# When will ISS return to approximately the same projected location on Earth's surface?

The ISS sailed over my country, Sri Lanka on the eve of yesterday (14th October), and there was some news coverage on the event. While the reporting wasn't particularly scientific or even factual (I'm still cringing because one of the news outlets called it the International Space Center), I was happy that such incidents gets a news coverage and possibly inspires kids for space exploration.

However, I was wondering if this incident was newsworthy, because I know for a fact that the ISS does around 15.5 orbits of 92 minutes a day. So I am thinking this shouldn't exactly be a rare occurrence, and the ISS should come back to approximately the same projected surface location on Earth pretty quickly (not exact location, but within ~250km on ground of the projected path of a previous orbit). However, I don't have the know-how to do the math.

What sort of time period does it take for the ISS to come close to a previous orbit, such that the distance between projections of the two orbits are within ~250km on the ground?

• Do you think that the answer to How long does it take for ISS to travel over all possible places of the world one time? addresses your question, or are you asking something different? – uhoh Oct 15 '19 at 6:20
• @uhoh That question is intriguing. But I'm not sure I got a good answer there. Not sure how to process the information in those answers. – sampathsris Oct 15 '19 at 6:24
• Okay, I'll write a better, more focused answer to this question, so that this one should not be considered a duplicate. – uhoh Oct 15 '19 at 6:25
• Huh,. Closer to the latitude of the ISS's orbital inclination , visible passes are more frequent. I live at about 41° north, and the ISS makes multiple visible passes most days of the year, with intermissions of a few weeks when it switches from morning to evening or back. – notovny Oct 15 '19 at 22:09