About
About Revisit Time
A free calculator for a question the rest of the free web does not answer: what service can a constellation of a given size actually promise at a given latitude.
Why it exists
There are excellent satellite trackers. They answer where a spacecraft is now, and when it will next pass over you. There is also excellent professional software for coverage analysis, priced and specialised for engineers who already know the answer they are looking for.
Between the two sits a question that gets asked constantly and answered badly: if the fleet has this many satellites, at this altitude and inclination, what can be promised to a customer at this latitude, in worst-case outage and service minutes per day. That question comes up in business plans, investor conversations, regulatory submissions and sales meetings, usually long before anybody has an engineering team free to model it. This site answers it in the units those conversations use.
What it is not
- Not affiliated with, endorsed by, or sourced from any satellite operator, manufacturer or agency. No operator data is used. Scenario configurations are illustrative, and the constellation shape pages use publicly documented shell parameters flown as idealised geometry. A shape is not a fleet: naming one after an operator identifies a published pattern, not that operator's actual constellation or service.
- Not a replacement for full-fidelity analysis. The model is geometric, and the method page lists exactly what it leaves out.
- Not a data collector. There is no account, no tracking, no analytics and no server-side computation. Every number is calculated in your browser, and nothing you type is transmitted anywhere. See privacy.
How it works
The site is a static build. One physics module produces every figure: the validation harness that runs before each release, the numbers written into the scenario pages when they are built, and the live calculation in your browser when you move a control. There is no possibility of the article text and the tool disagreeing, because the article text is generated from the tool.
Configurations are shareable. Every control is written into the address bar, so any result can be sent as a link and reopened exactly as you left it.
Corrections
The model is deliberately simple and its assumptions are stated in full on the method page, including the cases where it will surprise you. If a result there looks wrong, the fastest way to check is to reproduce the case in GMAT or Orekit and compare against the stated assumptions rather than the intuition.