Both, faster rotation and smaller length contribute to larger natural dampening factors. His findings can be summarized as a statement of vibration instability of any tether that is too long or rotating too slowly. In 1997, Vigneron proposed and experimentally verified the stability criteria for a rotating tether holding a payload.
In 1995, Tyc speculated that large flexible booms attached to the tether, OEDIPUS-A, acted as a surprisingly effective dampening mechanism because of their high-frequency, high-strain whipping oscillations induced by the oscillations of the tether. Even changes of tether temperature due to entering sunlight or shadow may result in vibration, which ultimately must be damped. Of course, aero-capture, as in, is the worst case, in terms of vibration excitation, but some vibration will be excited in the LEO bolo, as well, with each dip of the tether arm in the deeper layers of atmosphere. In 1995, Puig-Suari stated that, even after implementation of critical dampening, peak load due to tether vibrations exceeds steady-state load by 50%. Secondly, a damper should be used as most rigid materials themselves have very low internal mechanical energy dissipation.
Firstly, a material with low accumulation of elastic energy ( i.e., high rigidity) should be used for the tether. Therefore, two parametric measures should be taken. Such vibrations may easily result in tether straying from the correct capture or release point, or may even result in tether breakage. In 1996, Luo described an extreme wealth of rotating tether vibration types. The problem of rotating bolo (rotovator) stability has been extensively discussed by the research community. The author favors modern ion motors as near-term alternatives to momentum-neutral or MXER systems. Therefore, alternative engineering approaches to MXER should be considered first. In addition, a high degree of difficulty (III) in R&D is expected for many components.
But MXER is highly speculative research Sorensen, in 2003, lists several components of the MXER bolo as having a NASA TRL (technology readiness level) equal to 3 (only proof-of concept available), and two key technologies (tether coating and tether libration control) having a TRL equal to 2 (only technology concept was formulated). Even for sub-km/s delta-v offered by bolo configurations built with existing materials, a MXER (magnetic-exchange electrodynamic reboost) drive option still exists. An example of momentum-neutral tether design may be found in. Unfortunately, around the Earth, the only such body is the moon, and series of tethers able to handle at least 1.6 km/s tip speed are necessary for harnessing the orbital momentum of the moon rocks. The LEO bolo can even operate the propellant-free, extracting momentum necessary for orbital transfer from the momentum of bodies in higher orbits.
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