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Of course, the latter question cannot be answered without the former: our first task is to estimate likely time delay measurement accuracy. The goal of this work is to enable that via a ``Time Delay Challenge'' (TDC) to the community. Independent, blind analysis of plausibly realistic LSST-like lightcurves will allow the accuracy of current time series analysis algorithms to be assessed, and also allow us to make simple cosmographic forecasts for the anticipated LSST dataset. This work can be seen as a first step towards a full understanding of all systematic uncertainties present in the LSST lens dataset, but it could also provide valuable insight into the survey strategy needs of a Stage IV time delay lens cosmography program.   In We start in \S \ref{sec:motivation} by defining two figures of merit that capture, approximately, the cosmological precision and accuracy implied by a set of time delay estimates and that will be used to assess the performance of teams that accept the time delay challenge. Then, in  \S \ref{sec:light_curves} we describe the simulated data that we have generated for the challenge, including some of the broad details of observational and physical effects that may make extracting accurate time delays difficult, without giving away information that will not observationally knowable during or after the LSST survey. In \S \ref{sec:structure} we describe the structure of the challenge, how interested groups can access the mock light curves, and the ensemble average time delay distance accuracy criterion that we will use to assess their perfomance.