“Gaps” are defined as time during which science observations are suspended while other spacecraft operations are performed.

R-SCI-400       During nominal science operations, gaps shall represent less than 7% of the total observing time per target during one year.

It is desirable that gaps represent less than 5% of the total observing time per target during one month.

The probability that N successive transits of the same planet are observed is given by p_N= d_f^N, where d_fis the fractional duty cycle of the instrument. In order to achieve an 80% probability that all transits of a three transit sequence are observed, a duty cycle of 93% is needed. The requirement for planet-finding is therefore that gaps do not occur over more than 7% of the time in one year, with a loss by gaps as small as 5% in one month being desirable.

R-SCI-410       The amplitude of the first side lobe of the power spectrum response function of the observation time series shall be less than 1% of the main peak. This first side lobe shall be separated by at least 70 mHz from that main peak.

Periodic gaps produce aliases (1st order side lobes) around the peaks of interest for asteroseismology analysis.

This requirement is imposed for asteroseismology. Gaps in the data produce side lobes in the power spectrum, which make oscillation mode identification ambiguous. Periodic gaps in the data must be minimised, as they will produce the most severe side lobes in the power spectra.

 

References

PLATO – Revealing habitable worlds around solar-like stars
Definition Study Report, ESA-SCI(2017)1, April 2017