PARASOL and CALIPSO: Experience Feedback on Operations of Micro and Small Satellites

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PARASOL and CALIPSO  Experience Feedback on
Operations of Micro and Small Satellites

• Fabienne Serène and Nathalie Corcoral
• CNES
• Centre Spatial de Toulouse
• 18 avenue E. Belin
• 31401 Toulouse cedex 9 
• FRANCE

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SUMMARY

• Introduction
• Operations description
• Ground segments
• Operation management and associated manpower
• Experience feedback
• The future

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INTRODUCTION the missions

• PARASOL is the 2nd microsatellite in the CNES
  MYRIADE series .- Carrying a wide-field imaging
  radiometer/polarimeter called POLDER designed to
  improve our knowledge of the radiative and
  microphysical properties of clouds and
  aerosols.- Launched the 18th of December 2004
  by an Ariane 5 G from Europes spaceport in
  Kourou, French Guiana, in-orbit for 18 monthes.

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INTRODUCTION the missions

• The CALIPSO 2nd small satellite in the PROTEUS
  series (NASA/CNES). - payload composed of one
  backscattering Lidar, main instrument equipped of
  a 1 meter telescope, a visible camera, and an
  infrared imager.Measurement of the vertical
  distributions of aerosols and clouds in the
  atmosphere, optical and physical properties of
  aerosols and clouds.- launched the 28th of
  April 2006 from Vandenberg with CLOUDSAT. SELV B
  Class (Delta2) launcher supplied by NASA.

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INTRODUCTION the A-TRAIN
Sun synchronous 705 km

• PARASOL and CALIPSO are flying in formation with
  AQUA, AURA (NASA) and CLOUDSAT (NASA/CSA) as part
  of the so-called A-TRAIN. These satellites, to
  be joined later by NASAs Orbiting Carbon
  Observatory (OCO) in 2008, for the first time
  ever combine a full suite of instruments for
  observing clouds and aerosols, from passive
  radiometers to active lidar and radar sounders.

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OPERATIONS linked to the A-TRAIN

• CALIPSO station keeping is obtained by following
  a reference grid with maintenance of the ground
  track at the equator .
• For PARASOL , the choice was to implement slavery
  on relative orbital position. Station keeping
  between a target (AQUA) and a chaser (PARASOL).
• In addition, CLOUDSAT and CALIPSO respect the
  formation flying rules, with CLOUDSAT slaved to
  CALIPSO, CLOUDSAT being located within CALIPSO
  control box limits.
• gt needs a close coordination between satellites
  teams - Daily ephemeris automatic exchanges
  between all satellites via a NASA dedicated
  server - regular teleconferences, annual
  meeting- The global surveillance of the A-TRAIN
  is insured by the CCS (Constellation Coordination
  System) at NASA Goddard Space Center in
  Washington.

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OPERATIONS linked to the A-TRAIN
? 21.5 s
? 21.5 s
PARASOL
AQUA
131s (8 deg)
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OPERATIONS linked to the A-TRAIN
CALIPSO

• This customized grid is shifted by 215 km East
  from the nominal WRS-2 grid.
• The World Reference System-2 Grid is usually
  defined at Descending node. However CALIPSO plans
  to maintain to a WRS-2 grid defined at the
  ascending node.
• A sample of the CALIPSO control grid is shown on
  the right.

WRS-2 Ascending node have been computed from 1st
descending node of 295.40 equivalent to 1st
Ascending 103.02
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OPERATIONS linked to the A-TRAIN

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Routine OPERATIONS

• PARASOL / CALIPSO routine operations consists
  in- programming the on board transmitter twice
  a week for PAR (switched-on before a pass, dump
  the HKTM during the pass and immediately
  switched-off after the pass, 7 days planned) and
  once a week for CAL (dump the HKTM during the
  pass, read the mass memory, transmitter never
  switched off, 7 days planned) - programming the
  guidance of the spacecraft and the SADM guidance
  twice a week for PAR (7 days planned each time)
  and every days for CAL (7 days planned each time)
  - programming the instruments once a week for
  PAR and CAL (7 or 8 days planned each time,
  images and PLTM dump), - refresh the on board
  UTC time once a week- regular DMU maneuvers
  (A-TRAIN)

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Routine OPERATIONS

• PARASOL typical operations consists in- For
  PAR modifying once a month the satellite attitude
  control (moon dazzling on SST, during 5 to 10
  days each month)- evaluating monthly the
  calibration needs for gyros, magnetometers, and
  checking the solar sensors status
• CALIPSO typical operations consists in-
  regular equipment expertises (health checking)
  and temporary spare equipment switching on -
  Payload managing during Sun eclipse by the Moon
  and randomly, Solar flares management, Hubble
  Space Telescope avoidance

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Routine OPERATIONS

• CALIPSO / PARASOL routine daily activities -
  Orbit determination computed every morning (
  satellites location within its A-TRAIN control
  box is calculated and checked, orbit comparison
  between AQUA, CLOUDSAT, CALIPSO and PARASOL )-
  After each pass, the platform telemetry is
  automatically monitored to check the satellite
  general status and archived on dedicated
  computers - After each pass, the payload TM is
  automatically recovered by dedicated computers.
  For PARASOL, mission scientific products
  generated daily (L0 and L1) at CNES and sent to
  the Scientific community (ICARE, Lille). For
  CALIPSO, the TM is sent to the MOCC (Mission
  Operation Control Center, in LaRC), the MOCC
  generates the L0 and L1 scientific products.
• ALL THESE ACTIVITIES ARE REALISED AUTOMATICALLY

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Routine OPERATIONS

• PARASOL / CALIPSO / other satellites common
  ground activitiesGround stations shared by
  the PROTEUS and MICROSAT missions, gt the
  passes planning is realised once a week, taking
  into account all on-orbit missions requirements.
  This is achieved partly by an automatic process,
  but it also requires to be modified by hand to
  take into account all exceptional satellites (ex.
  Maneuvers) or ground activities (ex. Ground
  station maintenance). Today, the passes
  planning , managed by a software called ARAMIS,
  takes into account three satellites, PARASOL,
  CALIPSO and DEMETER (the first MYRIADE satellite,
  in orbit since two years), and 5 ground stations.

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Routine OPERATIONS

• The task scheduling AGENDA - Operations
  Coordination Group meetings (OCG), hold once a
  week for each mission (previous operations
  summarized, next ops. planning, earth terminals
  reservations approval, Sequence Of Events
  approval).- After the OCG, all processes are
  programmed by an operator for the next 7 days,
  (using a task scheduler software called
  AGENDA) ?TC automatically generated, ?TM
  automatically stored, ?In case of anomaly
  during working hours of working days, an
  alarm is generated and the operator is
  automatically informed by phone.
• ? In case of anomaly during week-ends or days
  off, an alarm is generated and a
  24/7 manpower is automatically
  informed by phone.

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GROUND SEGMENTS

• MOGS Mission Operation Ground center For
  PARASOL, separated in two parts, one (L0 and L1)
  located in CNES Toulouse (including X Band
  station), and the other one called ICARE and
  located in Lille (Northern of France).For
  CALIPSO, a Mission Operation Control Center
  located in NASA Langley Research Center in
  Virginia, and a Payload Data Delivery System (X
  band station and Network).
• and SOGS Satellite Operation Ground CenterBoth
  PARASOL and CALIPSO SOGS are based in CNES
  Toulouse Space Center. This part of the Ground
  segment is used to operate the satellites,
  perform the monitoring and platform controls,
  orbit and attitude control, payload service and
  satellite expertise.

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GROUND SEGMENTS Satellites Operation Ground
Segment SOGS

• Similar SOGS for both satellites - Common
  network of S-Band Earth Terminals called TTCET
  for TM/TC link with the satellites, and which can
  download Doppler measurements for the orbit
  control (Kiruna Sueden, Aussaguel France) one
  or more CNES 2 Ghz stations which can be kitted
  to be adapted to the small and micro satellites
  ground constraints (Kiruna and Hartebeesthoek
  South Africa)- A X-Band station called TETX
  which is dedicated to the acquisition of high
  rate mission telemetry (located in CNES Toulouse
  Space center) - ARAMIS (used to plan passes for
  all in-orbit PROTEUS and MYRIADE satellites)-
  Dedicated Satellites Control Centers (SOCC), one
  / satellite familly,- A common archiving system,
  a common configuration management system, and a
  common Data Transmission Network (provides the
  connexion between the stations and the SOCC, the
  stations and the Mission Centers (MOCC), the SOCC
  and the MOCC. Architecture relies on the
  multi-missions resources at CNES

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GROUND SEGMENTS Satellite Operation Control
Center

• SOCC (similar but different)- designed to
  support up to 7 on-orbit satellites belonging to
  5 different missions ( due to differences between
  satellites, not shared by PROTEUS and MYRIADE)
  - same architecture, based on the use of
  Personal Computers - TM/TC real time
  management, TM display using mimics, orbit and
  guidance management, TM monitoring and archiving,
  file transfer management- ground software
  shared between PROTEUS and MYRIADE (used with
  dedicated configurations), satellites data base
  management is specific to each family, as well as
  missions interface management is specific to each
  mission- Nominal, test and LEOP SOCC for each
  family.

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SEF
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OPERATION MANAGEMENT AND ASSOCIATED MANPOWER

• Operation team composed of a satellite
  responsible, a ground responsible, a flight
  dynamics engineer, the mission programming
  specialist and an operator for the routine
  monitoring, management insured by the mission
  operation manager. Sometimes, satellite experts
  and ground system experts. gt This organisation
  allows to work with a minimum manpower available
  only during working hours of working days.
• Alarm detection dedicated software called SYGALE
  phones automatically a 24/7 manpower . Some
  actions may be needed to put the satellite in a
  secure safe-hold mode, a first investigation is
  made to prepare the activities of the next
  working day. This is only possible thanks to
  these specific platforms which are designed to
  withstand a safe-hold mode of several days
  without damages.

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OPERATION MANAGEMENT AND ASSOCIATED MANPOWER

• Automatic mode for routine operations in nominal
  mode, routine operations can be foreseen and are
  performed automatically. Spacecrafts status are
  checked automatically by monitoring telemetry,
  and in case of non compliance, alarms are raised.
  Some specific red alarms may require a rapid
  intervention from the ground, even during days
  off.
• Other extra activities are always performed with
  manpower, for obvious safety reasons. Can be
  performed either during working hours or non
  working hours (nights, week-ends and days
  off).Case for launch phase, the begin of life
  activities, the rise up maneuvers
• Other unusual activities (e.g. On Board Computer
  new software upload, emergency maneuver) are
  planned, as possible, during working hours, and
  with a re-enforced team.

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EXPERIENCE FEEDBACK

• Since June 2004 7 satellites on-orbit, operated
  automatically. For one of them, the first
  telemetry has been received 20 hours after
  launch, the acquisition sequence being completely
  automatic.
• Operations are reduced to a minimum thanks to
  autonomous platforms and ground automatic
  processes.
• Number of passes reduced to a minimum.
• For MYRIADE, the safe mode robustness has been
  tested several times in orbit. Nevertheless, this
  way of functioning has an interest only if the
  operations needed to recover the nominal
  operating mode are reduced (which is not the case
  for PROTEUS satellites. For micro satellites,
  these operations can be managed in two days (
  with less than ten passes).

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EXPERIENCE FEEDBACK

• Operations preparation is less important on this
  kind of platforms since redundancy philosophy is
  reduced. This is not the case for the functional
  end-to-end tests which are under the satellite
  project team responsibility.
• Concerning the ground segment, the automation of
  daily sequences is a great success. However, the
  major difficulty was to obtain an actual routine
  mode, with fully operating automatic processes
  and minimum manpower (e.g. unexpected external
  noise (such as network problems) can easily
  disturb the whole system and by the way stop the
  process.
• Ground system is complex (great number of
  interfaces), needs to have a permanent capability
  of adaptability, development and expertise
  (permanent updating of software and computers).
  This functioning requires to have operators
  during working hours (even with automatic
  processes), for the global monitoring,

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EXPERIENCE FEEDBACK

• difficulty to implement an automatic process for
  the passes reservation. ARAMIS is not fully
  capable to insure the compliance with all mission
  needs. The first loop of reservation is
  automatic, but a manual verification is
  unavoidable.
• For the management of the whole activity, the
  Operation Coordination meeting (lt 1 h), hold once
  a week is in accordance to the need (also hold
  each time an unplanned and urgent activity has to
  be discussed).
• One major challenge short preparations phases,
  to enter rapidly into a routine mode with a fully
  performing system (mission lifetime from 1 to 3
  years, compared to telecom platforms). This is
  facilitated by the organization itself, since the
  satellite project team is shared between new
  satellites under development and satellite under
  exploitation, and since the operational team is
  involved in the very beginning of the project.

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CONCLUSION

• From 2007 to 2010, several others satellites
  should join the pool (COROT, SMOS and JASON2
  satellites belonging to the PROTEUS family and
  PICARD, MICROSCOPE, the four ELISA of micro
  satellites family).
• To be done - improve the tasks automation (In
  particular ARAMIS, the passes reservation loop),
  to take into account in the near future all these
  satellites. - unify the different CNES networks
  used for the data transmission between ground
  stations , SOCC and MOGS of satellites operated
  by CNES (improvement of the network supervision
  for micro and small satellites, especially during
  week-end and days off ) gt to increase the data
  availability during this period.

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CONCLUSION

• MYRIADE and PROTEUS satellites operation
  management is a great success.
• the scientific data availability is now greater
  than 95 for on orbit satellites.
• Scientific products are available to the
  scientific community the day after their
  generation in orbit.
• This shows that this kind of operation management
  of low cost satellite families can be fully
  compliant to scientific requirements.