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Computing for Space Science – Current practice and future challenges
Peter Allan
Head, Space Data Division
Overview
• Brief overview of work of SSTD
• Software, data, archives
• Systems in space
• Challenges for the future
Work of SSTD
• Astronomy and Earth Observation• Design studies• Design, build and test instruments• Launch instruments (e.g GERB on Wednesday)• Science Operations• Communicate with spacecraft• Develop data processing systems• Process, archive and disseminate data• Long term data curation• Telescope pointing
GERB
Internal black-body
Front End Electronics
Scan Mirror
Telescope
Calibration Monitor
Quartz Filter
Earth View
Fold mirror and detector
18g
Launches
RAL Ground Station
• RAL antennae 12m plus 2.4m• Chilbolton 25m• Jodrell Bank 76m• NASA DSN
– several hundred 10m-class antennae ?
Ground Stations
• Equipment controlled by standard PC
• Standard protocols are the key– Developed by CCSDS
• Like IP, but tuned for use in space– Must handle long round trip
times (many mins to hours)– Must handle disjoint
connections– Power is always at a premium
Science Operations
Operations on Cluster
Double Star
Mars Express
General Computing
• Windows and Linux on desktop– A few Sun and HP workstations
• Linux, Solaris and Tru64 on science servers
• Windows servers for office system and technical tools (e.g. CAD)
Data Centres and Archives
• British Atmospheric Data Centre
• NERC Earth Observation Data Centre
• Cluster/Doublestar
• UK Solar System Data Centre– Solar data– Data on Ionosphere– Space plasma data
Software Engineering
• ISO 9001• Apply the “appropriate level” of rigour• Use appropriate methods
– Iterative development– Science code industrial strength app– Develop formal requirements
• Workshops on improving processes– Use of standard tools?– Departmental CVS repository?
Operating Systems for Space
• Operating systems for space– H/W is previous generation– No disk drives– Tapes replaced with solid state memory– Still use assembler for some applications– Starting to use unix-like systems– Web server in space
Data Analysis and Visualisation
• Languages– Fortran, C, C+
+, Java, Perl, Python
• IDL– ENVI
Data Processing and Analysis
• Starlink
• GGSPS
• AstroGrid
• NERC data grid
Starlink
• Software for processing astronomical data for nearly all wavelengths
• Integrated data processing tools
• Library for writing new tools
• Uniform data format• Fortran (+C) Java• Lasted for 26 years
GGSPS
• GERB Ground Segment Processing System
• Multi-national data processing system– Germany RAL Belgium RAL Users
• Written in C++ (mostly not OO)
256
dete
ctor
pix
els
282 steps
Satellite rotation period = 0.6 s
282 steps for full Earth disc = 169.2 s
Between each Earth scan, internal BB measurement taken for calibration
At correct viewing geometry, calibration monitor records scattered solar light as a relative measure over time
Average three scans in each channel to improve S/N
Total repeat time = 169.2*6 ~ 15 min.
2 channels: Total Total+quartz filter (SW)
Future Challenges
• Autonomy
– Rovers on Mars
– On board analysis of satellite imagery
• Interplanetary Internet
• Integrating Grid computing into daily work
Interplanetary Internet
• Spread communications infrastructure throughout solar system
• E-mail [email protected]
• Need the right protocols– Long round trip times!
Grid Computing
• AstroGrid
• NERC Data Grid
• Both about improving access to data– Search, merge, analyse
• Hooked into international data sources– IVOA
Grid Computing
• Examples from AstroGrid
– Improving access to data
– “What if” questions answered in minutes, not months
– Enabling rapid response to sudden bursts
Optical Data Archive X-ray Data Archive
Processing Pipeline
Astronomy from the Desktop
multi- views of a Supernova Remnant
Shocks seen in the X-ray
Heavy elementsseen in the optical
Dust seen in the IR
Relativistic electrons seen in the radio
Needles in a haystack Hambly et al 2001
- faint moving object is a cool white dwarf- may be solution to the dark matter problem- but hard to find : one in a million- even harder across multiple archives
yesterday
browserfrontend
CGIrequest
html
web page
DBengine
SQL
data
today
appl
icat
ion
webservice
SOAP/XML request
SOAP/XML data
DBengine
SQL
nativedata
anyt
hin
g
standard formats
tomorrow
appl
icat
ion
webservice
job
results
anyt
hin
g
webservice
webservice
webservice
webservice
webservice
Registry Workflow
GLUE Certification VO Space
standard semantics
publish W
SDL
gri
d c
onn
ect
ed
Image from
E
SO
Image + IRIS data
Gamma Ray BurstsGamma Ray Bursts
D. Ducros, ESAReprocessing of ionospheric STP datachange coords from earth to celestial
Collate data frommultiple telescopesover months - meta data issues
Localise GRB alertin minutes – as faderapidly.
SWIFT satelliteobserves gammaray burst
Compare against SNlight curves – bump shows eveidence for a SN in the GRB(Price et al, 2002)
Interaction with observatory pipe-lines
Cross reference multi-λdata – ID pre-cursorand or environment
Large computationalphotometric redshift calcs on multi-λ > gives distance
Questions ?
yesterday
browserfrontend
CGIrequest
html
web page
DBengine
SQL
data
today
appl
icat
ion
webservice
SOAP/XML request
SOAP/XML data
DBengine
SQL
nativedata
anyt
hin
g
standard formats
tomorrow
appl
icat
ion
webservice
job
results
anyt
hin
g
webservice
webservice
webservice
webservice
webservice
Registry Workflow
GLUE Certification VO Space
standard semantics
publish W
SDL
gri
d c
onn
ect
ed