Simulations of triple microlensing events I: detectability of a scaled Sun-Jupiter-Saturn system

Up to date, only 13 firmly established triple microlensing events have been discovered, so the occurrence rates of microlensing two-planet systems and planets in binary systems are still uncertain. With the upcoming space-based microlensing surveys, hundreds of triple microlensing events will be detected. To provide clues for future observations and statistical analyses, we initiate a project to investigate the detectability of triple-lens systems with different configurations and observational set-ups. As the first step, in this work we develop the simulation software and investigate the detectability of a scaled Sun-Jupiter-Saturn system with the recently proposed telescope for microlensing observationson the 'Earth 2.0 (ET)' satellite. With the same Delta chi(2) thresholds of detecting a single planet and two planets, we find that the detectability of the scaled Sun-Jupiter-Saturn analogue is about 1 percent and the presence of the Jovian planet suppresses the detectability of the Saturn-like planet by similar to 13 percent regardless of the adopted detection Delta chi(2) threshold. This suppression probability could be at the same level as the Poisson noise of future space-based statistical samples of triple-lenses, so it is inappropriate to treat each planet separately during detection efficiency calculations.