Conclusions

1
Conclusions Questions Power

• Platform will provide AMS one 28VDC bus, current
  lt100A, in-rush current lt5mA/msec.
• CAST will provide detailed specs of 28VDC power
  supply.
• AMS (Giovanni) will discuss these specs with
  CAEN.
• AMS (Mike) will
• develop clear understanding of AMS power
  requirements
• Before T-3 weeks in test area
• T-3 weeks to T-1 hour
• T-1 hour to T-2 min
• T0 to L900sec
• L900sec to L2orbits
• After L2orbits (stable, nominal operation)
• 28V vent pump?
• 28V to 120V DC-DC converter 600W for CC
• 28V for CAB/CCS study 2 years, 2 Me
• AMS (Mike Marco) will try to operate flight
  vent valve from AMS UPS.
• AMS (Mike) will describe the power interfaces
• AMS to platform,
• AMS to EGSE
• AMS umbilical to PAD

2
Conclusion Questions Telecommanding

• Commanding from China only, via Ground Station in
  Xian.
• Windows for 31 degree orbit typically 7min, 6
  passes/day (1 orbit 94.6 minutes)
• Uplink capability 2000 bits/sec
• This would require large rework of anticipated
  AMS flight procedures because AMS design
  considered almost always have telecommand and
  telemetry (duty cycles greater than 70).
• Platform ALWAYS has priority for commanding
• At beginning, until AOCS stable, platform needs
  most of commanding capability.
• Once platform is stabilized, AMS requires the
  possibility for maximum commanding bandwidth and
  availability consistent with platform
  maintenance.
• AMS will receive commands over 1553B from OBDH
  uplink inject data.
• The platform uses transformer coupled stubs (the
  same as AMS).
• Commanding AMS Frame is 64 Bytes.
• Ground formatting and RT addressing TBD.
• AMS will use a single command type from CAST
  point of view (fixed headers, variable contents),
  as foreseen with NASA.
• AMS will have 4 RT addresses 4, 7, 13, 28.
• AMS will modify two JIM-AMSW1553 boards (add
  some DDC chips).
• AMS needs time broadcast. Accuracy of time
  delivery to be understood.
• Dont forget about pad umbilical (it seems we can
  use flight TC/TM path, TBC).

3
Conclusion Questions Telemetry (Eng. Data)

• Eng. Data requested by OBDH from AMS over 1553
  and downlinked continuously. Received whenever
  passing over ground stations.
• Plan to also record complete stream (AMS
  platform Eng. Data) in DDR and playback/downlink
  via high rate system.
• Very preliminary set of ground stations
• Guangzhou (22 deg ?)
• Maspalomas (28 deg)
• Malindi (-3 deg)
• Coverage Orbits/day and duration TBD by CAST
  from STK database.
• Expect few minutes for several orbits each day,
  each station.
• Total of 2 hours/day TBC.
• Bandwidth 4096 bits/sec Priority for platform
• Platform requirements during nominal operations
  (after stabilization, etc) 1536bit/s
• Rest (2560bits/sec) for AMS.
• AMS data would be split into two streams with
  different RT SubAddresses
• High Priority Stream
• 32 Bytes messages (TBC)
• No CCSDS formatting
• Will be down linked continuously (as mission
  critical data)
• Low Priority Stream
• Format to be worked out

4
Conclusions Questions High Rate Data

• DDR capacity of 180 Gbits is OK.
• Proposed design of platform downstream from DDR
  looks OK
• QPSK,
• X-band at 8.3 GHz,
• 150 Mbps downlink
• However as AMS can output at rates gtgt 2Mbps, AMS
  requests CAST to examine
• higher rate input to DDR (for example, up to 80
  Mbps).
• non-constant data rates from AMS (for example 0
  or 80 Mbps).
• Synchronization of AMS and DDR will need to be
  worked out.
• Physical layer (TTL, LVDS, PECL, etc) to be
  worked out depending on maximum data rate.
• Add bypass mode to directly transmit live AMS
  data in real time.
• AMS will investigate the possibility to gain
  access to multiple X-Band ground stations, as for
  low rate data
• Guangzhou (22 deg ?), 11meter ?
• Maspalomas, Canary Islands, Atlantic Ocean (28
  deg), 11m ?
• Malindi, Kenya, Africa (-3 deg), 10m or 6.5m ?
• Coverage Orbits/day and duration TBD by CAST
  from STK database
• Expect again, few minutes for several orbits
  each day, each station
• Total of 1 hours/day/station TBC.
• Data format to be worked out. Right now AMS
  outputs CCSDS packets of length 4080 bytes.

5
Conclusions Questions Ground Stations

• Until further definition of low rate and high
  rate systems is available, it is too soon to
  discuss ground station interfaces.

6
Conclusions Questions AOCS

• Presentation was based on 31 degree orbit and
  27200 Am2, both of these are likely to be revised
  (see other notes).
• Prof Ting requested that CAST (via a request to
  CALT) provide a table of possible total payload
  weight (platform plus experiment) versus orbital
  inclination for CZ-3B launch to 500km circular
  orbit for possible inclinations.
• More precise moments-of-inertia of AMS should be
  provided by AMS (R.Becker)
• AMS agrees to CAST request that dipole moment
  will be aligned to lt 1 degree to be confirmed
  by magnet group.
• CAST to study what happens when
• magnet gets turned on (field increases linearly
  over 2 hours),
• turned off (field decrease linearly over 2 hours)
  
• during Quench (magnetic field disappears in 45
  sec) ?
• AMS Systems which exhaust under nominal operation
  - TRD Gas system and Magnet He have zero thrust
  vents.
• Over three years AMS will lose linearly 360 kg of
  He (symmetric about c.o.g.) and 30kg of Xe/CO2
  from TRD gas tanks. AMS can provide these
  changes as they occur.
• Off nominal venting is through burst disks not
  through zero thrust vents more data later from
  AMS.
• CAST requests to mount solar sensor (small box)
  on top of AMS OK.
• CAST requests access to AMS GPS and AST star
  tracker data in flight format to be determined.
• Does AMS need attitude data from the platform ?
  To be studied by AMS.
• CAST to determine fuel consumption in emergency
  mode AOCS
• It may be better to ramp down magnet during
  emergency mode to save fuel.
• Request report from CAST with sketches of all
  coordinate systems mentioned in presentation
• AMS zenith pointing requirement is maximum of 45
  degrees, as AMS field-of-view is 45 degrees half
  opening angle. Physics impact of zenith pointing
  at 45 degrees to be studied by AMS. Failure to
  meet this requirement has to be assessed as well.
  AMS needs better data (longer term) on fraction
  of time proposed solution meets this requirement.

7
Questions and conclusions Structures

• Pictures of new idea from R.Becker delivered.
• CAST to provide preliminary .stp file by 10 Jan
  06.
• FEM in .op4 format of payload will be available 9
  Jan 06 from Jacobs (B.Summer) by e-mail to Ding
  Xiaobo. AMS (R.Becker) will translate to .bdf
  and put both .op4 and .bdf versions on ftp site
  and send CD by express mail.
• Model
• Without crates/radiators
• Without AMS to platform support structure
• Includes EHV, RHV, E-Crates and lower USS
  diagonals and lower USS centerbody to support
  RICH and ECAL.
• CAST will add lumped masses for crates/radiators
  (mass to be provided by R.Becker 14 Jan 06) for
  each of 8 attachment points and AMS support
  structure based on inputs from R.Becker 14 Jan 06
  (first guess on beam cross-section and weight).
  Estimated first results 14 Feb 06.
• AMS magnetic dipole moment direction will be
  parallel to solar array axis x(AMS) y(B of
  AMSS), z(AMS) - z(B of AMSS).
• Weight of payload is currently estimated to be
  6537 kg according to table of Kounine
  (0107_weight_amss.pdf) (following instructions
  from Prof.Ting only A.Kounine will provide this
  number and updates to this number). In this
  figure there are big uncertainties associated
  with Magnet, Electronics, TCS and AMS-Structure
  subsystems. AMS will work on more precise weight
  estimate. CAST requests this weight be reduced to
  6300kg to reach 30 deg circular orbit at 500km.