TIPS Meeting
19 December 2002, 10am, Auditorium
1. Observing Solar System Objects with JWST Ed Nelan
2. COS - Updates on COS Development
Ken Sembach
3. NICMOS Status
Tommy Wiklind
Next TIPS Meeting will be held on 16 January 2003.
Observing Moving Targets with JWST
Ed Nelan
TIPS
Dec 19, 2002
Observing Moving Targets with JWST
Ed Nelan
TIPS
Dec 19, 2002
Ron Henry, Wayne Kinzel, Andy Lubenow, Knox Long,
Vicki Balzano, Larry Petro, John Isaacs, Mark Abernathy,
Rusty Whitman, Bill Workman
Moving Targets
• Observations of moving targets with JWST is not part of
the baseline plan.
– Currently, there is no requirement for JWST to track a moving target
• The STScI proposal for the JWST Science & Operations
Center (S&OC) does not include support for observations
of moving targets.
• Science Working Group's interest in Solar System objects
motivated a study by STScI to estimate the cost to the for
supporting such observations.
Moving Targets
•
Cost estimates in this study are for the Ground System (S&OC), i.e.,
STScI, only.
•
Cost for flight software development not included.
– We did not investigate if JWST can track moving targets, or the cost in
doing so (TRW)
– We did not estimate the additional cost for FGS FSW (CSA)
•
Can the Science Instruments observe the bright planets?
– We did not address the cost for SI modifications (SI teams)
Moving Targets
•
Moving Targets are Solar System bodies:
–
–
–
–
–
Kuiper Belt Objects
planets
moons of planets
asteroids
comets
Compared to stars, they are nearby, and they move
•
–
–
JWST parallax
ephemeris
Moving Targets
Outline of this presentation:
•
•
Why observe moving targets with JWST ?
What angular rates might be encountered?
•
Costs:
– Observatory efficiency, scheduling
– Operations, proposal preparation, planning & scheduling ($)
– Software development, I&T, maintenance ($$)
Why Observe Moving Targets?
Shoemaker-Levy 9
Why Observe Moving Targets?
Shoemaker-Levy 9 and Jupiter Impacts
Why Observe Moving Targets?
• Between 1994 and 1996 ~35% of all HST public out reach
releases involved Solar System observations.
• But only ~2% of the HST program was dedicated to Solar
System observations.
What’s involved in
Moving Target Observations?
•
Fixed targets (stars, galaxies, e.g.) are stationary with respect to the
guide star.
•
A Solar System object moves with respect to a guide star
•
Proposal Preparation, Planning & Scheduling:
– Ephemeris
– JWST parallax
– Tracking.
•
Complicates selection of the guide star
Fixed Target Observations
Fixed
target
*
*
Science
Instrument
FGS
Moving Target Observations
Moving
target
*
*
*
Science
Instrument
FGS
At what angular speeds do
Solar System bodies travel?
From J. Nella,JWST kickoff Meeting, 10/23/02
1 mas / sec
Angular rates of Neptune within JWST FOR
5 mas / sec
Angular rates of Jupiter within JWST FOR
25 mas / sec
Angular rates of Mars within JWST FOR
Angular rates of selected objects within JWST FOR
Object
Min. Rate
(mas/sec)
Max Rate
(mas/sec)
Mars
Jupiter
Jupiter,Io
Saturn
Uranus
Neptune
Pluto *
KBO
2.5
0.070
0.004
0.040
0.020
0.004
0.160
0.002
28.6
4.5
10.2
2.9
1.4
1.0
1.0
0.5
Distance
Traveled in 10 Time to Travel 1’
hrs at Min Rate at Max Rate (hrs)
(asec)
90.0
2.5
0.14
1.4
0.7
0.14
5.7
0.07
* Includes motion about Pluto-Charon barycenter
0.6
3.7
1.6
5.7
17
24
24
48
Moving Target Observations may require
long guide star track lengths
Moving
target
*
*
*
Science
Instrument
FGS
Moving Target Observations may require
short guide star track lengths
Moving
target
*
**
Science
Instrument
FGS
Proposal Preparation, Planning and Scheduling
• The position of a Solar System object on the celestial
sphere as seen from JWST will depend upon the the
spacecraft’s position in its orbit about L2.
– Orbit has a radius of 800,000km
– Period of about 120 days.
• S/C’s predicted position will be uncertain by TBD% when
forecast one year in advance (proposal preparation time).
– Station keeping maneuvers difficult to predict.
– Implications for S&OC’s generation of LRP.
• To investigate, we assumed 10% ephemeris uncertainty.
gs2
JWST in L2 Orbit
gs1
gs2
JWST in L2 Orbit
gs1
gs2
JWST in L2 Orbit
gs1
gs2
JWST in L2 Orbit
gs1
JWST in L2 Orbit
gs
Not a problem with HST
in low orbit, Earth’s
ephemeris is well known.
Proposal Preparation, Planning and Scheduling
Object
Positional
Uncertainty
(asec)
Jupiter
24
Saturn
13
Uranus
5
Neptune
2
Pluto
1
KBO
0.7
Uncertainty of a Solar System object’s position as seen by JWST
due to a 10% error in spacecraft’s one year predicted ephemeris.
Proposal Preparation, Planning and Scheduling
• If bad pixels in FGS cause loss of lock on guide star:
– need an accurate ephemeris to verify the path of a guide star across
the FGS while JWST tracks target is free of bad pixels.
• If the FGS can guide across bad pixels:
– the uncertainty of the JWST predicted ephemeris is unlikely to
present a major problem (proposals can be flight ready many
months in advance)
• Uncertainty in long range forecast of spacecraft ephemeris
might delay final selection of a guide star until a few
months before observations occur. Impacts LRP.
Observatory Efficiency, Event Driven Schedule
flexible
constrained
Plan window
Visit duration
Visit with long plan window
HDF
Visit with short plan window
1.5 hours after SL-9 Impact
JWST Event Driven Schedule
Will observations of moving targets cause a loss of observatory efficiency?
•
•
•
•
•
•
Observations will execute as visits within plan windows.
Plan windows will overlap in time.
Each plan window contains only 1 visit.
Ideal Plan window is long compared to the visit duration.
Visits execute at the earliest time possible.
This approach minimizes gaps in observatory activities
JWST Event Driven Schedule
• Overlapping Plan windows allow observations to execute
according to events, and not be restricted to absolute times.
Visit 1
Visit 2
Visit 3
Visit 4
time
JWST Event Driven Schedule
• If visit 2 fails, visit 3 executes early. No idle gap,
observatory efficiency preserved.
Visit 1
Visit 2
Visit 3
Visit 4
time
JWST Event Driven Schedule
• If visit 2 fails, visit 3 executes early. No idle gap,
observatory efficiency preserved.
Visit 1
Visit 2
Visit 3
Visit 4
time
JWST Event Driven Schedule
• If visit 2 fails, visit 3 executes early. No idle gap,
observatory efficiency preserved.
Visit 1
Visit 2 fails
Visit 3 executes early
Visit 4 executes early
time
JWST Event Driven Schedule
• When time constrained observations populate the schedule,
loss of observatory efficiency can result if failures occur
Visit 1
Visit 2
Visit 3
Visit 4
time
JWST Event Driven Schedule
• When time constrained observations populate the schedule,
loss of observatory efficiency can result if failures occur
Visit 1
Visit 2
Visit 3
Visit 4
time
JWST Event Driven Schedule
• When time constrained observations populate the schedule,
loss of observatory efficiency can result if failures occur
Visit 1
Visit 2
Visit 3
Visit 4
time
JWST Event Driven Schedule
• When time constrained observations populate the schedule,
loss of observatory efficiency result when failures occur.
Visit 1
Visit 2
Visit 3
gap
Visit 4
time
Distribution of target-local HST plan windows for
Solar System targets, 2000-2002
Visit with short plan window
1.5 hours after SL-9 Impact
Visit with long plan window
Saturn
JWST Event Driven Schedule
Observations of most Solar System objects can be scheduled
when required tracking rates are very low.
• If guide star availability is the only constraint, visits can
have long plan windows, and flexible scheduling.
• If target-local considerations determine plan window,
restrictive scheduling results.
– Visits cause loss of efficiency when visits upstream in the queue
fail. Same as time constrained observations of fixed targets.
• Degradation of observatory efficiency due to Solar System
observations not expected to be significant.
JWST Event Driven Schedule
Suppose all visits to all targets are of the same length and
– JWST spends 3% of its time observing solar system targets,
– And 20% of these observations are time constrained,
– And only 10% of all observations upstream in the queue (including fixed
targets) fail.
•
Then the loss of observatory efficiency due to time constrained (Solar
System and fixed target) observations is, assuming all visits are of the
same length;
0.03 ∗ 0.2 ∗ 0.1 = 0.0006 = 0.06 %
Proposal Preparation, Planning and Scheduling
Ascending levels of complexity for observing moving targets
Object
Position
Tracking
Advanced
Scheduling
Moving Target
Enhancements
Ground
System
Flight
Software
Star, Galaxy
R.A., Dec
no
year
no
no
KBO
Ephemeris
no
year
yes
no
Slow < µ0
Ephemeris
no
many
months
yes
no
Fast > µ0
Ephemeris
yes
months
yes
yes
Comets
Orbital
Elements
yes
Weeks,
days
yes
yes
Cost to S&OC for Observing Solar System Bodies
•
To facilitate costs analysis:
– adopted an operations concept
– identified requirements levied on the ground system and flight software to
implement concept.
– estimated $$ cost to meet the requirements.
– estimated the cost for daily operations.
•
The $$ cost to the S&OC is dominated by software development
needed for the proposal preparation, planning, and scheduling systems.
Observing moving targets with JWST
Concept Assumptions
•
All observatory level restrictions applied to fixed targets apply to
moving target observations.
•
Science instrument modes and target acquisition schemes used for
fixed targets will suffice for moving target observations.
•
JWST can track targets using an ephemeris.
•
Only one guide star used for a visit. It shall be within the same FGS
detector for the duration of the plan window.
Observing moving targets with JWST
•
Concept supports observations of any moving target. Flight software
and hardware set the limits.
•
Concept is similar to HST approach, but is consistent with event
driven schedule architecture.
•
Concept is not optimized for observations when the guide star
availability time is less than the time required to gather the science
data (fast comet).
– Get science by scheduling multiple visits with short plan windows, each
with new guide star.
– Operations impact might be acceptable if instances are rare.
Observing moving targets with JWST
• For economy we assumed maximum re-use of the HST
moving targets ground system (APT, MOSS)
– ~500,000 lines of code!!!
• Concept results in ~12% increase in the size of APT, the
Planning & Scheduling System, and the Guide Star
Selection System.
Observing moving targets with JWST
Summary from the S&OC perspective.
•
Observing Solar System objects with JWST will be easier than with
HST (L2 vs low Earth orbit).
•
Time constrained observations of Solar System bodies are not likely to
significantly reduce observatory efficiency (requirement is > 70%)
•
Software for PP&S and GS selection system increases in size by ~12%
over that needed for observing fixed targets.
Observing moving targets with JWST
•
Cost to S&OC for software development, maintenance, I&T and 2
years of operations is estimated to be $2.7M
– 5% increase in the baseline (fixed target) proposal.
•
Afterwards, cost for yearly operations ~ $250K.
– 2% increase for daily operations.
•
Total cost to the project can be determined when flight software &
hardware impacts are considered.
•
Will it happen?
– ????
Why, or Why Not, Observe Moving Targets?
Shoemaker-Levy 9
TIPS Meeting
19 December 2002, 10am, Auditorium
1. Observing Solar System Objects with JWST Ed Nelan
2. COS - Updates on COS Development
Ken Sembach
3. NICMOS Status
Tommy Wiklind
Next TIPS Meeting will be held on 16 January 2003.
SPACE
TELESCOPE
SCIENCE
INSTITUTE
Operated for NASA by AURA
An Update on the COS Development
Status
TIPS
19 December 2002
COS Optical Layout
NCM3a, 3b, 3c
(Focusing mirrors)
Calibration Platform
4 lamps, 3 beam splitters
NUV Detector
(MAMA)
NCM2
(Collimating mirror)
FUV Detector
Head (DVA)
External Shutter
(not shown)
Aperture Mechanism
positions 1 of 2 Apertures
2 degrees of freedom
(x & y translation)
Cosmic Origins Spectrograph
Hubble Space Telescope
Calibration
Fold Mirror
OSM2
positions 1 of 5 optics
1 degree of freedom
(rotation)
OSM1
positions 1 of 4 optics
2 degrees of freedom
(rotation, focus)
COS Instrument Timeline
• N2 purge testing / alignment completed at Ball
– test is not designed to confirm focus/spectral resolution
• Instrument being installed in enclosure
• Initial delivery to GSFC in late February 2003
– EMI and acoustic testing followed by mini-functional
• Thermal balance and science calibration in vacuum
will occur in late April through early June 2003
• Final instrument delivery to GSFC in June 2003
COS under N2 purge in
cleanroom at BATC
Sample G285M Science/Wavecal
Wavecal
• Wavecal – 3 bright stripes
on left.
• Science – 3 weaker
stripes on right.
• The sources of the glints
have been identified and
remedied.
Science
glint
NUV G285M PtNe Wavecal Spectra - N2 Purge Data
Single grating tilt
yields 3 stripes
Resolution
R ~ 20,000
NUV G230L PtNe Wavecal Spectra - N2 Purge Data
Resolution ~ 1.2 Å
Wavelength (Å)
Three grating tilts required
to cover the full range shown
FUV G160M PtNe Wavecal Spectra - N2 Purge Data
COS Instrument Status (FUV)
• All optics installed and aligned
• FUV-01 flight detector currently installed
• FUV-02 spare detector undergoing final
acceptance/qualification testing
• Team may propose a swap of spare and flight if
spare has significant performance advantages over
FUV-01; recommendation awaiting outcome of
FUV-02 testing over the next 2-4 weeks
COS Instrument Status (NUV)
• Flight detector (NUV MAMA) installed
• All optics installed and aligned – small alignment
errors detected during N2 purge testing have been
corrected
– Source of glint identified
– Camera optic aligned
– OSM1 flatfield tilt position verified
COS Instrument Status: Current Issues
• FUV detector swap? FUV02 (currently designated
as spare) may provide higher quantum efficiency,
but needs consideration of other qualities (flat
field, background, etc.): decision TBD
– FUV02 vacuum leak fix corrected with elliptical O-ring
– Door mechanism operated >40 times
– Still needs final vibe and thermal vacuum tests
COS Performance (FUV)
COS Performance (NUV)
FUV01 and FUV02 Quantum
Efficiencies
FUV01
FUV02
FUV02 / FUV01 QE Comparison
COS Instrument Status: Current Issues
• Manufacturing flaw caused the D2 lamps to fail
under vibration
– Source of problem identified
– New lamps manufactured (two not suitable)
– Vibe and TVac tests ongoing (look good)
• Two lamps passed random vibe and sine burst tests
• Being installed in flight housings
Calibration Platform Random Vibration Test
STScI Ground System Development
Phase 1 (1/1/00 – 6/30/00)
O Macro Development
O Reconfigurations
Phase 2 (7/1/00 – 12/31/00)
O NUV Timetag Mode + Darks
O FUV Timetag Mode + Darks
Phase 3 (1/1/01 – 6/30/01)
O FUV & NUV Accumulation Science Exposures
O FUV & NUV Target Acquisition Exposures
O FUV & NUV Target Peakup Exposures
Phase 4 (7/1/01 – 12/31/01)
O Aperture Alignment Exposures
O OSM1 Focus Alignment Exposures
O OSM1 Rotation Alignment Exposures
O OSM2 Rotation Alignment Exposures
O FUV & NUV FP Split Exposures
Phase 5 (1/1/02 – 6/30/02)
O FUV & NUV GO Wavelength Calibration Exposures
O FUV & NUV Flat Field Lamp Calibration Exposures
O FUV & NUV Automatic Wavelength Calibration
Exposures
O SAA Contours
Phase 6 (7/1/02 – 12/31/02)
O SMGT Preparations
O SMOV Special Commanding
O FUV & NUV Anomalous Recovery
O FUV & NUV Initial Turn-on
O FUV & NUV BOP Target Screening
Phase 7 (1/1/03 – 6/30/03)
O FUV & NUV Lifetime Adjustments
O Coordinated Parallels
STScI Ground System Development
• Phase 5 development completed
– All science / calibration exposure development is now complete
– A few miscellaneous commanding activities remain
• Phase 6/7 development in progress
– Bright object protection target screening in progress
– Initial preparations for SMOV and thermal vacuum tests begun
– Schedule being reworked in light of launch slip
STScI Thermal Vacuum
Preparations
• Instrument Scientists and Data Analysts will support TVac
activities at BATC
– Assisting with science calibration plan
– Perform science calibration activities in May 2003
– Interested in helping? Contact Keyes/Sembach
• Data gathering
– All COS thermal balance / science calibration data will be
permanently archived at MAST
– Data transfer document in preparation
COS Pipeline and Data Activities
• COS Pipeline (CALCOS)
–
–
–
–
Most modules are now complete
Spectral merging procedures for FP-POS positions in progress
Full testing to occur on integrated SI data
Draft of ICD-47 (P. Hodge) is being reviewed
• COS Header Keywords
– Standard header keyword selections/definitions for science and ACQ
exposures completed
– Established COS association requirements
– Keyword “dictionary” in progress
STScI User Support
• COS Instrument Handbook
– Development to begin in Spring 2003
• COS exposure time calculators
– Spectroscopic ETC and target acquisition ETC are in
preparation
– Now due January 2004
• STScI Instrument Division COS Staff
– Keyes, Sembach, Leitherer, Friedman, McMaster
• COS website
– http://www.stsci.edu/instruments/cos
– to be “zoped” early next year
TIPS Meeting
19 December 2002, 10am, Auditorium
1. Observing Solar System Objects with JWST Ed Nelan
2. COS - Updates on COS Development
Ken Sembach
3. NICMOS Status
Tommy Wiklind
Next TIPS Meeting will be held on 16 January 2003.
NICMOS Status
December 2002
1. Overview
2. Dewar Temperature Adjustment
3. HST Calibration Work Shop
4. Science (Mike Corbin)
NICMOS Status
December 2002
NICMOS is operational and is functioning according
to expectations (better instrument than in Cycle 7)
NICMOS Status
December 2002
NICMOS is operational and is functioning according
to expectations (better instrument than in Cycle 7)
Updates & News
NICMOS SMOV programs essentially completed
(coronagraphy performance moved to Cycle 11 calibrations)
GO science programs started June 2002
Regular calibration programs are running
New Instrument Handbook ready
NICMOS Status
December 2002
Special calibration & test programs
Adjustment of the Pupil Alignment Mechanism
no movement since Cycles 7 & 7N
Linearity measurements
done but not yet ready for CDBS
High S/N flat fields
done
New ‘grot’ and bad pixel masks
done
NICMOS Status
December 2002
Calibration Plans
Monitoring programs
Temperature monitoring
Multiaccum darks
Focus stability
Photometric stability
continuously
monthly
monthly/bi-monthly
monthly
One time programs
Dark Generator Tool
Intra-pixel sensistivity
High S/N capability
Polarimetry calibration
Grisms calibration
Sosey
Mobasher
Gilliland
Hines
Thompson
executed/DRIP
executed/DRIP
executed/DRIP
first epoch/waiting 2nd
completed
DRIP = Data Reduction In Progress
NICMOS Status
December 2002
Focus monitoring during
Cycle 7, 7N and post-NCS
NIC1
NIC2
NIC3
NICMOS Status
December 2002
On-going studies
post-SAA Cosmic Ray Persistence Removal
Absolute DQE measurement
Zero-point verification/photometric calibration
NICMOS Status
December 2002
Dewar Temperature
The NICMOS detectors are sensitive to temperature variations
Temperatures are measured at the Neon inlet and outlet (72.4 K)
NIC1 mounting cup temperature set point is 77.1 +/- 0.1 K but
has been slowly increasing during the last ~4 months
NICMOS Status
December 2002
NICMOS Status
December 2002
Dewar Temperature
The temperature increase is most likely due to
parasitics because of the approaching warm season.
A decision to increase the NCS’s compressor speed
to lower the temperature 0.05 K has been taken by
the NICMOS Group and forwarded to GSFC.
A further change in compressor speed when the cooler
season starts (April/May) is foreseen.
The compressor speed change is relatively small
(~10 rps).
NICMOS Status
December 2002
TALKS
HST Calibration Work Shop
NICMOS contributions
POSTERS
NICMOS Status
D. Calzetti
NICMOS Cycle 10 and Cycle 11 Calibration Plans
S. Arribas
The NICMOS Revival: Detector Performance
in the NCS Era T. Böker
NICMOS+NCS Era Darks L. Bergeron
Photometric Calibration of NICMOS
M. Dickinson
NICMOS Grism Performance in the Post Ice Age Era
R. I. Thompson
Coronagraphy with NICMOS
G. Schneider
Polarimetry with the NCS-enabled NICMOS
D. Hines
The NICMOS Cooling System:
Technology in the Service of Science T. Böker
Removal of post-SAA persistence in NICMOS data
M. Dickinson
Post-NCS NICMOS Focus and Coma Analysis E. Roye
Combining NICMOS Parallel Observations
A. Schultz
Pushing NICMOS Cycle 7 Calibrations M. Silverstone
NICMOS User Tools an Calibration Software Updates
M. Sosey
NICMOS Status
December 2002
SUMMARY
NICMOS is fully functional and operates according
to expectations
Calibration programs are up and running
NCS compressor speed needs to be adjusted in order
to keep the detectors at a constant temperature
TIPS Meeting
19 December 2002, 10am, Auditorium
1. Observing Solar System Objects with JWST Ed Nelan
2. COS - Updates on COS Development
Ken Sembach
3. NICMOS Status
Tommy Wiklind
Next TIPS Meeting will be held on 16 January 2003.
MEMORANDUM
TO:
Distribution
DATE:
December 19, 2002
SUBJECT:
Questions and Answers from December 19, 2002 TIPS Meeting
Observing Solar System Objects with JWST
Presenter – Ed Nelan
Q: Regarding the statistics on HST observations of Solar System targets, do we have the numbers between
the years 1996 - 2002?
A: We do not have the statistics at this point.
Q: Is the cost estimate for Ground System support of observing moving targets only for fast moving
targets? Can other strategies, like scanning, be used?
A: No, the cost estimate is for any type of moving targets observation. Note that not all moving targets, like
the Kupier Belt Objects, will require this level of support, but inner Solar System targets like planets will
require the support studied here. The current study did not include looking into the scanning strategy, and
that will have to wait till we have work out the dithering strategy first.
Q: What was the reaction to this study at the JWST Science Working Group (SWG) presentation? Any
action items created?
A: One key member of the SWG was not present at the presentation, but the reactions from the remaining
group include: when do we need the money to fund the work? Do we need to track moving targets? Would
the cost of the tracking be included as part of the TRW baseline? These are the questions that would require
answers before further actions.
COS – Updates on COS Development
Presenter – Ken Sembach
Q: Is every science exposure accompanied with a wavecal exposure?
A: A wavecal exposure is taken each time the OSM motor moves, which means every tilt changes will
result in a wavecal. GOs do have the option to specify their own wavecal for their science exposures.
Q: Is it possible to superpose the wavecal with science exposure?
A: No, this is not possible. Wavecal and science exposures have to be executed separately.
Q: Regarding the detectors’ QE measurements, were they done at the same deposition of the cathodes?
A: Yes, they were done just after the deposition of the cathodes; thus, it should be a fair comparison.
NICMOS Status
Presenter – Tommy Wiklind
Q: Do we have all the Calibration Workshop papers collected for the proceedings?
1
A: We do not have everything yet.
2