1. Cluster special operations in support of SWARM
A. Masson, P. Escoubet, R. Haagmans, M. Dunlop
Cluster deputy project scientist
European Space Astronomy Center (ESAC)

2. Outline Few words about the Cluster mission
Cluster-SWARM complementarity: brief historical perspective
On-going Cluster operations in support of SWARM
Future Cluster operations in support of SWARM ( )

3. 4 Cluster spacecraft, each with 11 instruments
Each spacecraft about 600 kg in mass (dry) carried 600kg in fuel)
71kg instrumentation.
1996 saw failed launch of Cluster, but mission was sucessfully resurected and the resussrected mission was laucnhed on July and august 2000.
1 ASPOC (K. Torkar, A)
Spacecraft potential control
2 CIS (I. Dandouras, F)
Ion composition (E<40 keV)
3 EDI (R. Torbert, USA)
(0.1<E<10 mV/m)
4 FGM (C. Carr, UK) Magnetic field
Fluxgate magnetometer (2x spacecraft)
5 PEACE (A. Fazakerley, UK) e-(E<30 keV)
6 RAPID (P. Daly, D)
High energy electrons and ions
(10<Eions<1500 keV/nuc, 20<Ee<400 keV)
7 DWP (M. Balikhin, UK) Wave processor
8 EFW (M. André, S) Double probe antenna E-Field
9 STAFF (P. Canu, F) Search coil & spectrum analyzer
10 WHISPER (J.-L. Rauch, F) Relaxation sounder
11 WBD (J. Pickett, USA), Electric field wave-forms

4. Magnetospheric regions observed by Cluster: dayside
Solar wind
Solar wind
Polar cusp
Auroral zone
Magnetopause

5. Dayside and nightside orbit

6. Scientific regions visited by Cluster: nightside

7. Example of bow shock crossing
Solar wind
Bow Shock

8. First full electric current measurement
Ampère’s law gives the current Jo = curl B Jo B B C1 C4 B B C2

9. Magnetosphere shaped by electric currents
[J. Green, 2000]

10. First instantaneous measurements of the ring current
C. Vallat, Ann. Geophys., 2005
Cluster/
IMAGE Jo
Current Jo = curl B C1 C2 C3 C4
IMAGE
Vallat et al., 2004
Vallat, C., et al., 2004
Brandt, P., et al., 2005

11. Extension (-> 2009): multi-scale
Solar wind

12. Extension (-> 2009): new regions dayside inc. AAR
Solar wind
Magnetopause:
subsolar point
Auroral zone:
Acceleration region
2001

13. New regions nightside: current disruption, AAR
Solar wind
2001
Low altitude cusp
Near Earth tail:
Current disruption

14. Cluster: what about now?
Still fit for the job?
- Is payload still ok?
- Are data used?
- Publications rate?

15. Payload Status May 2014 - Summary
C1 (FM5)
“Rumba” C2
“Salsa” C3
“Samba” C4
“Tango”
Thermal ions
(inc. composition)
HIA in magnet. mode (1hr/orbit)
Failed in 2000 (*)
Failed in 2009 (*)
CODIF fully operational
Electric field
1 gun failed
EEPROM failed
Fully operational
No use of gun beams
(avoiding interference with Whisper)
Only one gun used (<-> Whisper)
DC magnetic field
Thermal electrons
Energetic
electrons
Ions
Not working
Only heads 1 & 3
WEC
DWP
EFW
Probes 2 & 3 OK
Probes 2, 3, 4 OK
Probes 2 & 4 OK
Probes 1, 2, 3 OK 
STAFF
WBD
max. 10 min/hour
Whisper
= fully operational
Status: May/2014
(*) Telemetry areas from CIS/EDI are used by PEACE and RAPID
Instrument details are given in annex 1.
Not functioning since commissioning

16. User Statistics Cluster science archive 1800 registered users
+400 over the last two years
Active users ~ level.
Download volumes ~1-2 TB/month

17. Few words about Cluster

18. Few words about Cluster
180 publications/year
over the last 2 years

19. Cluster-Swarm collaboration
Swarm mission started in 2014 and nominal phase up to May 2018
Cluster-Swarm enhanced science:
How are the cusp, ring and tail currents coupled via field aligned currents to the ionosphere
What is the azimuthal characteristic of the ring current (asymmetry)?
Under which conditions ionosphere feedback (ion outflows, downward currents) is important to magnetosphere?
How are ultra low frequency (ULF) wave propagating to the ionosphere?

20. Cluster-Swarm: Cluster extension 2017-2018
Will operate Cluster during the full nominal mission of Swarm
Will double the number of conjunctions (Cluster-Swarm on same field line):
Dayside: 13 => 26 (polar cusp)
Nightside: 25 => 50 (substorms)
Local time differences between Swarm A/C and Swarm B will reach deg.
Measurement of current systems along wide longitudinal range
Polar cusp size in longitude and asymmetries
Cluster-Swarm conjunctions at different local times within a few hours

21. Cluster-Swarm 2015: polar cusp
=> Not too good conjunction in cusp
Cluster
04 Jan 2015

22. Cluster-Swarm 2017: polar cusp
good conjunction in cusp
Longitude coverage
06 Jan 2017
Cluster

23. Cluster-Swarm 2018: polar cusp
good conjunction in cusp
Cluster
05 Jan 2018

24. Cluster observations in the cusp
3 years of data
Three distinct boundaries
Size of a few RE
Size measured only meridionally
No information on size in longitude
From Lavraud et al., 2004

25. Cusp will be measured in longitude (local time)
2001
Zgsm
Zgsm
Ygsm
=> Size in longitude
=> Asymmetry dawn-dusk
Ygsm

26. Platform Status (3/3) - Solar Array Power
Perigee <11,000 km
2W degradation/year(*)
Observation since 2013:
The influence of radiation intensity and temperature are phase shifted by 90 deg
Radiation ~ cos(ωt)
Temperature ~ sin(ωt)
cos(ωt) sin(ωt) = ½ sin(2ωt)
(*) The forecast up to 2019 used extrapolated the data of the simulation made by D/TEC in 2012.
Their latest update, May 2014, was not considered because of large discrepancies with the observed telemetry.

27. Payload Status May 2014 - Summary
C1 (FM5)
“Rumba” C2
“Salsa” C3
“Samba” C4
“Tango”
ASPOC
Failed in 2000
End of operations
CIS
HIA in magnet. mode (1hr/orbit)
Failed in 2000 (*)
Failed in 2009 (*)
CODIF fully operational
EDI
1 gun failed
EEPROM failed
Fully operational
No use of gun beams
(avoiding interference with Whisper)
Only one gun used (<-> Whisper)
FGM
PEACE
RAPID
electrons
Ions
Not working
Only heads 1 & 3
WEC
DWP
EFW
Probes 2 & 3 OK
Probes 2, 3, 4 OK
Probes 2 & 4 OK
Probes 1, 2, 3 OK 
STAFF
WBD
max. 10 min/hour
Whisper
= fully operational
Status: May/2014
(*) Telemetry areas from CIS/EDI are used by PEACE and RAPID
Instrument details are given in annex 1.
Not functioning since commissioning

28. Payload – Forecast 2016/2018 Payload C1 (FM5) “Rumba” C2 “Salsa” C3
“Samba” C4
“Tango”
2016
2018
ASPOC
Failed in 2000
End of operations June 2008
CIS
HIA in Mag modes (1hr/orbit)
Failed in 11/2009
CODIF fully operational
No change expected
EDI
MCPs in highest level
FGM
PEACE
fully operational
HEEA low sensitivity
LEEA low sensitivity
HEEA v. low sensitivity
LEEA v. low sensitivity
<- 2018
RAPID
Probably OK
IES
IIMS
Failed 2007
Probably working Probably not working
Failed 2009
Probably working
Probably not working
 2018
WEC
DWP
EFW
Probe 2 & 3 OK
Probe 2 & 4 OK,
Probe 2 & 4 OK
Probe 1, 2, 3 OK 
STAFF
WBD (*)
Operations limited to
10 min/hour
Whisper
(*) In case of no NASA funding, Panska Ves station and BM2 can be used to acquire
WBD . More Instrument details in annex 1.
= fully operational

29. Cluster inter-spacecraft distances
Multi-scale constellations
GI operations completed
Auroral acceleration region
Inner magnetosphere
Largest inter-spacecraft distance achieved in 2012: km
Smallest distance achieved in 2013: 4 km