Transcript Using EOP and Space Weather Data for Satellite Operations

Using EOP and Space Weather Data for
Satellite Operations
David A. Vallado and T. S. Kelso
Analytical Graphics Inc.
Center for Space Standards and Innovation
AGI
Paper AAS 05-406, Presented at the AAS Astrodynamics Specialist Conference, Lake Tahoe CA August 7-11, 2005
Outline
• Introduction
–
–
–
–
Definitions
Problem
Objectives
Motivation
• Analysis
– EOP
– Space Weather
• STK Files
• Summary
AGI
Pg 2 of 39
www.centerforspace.com
Definitions
• Earth Orientation Parameters (EOP)
– Assist transformation between Celestial and Terrestrial
Coordinate Frames
• Celestial – GCRF (generic ECI)
• Terrestrial – ITRF (generic ECEF)
– UT1, LOD, xp, yp, AT
• Space Weather Data
– Incoming solar radiation effects the atmosphere
• Geomagnetic
– kp, ap
» Eight 3-hourly and daily averages
• Solar radiation
– F10.7
» Daily values
– Affects upper atmospheric temperature and density
• Large factor in determining atmospheric drag effect on satellite
orbits
AGI
Pg 3 of 39
www.centerforspace.com
Problem
• EOP and space weather data needed to support tasks
– Mission Design
• Fuel budgets
• Lifetime maneuver / orbit box planning
– Real-time Operations
• Few days into the future
• Mission planning a few months ahead
• Anomaly resolution a few months in the past
• Available data is “chaotic” at best
– Mix of predicted and observed values
– Post processing data often takes a month or more
– No synchronized update schedule for all parameters
• Need seamless file of data to accomplish each mission task
AGI
Pg 4 of 39
www.centerforspace.com
Objectives
• Analyze currently available data
• Recommend best option for splicing data
• Discuss setup of data files
– Available on CelesTrak website
• STK compatible
AGI
Pg 5 of 39
www.centerforspace.com
Motivation
• So What?
– With analytical theories (i.e. SGP4), it mattered little
• TEME example
– AFSPC still uses two-line element set data in TEME (never officially defined!)
» Time sometimes assumed to be UTC
» No polar motion, no ECI/ECEF distinctions
• SGP4 only approximated atmospheric drag
– No use of solar indices
– No rigorous application of force models
– With numerical techniques, EOP and space weather are required inputs
• Integrate in inertial
• Apply forces in fixed
• If you use incorrect values of
– EOP
• A few meters
– Space Weather
• 1s to 1000s of kilometers
AGI
Pg 6 of 39
www.centerforspace.com
EOP Data Sources
•
1. General Directory:
–
–
http://hpiers.obspm.fr/eoppc/eop/eopc04
*Current data (Current year to date) – updated Daily (~1400 UTC)
•
•
–
Historical data (1962 to date) – updated Daily (~1400 UTC)
•
•
•
http://hpiers.obspm.fr/eoppc/eop/eopc04/eopc04.62-now
http://hpiers.obspm.fr/eoppc/eop/eopc04/eopc04_IAU2000.62-now
2. General Directory:
–
–
http://maia.usno.navy.mil/
Current data (t-3 months-date + 90 days) – updated Daily (~1705 UTC)
•
•
–
http://maia.usno.navy.mil/ser7/finals.daily
http://maia.usno.navy.mil/ser7/finals2000A.daily
Historical data (1973 to date + 1 year) – updated Weekly (Thursday)
•
•
•
http://hpiers.obspm.fr/eoppc/eop/eopc04/eopc04.05
http://hpiers.obspm.fr/eoppc/eop/eopc04/eopc04_IAU2000.05
http://maia.usno.navy.mil/ser7/finals.all
http://maia.usno.navy.mil/ser7/finals2000A.all
3. General Directory:
–
–
http://earth-info.nima.mil/GandG/sathtml/eopp.html
Current data – updated Weekly (Thursday)
•
•
•
Coefficients effective for the following week starting Sunday.
Multiple files, 5 is last digit of year, 255 is the day of the year in the example below
ftp://164.214.2.65/pub/gig/pedata/2005EOPP/EOPP5255.TXT
* Not necessarily needed for processing, use 62-now files
AGI
Pg 7 of 39
www.centerforspace.com
Summary of EOP Data Files
1962
IERS
EOPC04.62-now
(UT1, xp, yp,, LOD, , , X, Y)
-3 months
1973
00:00
USNO
Finals.daily, Finals2000a.daily
(UT1, xp, yp,, , , X, Y)
+ 90 days
USNO
Finals.all, Finals2000a.all (UT1, xp, yp)
00:00
Sunday
NGA
EOPPyddd.txt
(UT1, xp, yp)
+ 1 year
23:59
Saturday
14:28
PAST
AGI
Current Time,
T
Pg 8 of 39
FUTURE
www.centerforspace.com
Space Weather Data – Current
•
1. General Directory:
–
–
ftp://ftp.ngdc.noaa.gov/STP/GEOMAGNETIC_DATA/INDICES/KP_AP/
Current data – updated Monthly (~22nd – 24th)
•
•
•
–
•
Each month is a .vx where x is the month (1-12). When the year is complete, it’s simply 2005
ftp://ftp.ngdc.noaa.gov/STP/GEOMAGNETIC_DATA/INDICES/KP_AP/2005.v1
Data assembled from 1950 to 2005 (atmosall.txt)
–
Numerous omissions exist in the data (above file is linearly interpolated)
Current data—updated daily
• Includes observed F10.7 daily values
• ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SOLAR_RADIO/FLUX/DAILYPLT.OBS
2. General Directory:
–
–
http://www.sel.noaa.gov/Data/index.html
Current data – updated 3-Hourly
•
–
Current data – updated Daily (~0230 UTC)
•
–
No 3hrly values
http://www.sel.noaa.gov/ftpdir/latest/45DF.txt
Predicted data – updated Monthly (~3rd of the month)
•
•
•
AGI
http://www.sel.noaa.gov/ftpdir/indices/quar_DSD.txt
Predicted data – updated Daily (~2114 UTC)
•
•
–
http://www.sel.noaa.gov/ftpdir/indices/quar_DGD.txt
Includes f10.7 monthly values predicted for about 2 years into the future
Also has some old data which [depending on the access time] is overcome by actual measurements
http://www.sel.noaa.gov/ftpdir/weekly/Predict.txt
Pg 9 of 39
www.centerforspace.com
Summary of Space Weather Data Files
00:00
-1 month
Current Year
00:00
1 month
00:00
yyyy.vm
(daily F10.7, daily and 3 hrly kp, ap)
- 3 months
Quar_dgd.txt (3 hrly kp, daily ap)
Quar_dsd.txt (daily F10.7)
45df.txt
(daily F10.7, ap)
- 6 months
Predict.txt
(monthly F10.7)
+ 45 days
+ 6 year
14:28
PAST
AGI
Current
Time, T
Pg 10 of 39
FUTURE
www.centerforspace.com
I. EOP Data
AGI
Pg 11 of 39
www.centerforspace.com
EOP Parameters - Historical
1.00
0.80
0.60
0.40
xp "
0.20
yp "
DUT1 s
0.00
LOD s
dpsi "
-0.20
deps "
-0.40
-0.60
Leap Seconds
-0.80
-1.00
Jan-62 Jan-66 Jan-70 Jan-74 Jan-78 Jan-82 Jan-86 Jan-90 Jan-94 Jan-98 Jan-02 Jan-06
AGI
Pg 12 of 39
www.centerforspace.com
Analyses
• Series are recomputed
– IERS
• Twice weekly
• Some smoothing due to use of Vondrak algorithm
– Removes high-frequency noise
– USNO
• Weekly ?
• Comparisons Useful
– Within Organizations
• USNO
– Bulletin A and B
» , 
» X , Y
– Between Organizations
• USNO, IERS, NGA
– Note that axes scales and units are not constant
AGI
Pg 13 of 39
www.centerforspace.com
Analysis
• USNO
– Bltn A and Bltn B values
5.0
• , 
• Bull B values only from
Jan 1, 1989
-5.0
-15.0
• Bltn B dpsi some
anomalies
msec arc
– Reasonably consistent
-25.0
B dpsi m"
B deps m"
A dpsi m"
-35.0
A deps m"
– Sep 1999
-45.0
-55.0
-65.0
Jan-89
AGI
Jan-91
Pg 14 of 39
Jan-93
Jan-95
Jan-97
Jan-99
Jan-01
Jan-03
Jan-05
Jan-07
www.centerforspace.com
Analysis
• USNO
5.0
– Bltn A and Bltn B values
• X , Y
• Values from 1973
0.0
– Values before 1990
– Bltn B some anomalies
A dX m"
msec arc
• Additional variations
-5.0
A dY m"
B dX m"
B dY m"
-10.0
• Sep-Oct 1999
-15.0
-20.0
Jan-73
AGI
Jan-77
Pg 15 of 39
Jan-81
Jan-85
Jan-89
Jan-93
Jan-97
Jan-01
Jan-05
www.centerforspace.com
Comparisons
• Between Organizations
– USNO (Bltn A and Bltn B)
and IERS (EOPC04)
0.04
0.03
0.02
• Before 1984
– Larger variations
– FK5 instituted
• Before 1997
– Smaller variations
– Update to Equation of the
equinoxes
• Note last few values
– See next slide
AGI
0.01
D xp "
0
D yp "
D dut1 s
-0.01
D lod s
-0.02
-0.03
-0.04
Jan-73
Jan-77 Jan-81
Pg 16 of 39
Jan-85
Jan-89 Jan-93
Jan-97
Jan-01 Jan-05
www.centerforspace.com
Comparisons (Cont)
• Between Organizations
– USNO (Bltn A and Bltn B)
and IERS (EOPC04)
• Last few days appear to
differ (IERS and USNO)
• On Feb 22 for xp
– 0.035728 IERS
– 0.03383 USNO
• On May 5 for xp
– 0.035699 IERS
– 0.035491 USNO
• IERS Delta = 0.000029
• USNO delta = -0.031661
AGI
0.002
0.0015
0.001
0.0005
D xp "
0
D yp "
D dut1 s
-0.0005
D lod s
-0.001
-0.0015
-0.002
Jan-97
Pg 17 of 39
Jan-99
Jan-01
Jan-03
Jan-05
Jan-07
www.centerforspace.com
Comparisons (FK5 Corrections)
• Between Organizations
– USNO (Bltn A and Bltn B)
and IERS (EOPC04)
• Data availability
– Bltn B values only after
Jan 1, 1989
0.02
0.015
0.01
B D dpsi "
0.005
B D deps "
• Each appear to have noise
A D dpsi "
A D deps "
0
-0.005
-0.01
Jan-73 Jan-77 Jan-81 Jan-85 Jan-89 Jan-93 Jan-97 Jan-01 Jan-05
AGI
Pg 18 of 39
www.centerforspace.com
Comparisons (IAU 2000 Corrections)
• Between Organizations
– USNO (Bltn A and Bltn B)
and IERS (EOPC04)
• Data availability
0.006
0.004
– EOPCO4 Values after
Jan 1, 1984
0.002
• Bltn B appears to better
follow EOPC04
0
B D dX "
B D dY "
A D dX "
A D dY "
-0.002
-0.004
-0.006
Jan-84
AGI
Pg 19 of 39
Jan-88
Jan-92
Jan-96
Jan-00
Jan-04
www.centerforspace.com
Coefficient Approach
• NGA provides coefficients
– Continuous representation of
• UT1, xp, yp
– Lacks LOD, , , X , Y
• Generally smaller order effects
• Long-term behavior of EOP coefficients
– xp, yp reasonable to use past the end of a data file
– UT1 not recommended past about a month
AGI
Pg 20 of 39
www.centerforspace.com
Comparisons – Long Term
• EOPC04 to NGA
Coefficients
– One year different
epochs are shown
– Notice variability
– Runoff for UT1, xp
– Current week is valid
(highlighted)
0.04
0.03
0.02
0.01
xp "
0
yp "
dut1 s
-0.01
-0.02
– Note 0.04 s ≈ 280m at 7
km/s
AGI
-0.03
-0.04
-100
Pg 21 of 39
-50
0
50
100
www.centerforspace.com
EOP – How to Splice Together
• EOPC04
– Use 62-now file
• Up to current day
• Recomputed frequently
• USNO Predicted Bulletin A
– Use .daily file
• Daily values (t-3 months to t+3 months)
– Updated daily
• USNO Predicted Bulletin A
– Use .all file
• 1 year predictions
• Data availability
– Use last known file of each if any are not available
– Values are “acceptable” for short periods of time (~week)
AGI
Pg 22 of 39
www.centerforspace.com
II. Space Weather Data
AGI
Pg 23 of 39
www.centerforspace.com
Space Weather
• Tracked for many years
– Data to the 1930s
• Older data
– Has numerous missing dates
• Physically a zero means little here!
• Corrected in our files
– Quality flag set to 4 as an indicator
• Includes seasonal/solar cycle variations
– Observed and adjusted to 1.0 AU values
• DRAO and Lenhart values
– Atmospheric models use both
AGI
Pg 24 of 39
www.centerforspace.com
Sensitivity Results
• Atmospheric Drag (see Vallado AAS 05-199)
– Large variations
• Changing the atmospheric model
• Changing how the input data is interpreted
– F10.7 at 2000 UTC
– Last 81-day average F10.7 vs. the central 81-day average
– Using step functions for the atmospheric parameters vs
interpolation
– Many others
– Point to take away:
• 1-1000 km ephemeris differences are possible
• Unable to determine if from data interpretation or model
differences
AGI
Pg 25 of 39
www.centerforspace.com
Space Weather – Predictions
• Lots of Variability
– Constant F10.7
• Not very accurate
• Never use 0.0!
– Schatten
• Varies with each solar cycle
– Polynomial Trend (Vallado 2004, 535)
• Matches several solar cycles
• F10.7 = 145 + 75*COS{ 0.001696 t – 0.35*SIN(π + 0.001696 t )}
– t is the number of days from Jan 1, 1981
AGI
Pg 26 of 39
www.centerforspace.com
Historical and Polynomial Trend
300.0
250.0
200.0
f107
CtrF107
150.0
apavg
Trend
100.0
50.0
Solar Cycle
19
Solar Cycle
20
Solar Cycle
22
Solar Cycle
21
Solar Cycle
23
0.0
Jan-50
AGI
Jan-54
Jan-58
Jan-62
Jan-66
Jan-70
Jan-74
Jan-78
Jan-82
Jan-86
Pg 27 of 39
Jan-90
Jan-94
Jan-98
Jan-02
Jan-06
www.centerforspace.com
Schatten Predictions
300
Trend
Apr-95
Oct-95
Mar-96
Oct-96
Schatten Oct 96
Mar-97
Sep-97
250
Jan-98
Jun-98
Actual
Jan-99
Schatten Sep 97
Trend
Apr-99
Jun-99
Sep-99
200
Dec-99
Apr-00
Jul-00
Sep-00
Schatten Jul 02
Jan-01
May-01
Jul-01
150
Dec-01
Mar-02
Jul-02
Nov-02
Mar-03
Jul-03
100
Nov-03
Mar-04
Jul-04
Nov-04
Schatten Mar 05
Mar-05
Last F10.7
50
27-Nov-93
AGI
Mon Avg F10.7
20-May-99
09-Nov-04
02-May-10
23-Oct-15
Pg 28 of 39
14-Apr-21
05-Oct-26
27-Mar-32
www.centerforspace.com
Statistics Comparisons
Combined Results
Avg
Deviation
Standard
Deviation
Ctr 81-day – Daily F10.7
15.00
21.99
Last 81-day – Daily F10.7
17.17
24.92
40.0
Trend 81-day – Daily F10.7
20.79
29.88
35.0
Monthly Trend – Monthly F10.7
15.33
21.85
Individual Results
Schatten Std Dev
Schatten Avg Dev
30.0
Trend Std Dev
25.0
• Variability ‘same’ between
– 81-day averages and daily
values
– Monthly trend and monthly
averages
Trend Avg Dev
20.0
15.0
10.0
5.0
– Predicted (3-day, 45-day and 2
year) solar flux values
0.0
0
12
24
36
48
60
72
84
96
108
120
132
144
Months of Prediction with Actuals
AGI
Pg 29 of 39
www.centerforspace.com
Observed / Adjusted values
40.0
30.0
Drao (obs) Lenhart (adj)
data
20.0
10.0
0.0
-10.0
-20.0
Drao (obs) Drao (adj) data
-30.0
-40.0
Jan-50
AGI
Jan-54
Jan-58
Jan-62
Jan-66
Jan-70
Jan-74
Jan-78
Jan-82
Pg 30 of 39
Jan-86
Jan-90
Jan-94
Jan-98
Jan-02
Jan-06
www.centerforspace.com
kp – ap Conversions
• Rigorously defined
– 1940 – Chapman and Bartels – Geomagnetism
– Discrete values
• Values exist that are not in the discrete values
– Finding 3-hourly ap values for the last month
– Finding kp values from predicted ap values
• Some Interpolation clearly required
– Approaches
• Linear Interpolation
• Iteration
• Spline
AGI
Pg 31 of 39
www.centerforspace.com
Comparison of Conversions
• Techniques – Interpolate, Iterate, Splines
– Between approaches (left)
– To exact values (right)
25
25
Iterate - Spline
20
20
Iterate - Interpolate
Iterate
15
Iterate - Cubic Sp
15
Delta ap to exact
10
Delta ap
Interpolate - Spline
Interpolate - Cubic Sp
5
Spline - Cubic Sp
0
10
Interpolate
5
Spline
0
-5
-5
-10
-15
-10
0
1
2
3
4
5
6
7
8
9
0
kp
AGI
1
2
3
4
5
6
7
8
9
kp
Pg 32 of 39
www.centerforspace.com
Splining technique closure
5
0.025
0.02
4
0.015
3
Delta ap on closure
Delta kp on closure
0.01
0.005
0
-0.005
2
1
0
-0.01
-1
-0.015
-2
-0.02
-3
-0.025
0
1
2
3
4
5
6
7
8
9
0
50
100
150
200
250
300
350
400
ap
kp
Note small scales
AGI
Pg 33 of 39
www.centerforspace.com
III. File Setup
AGI
Pg 34 of 39
www.centerforspace.com
File Setup
• Proceeding can be complex and time consuming
– CSSI (Dr. Kelso) has done the work for you!
– http://celestrak.com/SpaceData
• Files updated every 3 hours
• STK compatible
• Ability to generate custom-sized datasets
– Smaller data sets may perform better on some more limited
installations
– Naming indicates start date
• Schedule
– EOP and Space weather files ready today
– Operational in next STK release
AGI
Pg 35 of 39
www.centerforspace.com
Files
• C:\Program Files\AGI\STK 6.0\DynamicEarthData
– EOP Files
• EOP1962-01-01.txt
• EOP1973-01-02Old.txt
(New STK File)
(Existing STK file)
– Space Weather Files
• Atmos1957-01-01.txt
• Atmos1957-01-01Old.txt
(New STK File)
(Existing STK File)
– Shorter files also available for about the last 5 years
AGI
Pg 36 of 39
www.centerforspace.com
Additional Information
• Common changes for both files
– All ASCII text
– Start dates can be set to a time before the current date
• Naming convention permits quick determination
– Set an end date
– Observed and predicted sections consistent
– Spacing minimized (file size)
• Maintain free-field read capability
– Indicate number of data points
AGI
Pg 37 of 39
www.centerforspace.com
Additional Information
• Specifics
– EOP
• Add day, month, year to data
• Switch to predominantly IERS EOP-C04 data from USNO Bltn A data
– Data now available from 1962 instead of 1973
•
•
•
•
•
Removed data for errors in xp, yp, and UT1
Added LOD, , 
Added AT, X, Y into one file
Last values set to zero
Include automatic leap second introduction
– Space Weather
• Data from 1957 to date (more is possible)
• Added centered 81 day in addition to last 81 day average values, observed and
adjusted
• Spliced past, current, and predicted data
• New structure for predicted data
– Monthly and Daily sections
• Trend values for long term prediction possible
AGI
Pg 38 of 39
www.centerforspace.com
Conclusions
• EOP and Space Weather data
– Not high visibility
• However, large variations in numerical results
– Ap/kp conversion
• Recommend using Cubic Spline approach
– Predicted solar flux values
• Polynomial trend available for long term use
• Reasonable statistics to existing Schatten files
– Your single source for consolidated values available:
http://celestrak.com/SpaceData/
AGI
Pg 39 of 39
www.centerforspace.com