  Rotational spin-up due to outgassing of comet nuclei has been identified as a
possible mechanism for considerable mass-loss and splitting. We report a search
for spin changes for three large Jupiter-family comets (JFCs): 14P/Wolf,
143P/Kowal-Mrkos, and 162P/Siding Spring. None of the three comets has
detectable period changes, and we set conservative upper limits of 4.2 (14P),
6.6 (143P) and 25 (162P) minutes per orbit. Comparing these results with all
eight other JFCs with measured rotational changes, we deduce that none of the
observed large JFCs experiences significant spin changes. This suggests that
large comet nuclei are less likely to undergo rotationally-driven splitting,
and therefore more likely to survive more perihelion passages than smaller
nuclei. We find supporting evidence for this hypothesis in the cumulative size
distributions of JFCs and dormant comets, as well as in recent numerical
studies of cometary orbital dynamics. We added 143P to the sample of 13 other
JFCs with known albedos and phase-function slopes. This sample shows a possible
correlation of increasing phase-function slopes for larger geometric albedos.
Partly based on findings from recent space missions to JFCs, we hypothesise
that this correlation corresponds to an evolutionary trend for JFCs. We propose
that newly activated JFCs have larger albedos and steeper phase functions,
which gradually decrease due to sublimation-driven erosion. If confirmed, this
could be used to analyse surface erosion from ground and to distinguish between
dormant comets and asteroids.
