View
373
Download
0
Category
Tags:
Preview:
DESCRIPTION
Citation preview
Space Telescope Science Institute
The Role of Science and Operationsin the James Web Space Telescope
Mission DevelopmentPresenter D.G. Hunter
Co-authors H.S. Stockman
K.S. Long
Track T5 May 20, 2004
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
JWST Science• Detect First Light (After the
Big Bang) First luminous objects -
protogalaxies, supernovae, black holes
• Assembly of Galaxies Merging of protogalaxies,
effects of black holes, history of star formation
• Birth of Stars and Planetary Systems How stars form in dust clouds How chemical elements are
produced and recirculated
• Planetary Systems and the Origins of Life Formation of planets Direct observation of other
systems Outer Solar System
Observatory Design Features
Science Instruments
Spacecraft Sunshield
25 m2 Primary Mirror
JWST Will Operate at Sun-Earth L2
• L2 allows blocking Sun, Earth & Moon light
• Passive cooling to ~50K
• Stable environment
• Easy communication
Science Instruments
GuiderMIRI
NIRSpec NIRCam
Science InstrumentsMid-Infra-Red Instrument (MIRI)
• 100x sensitivity over previous systems
• Imaging and spectroscopy capability
• 5 to 28 microns• Cooled to 7K by Cryostat or
Cyrocooler• Combined ESA/NASA
contributions
Fine Guidance Sensor (FGS)• Ensures guide star availability with
>95% probability at any point in the sky
• Includes Tunable filters for Narrowband Imaging
• CSA provided
Near Infra-Red Camera (NIRCam)• Detects first light• 0.6 to 5 microns• 4 Imaging modules each with a 2.3’
x 2.3‘ FOV (short 4kx4k, long 2kx2k)
• Coronagraph capability• FPA’s passively cooled to 30K• UofAz/LMATC instrument
Near Infra-Red Spectrometer (NIRSpec)• Studies galaxy formation, clusters,
chemical abundances, star formation, and kinematics
• 0.6 to 5 microns • Simultaneous spectra of >100
objects• 9 square arc minute field of view• FPA’s passively cooled to 30K• Resolving powers of ~100 and
~1000.• ESA provided with NASA Detectors
& Microshutter
Operations• Five year mission lifetime - propellant tanks sized
for 10 years• Guaranteed Time Observations for Instrument
Scientists• General Observing via a peer reviewed proposal
selection process (as for the Hubble Space Telescope)
• Scheduling (long-term and short-term observation plans)
• Event driven execution of uploaded operations plan• On-board procedures, high level commands• Data download and archive• On-the-Fly data calibration
Mission Schedule
Mission ParticipantsNASA
ESA
CSA
Project lead at Goddard Space Flight Center (GSFC)
Observatory Contractor: Northrop Grumman Space Technology (NGST)
Science and Operations Center at the Space Telescope Science Institute (STScI)
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
The STScI Hubble Heritage• Successful preparation and
checkout of 10 instruments (+2 in SM4).
• Proven and evolving software systems for all aspects of science operations: Proposal management Guide star selection (GSC II) Science planning (APT) Scheduling (Spike) Hubble archive “On-the-fly” calibration
management (OPUS) Grants management (GMS)
• Outstanding record of public and astronomical outreach
STScI Role in JWST• Manage the science program from observing program
solicitation and selection to grants management and science outreach support.
• Operate JWST - beginning in commissioning• Develop the science and operations ground systems• Perform ground segment verification• Perform end to end testing• Scientific and Public outreach • Support the Project and JWST teams during the
development phase: Mission architecture & system engineering ISIM & Scientific instruments & ISIM flight software Optics and wavefront sensing and control Science and operations input to many working groups
The JWST Ground System
ProposalPreparation
ProposalSelection
SciencePlanning
OperationsScheduling
FlightOperations
DataManagement
DataArchive
Ground SysEngineering/Maintenance
FlightSystem Eng
Testbeds &Simulators
FlightDynamics
WavefrontControl
InstrumentCalibration
CommandManagement
Flight SWMaintenance
Astronomers
Uplink- Observation Plan- Ephemeris- Commands-Flight S/W-Ranging
JPL Deep SpaceNetwork
JWST Ground Processes and Key Relationships
Downlink- Event Logs-R/T Eng Telemetry-Recorded Telemetry-Ranging-Flight S/W
JWST
- On-Line Documentation- Electronic Forms- Proposal Tools
- TAC review- Electronic Forms
- Long-term plan- Weekly schedule- WFE Sensing- WFE Control- Station Keeping
- Weekly Schedule- Contact Schedule - Eng Activities- Command Loads
- R/T Operations- Uplinks- State evaluation- Data capture- Eng Trend
- L0 Processing- Sci Data QA- SI Calibration- Short Term Storage
- Long-Term Storage(Sci & Eng)- Browsing- Retrieval- SI Calibration- Distribution
- WFE Determination- Mirror Actuator Commands
- FSW Upgrades- Patches- Tables
- SI Procedures- Anomaly Analysis- GSW Requirements- Data Base Management- Vendor OS & Tools- Ground HW / SW Maintenance / Upgrades
- H/W Testbeds- SW Simulators- System I&T- SSM/OTA/ISIMTest Environment
- Orbit Determination- Station Keeping- Ephemeris- Momentum Monitoring
- Anomaly Analysis- Eng Trend Analysis- Degradation Prediction- FSW Requirements
- Algorithms- Reference Data- Performance Reports
- Proposals- Science Data
- Visit Scripts
JWST Ground Processes
The Planning System Interface• Exposure Time calculators
• Optimum background/roll range
• Orientation planning with Guide Star Catalog II Target coordinates in JWST
frame NIRSpec target selection tool Allowable & Optimum roll angles Dither pattern selection and
optimization Predicted glare from bright
objects Acquisition/offset target
selection
• Calibration & engineering operations will also be planned using this planning tool.
Hubble Planning ToolAdvanced Camera for Surveys
Participation in Development• Inform the Observatory development
process of the science and operations drivers for, and consequences of each design decision.
• Ultimate objectives: achieving a high scientific return, reduced lifecycle cost, efficient operations and design.
Influencing Development - 1• Develop and maintain the Mission Operations Concept• Systems Engineering
Participate in requirements development. Evaluate the operations consequences for system level
trades.
• Science Instrument Teams Develop operation concepts with common approaches Develop the calibration plans Gain knowledge of the instruments’ design & behavior Develop the tools and resources the astronomy community
will need for high yield science.
• Flight software Ensure commonality of commanding approaches, syntax and
terminology Develop on-board procedures.
Influencing Development - 2• Integration and Test
Develop and manage the Project Reference Database Provide test conductors who will migrate to the operations
team Develop operations procedures - test against simulators
and with the ground system in the loop with the flight systems.
• Commissioning Develop plans and procedures, working with the flight
systems developers Operate observatory.
Value Added - Mission Simulator• JWST Mission Simulator - simulates execution of science
observations Informed the transformation of the science objectives into the
observatory requirements.
http://www.stsci.edu/jwst/science/jms/index.html Important science influence on requirements
• Field of Regard• Continuous viewing zone• Continuous exposure at same orientation…
Anti-Sun LOS Allowable
ObservatoryField-of-Regard
SUN
Exclusion< 27° fromAnti-Sun Exclusion Zone
< 85° from Sun
Observatory Field-of-Regard (FOR)
Value Added - Fine Guidance Sensor Architecture
• Separation of Fine Guidance Sensor from Near-Infrared Camera. Reduced operational complexity Improved architecture for science Improved management structure.
Value Added - Day in the Life Simulations
• Developed prototype of flight software for event-driven operations including: Executive and processing functions On-board procedure scripts Commands and telemetry for science instruments and spacecraft
• Executed on top of Command and Data Handling System flight code running on a flight representative single board computer.
• Loaded and ran six days of observation plans for three science instruments.
• Produced detailed event logs plus memory and CPU statistics.
• The exercise: developed detailed requirements, confirmed the event driven design with flight like operations, produced flight like prototypes for the flight software.
• Now preparing to implement more complex scenarios.
System Trades - Momentum Management
The JWST attitude required for each science observation results in solar torque being generated by the sunshield.
Unloading momentum disturbs the orbit. Propellant consumption affects the mission lifetime. Constraining the scheduling of observations to manage
momentum accumulation adds significant complexity and may compromise science.
Momentum Profile for First 400 Days of Mission Schedule JMS v1.0_wmk135, 1 Day Max Visit Duration, 40 Nms Limit
0
5
10
15
20
25
30
35
40
45
0 50 100 150 200 250 300 350 400
Start or End of Visit [MJD-56019]
S/C
Mom
entu
m R
SS
[Nm
s]
. 20 65 58 158 43 28Days Between Dumps
Abrupt change in slope due to momentum dump or target change.
Targets at Ecliptic Coordinates (0,*)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
-50 0 50 100 150 200 250 300 350 400
Visit Start Time [MJD - 52000]
Cum
ula
tive
Fra
ctio
nal
Sky
Are
a
Solar Avoidance
10 Day VisitScheduling
0°
30°
45°
60°
15°
90°75°
Ecl
iptic
Lat
itude
Red indicates times where the target is in the field of regard, but a 10 day visit cannot schedule.
Ongoing Challenges• Aspects of operations are highly sensitive to the
flight segment design, such as: Momentum management - smaller sunshield is better Stray light avoidance - larger sunshield is better Both affect scheduling of science observations. Importance of operations involvement in design
trades
• Funding profile - Pressures on Phase A/B funding Lowest lifecycle cost often requires higher initial outlay but
few missions have sufficient early funding. Prioritization of effort in high impact areas.
• Not everyone has learned the same lessons Different missions follow different paradigms Demonstrate merits of approach by example.
Recommended