1. Maxim Pathfinder Prework 16 August 1999

2. Maxim Pathfinder Prework Topics
General
Orbit and Pointing
Data Acquisition Concepts
Operations Concepts
Suggestions for Study
Work Style this Week

3. 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 <
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

4. 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
Optics
Det
Line of sight
Optics
Det
Line of sight
Optics
Det
Line of sight
Optics
Det
Line of sight
Optics
Det
Line of sight

5. 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

6. 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.

7. 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.

8. 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.

9. 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 9:30 to synchronize everybody for the day
Informal splinter meetings of affected parties