Lunar Case 9a: Polar Orbit - Sensor Position B
Scenario 9a tests Keplerian propagation of the Apollo LM model in a low-fidelity 8x8 GRAIL gravity field with Sun and Earth perturbations. A sensor is included in this scenario that provides additional sensed states at a position offset from the center of mass specified below.
Constants and models
The gravitational constant is defined from the GRAIL model specified in the table below. The ephemerides are: DE440. Time is expressed in UTC. Although test case initial conditions may be in the future, the following constants are used: TAI − UTC = 37 sec; DUT1 = 0.0 sec Low-Fidelity GRAIL uses the GRAIL gravity model of degree and order 8 (i.e. 8x8 GRAIL).
Initial Conditions
| Scenario | Lunar Case 9a: Polar Orbit - Sensor Position B | |||
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| Body | Apollo Model | |||
| Orientation | Major axis is approximately along the velocity vector quaternionWrtMi = [0.137636538714161 -0.722405126130431 0.66454559455915 0.132537427556468] Where the components are ordered [W X Y Z]' |
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| Rotation | [0, -0.05008, 0] deg/s To be specified in inertial frame. Body angular rate w.r.t. MI expressed in body |
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| Sensor Position | Position B Body Coordinates = [0.5, 1.0, -2.0] m |
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| Gravitation | Low-Fidelity GRAIL | Gravity Gradient Effects | Off | |
| Sun/Earth Perturbations | On | Duration | 28,800 s | |
| Output Interval | 60 s | Output Format | CSV | |
| Initial states | ||||
| Time | 2026-1-28 6:42:03.51 UTC corresponds to output j2000UtcTime_s J2000 epoch of January 1.5, 2000 = -2451545.0 days Using 37 leap seconds j2000TtTime_s = j2000UtcTime + 32.184 + 37 = j2000UtcTime + 69.184 (s) Note that delta UT1/UTC is not relevant for checkcase and is thus not specified |
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| Frame | Planet-Centered Inertial | |||
| Position (m) |
miPosition_m_X miPosition_m_Y miPosition_m_Z |
16399.51954901463 -696336.1908584647 1722730.536496220 |
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| Velocity (m/s) |
miVelocity_m_s_X miVelocity_m_s_Y miVelocity_m_s_Z |
132.0661535881654 -1500.512866792463 -607.7719139949826 |
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Latest Results
Posted :
| Sim | Raw Data Link |
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Interactive Plots
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Note: pp_euler variables are Euler angles automatically calculated from sim provided quaternions.
A link to the conversion used can be accessed from the References menu in the navigation bar.
Note: All quaternions are modified to be scalar positive.
Note: pp_miPositionOfSensorWrtCm_m_X/Y/Z are post-processed variables calculated by
differencing miSensedPositionOfSensor_m_X/Y/Z with miPosition_m_X/Y/Z .
Load Data
A CSV file matching the format of the files found in the "Latest Results" table can be loaded from the input below to compare to the results from the Lunar Check Case study, this is a temporary load in your browser only.