This answer to Would we have spotted the ascent stage of Apollo 11's Eagle if it was still in orbit around the Moon? and discussion under it suggests that as a check of the orbital propagation calculations for the Apollo 11 ascent stage which show it may have been in a survivable orbit, the author should have repeated their calculations for the PFS objects as a check on their methods.
note: PFS = Particles and Fields Subsatellite 1, 2
The calculation is described below. Here, I would like to ask:
Question: Are the initial conditions for the Apollo PFS objects' orbits known (or knowable) as well as they were for the Apollo 11 ascent module? Could these calculations have been repeated for them to verify this GMAT-based methodology?
From the paper in arXiv
The simulator used is the General Mission Analysis Tool (GMAT) which was developed by NASA and is freely available online (NASA, 2019). This environment has been certified by NASA for use in mission planning. GMAT allows for the substitution of gravity models, and can natively load and interpret GRAIL models, which are also freely available. Lunar gravity is modeled using spherical harmonics, and GRAIL models are available with harmonic degree and order as high as 1200. The simulations reported here used the “gggrx 1200a sha.tab” model. The computation required to propagate a simulation increases roughly as the square of the harmonic degree/order, and this places a practical limit on the fidelity of the model that can be used. Simulations described here were run with degree/order of the models set to 200, and in this case a simulation of ten years of spacecraft time completes in about 8 hours. Trial runs with degree and order as high as 1000 showed very similar results relative to “standard” runs at 200, suggesting that the major conclusions of this work would stand up even if significantly greater computation had been dedicated to the task. The simulation results also have been verified by a third party using a lunar orbit simulation tool that is completely independent of GMAT.
- arXiv: James Meador (2021) Long-term Orbit Stability of the Apollo 11 Eagle Lunar Module Ascent Stage abstract shown below update: Published and Open Access in Planetary and Space Science 205 (1) October 2021, 105304 Long-term orbit stability of the Apollo 11 “Eagle” Lunar Module Ascent Stage and potentially readable here
- Github: RogerTwank/Eagle details of calculation, linked to as (Meador, 2020) in the arXiv paper.