1. Selection of the SC Constellations in the Frameworks of the IACG/ISTP Campaign 2 Space Research Institute (IKI) Russian Academy of Sciences http://iki.cosmos.ru/ Satellite Situation Center (SSC) http://iki.cosmos.ru/vprokhor/ssc.htm Victoria Prokhorenko and Ravil Nazirov

2. Abstract xThe spacecraft (SC) constellations selection is one of the steps to provide the planning of the simultaneous multi-point measurements in the desirable spatial positions. This report presents the methods developed in IKI for the spacecraft constellations selection in accordance with the various scientific goals and criterion. We consider as an example the application of this method to the goals of the IACG/ISTP Campaign 2 2

3. IACG/ISTP Campaign 2 Geophysical Regions of the Interests zMagnetospheric boundary layer (BL) zMagnetopause (MP); zCusp/cleft (CUSP); 3

4. IACG/ISTP Campaign 2 Missions and SC Considered zINTERBALL (RKA): yTail probe (IB_TAIL, or IB_1) yAuroral probe (IB_AUR) yMagion 5 (IB_MAG5) zGEOTAIL (NASA/ISAS) zPOLAR (NASA) 4

5. Criteria of the Favourable Spatial Position (FSP) zFSP1: The IB_TAIL or GEOTAIL is located in the simulative boundary layer or cusp/cleft region zFSP2: The IB_AUR or IB_MAG5 or POLAR is located in the cusp/cleft, or diurnal (6 h < MLT < 18 h) auroral region (AUR) or polar cap (CAP) simultaneously with FSP1 zFSP3: The part of the FSP1 or FSP2 events corresponding to the magnetic conjugations between any couple of the considered SC 5

6. Magnetic Conjugation Criterion zThe value of the relative geocentric angular distance between footprints of the magnetic field lines passing through the couple of SC positions is considered  The value of the mentioned angular distance less then 5  is used as a criterion of the magnetic conjugation zTsyganenko 87 (kp = 2) + IGRF 95 magnetic field model is used during magnetic mapping zThe stop trace altitude 110 km above the Earth surface is used during magnetic mapping 6

7. The Following Steps Are Fulfilled During the SC Constellation and Multi-satellite Magnetic Conjugation Selection: zThe long-term prediction of the each SC position, its magnetic mapping to the Earth's surface, and the simulated geophysical regions identification in the SC location zThe FSP database is carried out for each month. The common graphical display of all FSP time-distribution during month is created (See the FSP plot for May 2000 on the next slide as an example) zThe SC constellation is selected when two or more SC are taking part simultaneously in the FSP (See the slide # 10 as an example) zThe magnetic conjugation common (MCC) plot is created by the similar way using predicted conjugation of each couple of the SC (See the MCC plot for May 2000 on the slide # 11 as an example) zThe MCC plot make it possible to select the multi-satellite magnetic conjugation, when more then 2 SC simultaneously take part in the conjugation 7

8. Common plot of the 4 SC FSP Time-distribution on May 2000 (See the comments on the next slide) 8

9. Description of the FSP Common Plot for 4 SC zThe time intervals of the each SC passing trough the FSP are shown on the plot. Date is shown along the x-axis, the UT - along the y-axis zThe different color is used for each SC specified by the SC name color in the head of the plot (The red color - for the first SC, the turquoise - for the second one, and so on) zThe time-intervals segments concerning the different SC participation in the FSP are shown (by the different color) on the different line (parallel to the y-axis) located in the frameworks of the corresponding day. The first line is used every day for the first SC mentioned in the list (IB_TAIL), the second line - for the second SC (MAG_5), and so on zThe moments of the orbits cross-sections with the simulated magnetopause are shown by the "diamond" symbol and the cross- sections with the simulated bow shock - by the "cross" symbol 9

10. 10 SC Constellation Selection on May 2000

11. MCC Plot for May 2000 (See the comments on the next slide) 11

12. Description of the MCC Plot zThe time intervals of the magnetic conjugation are shown on the plot. Date is shown along the x-axis, the UT - along the y-axis zThe different color is used for each SC specified by the SC name color in the head of the plot (the red color - for the first SC, the turquoise - for the second one, and so on) zThe time-intervals segments concerning the different SC participation in the conjugation are shown (by the different color) on the different line (parallel to the y-axis) located in the frameworks of the corresponding day. The first line is used for the first SC mentioned in the list (IB_TAIL), the second line - for the second SC (MAG_5), and so on zTwo equal segments in the frameworks of one day show the magnetic conjugation of two SC of the corresponding colours zThis plot permit to find the cases of the multisatellite magnetic conjugation. See as an example the time interval: 21 - 24 UT on 17 May 2000 12

13. Multi-satellite Magnetic Conjugation Superposed by the Selected Constellation List on May 2000 13

14. Graphical Display of the Orbital Information for Selected SC Constellation on May 17-18, 2000 as an example zVarious symbols mark the SC passing through the simulative geophysical regions. The region designations are shown on the left vertical table zThe UT (hours) is shown along the x-axis. Range of x-axis corresponds to the time-interval selected zDate is shown near the left border of the x-axis zColors and lines (parallel to the x-axis) are specified for each SC zThe moments of the magnetic conjugation are shown by the colored points located above the region's symbols zThe polar diagram shows footprints of the SC as a corrected geomagnetic co-ordinates: co-latitude - local time zThe tabular display of the SC co-ordinates on the considered time-interval is available as well (See the next slide) 14

15. Tabular Display of the Orbital Information for Selected SC Constellation z5 ASCII files are created for each time interval. The colored buttons permit to access the files as follows:  The first one contains the moments and co-ordinates of the magnetic conjugation of the IB_1 and another 3 SC  The second one shows the conjugation of the IB_MAG5 and another 3 SC  The third one shows the conjugation of the POLAR and another 3 SC  The forth one shows the conjugations of the GEOTAIL and another 3 SC  The fifth file shows the simultaneously co-ordinate of the four SC with 10-min step zPush the buttons to download the ASCII files corresponding to the time-interval May 17, 20 UT- May 18, 06 UT as an example 15 cnj fsp

16. The ground-based support of the SC constellation zThe next slides show the method of the ground-based support selection, using the SuperDARN radars (SDR) as an example zThe common plot of the conjugation of SDR area and considered SC is created and superposed by the list of the selected SC constellations zThe red boxes on the slides show the preferable time intervals for each SDR pair 16

17. Magnetic Conjugations of the SC and SUPER-DARN radar pair 1 (SASKATOON & KAPUSKASING) Superposed by the Selected Constellation List on May 2000 17

18. Magnetic Conjugations of the SC and SUPER-DARN Radar pair 2 (GOOSE-BAY & STOKKSEYRI) Superposed by the Selected Constellation List on May 2000 18

19. Magnetic Conjugations of the SC and SUPER-DARN radar pair 3 (THYKKVIBAER & HANKASALMI) Superposed by the Selected Constellation List on May 2000 19

20. Models of the Magnetosphere zThe internal magnetic field - standard IGRF 1950-1995 zThe external magnetic field - Tsyganenko, T87, T89, and T96 zThe magnetopause - Sibeck et al, JGR, 1991, v. 96, p. 5489 zThe bow shock - Fairfield, JGR, 1971, v. 76, p. 6700 20

21. The Data Exchange zThe orbital elements of the INTERBALL determined by the ballistic center of the KIAM (Keldysh Institute of Applied Mathematics Russian Academy of Sciences) and the orbital elements of the other SC distributed by IACG (Inter-Agency Consultative Group) via INTERNET web site: http://nssdca.gsfc.nasa.gov/anon_dir/active/iacg/ELEMENTS/ are used as the initial data for the SC positions calculation http://nssdca.gsfc.nasa.gov/anon_dir/active/iacg/ELEMENTS/ zIKI has fulfilled the long-term (up to October 2000) prediction of the SC constellation and has distributed it via WWW web site http://iki.cosmos.ru/vprokhor/camp2.htm http://iki.cosmos.ru/vprokhor/camp2.htm zSee as an example the selected list of the SC constellation for May 2000: http://iki.cosmos.ru/vprokhor/camp2/200005/list.htm http://iki.cosmos.ru/vprokhor/camp2/200005/list.htm 21

22. Summary zThe results of the mentioned analysis are used during the joint interagency investigations planning zThe list of the SC, criteria of the constellation and the models of the magnetosphere can be extended tacking into consideration new Missions and Campaigns zThis report was virtually presented on the IKI scientific seminar “Mechanics, Control and Informatics”. See electronic materials in the site: http://iki.cosmos.ru/seminar/e_virtual.htm http://iki.cosmos.ru/seminar/e_virtual.htm 22

23. Acknowledgements 23 Authors are grateful to Lev Zelenyi and Sergey Savin for the fruitful discussion of the goals and criteria for the SC constellation selection.