of NASA? A: ~ 1 week). 14 Sep.: Discussion with J. re content of p.'s at NASA HQ. Oct. Panel Review.
S/c: Sept. or Oct., Solar-B meeting (First Step) with selected contractor.
(Whyndham) Letters of intent now in, (grant details soon),
PM full time, draft Management plan (manplan) (copies given) contents.
Invited comments about it.
Engineering teams building up, but need to identify
areas for study which will assist the AO process - but major tech. areas
defined by US part.
Systems engineering - embedded approach (like PA) -
focus on system requirements - (i.e. Science.) - and interface content.
Situation is that operating parameters of EIS being
formed - need to put against science use, look for problems.
Schedule, milestones - essentially: series of meetings, punctuated by iterations
of EIS baseline design or options, and iteration of Science requirement.
For AO response, tradeoff analysis of various options Aug/Sep.
NB new set ("version"?) of H. Hara EIS design notes. Topics: (my remarks -- thus)
(presented by Hara, assume others
involved)
Some new ideas about MDP content. Still very fluid.
Cases A-B-C show various levels of MDP functionality wrt EIS. e.g.
extraction of spectral lines. Data emergence rate from Instruments
a concern. Link may be RS422 - rates ~1 Mbps (lower?). This drives
towards PLAN B or C (In "A" the link labelled RS422 would have
to exist within EIS anyway!). Telemetry hierarchy (3 layers) incl. VCDU:
Virtual Channel Data Unit.
(Watanabe) - likely to settle with recent ISAS practice
: distribution of 51 V unreg +x (6?) -y (11?).
Use of visible light path (ND filter), detector at zero order position (needs baffle)
(Whyndham, work by Gowen,
McCalden). Obvious need for reduction of data rate at bottom of "tree"
(CCD=top of tree). Look at each stage, what can be done to reduce data
there? Instrument coordination - not yet considered. architecture - working
on much the same lines as MDP studies already shown. Shown block diags
(RAG). separate branches, Control (response to cmds), Engineering (HK),
Science Data stream. Need to have availability of response to commands
at all times: i.e. reduce load on processor where possible.
observing modes : ref RAG's
EIS Operational Concepts - frame processing cycle - hardware setup
(data production) vs data processing (data reduction). Concept of window
table. Use of this in various modes: 1: Continuous; 2: Snapshot,
3: Burst, 4: Intermediate
observations controls : frame
rate, shutter speed, scanning (incidentally high cadence scanning (~1s)
with the ability to do long jumps (many steps) could be v. useful).
System Requirements - NB "system"=EIS.
top-down approach. need priority of requirements and input/feedback from
user community. (Science Team).
science requirements - need
to trace correspondence of requirements and instrument specifications -
freeze requirements at some later date (when?)
wavelength range - refer to
Science Notes
. Some debate but not much. Keep coming back to baseline range!
science scenarios - table of
studies in Science
Notes . Further discussion of these : UK science meeting 28/7/98.
structural tradeoffs -
ref BU report. "EIS structural analysis 20/7/98" S. Mahmoud.
This shows FE analysis of two structures. Since little concern about stiffness
of composite structures, chosen to examine properties of Al structures.
Baseline and Cassegrain options shown in report. Conclusion is that
baseline=stiffer, cassegrain=lighter. Leg mounting - what will be the
transmission of forces back to the mounting interface? need to consider
this. Note that baseline for EIS is not to have actuated mounting legs.
Areas to develop - look for ideas of mounting the primary and secondary
wrt detector plate - metering rods?. Thermal, vibration response
of a such a structure.
optical modelling - to
gain knowledge of tolerances etc. work done by Whyndham + R. Hunt. at MSSL.
consider optical system in two halves, light gathering and dispersive.
Have mainly considered properties of dispersive part (grating). Properties
of SVLS gratings - examined IDL code by Hara and papers by Hara ... , Harada
.... Proceed by implementing SLVS grating as subroutine (C) of Zemax (proprieatary
ray trace s/w). Eventually converged on same optical layout and ruling
parameters. Can optimise against various criteria - best focus, wavelength
range, mechanical tolerance. Can now use Zemax to explore ... Find ~150
microns tolerance of focal plane (with current params) - not a problem
to put it there, struggle to keep? Need thermal studies!. How to
model holographic gratings - need to know full details of fringe pattern?
Cassegrain light gathering optics also looked at. Generally agree with
the view that tolerance for secondary mirror could be tight, due to magnification
of system. Analyses may be rapidly done on proposed configurations.
tolerances, gratings - nuff
said
prefilter, hood - have
had MSFC study for a while but not yet digested. Reviewed this. Distribution
of particles becomes clear (Solar-B orbit -> k=1). Now need to understand
response of filter (mesh support) to particle hits - ref guidlines in MSFC
study. ask Zarnecki. Integrate over curve to develop stray light
prediction vs. budget. Case of Baseline (inside) and some options (at front,
and with hood - various lengths). Noted existence of diffraction pattern
in certain TRACE data (171 A)- origin is 70 lpi filter mesh!
filters, shutter - mentioned
availability of TRACE design + motor spec. - newly identified need for
short exposures. Expect to replicate at MSSL, perform life tests, etc.
done before: DPU electronics & software issues
architecture
observing modes
observations
controls
architecture - Firewire at
interface? - expect to have the ability to select sub-frames (>1) for
readout. Needs development.
cooling - what's the ideal
temperature?
baking - no progress
Spikes (RDB) in TRACE data -
Spike caused by radiation hits when phase of orbit takes spacecraft through
trapped particles. Can not be excluded from data by thresholding - need
another technique or prevent entirely. concern about shielding only 0.1
inch Al, maybe need 0.3 ?
Tradeoffs & criteria
Main criteria - "Science, Feasibility, Cost."
Need to keep in mind what we expect in the list of components
to be supplied from US, with ranking.
4. ongoing
5. ongoing
6. draft for comments
7. SDT - occurred, minutes will eventually be distributed
11. need info if it exists
12,13,14 ongoing
15 not yet
16 progress as reported
17 NEED to get further with this!
18 and this
19,20,21 no progress
22 ongoing
23 ongoing, need to synchronise studies in J/UK
24 small start made
26 no prog.
27 needs documentation?
28 limb could be problem (spicules) or weak emission
29 no pro. but requests accumulating
30 almost digested, need to think about particle + filter
interaction
These actions were added:
Action 31: (MSSL) generate a list of components expected
from US, to compare with proposals. Aug. 3
Action 32: (MSSL+BU) Thermal properties of (al, or
whatever else) structures -> derive tolerances. Aug/Sep
Action 33: (MSSL) Table of moving parts, revise when
proposal received. Aug. 3
Aug. or Sep (proposals then in existence), suggest
UK, date TBD