1. Flight Dynamics Michael Mesarch Frank Vaughn Marco Concha 08/19/99
MAXIM
Flight Dynamics
Michael Mesarch
Frank Vaughn
Marco Concha
08/19/99

2. Mission Assumptions Orbit Assumptions Maneuver Requirements
Two spacecraft (optics and detector) in near-circular Heliocentric orbit at 1 AU ( Drift-away orbit)
Launch in
Mission Lifetime: 3 years required
Maneuver Requirements
Desire to point to 150 inertial targets over 3 year mission lifetime
Separation along optical axis to be maintained at 450 km  10’s of meters
Misalignment perpendicular to optical axis  5 mm

3. MAXIM Range from Earth

4. MAXIM Trajectory in Solar Rotating Coordinates

5. Formation Flying Challenge
The MAXIM formation flying concept is new - combination of previous implementations with a wrinkle
Landsat-7 and EO-1 maintain a constant distance between each other in the same orbit while imaging the earth - image comparison is achieved because of close distance between s/c
Constellation-X utilizes multiple s/c to observe the same target without any restriction on relative position
MAXIM combines both constant separation and constant attitude/pointing. The detector s/c must ‘fly’ around the optics s/c continuously during an observation - its orbit will continually change. L7
EO1 d L2
Constellation-X d
Maxim

6. Stationkeeping and Pointing Control
Only simple cases have been considered :
Continuous viewing of Ecliptic Pole
Optics and detector S/C are in circular orbits which differ by a small inclination angle to achieve initial 450 km separation
Continuous acceleration of detector S/C away from optics S/C at  1.7x10-8 (m/s2) will cancel relative out-of-plane motion for short periods
Rotation to view opposite pole requires acceleration on the order of 4 degrees of magnitude higher
Long-term effects require additional analysis
Targets in Ecliptic plane
Optics and detector S/C are in circular co-planar orbits which differ in semi-major axis to achieve initial 450 km separation
Preliminary analysis indicates that maintaining 450 km separation is feasible in the short-term by canceling the initial velocity difference between the S/C, but this results in a larger separation in the long-term,( i.e, half an orbit later).
How to maintain pointing in this case is not clear - requires management of multiple orbital variables
Design of a pointing control strategy will not be a trivial undertaking

7. Ecliptic Pole Pointing - Uncontrolled
Optics
Detector

8. Ecliptic Pole Pointing - Controlled
Detector
Optics

9. Further Work
Perform more detailed analysis on the simple cases considered to be certain the dynamics is fully understood
Formulate a pointing control strategy
Determine control authority (acceleration,thrust) required to transition from one target to another in a ‘reasonable’ amount of time (days?)