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2. Do pointing and mapping trades to determine preliminary navigation (position) accuracy requirements

What payload functions will the navigation data be used for?

Payload data processing (mapping) Payload pointing

Sec. 5.4

3. Determine whether orbit control or maintenance is needed

Geosynchronous stationkeeping Constellation stationkeeping Altitude maintenance Maintaining orbit elements Mid-course corrections

Chap. 7, Sea 11.7.3

4. If yes, do trade on autonomous vs. ground-based orbit control

Is reduced operations cost and risk worth introducing a nontraditional approach?

Sees. 2.12, 11.7.1, 11.7.3

5. Determine where navigation data Is needed

Is it needed only at ground station for mission planning and data evaluation? Is it needed on board (orbit maintenance, Sun vector determination, payload pointing, target selection)? Is navigation (or target location) data needed by several end users who may get information directly from the spacecraft?

Sec. 2.1.1

6. Do autonomous vs. ground-based navigation trade

Does reduced operations cost and risk justify a nontraditional approach? Is there a need for real-time navigation ' data?

Sees. 2.1.1, 11.7.1

7. Select navigation method

See Sec. 11.7.2 for main options

Sec. 11.7.2

8. Define G&N system requirements

Top-level requirements should be in terms of what is needed (mapping, pointing, constellation maintenance, level of autonomy), not how the mission is done

Sees.

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