Maxim Pathfinder

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Maxim Pathfinder

• Maxim Pathfinder Prework
• 16 August 1999

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Maxim Pathfinder Prework Topics

• General
• Orbit and Pointing
• Data Acquisition Concepts
• Operations Concepts
• Suggestions for Study
• Work Style this Week

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General

• Maxim Pathfinder is an X-ray telescope, preparing
  for a larger X-ray telescope - the real Maxim
• Chandra and Constellation-X are precursors to
  Maxim
• NGST, LISA and SIM are missions, active or
  proposed, which will employ technology applicable
  to Maxim ns/index.htm
• Possible new start mission in 8 to 12 years
• Primary payload on one or two launch rockets
  (probably 1)
• 3-year lifetime
• Very good (incredibly good?) pointing stability
• Formation flying required to keep optics
  spacecraft and detector spacecraft properly
  aligned
• See PathDesign2.doc (distributed Friday) for more
  info

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Orbit and Pointing

• Orbit parameters required
• Orbit which permits formation-flying two
  satellites 450km apart, looking perpendicular to
  the sun-satellite line
• Only very small disturbance parameters allowable
  during observations lasting up to 7 days

1. Assume the plane of this sheet is
perpendicular to the sun line. 2. Maxim can look
in any direction in the plane of this sheet 3.
Maxim can look out of the plane of this sheet by
only 10 4. Any celestial target can be viewed
within a period of 6 months
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Data Acquisition Concepts

• Observations may last several days, but data
  probably should be downlinked at intervals as the
  observation progresses
• Instrumentation on optics spacecraft will produce
  10kbps spacecraft engineering data
• Instrumentation on detector spacecraft will
  produce 10kbps spacecraft engineering data
• Recommend whether each spacecraft should downlink
  separately, or one should relay data from both
  satellites

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Operations Concepts

• Early orbit operations will require adjustment of
  the 64 flat mirrors. This implies either an
  onboard automated process or real-time ground
  interaction.
• Target acquisition also may be either automated
  onboard or accomplished with real-time ground
  interaction (potential trade study).
• Rapid slew from target to target is not required.

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Suggestions for Study

• Recommend the type of orbit or trajectory best
  suited to this mission.
• Compare the pros and cons of having independent
  data links from each satellite to ground vs.
  having one satellite collect all the data for
  both and relay that to the ground.
• Does each satellite have independent data storage
  or does that function get combined in one or the
  other of the satellites.
• Determine the best means of pointing the
  satellites and maintaining pointing during
  observations.
• Determine whether data should be stored and
  dumped at intervals or maintain continuous
  contact, and whether ground antennas should be
  shared with other missions or dedicated to this
  mission.
• Perform analysis of the thermal problems,
  recommend and size radiators and other cooling
  devices.

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More Suggestions for Study

• Recommend placement of spacecraft subsystems on
  both satellites, determining mass and momentum
  properties.
• Recommend a power subsystem for each satellite.
• Consider radiation precautions needed and
  recommend necessary protection.
• Recommend propulsion needed to achieve the
  mission orbit (once we determine what it should
  be) and recommend propulsion which may be needed
  if pointing and stabilization cannot be
  accomplished with wheels or other means.
• Analyze potential effects of solar wind and how
  that may affect pointing control of the
  satellites.
• Identify technology developments needed to enable
  accomplishing the mission. Identify the expected
  technology developments benefiting this mission
  starting 10 years in the future.

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Work Style this Week

• Emphasize a collaborative approach
• Many of the parameters the DET needs (mass, size,
  power) will require a negotiated agreement
  between affected parties
• Maxim team and DET personnel need frequent
  interaction
• Scorecard of agreed parameters for reference by
  all
• Morning meeting each day at 930 to synchronize
  everybody for the day
• Informal splinter meetings of affected parties