GAIA

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GAIA Programme Technology Activities by O.Pa
ce GAIA Study Manager ESA-D/SCI-PF
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GAIA-General Schedule (Launch mid-2011)
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GAIA-General Schedule (Launch mid-2010)
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GAIA Technology Activities (1/2)

• Payload related activities
• optimum compression algorithm (3rd Q 2002)
• payload data handling electronics (1st Q 2002)
• CCD and FPA technology demonstrators (3rd Q
  2001)
• validation of CCD performance (completed)
• database architecture (ongoing)
• large Size SiC mirrors (1.7mx0.7m) (1st Q 2002)
• laser metrology and optics active control
  (back-up) (3rd Q 2002)
• high-stability optical benches (basic angle
  verification) (2nd Q 01)
• ultra-stable large size SiC structure for PL
  optical bench (2d Q 02)

Starting Dates
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GAIA Technology Activities (2/2)

• Spacecraft related activities
• ground verification/calibration (1st Q 2002)
• large size deployable solar array/sunshield
  assembly
• (1st Q 2002)
• phased array antenna (2nd Q 2001)

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GAIA- Technology Activities Schedule
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Brief Activities Description
Payload Related
Activities (1/9) 1) G16 Optimum Compression
Algorithm Objectives to identify and
validate losses or quasi losses compression
algorithms to be applied on-board and in real
time to reduce as much as possible the GAIA
An efficient on-board data compression, taking
advantage of the advanced processing
technologies, could allow not only the
transmission of higher data rate, but will also
make more viable the spacecraft design,
alleviating critical design constraints on-board
as well on the ground, with reduction of the
overall cost This activity should first
identify, study and develop the most suitable
algorithm, then implement the algorithm within
the GAIA payload environment, with trade-off on
hardware/software.
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Payload Related Activities (2/9)
2) G21 Payload Data Handling Electronics
Objectives - to design an overall
implementation architecture, with minimum
representative bread-boarding, for the PDHE to
coop with the driving critical parameters, i.e.
2x250, 2D arrays and 2x300 video chains, 16 bit
resolution at a few Mbps, to work simultaneously
- to discriminate in real time the star signal
(50 e-) from the background signal - to
drastically reduce (data link limitation) FPA
data rate (2x300 flows at few Mbps
individually) - to control and
minimise power dissipation of FEE at FPA level,
to avoid thermo-elastic distortion to optics
- to multiplex and store data
on-board between transmission windows
(300 Gbits).
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Payload Related Activities (3/9)
3) G 01/05 CCD and Focal Plane Technology
Demonstrators Activities included
- Focal Plane Accommodation -
GAIA CCD Development - Front-end
Electronics Main objectives - Develop
and characterize scientifically fully
representative CCD samples demonstrate
the achievement of electro-optical performance
levels required for each GAIA instrument
(ASTRO, RVS and MBP). - Develop
representative Engineering and Qualification
Models (EQMs) of the focal plane
assemblies (complete FPAs including detectors
and read-out electronics) for each of the
three different GAIA instruments. - Validate
the above complete FPA design by performing
end-to-end system tests. Furthermore, the EQMs
are to be conceived in such a way as to allow
the Agency to carry out actual astronomical
measurements with the delivered FPAs at a
ground-based observatory. - Establish
validate space-worthy manufacturing processes for
all the concerned components/assemblie
s to demonstrate the technical and
production feasibility of complete GAIA flight
FPAs.
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Payload Related Activities (4/9)

• 4) G25 Validation of CCD Performance (completed)
• Objectives
• To validate, through testing on representative
  bread-boards, at least
• the following main critical topics of the 9
  ?pixel CCDs performances
• the feasibility of small pixel size with
  required electro-optical
• performances
• the accuracy of centroiding which can be
  achieved using thinned backside CCD
• the efficiency of TDI mode of operation for very
  faint target stars and its impact on centroiding
• the demonstration of windowing mode operation for
  the serial register and for output stage.
• The study has been just completed successfully
  and have confirmed the validity of the GAIA
  design assumptions.

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Payload Related Activities (5/9)

• 5) G24 Data Base Architecture (ongoing)
• Objectives
• Study and design a suitable data base
  architecture to temporary
• store, archive, and process the satellite
  retrieved stellar data.
• As a complementary goal, to produce a physical
  design
• (machine, etc.) for a data analysis system,
  which could handle the
• real satellite data.
• Existing inputs (data model, prototype, and
  representative analysis tasks)
• are being used to refine the GAIA data model, and
  to develop
• an advanced prototype system with well documented
  core system,
• to be used for the final mission reductions.
• The running activity would require the
  implementation of large
• (Terabyte-size) data base together with the study
  of large-threaded
• distributed data processing.

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Payload Related Activities (6/9)

• 6) G9 Large Size SiC Mirrors (1.7mx0.7m) for
  the GAIA
• Instruments
• Objectives
• to validate the polishing technology of large,
  off-axis, strongly
• aspherical surface
• to validate the mirror mounting (stability,
  impact on WFE)
• to validate the polishing on representative SiC
  off-axis surface,
• smaller than the real one, but presenting
  all the characteristics
• (slope, offset) critical for polishing
  technology
• Furthermore, the mirror shall be
  representative from the
• physical characteristics point of view, to
  allow final test while
• mounted on the optical bench sample
• to validate the mounting concept on a
  representative spherical
• mirror under representative environmental
  conditions.

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Payload Related Activities (7/9)

• 7) G14 Laser Metrology and Optics Active Control
  (back-up)
• This concept of the optics active control has
  been developed, together
• with an interferometer approach with beam
  combiner, by Alenia Space,
• in alternative of the passive solution,
  developed by Astrium and assumed
• as baseline for GAIA. The activity is kept as
  back-up of the passive concept.
• Objectives
• Design, implement, validate, and space qualify
  the
• ultra-high resolution laser metrology system,
  to be used in active
• control loop for the stabilisation of the
  GAIA optical configuration
• (including the basic angle control), and to
  support the interferometer
• co-phasing (optical path absolute
  measurement)
• ultra-high resolution tip-tilt mechanism, to be
  used for the co-phasing
• and rigid motion control of the astrometric
  instrument mirrors
• (few picometers).

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Payload Related Activities (8/9)

• 8) G26 High-Stability Optical Benches (basic
  angle verification)
• Follow-on of the contract with Astrium-TPD, of
  the preliminary
• bread-boarding and test-bed activity for the
  Basic Angle measurements
• device. The contract results have
  proven the feasibility to
• measure fringe pattern with
  accuracy of in the order of
• 10 picometers, corresponding to a
  Basic Angle variation
• of few micro-arcseconds.
• Objectives of the follow-on
  activity
• assess the optical system technologies and
  materials suitable
• for achieving the stabilities required by the
  measurement
• system for the GAIA basic Angle
• design, develop, and test a representative
  scaled GAIA optical
• bench (torus plus angle measurement bars) for
  demonstrating
• picometer stability over periods of up to 3
  hours.

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Payload Related Activities (9/9)

• 9) G10 Ultra-Stable Large Size SiC Structure for
  PL Optical Bench
• Objectives
• to select and validate the manufacturing
  technology for the
• elementary struts to form a torus sustaining
  the GAIA optical
• bench (4.25 m diameter)
• to select and validate an assembly technology for
  the elementary struts, compatible with the loads,
  sustained and transmitted by the optical bench,
  with a very tight stability and stress
  requirements
• to manufacture a representative optical bench
  sample, to be tested
• (thermal distortion) under GAIA environmental
  conditions combined
• with the mirror sample, developed and
  delivered by the contractor of
• technology activity G09, large Size Mirrors
  (1.7x0.7m) for the GAIA
• Instruments.

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Spacecraft Related Activities (1/5)

• 10) G22 Ground Verification/Calibration
• Objectives
• to identify and detail a ground
  verification/calibration approach for
• the GAIA payload, which minimises the effort
  and resources (in terms
• of time, manpower effort, ground support
  equipment, ground facilities)
• while demonstrating with a sufficient level of
  confidence the capability
• of the payload to meet its performance in
  orbit
• to establish a calibration plan, including all
  the calibration activities
• on-ground and in-orbit
• If would happen that a given calibration
  approach is proven not to be
• implementable on-ground, an alternative
  in-orbit calibration
• procedure/method shall be identified together
  with the impact on
• the payload design, if any.

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Spacecraft Related Activities (2/5)

• 11) G11 Large Size Deployable Solar
  Array/Sunshield Assembly
• Objectives
• to study and select candidate technology (solar
  cells, rotary joints)
• by taking into account also mass reduction of
  the assembly
• (9.5 m diameter, 130 kg mass)
• to trade-off design based on distributed type
  of cell technology
• (e.g. thin film cell) and design based on the
  results of the GAIA
• Concept and Technology Study (i.e GaAs cells)
• Trade-off criteria must include also
  technology maturity, mass reduction,
• availability of material in Europe, and cost
• to demonstrate the feasibility of a large size,
  deployable solar array/
• sunshield assembly to be used for GAIA, by
  dedicated and
• representative bread- boarding activities
• to identify needs for (delta-)qualification(s)
  of elements of the
• proposed design, by performing adequate
  bread-boarding and testing
• activities (functional test, environmental
  test, mechanical test) to allow
• elements qualification, with the relevant cost
  estimation.

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Spacecraft Related Activities (3/5)

• 12) G12 Large Phased Array Antenna
• Follow-on of the contract with Alcatel High
  Gain Antenna for
• Interplanetary Missions, dedicated to study
  phased array
• design for Plank and GAIA.
• Objectives
• establish a design and demonstrate the
  feasibility of an
• electronically steering (3600 azimuth, 150
  elevation) phased
• array antenna, satisfying the GAIA needs (1.5
  Mkm distance,
• gain 18 dBi, 4 Mbps data rate, output power
  36 W, 3 dB
• TM recovery)
• The activity will be run in two phases
• design phase, with final design, development
  and verification plan
• for the assembly, and assessment of relevant
  costs
• development, with demonstration of feasibility
  of the equipment
• by bread-boarding and test activities on
  critical functions/
• components, identified during the previous
  phase.

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Spacecraft Related Activities (4/5)

• 13) G23 Inch Worm Mechanism
• Purpose of the mechanism is to insure optical
  quality in-orbit, by recovering
  optical misalignments, may be induced by launch
  effects, by means of a 5-DOF refocusing
  mechanism (two tilts and two translations),
  based on inch-worm piezo-actuators, working at
  low temperature (150- 200K), with dynamical
  range up to 200 micron and position accuracy
• Objectives
• detail design of the mechanism, with definition
  of the demonstrator
• concept to validate identified risk and open
  issues
• procure and characterise a single inch-worm
  actuator for the use with
• GAIA
• design and build a demonstrator of the
  mechanism (hexapod) including
• 6 inch-worms and a launch locking device
• perform environmental tests of the demonstrator.

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Spacecraft Related Activities (5/5)
14) G13 mN FEEP Full Qualification The GAIA
reaction control system assumes among other
things, a continuous thrust of mN FEEPs (Field
Emission Electrical Propulsion) to
control the satellite scanning law and attitude
for a mission lifetime of 5 years, extendible to
6 years. This solution was baselined to satisfy
the strict requirements on satellite pointing
accuracy, e.g. rotation rate stability
better than 0.001 /s, over a period of 3 hours
(Hipparcos performance was 1.5/s over 2
hours). Since the FEEP system required by GAIA
will be designed and qualified in the context of
the SMART-2 project, this activity will
concentrate on the qualification of a mN FEEP
for a continuous thrust of 6 years, by performing
the test in on-ground facilities.
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Conclusions

• The GAIA project schedule, allowing for a launch
  in
• mid-2011, can be easily modified for a launch
  in mid-2010
• All the Technology Development Activities
  (TDA),
• required to validate the GAIA system design
• approach, have been identified, described, and
  quoted
• The GAIA TDA Plan have been approved and
  inserted
• in the D/SCI Technology Plan for the years
  2000-2004,
• with an assigned budget
• The D/SCI TDA work and procurement plan has been
• approved by the ESA IPC (Industrial Policy
  Committee)
• at their 20 December 2000 session
• ESA is now working on the implementation of the
  TDA
• Plan for GAIA, planned to be completed by
  mid-2004.